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2009.02.11 1 of 100 Course IIW: 141 - TIG WELDING OF STAINLESS STEEL This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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Page 1: stainless steel course modules - histproject.nohistproject.no/.../stainless_steel_course_modules_compressed(2).pdf · Stainless steel compared to unalloyed steel and aluminium alloys

2009.02.11 1 of 100

Course IIW: 141 - TIG WELDING OF STAINLESS STEEL

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

Page 2: stainless steel course modules - histproject.nohistproject.no/.../stainless_steel_course_modules_compressed(2).pdf · Stainless steel compared to unalloyed steel and aluminium alloys

2009.02.11 2 of 100

List of contentMODULE 1.......................................................................................................................................... 5

Activity Based Training .................................................................................................................. 5 Normative references ...................................................................................................................... 8

MODULE 2........................................................................................................................................ 12 Welding symbols according ISO 2553 (A6) ................................................................................. 12 Types of butt welds ....................................................................................................................... 13 Types of fillet welds ...................................................................................................................... 13 Supplementary symbols ................................................................................................................ 14 Joint preparation for butt welds, welded from one side ................................................................ 14 Joint preparation for T - joints, welded from one side ................................................................. 21 Role of inspection and quality control (B9) .................................................................................. 23 Introduction to ISO 3834 (B9) ...................................................................................................... 24 Summary comparison of ISO 3834, Parts 2, 3 and 4 .................................................................... 26 Stainless steel compared to unalloyed steel and aluminium alloys (PSS1) .................................. 30 Definition of stainless steel ........................................................................................................... 30 Identification of stainless steel ...................................................................................................... 30 The working environment of the fabrication shop, general hazards, dust, heavy and hot material, cables (A4) .................................................................................................................................... 33 Handling of stainless steel in the workshop and the use of tools for stainless steel (PSS2) ......... 36

MODULE 3........................................................................................................................................ 37 Personal protective equipment and clothing (A3)......................................................................... 37 Noise hazards (A3)........................................................................................................................ 40 Suitable cutting processes for different types of steel to achieve a suitable cutting surface (A8) 41 Flame cutting, Principle and parameters, cutting blowpipes, cutting machines, quality of cut surface ........................................................................................................................................... 42 Other cutting processes as: plasma, laser, mechanical cutting...................................................... 42 Safety precautions for cutting (PSS1) ........................................................................................... 44 Burns and fires, fire prevention, fire fighting (A3) ....................................................................... 44

MODULE 4........................................................................................................................................ 46 Welding procedures and instructions. ........................................................................................... 46 Methods for joint preparations in stainless steel (PSS2)............................................................... 50

MODULE 5........................................................................................................................................ 52 Principle of welding consumables and functions of each type of welding consumable (A5) ...... 52 Shelding gases, backing gases....................................................................................................... 54 Selection of Welding Gas ............................................................................................................. 54 Classifications of welding consumables (A5) ............................................................................... 55 Storage drying and handling (A5) ................................................................................................ 57 Types of welds and joints, characteristics, size, surface finish (A6) ........................................... 57 141 - TIG and 15 - PAW............................................................................................................... 57 131/135 MIG/MAG...................................................................................................................... 58 136 - FCAW .................................................................................................................................. 58 121 SAW ....................................................................................................................................... 58

MODULE 6........................................................................................................................................ 60 Specific rules and regulations (A3) ............................................................................................... 60 Electric shock (A3)....................................................................................................................... 61 Steps to Prevent Electrical Shock ................................................................................................. 63 Emergency Procedures:................................................................................................................. 64 UV- and heat radiation (A3).......................................................................................................... 64

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

Page 3: stainless steel course modules - histproject.nohistproject.no/.../stainless_steel_course_modules_compressed(2).pdf · Stainless steel compared to unalloyed steel and aluminium alloys

2009.02.11 3 of 100

Eye hazards ................................................................................................................................... 66 Welding fumes .............................................................................................................................. 67 Hazardous substances.................................................................................................................... 70 Removal of hazardous welding dust ............................................................................................. 72 Detectable of internal imperfections of welds (B8) ...................................................................... 75

MODULE 7........................................................................................................................................ 78 Inspection and testing.................................................................................................................... 78 Survey of specific weld imperfections and their cause (B5)........................................................ 80 111 - SMAW troubleshooting ....................................................................................................... 80 141 - TIG welding ......................................................................................................................... 81 Problems and corrections .............................................................................................................. 81 131/135 MIG/MAG...................................................................................................................... 82 Weld Discontinuities ..................................................................................................................... 83 Flux Cored Arc Welding (136 - FCAW) Troubleshooting ........................................................... 86 111 - SMAW ................................................................................................................................ 88 Electroslag troubleshooting........................................................................................................... 89 Oxyfuel gas welding...................................................................................................................... 90

MODULE 8........................................................................................................................................ 92 Introduction to ISO 14731 Welding Coordination (B9) ............................................................... 92 Welding related tasks of the welding coordinator......................................................................... 93 Welding personnel......................................................................................................................... 93 Quality records .............................................................................................................................. 95 Surface inspection on cracks and other surface imperfections by visual testing (B8) .................. 95 Welders qualification and qualification standards ...................................................................... 110 Accredited and none-accredited certification.............................................................................. 110 Maintenance and prolongation of certificates ............................................................................. 110 Essential variables for the certificates ......................................................................................... 111

MODULE 9...................................................................................................................................... 112 Delivery of the product. .............................................................................................................. 112 The European Welded Product Directives. ................................................................................. 113 The European Welded Product Standards................................................................................... 114 The EN ISO 3834........................................................................................................................ 116 Identification and traceability...................................................................................................... 118 Quality records ............................................................................................................................ 118

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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MODULE 1 Activity Based Training Instead of utilizing the traditional methodology whereby the student moves through a traditional education with theoretical content from A to Z, followed by hands on training, this course will use an Activity Based Training (ATB). With ATB it is understood that the training follow the production activities according the production path of a predefined structure or product. The course will also exploit a blended approach whereby different delivery technologies for the content itself will be used. The course has been divided into 9 different modules and three of these are modules where the major part of the hours will be utilized for practical work. This means that the students have to participate together in a workshop or laboratory. This is an important aspect of the methology itself. When working in an industrial environment the student has to work together with other personnel in order to meet the requirements in quality, time schedules and so forth. The team building effort, its importance for the final product and its importance for the total quality of the production environment must be stressed during the educational process. In a welding environment today the students will work together with other persons from different cultures, with different educational backgrounds and with different practical experience, which will require a profound focus on flexibility and open minded attitude towards other people. Few if any other educational routes will demand such flexibility to the student itself and to the students behaviour on a short and long term basis.

The course will consist of several job-elements. The figure shows how one job-package is built up of different elements, some are pure theory elements and other is a mixture of theory and hands-on training. The training will be carried out in the workshop, shop, or in a laboratory. Video streaming and/or videoconferencing will be used in Shop/Theory packages.

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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Job Package. A job package might contain several job elements. A job package is a complete documentation package of specific activities that must be mastered in the welding industry in order to handle the whole production process. It contains at least the following information:

i. Drawing of the structure to be fabricated ii. Work description with which methods shall be used in the production iii. Work description with process description of the work process for reaching the target

and the knowledge required iv. Quality assurance requirements for the ingoing elements v. Quality assurance description of the outgoing elements vi. Work package description for the work to be done vii. Reference to available resources for the work viii. Reference to environmental resources or requirements or restrictions ix. Requirements for knowledge, prerequisite or knowledge that has to be obtained x. Cooperation strategy with other in a defined group or to related groups

However, some basic prerequisite knowledge must be mastered by the production staff in order to follow the knowledge requirements. The knowledge and competence requirements include: •Ability to work in a multicultural environment with the colleagues due to exchange of mobile personnel across borders and among mechanical industry companies •Ability to understand and communicate the content in the job packages to the colleagues in a multilingual working environment •Ability to understand his/her responsibility in the production chain and to communicate the need for knowledge. •Ability to search for relevant learning and training material when needed. •To understand how a process plan might be visualized by utilizing a project plan.

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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A general design of a learning element. This element consists of both theoretical content as well as practical work. We can also see that the practical task, when completed shall be verified by the student as well as by a 3-part. This will both ensure that the student feel responsible for the part itself, but also be aware of the quality assurance aspect which is very important withing the welding activities. This is a simplified design where no loops are included in the process flow. A central philosophy within fabrication is that the person who produce a product shall not be the one carrying out the quality control of the same product. To establish the same methology in education one aims at introducing an alternative production flow whereby the product alternate between students or student groups.

A product is alternating between students during the fabrication process. When produced by student A at a certain stage then student B will carry out the quality control of the part. Student B will then use the part from A in his own production and then transfer it back to A for the following quality control. This means that the students shall be familiar with and use the definitions and actions that are common in the industry. It will consequently be mandatory to switch the objects for this purpose in order to avoid that a person verifies himself. If defects or non-conformance is found then the necessary corrective actions have to be carried out by the student. The use of objects should reflect the typical industry environment that is domination in the area where the course is held in order to create a more relevant training domain. But when this is done, then he other examples and references in the material should be selected from a similar industrial background in order to make tis relevant fro the student .

Delivery.

The structure described here is a structure that can be used in different environments. The structure has not been designed for a special delivery method. However, when that has been said, it is possible to use a highly structured an d rigid structure whereby you may control an verify all steps of the student, If that is the correct way of carrying out the course is of course another question.

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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The structure that follows is a an idea of which elements that a course should contain, if its running as a web course or if its running as a face-to face course without having access to the web itself. Normative references In the following table is a list of some of the European (EN) standards within the welding sector. This list is not complete. Bold documents are of special importance

DokNo Name Year

EN 287-1 Qualification test of welders - Fusion welding - Part 1:Steels 3. 2004

EN ISO 9606-2 Qualification test of welders - Fusion welding - Part 2:Aluminium 1. 1999

EN ISO 9606-3 Qualification test of welders - Fusion welding - Part 3; Copper and copper alloys

1. 1999

EN ISO 9606-4 Qualification test of welders - Fusion welding - Part 4: Nickel and nickel alloys

1. 1999

EN ISO 9606-5 Qualification test of welders - Fusion welding - Part 5: Titanium and titanium alloys

1. 1999

EN ISO 15607

Specification and qualification of welding procedures for metallic materials - General rules (ISO 15607:2003) 2004

EN ISO 15609-1

Specification and qualification of welding procedures for metallic materials - Welding procedure specification - Part 1: Arc welding (ISO 15609-1:2004)

2004

EN ISO 15614-1

Specification and qualification of welding procedures for metallic materials - Welding procedure test - Part 1: Arc and gas welding of steels and arc welding of nickel and nickel alloys (ISO 15614-1:2004)

2004

EN ISO 15610

Specification and qualification of welding procedures for metallic materials - Qualification based on tested welding consumables (ISO 15610:2003)

2004

EN ISO 15611

Specification and qualification of welding procedures for metallic materials - Qualification based on previous welding experience (ISO 15611:2003)

2004

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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2009.02.11 8 of 100

EN ISO 15612

Specification and qualification of welding procedures for metallic materials - Qualification by adoption of a standard welding procedure (ISO 15612:2004)

2004

EN ISO 15613

Specification and qualification of welding procedures for metallic materials - Qualification based on pre-production welding test (ISO 15613:2004)

2004

EN 288-9 Part 9: Welding procedure test for pipeline welding on land and offshore site butt welding of transmission pipelines 1999

EN ISO 3834 Welding coordination - Tasks and responsibilities 2005

EN ISO 3834-1 Quality requirements for welding - Fusing welding of metallic materials - Part 1: Guidelines for selection and use 2005

EN ISO 3834-2 Quality requirements for welding - Fusing welding of metallic materials - Part 2: Comprehensive quality requirements 2005

EN ISO 3834-3 Quality requirements for welding - Fusion welding of metallic materials - Part 3: Standard quality requirements 2005

EN ISO 3834-4 Quality requirements for welding - Fusion welding of metallic materials - Part 4: Elementary quality requirements 2005

EN 756 Welding consumables - Solid wires, solid wireflux and tubular cored electrode-flux combinations for submerged arc welding of non alloy and fine grain steels - Classification

2 2004

EN 970 Non-destructive examination of fusion welds - Visual examination 1998

EN 1011-1 Welding - Recommendations for welding of metallic materials - Part 1: General guidance for arc welding 1998

EN 1011-1/A1 Amendment A1 - Welding - Recommendations for welding of metallic materials - Part 1: General guidance for arc welding 2002

EN 1011-1/A2 Amendment A2 - Welding - Recommendations for welding of metallic materials - Part 1: General guidance for arc welding 2004

EN 1011-2 Welding - Recommendations for welding of metallic materials - Part 2: Arc welding of ferritic steels 2001

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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EN 1011-2/A1 Amendment A1 - Welding - Recommendations for welding of metallic materials - Part 2: Arc welding of ferritic steels 2004

NS-EN 1011-3 Welding - Recommendations for welding of metallic materials - Part 3: Arc welding of stainless steels 2000

EN 1011-3/A1 Amendment A1 - Welding - Recommendations for welding of metallic materials - Part 3: Arc welding of stainless steels 2004

EN 1011-5 Welding - Recommendations for welding of metallic materials - Part 5: Welding of clad steel 2003

EN 1418 Welding personnel - Approval testing of welding operators for fusion welding and resistance weld setters for fully mechanized and automatic welding of metallic materials

1998

EN ISO 4063 Welding and allied processes - Nomenclature of processes and reference numbers (ISO 4063:1998) 2000

EN ISO 5817 Welding - Fusion-welded joints in steel, nickel, titanium and their alloys (beam welding excluded) - Quality levels for imperfections (ISO 5817:2003)

2003

EN ISO 6520-1 Welding and allied processes - Classification of geometric imperfections in metallic materials - Part 1: Fusion welding (ISO 6520-1:1998) 1998

EN ISO 6520-2 Welding and allied processes - Classification of geometric imperfections in metallic materials - Part 2: Welding with pressure (ISO 6520-2:2001) 2002

EN ISO 9692-1 Welding and allied processes - Recommendations for joint preparation - Part 1: Manual metal-arc welding, gas-shielded metal-arc welding, gas welding, TIG welding and beam welding of steels (ISO 9692-1:2003)

2004

EN ISO 9692-2 Welding and allied processes - Joint preparation - Part 2: Submerged arc welding of steels (ISO 9692-2:1998) (Corrigendum AC:1999 incorporated)

1998

EN ISO 9692-3 Welding and allied processes - Recommendations for joint preparation - Part 3: Metal inert gas welding and tungsten inert gas welding of aluminium and its alloys (ISO 9692-3:2000)

2001

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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EN ISO 9692-3/A1 Amendment A1 - Welding and allied processes - Recommendations for joint preparation - Part 3: Metal inert gas welding and tungsten inert gas welding of aluminium and its alloys

2004

EN ISO 9692-4 Welding and allied processes - Recommendations for joint preparation - Part 4: Clad steels (ISO 9692-4:2003) 2003

Page Title Comment Table with reference literature to be read in addition to the course documentation for the individual modules. This table to be compiled according to the national availability of reference literature.

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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MODULE 2 Welding symbols according ISO 2553 (A6) The weld joint is where two or more metal parts are joined by welding. The five basic types of weld joints are the butt, corner, tee, lap, and edge. Special symbols are used on a drawing to specify where welds are to be located, the type of joint to be used, as well as the size and amount of weld metal to be deposited in the joint.

A standard welding symbol consists of a reference line, an arrow, and a tail. The reference line becomes the foundation of the welding symbol. It is used to apply weld symbols, dimensions, and other data to the weld. The arrow simply connects the reference line to the joint or area to be welded. The direction of the arrow has no bearing on the significance of the reference line. The tail of the welding symbol is used only when necessary to include a specification, process, or other reference information.

The term weld symbol refers to the symbol for a specific type of weld: fillet, groove, surfacing, plug, and slot are all types of welds. Some of basic weld symbols are shown in the next figures. Types of butt welds

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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2009.02.11 12 of 100

Single V preparation Double V preparation

Types of fillet welds

The leg length of a fillet weld is located in front of the weld symbol (triangle). The dimension is in millimeters preceded with the letter Z or by the letter ”a”. In addition to basic weld symbols, a set of supplementary symbols may be added to a welding symbol. Some of the most common supplementary symbols are shown in the following figure.

Supplementary symbols

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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Weld this joint on site Inspect by NDT, Weld, Paint, etc.

Joint preparation for butt welds, welded from one side

Dimensions

Ref. No.

Workpiec

e thickness

t

mm

Designati

on

Symbol ISO 2553

Cross section

Angle

α ,β

Gap b

mm

Thickness of root face

c mm

Depth of

prepara-

tion h

mm

Welding process ISO 4063

Illustration

Remarks

1.1 ≤ 2

Butt weld between

plates

with raise

d edge

s

- - - -

3

111

141

512

Usually

without

filler metal

- 1. 2. 1

~ t 3

111

141 13 141

6 ≤ b ≤ 8

~ t ≤ 1

1. 2. 2

≤ 4 3 < t ≤ 8 ≤ 15

Square

butt weld

-

0

- -

52

With temporary backi

ng

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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2009.02.11 14 of 100

1.5 5 ≤ t ≤ 40

Single –V Butt weld with broa

d root face

α ~ 60 0

1 ≤ b ≤ 4

2 ≤ c ≤ 4 -

111

13

141 -

1.6 > 12

Single-U butt weld with

V root

e

60 0 ≤ α≤ 90

0

8 0 ≤ β ≤ 12

0

1 ≤ b ≤ 3

- ~ 4

111

13

141

6 ≤ R ≤ 9

1.7 > 12

Single –V butt weld with

V root

e

60 0 ≤ α ≤ 90

0

10 0 ≤ β ≤ 15

0

2 ≤ b ≤ 4

> 2 -

111

13

141

-

1.8 > 12

Single-U butt weld (sloping

sides)

8 0 ≤ β ≤ 12

0

≤ 4 ≤ 3 -

111

13

141 -

3 < t ≤10

40 0 ≤ α ≤ 60 0 ≤4 3

111

13

141

1.3 8 < t ≤12

Single V butt

60 ≤ α ≤ 8 0 -

≤ 2 -

52

1.4 > 16

Steep-flanked single-V butt with backing

5 0 ≤ β ≤ 20 0

5 ≤ b ≤ 15 - -

111

13

With permanent backing

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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1.9.1

1.9.2

3 < t ≤10

Single-

bevel butt weld

35 0 ≤ β ≤ 60

0

2 ≤ b ≤ 4

1 ≤ c ≤ 2 -

111

13

141

-

111 6 ≤ b ≤ 12

1.10 > 16

Steep-

flanked

single-

bevel butt weld

15 0 ≤ β ≤ 60

0 ~ 12

- - 13

141

With permanent backi

ng

1.11 > 16

Single –J butt weld

10 0 ≤ β ≤ 20

0

2 ≤ b ≤ 4

1 ≤ c ≤ 2 -

111

13

141

-

Dimensions

Ref. No.

Workpiece

thickness

t

mm

Designati

on

Symbol ISO 2553

Cross section

Angle

α ,β

Gap b

mm

Thickness of root face

c mm

Depth of

prepara-

tion h

mm

Welding process ISO 4063

Illustration

Remarks

≤ 8 ~ t/2 111 141 ≤ t/2 13

2.1 ≤ 15

Square

butt weld

-

0 - -

52

111 141

2.2

3 ≤ t ≤ 40

Single-V

α ~ 600 ≤ 3 ≤ 2 - -

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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2009.02.11 16 of 100

111 141

α ~ 600

2.2

3 ≤ t ≤ 40

preparation

400 ≤ α ≤ 600

≤ 3 ≤ 2 - 13

-

α ~ 600

111 141

2.3 > 10

Single-V butt weld with broa

d root face and

backing run

400 ≤ α ≤ 600

1 ≤ b ≤ 3

2 ≤ c ≤ 4 -

13

-

α ~

600 111

141 2.4 > 10

Double-V butt weld with broad root face

400 ≤ α ≤ 600

1 ≤ b ≤ 4

2 ≤ c ≤ 6

h 1 = h 2 =

13

-

α ~ 600

111

141

symmetrical

X

2.5.1

~

13

-

400 ≤ α ≤ 600 111

141 α 1 ~ 600

α 2 ~ 600 2.

5.2

> 10 asymmetrical

X

400 ≤ α 1 ≤ 600

400 ≤ α 2 ≤ 600

1 ≤ b ≤ 3

≤ 2

~ 13

-

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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2009.02.11 17 of 100

1≤ b ≤ 3

111

13

2.6 > 12

Single-U butt weld with backi

ng run

80 ≤ β ≤ 12 0

≤ 3 ~ 5 -

141 c

Root run may be

necessary

2.7 ≥ 30

Double-U butt weld

80 ≤ β ≤ 12 0 ≤ 3 ~ 3

~

111

13

141

This type of joint preparation can also be produced asymmetri-cally in a similar manner to the asymmetrical X butt weld

2.8 3 ≤ t ≤ 30

Single-

bevel butt weld

350 ≤ β

≤ 60 0

1≤ b ≤ 4 ≤ 2 -

111

13

141

Root run may

be necessar

y

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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2009.02.11 18 of 100

2.9.1

2.9.2

> 10

T-joint both sides bevell

ed preparation

350 ≤ β ≤ 60

0

1≤ b ≤ 4 ≤ 2

=

sau

=

111

13

141

This type of joint

preparation can

also be produc

ed asymmetric-ally in

a similar manner to the asymmetrical

X

2.10 > 16

Single-J butt weld with backing run

100 ≤ β ≤ 20

0

1≤ b ≤ 3 ≥ 2 -

111

13

141

Root run

may be necess

ary

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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2009.02.11 19 of 100

> 30

≥ 2

=

< 2 ~

111

13

141

2.11 ≤

170

Double- J butt weld for

single

pass weldi

ng proce

ss

100 ≤ β ≤ 20

0

≤ 3

51

This type of joint

preparation can

also be produc

ed asymmetric-ally in

a similar manner to the asymmetrical

X

Joint preparation for T - joints, welded from one side

Dimensions

Ref.

No.

Workpiece

thickness t

mm

Designation

Symbol

ISO 2553

Cross section Angle α ,β

Gap b

mm

Welding

process ISO 4063

Illustration

3.1.1

t 1 > 2 t 2 > 2

Single fillet weld

70 0 ≤ α

≤ 100 0

≤ 2

3

111

13

141 3.1.

2 t 1 > 2 t 2 > 2

Single fillet weld

- ≤ 2

3

111

13

141

3.1.3

t 1 > 2 t 2 > 2

Single fillet weld

60 0 ≤ α

≤ 120 0

≤ 2

3

111

13

141

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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Dimensions

Ref. No.

Workpiece

thickness t

mm

Designation

Symbol

ISO 2553

Cross section Angle α ,β

Gap b

mm

Welding process

ISO 4063

Illustration

4.1.1

t 1 > 3 t 2 > 3

Single fillet weld

70 0 ≤ α

≤ 100 0

≤ 2

3

111

13

141 4.1.

2 t 1 > 2 t 2 > 5

Single fillet weld

2 ≤ t 1 ≤ 4

2 ≤ t 2 ≤ 4

60 0 ≤ α

≤ 120 0

-

3

111

13

141

≤ 2 4.1.3

t 1 > 4 t 2 > 4

Single fillet weld

- -

3

111

13

141

Role of inspection and quality control (B9) To ensure that a product has the right level of quality, some form of inspection is often required. This can involve such things as measuring the dimensions of a welded part. The measurement result is then compared with the applicable requirement for the welded part in question. If the requirements are fulfilled, the part can be approved. If the requirements are not fulfilled, the part will not be approved. A standard definition of Inspection is: "Measurement, investigation, testing or other classification of one or more characteristics or properties of a product and the comparison of the results with set requirements to determine whether they are fulfilled". Accreditation Within the European system, there are a number of standards (EN 45000 series) that include regulations for testing the ability of inspection organs. Its aim is to ensure that inspection organs in Europe carry out equivalent assessments so that the results can be approved by all the member countries. The inspection organs that are approved according to these requirements become accredited for a certain task. The following bodies can be accredited: 1 Laboratories.

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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2 Certification organs for products, quality systems, personnel. 3 First, second and third party inspection organs. Welding is a special process, which requires the coordination of welding operation in order to establish confidence in welding fabrication and reliable performance in service. The tasks and responsibilities of personnel involved in welding related activities, e.g. planning, executing, supervising and inspection, needing to be clearly defined. Welding coordination requirements can be specified by a manufacturer, contract or an application standard. Quality control The operations of a company are controlled to give products the right level of quality. This means that the daily activities follow the company's quality system, applying the directions contained in the quality manual and the instructions that are to be available at each workplace. One example of quality control is the application of welding procedure specification (WPS) in order to obtain the right level of quality in welds. Quality control as applied to welded products includes those activities which monitor the quality of the product – the operational techniques of checking materials, dimensional checks, inspection before, during and after welding, non-destructive testing, hydraulic or leak testing – in other words, activities which take place after the event and which check that everything has been carried out correctly. Introduction to ISO 3834 (B9) ISO 3834: „Quality requirements for fusion welding of metallic materials” ISO 3834 consists of 5 parts, under the general title Quality requirements for fusion welding of metallic materials: - Part 1: Criteria for the selection of the appropriate level of quality requirements - Part 2: Comprehensive quality requirements - Part 3: Standard quality requirements - Part 4: Elementary quality requirements - Part 5: Applicable documents ISO 3834 is not a quality management system standard replacing ISO 9001:2000 but a useful tool when ISO 9001:2000 is applied by welding manufacturers. ISO 3834 identifies measures that are applicable for different situations. They may be applied in the following circumstances: - in contractual situations: specification of welding quality requirements; - by manufacturers: establishment and maintenance of welding quality requirements; - by committees drafting manufacturing codes or application standards: specification of welding quality requirements; - by organizations assessing welding quality performance, e.g. third parties, customers, or manufacturers. ISO 3834 can be used by internal and external organizations, including certification bodies, to assess the manufacturer's ability to meet customer, regulatory or the manufacturer’s own requirements. ISO 3834 therefore provides a method to demonstrate the capability of a manufacturer to produce products of the specified quality. It was prepared such that: a) it is independent of the type of construction manufactured;

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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b) it defines quality requirements for welding in workshops and/or on site; c) it provides guidance for describing a manufacturer's capability to produce constructions to meet specified requirements; d) it provides a basis for assessing a manufacturer’s welding capability. ISO 3834 is appropriate when demonstration of a manufacturer's capability to produce welded constructions, fulfilling specified quality requirements, is specified in one or more of the following: - a specification; - a product standard; - a regulatory requirement. The selection of the appropriate part of ISO 3834 should be in accordance with the product standard, specification, regulation or contract. The manufacturer selects one of the three parts specifying quality requirements based on the following related to products: - the extent and significance of safety-critical products; - the complexity of manufacture; - the range of products manufactured; - the range of different materials used; - the extent to which metallurgical problems may occur; - the extent to which manufacturing imperfections, e.g. misalignment, distortion or weld imperfection, affect product performance. A manufacturer that demonstrates compliance to a level of this document is also considered to have established compliance to all lower levels without further demonstration (e.g. a manufacturer compliant to ISO 3834-2 demonstrates compliance with ISO 3834-3 and ISO 3834-4).

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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Summary comparison of ISO 3834, Parts 2, 3 and 4

The manufacturer shall review the contractual requirements and any other requirements, together with any technical data provided by the purchaser when the construction is designed by the manufacturer. The manufacturer needs to establish that all information necessary to carry out the manufacturing operations is complete and available prior to the commencement of the work. The manufacturer shall affirm its capability to meet all requirements and shall ensure adequate planning of all quality-related activities. A review of requirements shall be carried out by the manufacturer to verify that the work content is within its capability to perform, that sufficient resources are available to achieve delivery schedules and that documentation is clear and unambiguous. The manufacturer shall ensure that any variations between the contract and any previous quotation are identified and the purchaser notified of any programme, cost or engineering changes that may result. Items considered at or before the time of the review of requirements review: a) The product standard to be used, together with any supplementary requirements;

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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b) Statutory and regulatory requirements; c) Any additional requirement determined by the manufacturer; d) The capability of the manufacturer to meet the prescribed requirements. Sub-contracting When a manufacturer intends to use sub-contracted services or activities (e.g. welding, inspection, NDT, heat treatment), information necessary to meet applicable requirements shall be supplied by the manufacturer to the sub-contractor. The sub-contractor shall provide such records and documentation of his work as may be specified by the manufacturer. A sub-contractor shall work under the order and responsibility of the manufacturer. The manufacturer shall ensure that the sub-contractor can comply with the quality requirements as specified. The information provided by the manufacturer to the sub-contractor shall include all relevant data from requirements review and technical review. Additional requirements may be specified as necessary to assure sub-contractor compliance with technical requirements. Welding personnel The manufacturer shall have at his disposal sufficient and competent personnel for the planning, performing and supervising of the welding production according to specified requirements. Welders and welding operators shall be qualified by appropriate tests. The manufacturer needs to have appropriate welding coordination personnel. The welding coordinator shall have sufficient authority to enable any necessary action to be taken. Inspection and testing personnel The manufacturer shall have at his disposal sufficient and competent personnel for planning, performing, and supervising the inspection and testing of the welding production according to specified requirements. The non-destructive testing personnel shall be appropriate qualified/certified. When a qualification test is not required, competence shall be verified by the manufacturer. Inspection and testing Applicable inspections and tests shall be implemented at appropriate points in the manufacturing process to assure conformity with contract requirements. Location and frequency of such inspections and/or tests will depend on the contract and/or product standard, the welding process and the type of construction. Inspection and testing before welding Before the start of welding, the following shall be checked: - suitability and validity of welders’ qualification certificates; - suitability of welding-procedure specification; - identity of parent material; - identity of welding consumables; - joint preparation (e.g. shape and dimensions); - fit-up, jigging and tacking; - any special requirements in the welding-procedure specification (e.g. prevention of distortion); - arrangement for any production test; - suitability of working conditions for welding, including environment.

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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Inspection and testing during welding During welding, the following shall be checked at suitable intervals or by continuous monitoring: - essential welding parameters (e.g. welding current, arc voltage and travel speed); - preheating/interpass temperature; - cleaning and shape of runs and layers of weld metal; - back gouging; - welding sequence; - correct use and handling of welding consumables; - control of distortion; - any intermediate examination (e.g. checking of dimensions). Inspection and testing after welding After welding, the compliance with relevant acceptance criteria shall be checked: - by visual inspection; - by non-destructive testing; - by destructive testing; - form, shape and dimensions of the construction; - results and records of post-weld operations (e.g. post-weld heat treatment, ageing). Inspection and test status Measures shall be taken, as appropriate, to indicate, e.g. by marking of the item or a routing card, the status of inspection and test of the welded construction. Non-conformance and corrective actions Measures shall be implemented to control items or activities, which do not conform to specified requirements in order to prevent their inadvertent acceptance. When repair and/or rectification is undertaken by the manufacturer, descriptions of appropriate procedures shall be available at all workstations where repair or rectification is performed. When repair is carried out, the items shall be re-inspected, tested and examined in accordance with the original requirements. Measures shall also be implemented to avoid recurrence of non-conformances. Calibration and validation of measuring, inspection and testing equipment The manufacturer shall be responsible for the appropriate calibration or validation of measuring, inspection and testing equipment. All equipment used to assess the quality of the construction shall be suitably controlled and shall be calibrated or validated at specified intervals. Identification and traceability Identification and traceability shall be maintained throughout the manufacturing process, if required. Quality records Quality records shall include, when applicable: - record of requirement/technical review; - material certificates; - welding consumable certificates; - welding-procedure specifications; - equipment maintenance records; - welding-procedure qualification records (WPQR); - welder or welding-operator qualification certificates; - production plan;

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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- non-destructive testing personnel certificates; - heat-treatment procedure specification and records; - non-destructive testing and destructive testing procedures and reports; - dimensional reports; - records of repairs and non-conformance reports; - other documents, if required. Quality records shall be retained for a minimum period of five years in the absence of any other specified requirements. Application Conformity to ISO 3834-2 to 4 shall be claimed by a manufacturer using the normative references given in this part. Conformity to ISO 3834-2 to 4 may also be claimed by adopting other standards that provide equivalent technical conditions. Where other standards are adopted, they should only be used when they are referenced in product standards for constructions being made by the manufacturer. It is the responsibility of the manufacturer to demonstrate technically equivalent conditions when normative references other than those listed in this part are applied. Certificates issued following assessment by independent certification organizations or claims of compliance by a manufacturer with any part of ISO 3834 shall clearly identify the normative references or specifications used by the manufacturer. Stainless steel compared to unalloyed steel and aluminium alloys (PSS1) The consumption of stainless steel is increasing and will continue to do so. The reason of growth is increasingly demanding environment in the petrochemical industry and the process industry. Demand for these materials is also growing in industrial sectors such as foodstuffs, electronics, biochemistry and nuclear power. Stainless steel have also replaced other structural materials in many applications where it has been realized that stainless steel is cheaper in the long term, if both capital outlay and maintenance costs are taken into account. Two types of stainless steel have been more and more important: ferrite-austenitic (duplex) and fully-austenitic steels. The advantages of duplex steel are as follows:

- good weldability - considerably higher yeld strength - good resistance to stress corrosion, above all, but also to general corrosion and

pitting. Aluminum and aluminum alloys are structural materials with many good properties: with a proper design they do not corrode, they conduct electricity and they combine strength with low weight. Aluminum is considered to be a very important construction material in the future, especially in the automotive industry. Definition of stainless steel Stainless steels are defined as iron base alloys, which contain at least 11 % chromium. There are five types of stainless steels depending on the other alloying additions present, and they range from fully austenitic to fully ferritic. Identification of stainless steel The most important property of the high-chromium stainless steels is their corrosion resistance,

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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without which they would find little commercial use, as their general level of mechanical properties and forming characteristics can be equaled or exceeded by many other types of steel at a much lower cost. A chromium content above 12% also provides a considerable measure of oxidation resistance. Thus the stainless steels are used for both corrosion resisting and high-temperature creep resisting and heat resisting applications, the temperature of application usually increasing with increasing chromium content. The important factors, which must be considered in the design of the various types of stainless steels, are: - corrosion and oxidation resistance in the operating environment - mechanical and physical properties - fabrication characteristics from the point of view of both hot and cold working - welding - many of the stainless steels are required to be readily weldable, and welding must not impair the corrosion resistance, creep resistance or general mechanical properties. There are many different stainless steels, see figure, and the main types are listed below.

a) Ferritic steels, containing 11,5 – 30% Cr, up to 0,20% carbon, no nickel and often some molybdenum, niobium or titanium. They are ferritic at all temperatures and, therefore, do not transform to austenite and are not hard enable by heat treatment. Some of these can be highly corrosion resistance, and being fully ferritic are reasonably formable. They can in the less severe applications, replace the more expensive austenitic stainless steels. They are characterized by weld and HAZ grain growth, which can result in low toughness of welds. To weld the ferritic stainless steels, filler metals should be used which match or exceed the Cr level of the base alloy. To minimize grain growth, weld heat input should be minimized and preheat should be limited, and used only if necessary. b) Martensitic steels containing 11 – 18% Cr, 0 – 4% Ni, 0,1 – 1,2%C, and sometimes additions of molybdenum, vanadium, niobium, aluminum and copper. These are often alloyed to produce the required tempering resistance and strength. They are austenitic at temperatures of 950 – 1000 o C but transform to martensite on cooling, and the high hardenability makes them martensitic air

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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hardenable even in large section sizes. This can lead to difficulty in softening for machining and fabrication, particularly as they frequently alloyed to produce a high degree of tempering resistance. The steels are usually tempered to produce useful combinations of strength, ductility and toughness, and may be precipitation hardened. They have a tendency toward weld cracking on cooling when hard brittle martensite is formed. Chromium and carbon content of the filler metal should generally match these elements in the base metal. Preheating and interpass temperature in the 204 to 316 o C range is recommended for most martensitic stainless steel. Steel with over 0,20 % C often require a post weld heat treatment to soften and toughen the weld. c) Austenitic steels which contain 16 – 26% Cr, 8 – 20% Ni, up to 0,40% C. These steels also often contain additions of molybdenum, niobium or titanium and are predominantly austenitic at all temperatures, although depending o the composition and consequent constitution, some delta ferrite may be present. The austenite may have a varying degree of stability with respect to the formation of martensite, being transformed by cold work at room temperature in some compositions. The balance between the Cr and Ni + Mn is normally adjusted to provide a microstructure of 90 - 100% austenite. These alloys are characterized by good strength and high toughness over a wide temperature range and oxidation resistance to over 538 o C. Filler metal for these alloys should generally match the base metal but for most alloys, provide a microstructure to avoid hot cracking. Two problems are associated with welds in the austenitic stainless steels: - sensitization of the weld heat affected zone - hot cracking of weld metal. d) Precipitation hardening stainless steel are martensitic, semiaustenitic and austenitic. The martensitic stainless steel can be hardened by quenching from the austenitizing temperature (around 1038 o C) then aging between 482 to 621 o C. Since these steels contain less than 0,07% C, the martensite is not very hard and the main hardening is obtained from the aging (precipitation) reaction. The semiaustenitic stainless steel will not transform to martensite when cooled from the austenitizing temperature because the martensite transformation temperature is below room temperature. These steels must be given a conditioning treatment which consists heating in the range of 732 to 954 o C to precipitate carbon and/or alloy elements as carbides or intermetallic compounds. The austenitic precipitation hardening stainless steel remains austenitic after quenching from the solutioning temperature even after substantial amounts of cold work. They are hardened only by the aging reaction. This would include solution treating between 982 to 1121 o C, oil or water quenching and aging at 704 to 732 o C for up to 24 hours. If maximum strength is required in martensitic precipitation hardening stainless steels, matching or nearly matching filler metal should be used and the component, before welding, should be in the annealed or solution annealed condition. After welding, a complete solution heat treatment plus an aging treatment is preferred. The austenitic precipitation hardening stainless steel are most difficult to weld because of hot cracking. Welding should preferably be done with the parts in the solution treated condition, under minimum restraint and with minimum heat input.

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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e) Duplex stainless steel are the most recently developed group of stainless steel and have a microstructure of approximately equal amounts of ferrite and austenite. These steels have advantages over the conventional austenitic and ferritic steels in that they offer higher strength and greater stress corrosion cracking resistance. The duplex microstructure is attained in steels containing 21 - 25% Cr and 5 – 7 % Ni by hot working at 1000 to 1050 o C followed by water quenching. Weld metal of this composition will tend to be mainly ferritic because the deposit will solidify as ferrite and will transform only partly to austenite without hot working or annealing. •The alloying elements which appear in stainless steels are classed as ferrite formers and austenite formers:

Ferrite formers Chromium - provides basic corrosion resistance Molybdenum - provides high temperature strength and increases corrosion

resistance Columbium, Titanium - strong carbide formers Phosphorous, Sulfur, Selenium - improves machinability, causes hot cracking

in welds

Austenite formers Nickel - provides high temperature strength and ductility Carbon - carbide former, strengthener Nitrogen - increases strength, reduces toughness

The working environment of the fabrication shop, general hazards, dust, heavy and hot material, cables (A4) The welding processes are characterized by high temperatures, extensive fumes, light and heat radiation and risks from electric power. All these phenomena can endanger welder health, and potentially they are also dangerous for the environment. The basic task for health and safety is to eliminate these dangerous aspects of welding. General Hazards The general hazards in welding and cutting are: •Fire from sparks and spatter •Explosion and fires from reaction with welding gases •Asphyxiation •Electric shock •Inhaling toxic fumes and gases •Eye injuries from heat rays There are many regulations regarding safety in welding, which are derived from more general safety regulations, like 'General rules for hygienic and technical safety measures at work' and 'Regulations for personal safety means'. Every welder has the right and obligation to be protected under these regulations. The owner/operator is obliged to have a safety inspection performed on the welding equipments at least once every 12 months. A safety inspection, by a trained and certified electrician, is prescribed: - after any alterations - after any modifications or installations of additional components

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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- following repairs, care and maintenance - at least every twelve months. Measures - technical devices and equipment When planning a workplace, the working height plays an important part in creating the correct working position. In this context, positioners and lifting tables can be very useful. The working position is partly determined by the welder’s need to have his/her eyes close to the workpiece to be able to see the molten pool clearly while welding. If the working height is too low, the welder has to bend to see properly. A chair or stool might then be very useful. Working with the hands in a high position at or above shoulder level should be avoided whenever possible. In conjunction with heavier welding, the gun and hoses are also heavier and the load on the body is more static. A balanced load-reduction arm is very useful in this situation. Lifting the hoses off the floor also protects them from wear and tear, as well as facilitating wire feed. It is also a good thing if the workpiece is placed in a positioner and is positioned to ensure the best accessibility and height. A more comfortable working position can be created and, at the same time, welding can be facilitated as the joint is in the best welding position. Roller beds can be used for welding tubes or other cylindrical items. A hook or some other device on which the welding gun can be placed when it is not in use is another valuable piece of equipment. Hot work exposes workers to: - Molten metal - Toxic gases - Fumes and vapors - Harmful radiation - Excessive noise - Electrical shock - Fire hazards. Appropriate personal protective equipment (PPE) must be selected to protect the worker from these hazards. Fire watches in the area are required. Hot work operations include: - Gas Welding and Cutting - Electric Arc Welding - Carbon Arcing or Plasma Arc Cutting Each of these operations may present unique hazards. Electro- magnetic effects Current gives rise to a magnetic field around the conductor. The magnetic field is stronger closer to the conductor and rapidly subsides as the distance increases. A magnetic field is created around the welding cable and earth cable when welding is in process. Studies have indicated that one should not be exposed to strong magnetic fields. However, there is no evidence of any injuries. No limits have been yet set. Recommendations: You should make sure that as little as possible of the welding cable is directly adjacent to your body when welding. If you are right-handed, the welding machine should be placed on your right-hand side to avoid laying the welding cable on your lap or around your body. It is not a good idea to rest the welding cable around your body while erection welding (with the welding machine on the ground). Do not forget that MAGNETIC FIELDS can affect pacemakers and hearing aids.

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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Recommendations: - Pacemaker wearers keep away. - Wearers should consult their doctor before going near arc welding, gouging, or spot welding operations. Ancillary measures for preventing EMC problems: a) Mains supply - If electromagnetic interference still occurs, despite the fact that the mains connection is in accordance with the regulations, take additional measures (e.g. use a suitable mains filter). b) Welding cables - Keep these as short as possible - Arrange them so that they run close together (to prevent EMI problems as well) - Lay them well away from other leads. c) Equipotential bonding d) Workpiece grounding (earthing) - where necessary, run the connection to ground (earth) via suitable capacitors. e) Shielding, where necessary - Shield other equipment in the vicinity − Shield the entire welding installation. − Handling of stainless steel in the workshop and the use of tools for stainless steel (PSS2) For welding of stainless steels we have to respect following:

- welding will be made in special arranged spaces, where no other type of steel or material or alloys will be welded;

- the necessary tools and devices for welding and cleaning must be form stainless steel in order to avoid surfaces pollution elements welded;

- an accentuate cleaning of the elements and equipments has to be maintained; touching of the components will be made only with white cotton gloves in order to avoid surfaces degradation through impurities, dust ,metallic powder, oils;

- components manipulation will be carefully realized to avoid the damaging of the surfaces; - in welding spaces air currents have to be avoid; - welding has to be stopped if the outside temperature is bellow than + 5º C.

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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Example of stocking pipes and fittings, separating steel and stainless steel .

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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MODULE 3 Personal protective equipment and clothing (A3) Personal protective equipment especially designed for the task at hand must always be used when arc welding. Protective clothing must not be heavily soiled or torn. 1. Head Protection This provides protection a) against falls (e.g. crash helmets, cycle helmets, climbing helmets) b) against falling objects or against striking fixed objects c) against striking fixed objects (e.g. objects in confined spaces). 2. Eye Protection Welding helmet A welding helmet must always be worn when welding to protect the eyes and face from radiation and welding spatter. The welding helmet can be lowered in front of the face. The lens should be lowered using one hand instead of the "chin-up" method as repeated nodding can cause neck injuries. Welding lenses Welding helmets and welding lenses both have dark glass, so-called welding lenses. The welding lens is used to filter out UV and IR radiation. Only visible light is allowed to pass the lens. Lens protector Lens protectors are used in welding helmets and shields to protect the welding lens from spatter. Automatic welding lenses Automatic anti-dazzle welding lenses are also available. This type of welding lens darkens automatically the moment the arc is ignited and becomes lighter again when the arc is extinguished. Automatic welding lens can be set to different densities. Welding helmet with fresh-air supply Equipment is available for supplying fresh and cool air to the welding helmet. The positive pressure created inside the welding helmet prevents weld smoke from mixing with the air the welder inhales. Comfort is also enhanced and mist is prevented from forming on the welding lens. Relevant standards: a) EN169 welding filters b) EN175 welding eye protectors Always choose eye protection appropriate to the hazard and ensure that fits properly and is comfortable. Dirty lenses impair vision, causing eye fatigue and leading to accidents. The plastic lenses of eye protectors should be wet cleaned to avoid scratching; scratched lenses should be replaced, as should face shields if they become crazed or brittle with age. Safety spectacles and goggles should be issued on a personal basis and should be thoroughly cleaned before issue to someone else. 3. Foot Protection Safety footwear should comply with EN 345 (with toe protection of 200 or 100 joules). Footwear with anti-static or slip resistant properties should conform to EN 347. The choice of safety footwear should first be made on the basis of the protection required, but comfort is a significant issue and should not be ignored. Care should be taken in the choice of anti-static and conductive footwear. Both give protection against the hazard of static electricity and anti-static footwear also gives some protection against electric shock. However conductive footwear

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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provides no protection against electric shock and must not be used where this is a risk. Footwear should be checked for wear or damage and replaced if necessary. 4. Gloves Gloves may be used to give protection against toxic or corrosive chemicals, microbiological or radiological contamination, cuts and abrasions, impact, vibration or extremes of heat and cold. Standards for protective gloves are complex and basic standards are listed below. Gloves may additionally be described as of simple, intermediate, or complex design (a measure of their suitability for risks ranging from minimal to high); a performance level (usually on a scale from 0 to 4) may also be quoted. a) EN 407 for protection against heat and/or fire b) EN 421 for protection against ionizing radiation/radiation contamination c) EN 659 for protection against heat and flames Choose gloves appropriate for the job and consider whether long cuffs, gauntlets, or sleeve protectors may be required. Ensure that they offer good fit, comfort, and dexterity. Gloves rarely provide complete protection against hazards and this protection is much diminished by wear, damage, and chemical contamination. They should be checked before wear for cuts or pinholes and replaced if necessary. 5. Protective Clothing Protective clothing should be maintained as specified by the manufacturer.

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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Welder equipped with personal protection equipment.

In addition to the general protective clothing for welding and cutting operations, arc welding requires the following extra clothing: · Wear clothes made of materials heavy enough to protect against ultraviolet rays. · Wear dry welder’s gloves to protect against shock and electrocution. Noise hazards (A3) Noise is usually defined as undesirable sound and is a health hazard. Noise can cause hearing damage. Disturbing noise levels in combination with requisite ear defenders can make it difficult to communicate, which may lower the level of enjoyment in the workplace. Psychological well-being is also affected by noise. Noise abatement Sources of noise in a welding workshop are grinding, slagging and beating. This kind of work must be minimized. When grinding or hammering must be performed the use of equipment and aids that give the lowest possible noise levels is requested. Clang dampers It is the workpiece that generates most noise during grinding, slagging and beating. Using clang dampers will reduce the noise level considerably. Clang dampers are elastic dampers with a magnetic layer for fastening on the workpiece. Silenced machines Quieter hand-held machines have been developed during the last few years. Pneumatic slag picks and grinding machines are now fitted with silencers. Quieter grinding discs have been developed. Using modern equipment will reduce the noise level considerably. Noise absorbing screens Screens made of porous material such as mineral wool erected between the welding areas can limit the noise in many cases. The screen must be high and wide and located as close as possible to the source of the noise. By erecting absorbers above and beside the screen, noise can be reduced at

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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longer distances. Ear defenders In many welding shops the noise level is so high that ear defenders must always be used. Wearing ear defenders of down or earplugs will provide basic protection against background noise and unexpected sound. The noise level when slagging and beating is so high that ear cups are required. It is essential to wear ear defenders all the time in extremely noisy environments. Even short periods without protection can risk damaging your hearing. A hearing impairment cannot be cured.

Resume: Noise of 85 db (A) or higher might lead to hearing damage Safety measures: - noisy techniques to be substituted by quieter ones - protection from sound waves - isolation - spatial division - marking noisy areas - personal safety equipment (ear phones) - medical prevention and ambulance If the 85 db (A) level is reached - one must posses personal hearing protection equipment Above the level >90 db (A), standard noise protection is required for all employees. Suitable cutting processes for different types of steel to achieve a suitable cutting surface (A8) The three thermal cutting methods: flame cutting, plasma cutting and laser cutting are widespread and well known to most people. ' Flame cutting, Principle and parameters, cutting blowpipes, cutting machines, quality of cut surface Flame cutting is the traditional and clearly predominant method, but its use is slightly declining because of the increase in laser cutting and plasma cutting. Flame cutting remains a very useful cutting method, partly owing to its versatility. It covers the entire thicknesses range from 3 to 300 mm for unalloyed steels. By using special torches the field of application can be extended to thicknesses of up to 1000 mm or even more. The quality of cut is excellent when the cutting parameters are correctly set. In economic terms, flame cutting is clearly an alternative where numerically-controlled machines are used in conjunction with several torches in order to increase the productivity per employee. Other cutting processes as: plasma, laser, mechanical cutting Laser cutting give a high-quality cut, narrow kerfs and low heat transfer to the workpiece. The economic thickness for unalloyed steel is 2 to 3 mm. The use of laser cutting will increase, mainly

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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due to increased laser power output, which will enable thicker material thicknesses to be cut. The economic material thickness range for plasma cutting is 3 to about 20 mm. In this range plasma is faster then laser, but the quality of cut is not comparable. In an effort to compete with laser cutting, recent developments in plasma cutting have aimed to produce a system which is capable of producing cuts with completely square edges and narrow kerf width to enable higher cutting accuracy to be achieved. The resulting systems are commonly known as high tolerance plasma cutting and are characterized by torches having high current density cutting arcs. Smaller sets intended for manual cutting are usually air plasma, whilst larger mechanized installation use oxygen, nitrogen or argon mixtures as the plasma gas. Plasma power sources above 300 amps never use air. In connection with subsequent welding of air-plasma cut edges, weldability problems like pore formation and lack of fusion have been noticed. Investigations have shown that high concentrations of nitrogen in the cut edges are responsible for the problems. There are different ways to avoid the problems. One is to grind off the thin layer of the cut surface that has a high nitrogen concentration. This is an expensive method and it will reduce the productivity. Another way is to cut with oxygen plasma. An alternative to the thermal cutting methods is water jet cutting. The method emerged during the 1970s, when it was used to cut composites. Since then it has been developed to cut metals. This was made possible by adding abrasives to the jet, a technique known as abrasive water jet cutting. Using water jet cutting without abrasives it is possible to cut, in addition to composites, materials such as leather, rubber, textiles, wood, mineral wool and frozen foodstuffs. Abrasive water jet cutting can be used to cut sheet metal in gouges up to 50 mm, concrete up to 200 mm, stone and ceramics. Abrasive water jet cutting competes to some extent with the thermal methods, but as figure 1 shows, the cutting speed is very low, so the method is only competitive where some particular technical advantage can be exploited. Examples of such advantages are that the quality of cut is very good and that no heat is transferred into the workpiece the latter feature means that there are no deformation of the workpiece. Abrasive water jet cutting is also a suitable method for cutting surface treated materials like Zn, AlZn or polymer coated sheet metal, since this cutting method will minimize destruction of surface treatment.

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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Safety precautions for cutting (PSS1) In the table 1 are presented the representative cutting speed for different cutting methods.

Cutting speed (mm/min)

Materials Plate

thicknesses (mm)

Flame cutting

Plasma cutting

Laser cutting

Abrasive water jet cutting

Steel Steel Stainless steel Stainless steel Aluminum Aluminum

5 20 3

40 2 40

850 660

- - - -

4500A 2000A

5000B

500B

>6000B 1200B

2200 C -

6500 -

1000 C -

200 50

200

10-20 800 80

A - Nitrogen plasma with water injected, 500 A B - Gas plasma (Ar/H2), 240 A C - Carbon dioxide laser 1000W, with oxygen as cutting gas

Table 2 shows the cutting methods for different materials. Table 2

Material Cutting method Mild steels Stainless

steels Aluminum Titanium

Flame Plasma Laser Mechanical Water jet

+++ +++ +++ +++

+

+++ +++ +++

+

+++ ++

+++ ++

++ ++

+++ +++

+ +++ well suited ++ suited + possible

Burns and fires, fire prevention, fire fighting (A3) The basic precautions for fire prevention in welding or cutting work are: Cutting or welding must be permitted only in areas that are or have been made fire safe. When work cannot be moved practically, as in most construction work, the area must be made safe by removing combustibles or protecting combustibles from ignition sources. If the object to be welded or cut cannot readily be moved, all movable fire hazards in the vicinity must be taken to a safe place. If the object to be welded or cut cannot be moved and if all the fire hazards cannot be removed, then guards must be used to confine the heat, sparks, and slag, and to protect the immovable fire hazards. If these requirements cannot be followed then welding and cutting must not be performed. Suitable fire extinguishing equipment must be maintained in a state of readiness for instant use. Such equipment may consist of pails of water, buckets of sand, hose or portable extinguishers

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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depending upon the nature and quantity of the combustible material exposed. Fire watchers must have fire-extinguishing equipment readily available and be trained in its use. They must be familiar with facilities for sounding an alarm in the event of a fire. They must watch for fires in all exposed areas, try to extinguish them only when obviously within the capacity of the equipment available, or otherwise sound the alarm. Before cutting or welding is permitted, the area must be inspected by the individual responsible for authorizing cutting and welding operations. He must designate precautions to be followed in granting authorization to proceed preferably in the form of a written permit. Cutting or welding must not be permitted in the following situations:

- in areas not authorized by management - in sprinklered buildings while such protection is impaired - in the presence of explosive atmospheres (mixtures of flammable gases, vapors, liquids, or

dusts with air), or explosive atmospheres that may develop inside uncleaned or improperly prepared tanks or equipment which have previously contained such materials, or that may develop in areas with an accumulation of combustible dusts.

- in areas near the storage of large quantities of exposed, readily ignitable materials such as bulk sulfur, baled paper, or cotton.

Where practicable, all combustibles must be relocated at least 10 m from the work site. Where relocation is impracticable, combustibles must be protected with flameproofed covers or otherwise shielded with metal or asbestos guards or curtains.

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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MODULE 4 Welding procedures and instructions. The Manufacturer shall prepare the Welding Procedure Specification(s) (WPS) and shall ensure that these are used correctly in production. The welding procedures applied during production shall be as specific as possible, in order to clearly identify actions and parameters to be used for the required joint. However, if the relevant WPS contains data too detailed and not useful for the welder, dedicated work instructions may be used directly derived from such a WPS containing only the necessary data. These instructions have to refer directly to the welding procedure specification they derived from, e.g. by referring to the relevant WPS number. Considering that welding is a special process and that the quality of the welded joint cannot be properly controlled only by final tests, the welding procedures significant for the final product quality shall be qualified precisely prior to production. As a consequence, those Welding Procedure Specifications should be prepared in accordance with a Welding Procedure Qualification Record (WPQR). Normative references to the specification and to the qualification of welding procedures are given in the table.

Welding process Standard Material Scope Field of application

ISO 15607 WPS, WPQR General Rules

Qualification based on tested welding consumables ISO 15610 ISO 15611 Qualification based on previous welding

experience ISO 15612 Qualification by adoption of a standard welding procedure

All fusion welding processes

ISO 15613

All WPQR

Qualification based on pre-production welding test WPS Compiling ISO 15609-2

Gas Welding ISO 15614 - 1

Steels WPQR Qualification based on welding procedure test – Steels

ISO 15609-1 All WPS Compiling

ISO 15614 - 1 Steels and Nickel alloys WPQR Qualification based on welding procedure test

ISO 15614 - 2 Aluminium, Magnesium WPQR Qualification based on welding procedure test

ISO 15614 - 3 Steel castings WPQR Qualification based on welding procedure test

ISO 15614 - 4 Aluminium castings WPQR Qualification based on welding procedure test

ISO 15614 - 5 Titanium and zirconium WPQR Qualification based on welding procedure test

ISO 15614 - 6 Copper WPQR Qualification based on welding procedure test

ISO 15614 – 7 All applicable WPQR Qualification based on welding procedure test – corrosion resistance overlay, cladding restore and hardfacing

Arc welding

ISO 15614 – 8 All applicable WPQR Qualification based on welding procedure test - Welding of tubes to tube-plate joints

ISO 15609 – 3 All WPS Compiling Electron beam welding ISO 15614 – 11 All applicable WPQR Qualification based on welding procedure test

ISO 15609 – 4 All WPS Compiling Laser Welding

ISO 15614 – 11 All applicable WPQR Qualification based on welding procedure test

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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Underwater Arc Welding – Wet

Hyperbaric ISO 15614 – 9 All applicable WPQR Qualification based on welding procedure test

Underwater Arc Welding – Dry

Hyperbaric ISO 15614 – 10 All applicable WPQR Qualification based on welding procedure test

Standards for the qualification of welding procedures

Different methods for the qualification of welding procedures are available:

- welding procedure test – this method consists in welding a standardised test piece on which destructive and non-destructive tests are carried out in order to verify the achievement of required properties;

- use of approved welding consumables - this method of approval may be used if the welding consumables and the base material are not particularly affecting the welding quality, provided that heat inputs are kept within specified limits;

- previous welding experience - a welding procedure may be qualified by referring to previous experiences in welding if the Manufacturer is able to prove, by appropriate authentic documentation of an independent nature, that he has previously satisfactorily welded the same joint with reliable results;

- use of a standard welding procedure – a procedure is qualified if it is issued as a specification in the format of a WPS or WPQR based on appropriate qualification (e.g based on the relevant part of EN ISO 15614), not related to the Manufacturer and qualified by an examiner or examining body;

- Pre production Test - this method is the only reliable method of qualification for those welding procedures in which the resulting properties of the weld strongly depend on certain conditions such as: components, special restraint conditions, heat sinks etc., which cannot be reproduced by standardised test pieces; it is mostly used when the shape and dimensions of standardised pieces do not adequately represent the joint to be welded.

Even if different qualification methods are considered, the most commonly used are qualification by welding procedure test and pre-production test; however the applicable method of qualification is generally specified in either manufacturing codes, standards or contracts.

In order to demonstrate the achieved quality of the welded product, all the welding related documents (e.g. WPS, WPQR, Welder’s Qualification record, etc) shall be properly controlled.

This involves the preparation and maintenance of a procedure for the management of such documents, in order to identify issuance responsibilities, distribution methods, availability, and method for withdrawing obsolete documents. Even if it is not a normative requirement, a commonly adopted method to control documentation is the production of a written procedure, produced or approved by the welding coordinator, to be kept by the Manufacturer quality assurance department or directly by the welding coordinator himself.

In the next page a typical WPS form is reported, produced according to EN ISO15609-1.

WPS n° Rev. COMPANY NAME OR LOGO WELDING PROCEDURE SPECIFICATION (WPS)

Supp. WPQR Date Welding process(es) a) b) c)

Type(s) a) b) c)

JOINTS – Joint Type

Backing

Backing material

Joint drawiing

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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Weld preparation

Method of preparation & Cleaning

PARENT METAL Group n° To group n°

Spec. Type & grade

To Spec. Type & grade

Thickness

Outside Diameter

Other

WELDING CONSUMABLE GAS(ES) a) b) c) Gas(es) Mixture Flow Rate

Specification n° Plasma l/min

Designation Shielding a) l/min

Size Shielding b) l/min

Trade name Trailing l/min

Manufacturer Backing l/min

Flux design. EN Other

Flux Trade name ELECTRICAL CHARACTERISTIC - Weld deposit Current

Other Polarity

WELDING POSITION Mode of Metal Transfer

Position Tungsten Electrode Type & size

Welding Progression Electrode wire feed speed range

Other Other

PREHEAT TECHNIQUE Preheat Temperature String or weave beads

Interpass Temperature Orifice or gas cup size

Preheat maintenance Initial & interpass cleaning

Other Method of back gouging

PWHT and/or AGEING Oscillation Amplitude Freq.

Temperature Range Distance contact tube – work piece

Time Range (hour) Multiple, single pass (for side)

Heating rate Single or multiple electrodes

Cooling rate Torch angle direction of welding

Other Other

Filler metal Current Run(s) or Layer(s)

Welding process

EN designation or trade

name . Size (mm)

Type & polarity

Amperage A

Voltage V

Travel Speed

mm/min

Heat input KJ/mm

Other

MANUFACTURER APPROVED BY

Welding Procedure Specification Methods for joint preparations in stainless steel (PSS2) Most stainless steels are considered to have good weldability and may be welded by several welding processes including the arc welding processes, resistance welding, electron and laser beam welding, friction welding and brazing. For any of these processes, joint surfaces and filler metal must be clean. Since the coefficient of thermal expansion for austenitic stainless steels is relatively high, the

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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control of distortion must be considered in designing weldments of these alloys. The volume of metal in joints must be limited to the smallest size which will provide the necessary properties. In thick plate, a “U” groove, which gives a smaller volume that a “V” groove, should be used. If it is possible to weld from both sides of a joint, a double “U” or “V” groove joint preparation should be used. This not only reduces the volume of weld metal required but also helps to balance the shrinkage stresses. Accurate joint fit up and careful joint preparation, which are necessary for high quality welds also, help minimize. Joint location and weld sequence should be considered to minimize distortion. Strong tooling and fixturing should be employed to hold parts in place and resist tendencies for components to move during welding. When any of the gas-shielded processes are used, the tooling should also provide an inert gas backup to the root of the weld to prevent oxidation when the root pass is being made. This is particularly important when 141 - TIG welding pipe with insert rings to allow the weld metal to wet and flow together at the root of the joint. In welding pipe, insert rings, of the same composition as the filler metal should be used for the root pass and be welded by the 141 - TIG process. If copper chills are to be used near a weld area, they should be nickel plated to prevent copper pickup. If copper is in contact with the high temperature region of the heat-affected zone, it can melt and penetrate the grain boundaries of austenitic stainless steel causing embrittlement. The principal basic types of joints used in arc welding are the butt, lap, corner, edge and T configurations. Selection of the proper design for a particular application will depend primarily on the following factors: • the mechanical properties desired in the weld • the type of grade being welded • the size, shape and appearance of the assembly to be welded • the cost of preparing the joint and making the weld No matter what type of joint is used, proper cleaning of the workpieces prior to welding is essential if welds of good appearance and mechanical properties are to be obtained. On small assemblies, manual cleaning with a stainless steel wire brush, stainless steel wool or a chemical solvent is usually sufficient. For large assemblies or for cleaning on a production basis, vapor degreasing or tank cleaning may be more economical. In any case, it is necessary to completely remove all oxide, oil, grease, dirt and other foreign matter from the workpiece surfaces.

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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MODULE 5 Principle of welding consumables and functions of each type of welding consumable (A5) The welding consumables are presented in the tables below:

SymbolTensile strenght [N/mm2]Yeld

strenght [N/mm2] min.Elongation [%]

min.55610-7805501862690-8906201869760-9606901779880-10807901689980-118089015

SymbolWelding position1All positions2All positions, excepting the vertical down3Flat butt weld , flat fillet weld, horizontal-vertical fillet weld4Flat butt weld, flat fillet weld5Vertical down and positions according to symbol 3

SymbolMetal recovery [%]Type of current1≤ 105AC + DC2≤ 105DC3> 105 ≤ 125AC+ DC4> 105 ≤ 125DC5> 125 ≤ 160AC+ DC6> 125 ≤ 160DC7> 160AC + DC8> 160DC

Indicates mechanica

l properties

Covered electrode/ manual metal arc

welding

Type of electrod covering: B – basic covering R – rutile covering

Symbol of molten metal’s efficiency and type of currentSymbolMetal recovery[%]Type of current1≤ 105AC + DC2≤ 105DC3> 105 ≤ 125AC+ DC4> 105 ≤ 125DCIn order to demonstrate the possibility of utility in AC.,have to be performed tests with open voltage less then max. 65 VAC+ DCDCAC + DCDC

E CrMo1 B 4 4 H 5

Symbol of welding positionSymbolWelding positions1All positions2All positions, excepting the vertical down3Flat butt weld , flat fillet weld, horizontal-vertical fillet weld4Flat butt weld, flat fillet weld5Vertical down and positions according to symbol 3

SymbolHydrogen content, ml/100g deposited weld metal,max.H55H1010

Alloy SymbolChemical composition of all-weld metal, [%]CSiMn*PSCrMoVOther elementsMo0,100,800,40...1,50*0,0300,025---0,40...0,70------

MoV0,03...0,120,800,40...1,500,0300,0250,30...0,600,80...1,200,25...0,60---CrMo0,50,05...0,120,800,40...1,500,0300,0250,40...0,650,40...0,65------CrMo10,05...0,120,800,40...1,50*0,0300,0250,90...1,400,45...0,70------

CrMo1L0,050,800,40...1,50*0,0300,0250,90...1,400,45...0,70------CrMoV10,05...0,150,800,70...1,500,0300,0250,90...1,300,45...0,700,10...0,35---

CrMo20,05...0,120,800,40...1,300,0300,0252,0...2,60,90...1,30------CrMo2L0,050,800,40...1,300,0300,0252,0...2,60,90...1,30------

CrMo50,03...0,120,800,40...1,500,0250,0254,0...6,00,40...0,70------CrMo90,03...0,120,800,40...1,300,0250,0258,0...10,00,90...1,200,15Ni =

1,0CrMo910,06...0,120,600,40...1,500,0250,0258,0...10,50,80...1,200,15...0,30 Ni = 0,40...1,0

Nb=0,03...0,10

N=0,02...0,07CrMoWV120,15...0,220,800,40...1,300,0250,02510,0...12,00,80...1,200,20...0,40Ni = 0,8

W=0,40...0,60ZAny other agreed composition*Contents of Mn by 0,4 % ... 0,9 %, is for electrods with rutile cover and contents of Mn by 0,7 ... 1,5 % is for basic cover

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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Shelding gases, backing gases Influence of the Shielding Gas on: G.T.A.W., P.A.W., G.M.A.W., F.C.A.W. and L.B.W. Gas Tungsten Arc Welding (G.T.A.W.) or 141 - TIG Welding: Inert-gas arc welding process using a non-consumable tungsten electrode. Plasma Arc Welding (P.A.W.): Inert-gas arc welding using a non-consumable tungsten electrode. Gas Metal Arc Welding (G.M.A.W.): Metal-arc welding in which a continuous filler metal electrode is used. Shielding of the arc and weld pool is ensured entirely by an externally supplied gas. Laser Beam Welding (L.B.W.): A welding process in which the heat for welding is obtained from the application of a concentrated coherent light beam focused on the joint. The choice of shielding gas has a significant influence on the following factors: • Shielding Efficiency (Controlled shielding gas atmosphere) • Metallurgy, Mechanical Properties (Loss of alloying elements, pickup of atmospheric gases) • Corrosion Resistance (Loss of alloying elements, pickup of atmospheric gases, surface oxidation) • Weld Geometry (Bead and penetration profiles)

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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• Surface Appearance (Oxidation, spatters) • Arc Stability and Ignition • Metal Transfer • Environment (Emission of fumes and gases) Selection of Welding Gas

(1) Hydrogen–containing mixtures must not be used for welding ferritic, martensitic or duplex stainless steels

(2) For welding nitrogen–containing austenitic and duplex stainless steels, nitrogen can be added to the shielding gas

Classifications of welding consumables (A5) Covered electrode: A filler rod having a covering flux (for S.M.A.W.) used in arc welding, consisting of a metal core with a relatively thick covering which provides protection for the molten metal and stabilises the arc. Filler metal: Metal added during welding (brazing or surfacing). Filler rod: Filler metal in the form of a rod (e.g. for G.T.A.W.). Filler wire: Filler metal in the form of a coil of wire (e.g. for G.M.A.W. and S.A.W.) Flux: A fusible material used to protect the weld from atmospheric contamination, to stabilise the arc and to perform a metallurgical function (to prevent, dissolve, or facilitate removal of oxides and other undesirable substances). Flux cored electrode: Filler metal in the form of a small tube with flux in the core. The core provides deoxidisers and slagforming materials and may also provide shielding gases (some flux cored electrodes are self-shielding). Suggested welding consumables for welding stainless steels are:

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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(1) AISI: American Iron and Steel Institute (2) Covered electrodes for manual metal arc welding of stainless and heat resisting steels. There are two basic flux coverings: basic (B) or lime (direct current) and rutile (R) or titania (direct or alternating current) (3) Wire electrodes, wires and rods for arc welding of stainless and heat-resisting steels: G for G.M.A.W., W for G.T.A.W., P for P.A.W. or S for S.A.W.

(4) Tubular cored electrodes for metal arc welding with or without a gas shield of stainless and heat resisting steels

Storage drying and handling (A5) Welding consumables should be designed in accordance with the relevant standard. Consumables shall be with regard to the particular application, e.g. joint design, welding position and properties

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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required to meet the service conditions. Any special recommendations given by the manufacturer/supplier shall be observed. All consumables shall be stored and handled with care and in accordance with the relevant standards and\or the manufacturer/supplier recommendations. Covered electrodes, wire electrodes, rods and fluxes as well as their packaging, which show signs of damage or deterioration shall not be used. Examples of damage or deterioration are cracked or flaked coatings on covered electrodes, rusty or dirty wire electrodes and wire with flaked or damage protection coatings. Consumables returned to the stores shall be treated in accordance with the manufacturer/supplier’s recommendation before re-issue. Types of welds and joints, characteristics, size, surface finish (A6) Angle of bevel: The angle at which the edge of a component is prepared for making a weld. Bevel: An angular edge preparation. Backing strip: A piece of material placed at a root and used to control the penetration of a weld. Butt joint: a joint between the ends or edges of two abutting members aligned approximately in the same plane (i.e. making an angle to one another close to 180°). Butt weld: A weld in which the weld metal is deposited within the edge of a butt joint. Chamfer: Another term for bevel. Closed joint: A joint in which the surfaces to be joined (edges of two parts) are in contact while being welded. Concave fillet weld: A fillet weld in which the weld face is concave. Corner joint: A joint between the ends or edges of two parts making an angle of more than 30° but less than 135°. Cruciform joint: A joint in which two flat plates are welded to another flat plate at right angles and in the same axis. 141 - TIG and 15 - PAW The square-edge butt joint is the easiest to prepare and can be welded with or without filler metal depending on the thickness of the two pieces being welded. Part positioning for a square-edge butt joint should always be true enough to assure 100% penetration. When welding light gauge material without adding filler metal, extreme care should be taken to avoid lack of penetration or burn through. The flange type butt joint should be used in place of the square edge butt joint where some reinforcement is desired. This joint is practical only on relatively thin material (1,5 to 2,0 mm). The lap joint has the advantage of entirely eliminating the need for edge preparation. The only requirement for making a good lap weld is that the sheets be in close contact along the entire length of the joint to be welded. Corner joints are frequently used in the fabrication of pans, boxes and all types of containers. According to the thickness of the base metal, filler metal may or may not be required to provide adequate reinforcement on all corner joints. Make sure that the parts are in good contact along the entire length of the seam. All T joints require the addition of filler metal to provide the necessary build up. When 100 per cent penetration is required, be sure that the intensity of the welding current is adequate for the thickness of the base material. Edge joints are used solely on light gauge material and require no filler metal addition. The preparation is simple but this configuration should not be used where direct tensile loads are to be applied to the finished joint, since this type of joint may fail at the root under relatively low stresses.

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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131/135 MIG/MAG For 131/135 MIG/MAG welds, the root opening as well as the V angles can frequently be reduced from those normally employed in 111 - SMAW. The amount of weld metal per unit length can thus be reduced up to 30% by providing designs which require less filler metal. When designing 131/135 MIG/MAG welds for narrow grooves, it is often necessary to employ a high current density (spray transfer). 136 - FCAW In butt weld joints, the root openings and V angles can be reduced, often enabling a saving of the order of 40% in the amount of filler metal used in the joint. The optimum joint design will often be determined by the ease with which slag can be removed in multi-pass welds. In fillet welding, smaller sizes can be employed for the same strength. The deep penetration capacity of flux cored wire gives the same strength as the larger fillet from a 111 - SMAW electrode, which has low penetrating power. By comparison with 111 - SMAW electrodes, 136 - FCAW wires offer significant cost savings in a variety of ways, such as higher deposition rates, narrower grooves and sometimes two passes before stopping for slag removal. 121 SAW The groove openings are reduced compared to those required by other arc processes. The weld passes are heavier than for 111 - SMAW electrodes. For open root configurations, it is often desirable to provide a flux backing held in place by a copper chill bar or by a ceramic bar. For all processes, beveling is not required for thicknesses of 3,0 mm and less, but thicker base material should be beveled to form a “V”, “U” or “J” groove. The choice of joint details (angle, gap, thickness of root face) depends on the joint thickness, the position and the welding process.

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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MODULE 6 Specific rules and regulations (A3) Welding Safety (resume)

Hazard Factors to Consider Precaution Summary

Electric shock can kill

Wetness Welder in or on workpiece Confined space Electrode holder and cable insulation

Use dry insulation. Rubber mat or dry wood Wear dry, hole-free gloves. Do not touch electrically "hot" parts or electrode with bare skin or wet clothing. If wet area and welder cannot be insulated from workpiece with dry insulation, use a semiautomatic, constant-voltage welder or stick welder with voltage reducing device. Keep electrode holder and cable insulation in good condition. Do not use if insulation is damaged or missing.

Fumes and gases can be dangerous

Confined area Positioning of welder's head Lack of general ventilation Electrode types, i.e., manganese, chromium, etc. Base metal coatings, galvanize, paint

Use ventilation or exhaust to keep air breathing zone clear, comfortable. Use helmet and positioning of head to minimize fume in breathing zone. Read warnings on electrode container and material safety data sheet for electrode. Provide additional ventilation/exhaust where special ventilation requirements exist. Use special care when welding in confined area. Do not weld unless ventilation is adequate.

Welding sparks can cause fire or explosion

Containers which have held combustibles Flammable materials

Do not weld on containers, which have held combustible materials unless procedures are followed. Check before welding. Remove flammable materials from welding area or shield from sparks, heat. Keep a fire watch in area during and after welding. Keep a fire extinguisher in the welding area. Wear fire retardant clothing and hat. Use earplugs when welding overhead.

Arc rays can burn eyes and skin

Process: gas-shielded arc most severe

Select a filter lens, which is comfortable for you while welding. Always use helmet when welding. Provide non-flammable shielding to protect others. Wear clothing, which protects skin while welding.

Confined space

Metal enclosure Wetness Restricted entry Heavier than air gas

Evaluate adequacy of ventilation especially where electrode requires special ventilation or where gas may displace breathing air. If basic electric shock precautions cannot be followed to insulate welder from work and electrode, use

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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Welder inside or on workpiece

semiautomatic, constant-voltage equipment with cold electrode or stick welder with voltage reducing device. Provide welder helper and method of welder retrieval from outside enclosure.

Cluttered area Keep cables, materials, tools neatly organized.

Indirect work (welding ground) connection

Connect work cable as close as possible to area where welding is being performed. Do not allow alternate circuits through scaffold cables, hoist chains, or ground leads.

General work area hazards

Electrical equipment

Use only double insulated or properly grounded equipment. Always disconnect power to equipment before servicing.

Engine-driven equipment

Only use in open, well ventilated areas. Keep enclosure complete and guards in place Turn off engine before refueling.

Gas cylinders Never touch cylinder with the electrode. Never lift a machine with cylinder attached. Keep cylinder upright and chained to support.

Electric shock (A3) The physiological effects of electric current If electric current passes through the body, it can cause various injuries such as: - Burns - Cramp - Auricular fibrillation - Damage to the central nervous system. The effects of electrical current on the human body depend on: - Circuit characteristics (amount of current, resistance, frequency, and voltage). - The current’s pathway through the body. - How long the contact lasts. - Condition of the person’s skin (breaks in the skin or wet skin will lower the bodies resistance to the flow of electricity). In some cases low currents passing through the body can cause contraction of the muscles of the heart and lungs followed by failure of the heart and an inability to breathe. In normal circumstances gloves and shoes will serve to reduce the risk of shock from the ‘low voltage’ welding output (that is, 48 to 113 volts). The risk is increased if the contact resistance is lowered (for example, in wet conditions). Electricity can strike the human body and, depending on the current type, magnitude, duration, and

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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path, produce injuries (damage). The effects of alternating current are presented in table.

Amount of current in Milliamps (mA) Response

0.5-3 Start to feel the energy, tingling sensation 3-10 Experience pain, muscle contractions 10-40 Grip paralysis threshold (can't let go to source) 30-75 Respiratory failure 100-200 Heart fibrillation 200-500 Heart clamps tight Over 1,500 Tissue and organs burn

Particular danger exists at open circuit source voltage since this is the highest voltage of the welding circuit. Power sources should have protection for solid foreign objects and water penetration provided by the enclosure (IEC 60529). The degree of protection is indicated by the IP-code (International Protection) on the rating plate. Power sources for outdoor use shall have a minimum degree of protection of IP23. In order to minimize the chance of electric shocks, the highest open-circuit voltage value for the power source has to be defined. Some cases are distinguished: - normal workshop conditions, with good insulation for welder and welded parts, - conditions with "higher electric shock danger". Higher shock danger appears: in forced contact of electricity conducting parts with unprotected human body (e.g. when kneeling, sitting or leaning) if the free movement distance between the electric conducting components is less than 2 m when working sites are wet, damp or hot, as well as for working outside. The allowed open circuit voltage for the welding power source are shown in a simple table:

Workshop Higher danger of shock Transformer

net entrance 220 V

net entrance 380 V

S

55 V 80 V 48 V

Transducer

113 V

S 113 V

Commutation

113 V

with collector 113 V

without collector S 113 V

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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Inverter

113 V

S 113 V

The symbol S replaces the former symbols 42V and K.

Power sources for use in spaces with increased electrical danger (e.g. boilers) must be identified by

the (for “safety”) mark. However, the power source should not be in such rooms. Steps to Prevent Electrical Shock There are few steps that can be taken to prevent electrical shock. To prevent electrical shock: - Use well insulated electrode holders and cables. - Make sure welding cables are dry and free of grease and oil. - Keep welding cables away from power supply cables. - Wear dry hole-free gloves. - Clothing should also be dry. - Insulate the welder from the ground by using dry insulation, such as a rubber mat or dry wood. - Ground frames of welding units. - Never change electrodes with bare hands or wet gloves. Emergency Procedures: If someone is being shocked, follow these procedures: 1. Shut off the power immediately. The longer the person is in contact with the electricity, the more damage will be done. 2. Do not try to touch or approach the person until the power has been shut off, or you too will become a part of the circuit. Use a dry wood broom, leather belt, plastic rope, or something similar that is non-conductive such as wood or plastic to free the person from the energy source. 3. An electrical shock victim must go to the hospital even if they claim they are not hurt. Internal damage cannot be seen; only a physician can determine if the victim has been injured or not. 4. If the victim is unconscious, check to see that they have a pulse and are breathing. Initiate CPR or mouth-to-mouth resuscitation if necessary and if you are trained to do so. 5. Keep the person lying down and keep them warm to prevent shock. 6. Do not move the victim unless they are in immediate danger. Moving the victim could aggravate internal injuries or paralyze them since severe muscle contractions caused by electricity have been known to break bones in the victim. UV- and heat radiation (A3) Radiation arises from arc welding that the welder must be protected from this radiation, by wearing proper clothing and protective glasses (with filter). Radiation can be classified in three groups: - ultraviolet radiation (UV) (causes eyesight blurring, skin burns). - visible radiation (visible light) (blindness at long exposure). - infrared radiation (IR, heat radiation) (leads to eye lid inflammation, and eyesight nerve damage in extreme cases (cataracts), as well as skin burns). UV radiation is the predominant danger. Eyes and skin can both be damaged if not protected with a

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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welding shield, gloves and suitable clothing. The UV radiation from an arc is so strong that even reflections can cause eyesight blurring and skin burns. Short wave length UV radiation (130–175 nanometers) causes also the breakdown of oxygen to form ozone The cornea in the eyes is affected by UV radiation. The eyes start to chafe a few hours after being exposed to UV radiation. Usually this happens during the night. In this case, they are weld flash burns. Normally, weld flash burns will disappear after a couple of days without leaving any permanent damage. Repeated weld flash burns can cause permanent eye damage. The skin can react to UV radiation in the same way as sunburn, that is to say the skin becomes red and sore and will eventually start to peel. Therefore, it is essential you use gloves and button up your clothing around your neck so that no bare skin is exposed to radiation. Eye protection from electric arc radiation is accomplished by EN 169 filter with protection factor of 8 (low energy processes), up to 15 (high energy processes).

Protection factor Application 3 brazing and resistance welding 4 & 5 auxiliary welding operation 6 to 8 arc welding I=30-75 A 9 & 10 arc welding I=30-200 A 11 & 12 arc welding I=200-400 A 13 & 14 arc welding I over 400 A 15 arc welding with extremely high I

What measures can you use for skin protection from welding radiation? - wear tightly woven work-weight fabrics to keep UV radiation from reaching your skin. - button up your shirt to protect the skin on the throat and neck. - wear long sleeves and pant legs. - cover your head with a fabric cap to protect the scalp from UV radiation. - protect the back of your head by using a hood. - protect your face from UV radiation by wearing a tight-fitting, opaque welder's helmet. - make sure that all fabric garments are resistant to spark, heat and flame. Keep the fabrics clean and free of combustible materials that could be ignited by a spark. - what are some tips to know when using protective clothing? You should: - wear clothing made from heavyweight, tightly woven, 100% wool or cotton to protect from UV radiation, hot metal, sparks and open flames. Flame retardant treatments become less effective with repeated laundering. - keep clothing clean and free of oils, greases and combustible contaminants. - wear long-sleeved shirts with buttoned cuffs and a collar to protect the neck. Dark colors prevent light reflection. - tape shirt pockets closed to avoid collecting sparks or hot metal or keep them covered with flaps. - pant legs must not have cuffs and must cover the tops of the boots. Cuffs can collect sparks. - wear high top boots fully laced to prevent sparks from entering into the boots. - use fire-resistant boot protectors or spats strapped around the pant legs and boot tops, to prevent sparks from bouncing in the top of the boots. - remove all ignition sources such as matches and butane lighters from pockets. Hot welding sparks may light the matches or ignite leaking lighter fuel.

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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- wear gauntlet-type cuff leather gloves or protective sleeves of similar material, to protect wrists and forearms. Leather is a good electrical insulator if kept dry. - direct any spark spray away from your clothing. - wear leather aprons to protect your chest and lap from sparks when standing or sitting. - wear layers of clothing. To prevent sweating, avoid overdressing in cold weather. Sweaty clothes cause rapid heat loss. Leather welding jackets are not very breathable and can make you sweat if you are overdressed. - wear a fire-resistant skull cap or balaclava hood under your helmet to protect your head from burns and UV radiation. - wear a welder's face shield to protect your face from UV radiation and flying particles. You should not: - wear rings or other jewelery. − wear clothing made from synthetic or synthetic blends. − Eye hazards Why is eye protection important? - Eye injury can occur from the intense light and radiation from a welding arc and from hot slag that can fly off from the weld during cooling, chipping or grinding. - Protect your eyes from welding light by wearing a welder's helmet fitted with a filter shade that is suitable for the type of welding you are doing. - ALWAYS wear safety glasses with side shields or goggles when chipping or grinding a work piece if you are not wearing a welding helmet. What are the various components of eye protection for welders? - eye protection is provided in an assembly of components: - helmet shell - must be opaque to light and resistant to impact, heat and electricity. - outer cover plate made of polycarbonate plastic which protects from UV radiation, impact and scratches. - filter lens made of glass containing a filler, which reduces the amount of light passing through to the eyes. Filters are available in different shade numbers ranging from 2 to 14. The higher the number, the darker the filter and the less light passes through the lens. - clear retainer lens made of plastic prevents any broken pieces of the filter lens from reaching the eye. - gasket made of heat insulating material between the cover lens and the filter lens protects the lens from sudden heat changes, which could cause it to break. In some models the heat insulation is provided by the frame mount instead of a separate gasket. - choose a tight fitting helmet to help reduce light reflection into the helmet through the space between the shell and the head. - wear the helmet correctly. Do not use it as a hand shield. - protect the shade lens from impact and sudden temperature changes that could cause it to crack. - use a cover lens to protect the filter shade lens. Replace the cover lens if it gets scratched or hazy. - make sure to replace the gasket periodically if your helmet uses one. - replace the clear retaining lens to protect your eyes from broken pieces. - clean lenses periodically. - discard pitted or damaged lenses. For Arc welding, the correct filter shade is selected according to the welding process, wire diameter, and operating current. ALWAYS use suggested shade numbers instead of minimum shades.

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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For gas cutting, welding and brazing, the intensity of the light is much less than from arc welding. Lighter shade filter lenses are used with goggles in place of a helmet.

Dust particles or chemicals that can irritate the eyes may be present in many welding areas. Wearing contact lenses is not being advisable in such workplaces. Welding fumes Definition Hazardous substances in welding and allied processes are repairable air polluting substances generated by welding, cutting and allied processes, which at an intolerable concentration may be injurious to health. Classification Hazardous substances generated by welding and allied processes operations can be classified with respect to their occurrence and effects. Occurrence Hazardous substances are generated by welding and allied processes in the form of gases and/or particles. Particulate substances are dispersed as minute solid particles in the air. Inhalable fraction – The fraction of particles, which is inhaled through the mouth and nose into the body: it comprises particle sizes up to and exceeding 100 µm. In the past this fraction was called "total dust". Respirable fraction – The fraction of particles capable of penetrating into the alveoli (air sacs); it comprises particle sizes up to 10µ . In the past this fraction was called "fine dust". Airborne particles generated by welding are very small. In general, they have a diameter of less that 1µ m (in most cases less that 0.1 µm), are therefore respirable and called "welding fume". During thermal cutting and some allied processes the airborne particles generated are only partially respirable. Effects Gaseous and particulate substances generated by welding, cutting and allied processes can be classified according to their effects on different organs of the human body as follows: Lung-stressing (inert) substances – long-term intake of high concentrations leads to a restricted lung function which is due to a decrease in the exchange of oxygen, due to dust deposited in the lungs. These dust deposits are generally not pathogenic, they are reversible. Iron oxides and aluminum oxides are part of this group, for example: Toxic (poisonous) substances – have a toxic effect on the body, if a certain dose (=amount per unit

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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weight of the body) is exceeded. This is a dose-effect-relationship. Slight poisoning leads to mild health disorders; high concentrations of these substances in the inhaled air may cause very serious poisoning which results in death. Toxic substances are, for example, gases such as carbon monoxide, nitrogen oxide and dioxide, ozone, as well as oxides of metals such as copper, lead, zinc in the form of fume and dust. Carcinogenic (cancer-causing) substances – are substances that are known to cause malignant tumors. Welding and cutting operations create hazardous fumes and gases. In order to minimize inhalation of hazardous substances: - ventilation. - portable fans to create air currents that take fumes away from your face. - don’t get too close to an arc welder’s arc. - leave the area immediately and get medical help if you feel sick. Generation Hazardous substances generated by welding and allied processes may arise from: - filler materials - parent materials - shielding gases - coatings - contamination - ambient air At high temperature (due of arc or flame) by physical and/or chemical processes such as: - evaporation - condensation - oxidation - decomposition - pyrolysis - combustion Influencing factors The amount and kind of hazardous substances are also influenced - apart from the processes and materials used - by surface coatings and contamination as well as by the following factors: Current, voltage Higher welding current and welding voltage lead - for identical processes and materials to higher emission rates of hazardous substances. Type of current Higher emission rates are observed with a.c. current than with d.c. current. Diameter of the electrode Emission of hazardous substances increases with the electrode diameter. Type of coating Rutile coated electrodes have the lowest emission rates of hazardous substances while cellulose covered electrodes have the highest. Type of welding Overlaying produces higher emission rates of hazardous substances than joint welding.

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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Allowed values and recommended values In order to reduce the exposure of the welder to dangerous material, the allowed values are named: - OEL - values, or - MAC - defined values. OEL: these limit values specifies the average concentration, which does not normally represent a health risk during eight hours of work a day (level limit value). MAC is the highest allowed concentration of material that develops cancer, but does not lead to disease. MAC is the maximum permissible concentration of a chemical compound present in the air within a working are a which generally does not impair the health of the employee. That are scientifically backed criteria of health protection are definitive here, not the technical and economical feasibility of realizing them in practice. In general, the MAC-value applies only to single substances (pure substances) and is a long-term value, e.g. a time-weighted average concentration for an 8 hour exposure and a 40 hour working week (in four-shift operations for an 40 hours per week average over four successive weeks). Due to the fact that the concentration of different substances in the workplace atmosphere may fluctuate, short-term limit values have been laid down to allow evaluation when the time-weighted average' concentration (peak exposures) is exceeded over a short period. They are limited according to dose, duration, frequency and time intervals. The OEL value is also a medium value that refer to 8-hour daily working cycles, or 40-hours/ week. Short exposures can in some limited time have higher values. This is determined by the character of dangerous material, and duration and frequency of work in shafts. Hazardous substances Gaseous hazardous substances Argon (Ar) Non-toxic. Used as a shielding gas, alone or mixed with other gases. Heavier than air and can accumulate at the base of any closed vessel being welded and can form layers at the bottom of the welding operation in a badly ventilated welding shop. Essential to have extraction and circulation of the atmosphere around the welding point. Helium (He) Non-toxic. Used generally mixed with other gases (e.g. 50% helium 50% argon). Helium is not produced in this country but is imported from the United States and is therefore much more expensive than argon. Oxygen (O2) Non-toxic but it promotes rapid oxidation especially in the pure state. Atmosphere

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roughly 4 parts nitrogen to I part oxygen (the proportions required by the human body to enable it to function). Used in small quantities (1 % to 2%) mixed with argon for stainless steel welding. Carbon monoxide (CO) is generated in critical concentrations during 132 MAG welding with carbon dioxide or during metal-active-gas welding with mixed gases (with a high concentration of carbon dioxide) by thermal decomposition of carbon dioxide (CO2). Furthermore carbon monoxide is generated during any form of combustion with an inadequate oxygen supply. Nitrogen oxides (NOx = NO, NO2) are generated by oxidation of the atmospheric nitrogen (from the oxygen (O2) and the nitrogen (N2) of the air) at the edge of the flame or the arc. Nitrogen monoxide is generated at temperatures exceeding 1000 0C. Nitrogen monoxide oxidizes to nitrogen dioxide in the air at room temperature. Phosgene (COCl2) is generated, in addition to hydrogen chloride (HCl), by heating or by UV-radiation of degreasing agents containing chlorinated hydrocarbons. Gases from coating materials are generated by welding of workpieces with shop primers (surface coatings preventing corrosion) or with other coatings (paints, lacquers). Depending on the chemical composition of these coatings, not only metal oxides are generated, which are particulate, but also gases, e.g. carbon monoxide (CO), formaldehyde (HCHO), toluylene disocyanate, hydrogen cyanide (HCN), hydrogen chloride (HCl). Particulate hazardous substances Chromium-VI-compounds Hexavalent chromium compounds are generated in critical concentrations when using high-alloy covered electrodes for manual metal arc welding and also when welding with high-alloy flux- cored wires containing chromium. Chromium-VI-compounds may also occur in repair welding of materials coated with shop primers containing zinc chromates, a practice followed in the past. It can cause cancer and asthma-like problems. Nickel oxides (NiO, NiO2, Ni2O3) are mainly generated by: - welding with pure nickel and nickel-base alloys (from the filler material) - plasma cutting of high-alloy steel containing nickel (from the parent material) - thermal spraying with nickel-base spraying materials (from the spraying material). Can cause cancer and asthma. Toxic gaseous (hazardous) substances Carbon monoxide (CO) Very poisonous, odorless gas. In higher concentrations the oxygen-carrying capacity of the blood is impeded by the great affinity of carbon monoxide to hemoglobin (hemoglobin is necessary for transporting oxygen in the body). The result is a lack of oxygen in the tissues. Dizziness, lassitude and headache occur at a concentration of 150 ml/ m3 in the breathing zone. A level of 700 ml/ m3 causes fainting, increased pulse and breathing rates, ending in unconsciousness, respiratory paralysis, cardiac arrest and death. MAC value = 33 mg/ m3, 30 ml/m3. Nitrogen oxides (also called nitric oxides or nitrous gases) Nitrogen monoxide (NO) is a colorless, poisonous gas. Nitrogen dioxide (N02) is a brown-red, poisonous gas causing oxidation. Nitrogen dioxide is much more toxic than nitrogen monoxide and acts even in relatively low concentrations as an insidious irritant gas. At the beginning there is an irritation of the air passages and dyspepsia, followed for several hours (in general 4 to 12 hours) by an asymptomatic state, which in severe cases, ends in fatal pulmonary edema (accumulation of fluid

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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in the lungs). MAC value for N02 = 9 mg/ m3; 5 ml/ m3 MAC value for NO = 30 mg/ m3; 25 ml/ m3

Ozone (O3) Ozone is a colorless gas having a penetrating smell and being strongly toxic that is formed during arc welding when oxygen in the air is exerted to ultraviolet radiation. O2 molecules (oxygen) are converted into O3, which is the chemical formula for ozone. Ozone is a strong corrosive and can damage mucous membranes. Characteristic effects of ozone are a pungent or burning feeling in the throat, chest pains and difficulty in breathing. The risk of troublesome ozone levels is greatest when 141 - TIG and 13| MIG welding aluminum. Ozone (O3) is formed when oxygen is exposed to ultra violet (UV) radiation in the wavelength range from 130 to 175 nanometers. The oxygen required may be part of the gas mixture used, may be entrained from the atmosphere or the UV irradiation may reach the area just outside the shielding gas envelope. Ozone is an extremely active, oxidizing gas and will react with many other materials in the immediate area of the arc. Whilst its activity makes it particularly damaging to the respiratory system, its concentration in the breathing zone is usually reduced by its reactions with other materials. Since its generation depends on the intensity of UV radiation, the amount generated increases with current but may decrease with increasing amounts of particulate fume. High levels of ozone can be found however in high current gas metal arc welding of aluminum and high current gas tungsten arc welding. Ozone levels in the arc area may also be controlled by nitric oxide (NO) gas additions. It acts as an irritant gas on the respiratory organs and eyes. It causes an irritation of the throat, dyspepsia and possibly a pulmonary edema. MAC value = 0,2 mg/ m3; 0,1 ml/ m3

Phosgene (COCl2) (Carbonyl chloride or carbon dichloride oxide) Is an odorless, extremely poisonous gas with a musty smell. Initially (3 to 8 hours) there are slight symptoms, which may be followed by heavy irritations of the respiratory tract ending in pulmonary edema (accumulation of fluid in the lungs). MAC value = 0,4 mg/ m3; 0,1 ml/ m3

Removal of hazardous welding dust Protection from dangerous material (Ventilation) Ventilation is mostly the only way to dispose dangerous material, and these procedures are common: - natural ventilation (welding shop should be as large, airy and high as possible) - forced ventilation - vacuuming in the area of origination - wearing gas masks. The type of ventilation depends on the: - procedure - material - duration of operation with electric arc and/or flame torch - size of working surface. Certain procedures can diminish the concentration level of dangerous material as: - alteration of the process - so that less dangerous material is emitted - good positioning of the working object- or the proper position of the human body relative to welding - proper choice of parameters for welding and cutting

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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- optimal working conditions, for example, use of special cleaning equipment, devices that save gas, water resistance. A method of eliminating fumes consists of a suction unit fitted with a filter, from the suction side of which a large diameter, fixed, rigid tube is fitted (spot extractor). This tube passes down the shop (well above head height) and over every welding position or bench. Flexible tubes of a similar large diameter are fitted, which reach down to the welding position or bench. At the lower end of the flexible tube a collecting head is fitted (see Figs. l and 2). Spot extractor An efficient method of ventilating weld smoke is to use a spot extractor to collect the smoke as close to the arc as possible. There are a number of types of spot extractor - spot extractor arms - portable suction vents - welding guns with integrated extractor - fixed extractors (in welding table and fixtures). The spot extractor can be either a central ventilation unit or portable weld smoke filters. Portable weld smoke filters usually only take away solid particles while gas is allowed to pass through. Therefore, it is important that the weld smoke filter is located outdoors when welding in confined spaces so that the gas is transported out. Permanent welding positions (welding tents, etc.) are best equipped with an extractor arm that is connected to a central ventilation unit and can be set to the desired position anywhere in the working zone. Remember to place the vent so that the weld smoke does not pass the breathing zone. When erection welding on large structures, a suction hose with vent can be used that the welder is able to place above the weld joint. It is essential that the vent is placed as close to the weld joint as possible as the suction capacity decreases considerably as the distance increases.

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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Electrostatic precipitation can be utilized where it is inconvenient to install a fixed collector. Upon entering the precipitator, fume particles are charged electrostatically and then pass through an insulated sleeved tube to plates of opposite polarity to that of the particles. They are deposited on the plates, which are part of the filtering elements, and the air issuing from the unit is fume less and is returned to the atmosphere. Figure 17 shows a sectional view of a filter.

Efficient extraction of fumes is essential to the long-term health of the welder, as it may be many years until the effects of fumes inhaled over a long period are apparent. Almost all the toxic substances in the table above have a long-term effect on the respiratory tract and lungs, and in time seriously affect the health of the operator. Ventilation is considered to be sufficient if: - the ceiling height is not less than 5 m. - cross ventilation is not blocked by partitions, equipment, or other structural barriers. − welding is not done in a confined space. − Detectable of internal imperfections of welds (B8) Tack welding When welding the parts must be fixed in correct positions before welding is started. This can be achieved by tack welding. The tack weld should be strong enough to prevent the forces caused by expansion and contraction from deforming the weld joint more than is allowed. Tack welding depends on the task and is governed by following factors: - quality requirements - customer requirements - single or series production

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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- permitted imperfect shape of the weld - workpiece dimensions. Tack welding fillet welds. Tack welding for fillet welds is usually performed directly in the joint in one of the following ways: - permanent tack welds that are covered and fully or partially re-melted by the final welding. - permanent tack welds that are included as a component of the finished weld. - tack welds that are removed as the welding progresses. Tack welds are usually permanent. They are either welded over or the weld ceases in front of one tack weld and continues after it. The effective throat of a tack weld that is being welded over should be smaller than that of the finished weld to facilitate fusion of the tack weld. If the finished weld is to have an effective throat of 5 mm, it is a good idea that the tack weld has an effective throat no greater than 3 mm. For 111 - SMAW welding, the slag must be thoroughly cleaned from the tack welds to prevent slag inclusions in the finished weld. The requirements on the finished weld naturally also apply to the tack weld if the tack weld is permanent and to be included in the finished weld. Tack welding with temporary stays is also used for large steel structures. Length of tack welds and their relative distances Sometimes, the tack welds are specified in detail in welding plans and WPS. For large structures a minimum length of 50 mm for tack welds is often specified. For small workpieces the length of tack weld should be 5-20 mm. The distance between tack welds can also be specified. The reason for specifying the minimum length of tack welds and their relative distance is that they have been calculated and tested to withstand a certain load. These instructions must be followed to avoid unnecessary imperfect shape. There may also be metallurgic reasons to specify a certain length for tack welds on steel. A long tack weld cools slower than a short one. If a tack weld cools too quickly, the material in the HAZ may become too hard and crack. Welding parameters used for the rest of the welding are normally used for tack welding if no special instructions have been specified. Tack welding butt welds: - Permanent tack weld in the root. Tack welding in the root will be included in the finished weld and must therefore fulfil the same requirements as the finished weld. The length of the root tack weld, depending on the thickness of the material and the constraint conditions, is from 5-10 mm up to the maximum length of 100-200 mm using a coated wire electrode. A minimum length of 50 mm for all kinds of tack welds is prescribed for large structures. - Tack welding with round bar or wedge in the joint is a common method of tack welding both plate and pipe. The round bar being used must be of the same quality as the parent material. If this is not available, a round bar with the same, or preferably lower, carbon equivalent than the parent material can be used. This will prevent the material in the HAZ becoming too hard and cracking. The round bar must not contain higher levels of contaminants such as sulphur than the parent material. If wedges are used, they must have the same angles as the joint. The pieces of round bar or wedges are ground away as the root bead is welded. - Tack welding straps is a common method used for erection welding. Similarly to tack welding with round bar or wedges, this method means the perpendicular edge is not damaged. These tack welds are removed as welding proceeds in the same way as tack welding with round bar or wedges. The arc is ignited on one of the joint surfaces and a strap is formed by welding on each surface alternately.

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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MODULE 7 Inspection and testing In order to guarantee the application of all the fabrication procedures and the required properties for the product, appropriate inspections and tests shall be implemented during the manufacturing process Location and frequency of such inspections and/or tests will depend on the contract and/or product standard, on the welding process and on the type of construction. As a general rule the state of inspection and testing of the welded product have to be indicated in some way. Such a means shall be adequate to the type of product; as an example, a Fabrication and Control Plan may be required for big products (on which the testing activities are marked); while routing cards or confined space inside the manufacturing plant shall be sufficient for small series product to indicate the inspection and testing status. Table 5 reports a typical chart for tests to be carried out before, during and after welding operations. In some situations, the signature of the inspector1 shall be required in order to enhance the traceability of the welding and related process activities. Moreover, the reference number of the relevant test report shall be included, if required. All the procedures or instructions relevant to inspection and testing shall be made available to the inspection personnel, and properly controlled. As to NDT, testing activities (method, technique and extension) shall be carried out in consideration of and in accordance with the quality level of the product. Some of those parameters are reported in the manufacturing codes, where the designer chooses the class of the weld taking into consideration all of the above mentioned factors. All these aspects should be considered during the design review phase by the welding coordinator.

1 For some tests or checks (e.g. welding parameters, dimensional checks, visual testing, etc.) the welder or welding

operator itself shall be considered as inspector.

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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TEST

Tests before welding operations Reference procedure Checked

(date) Signature of the

inspector Reference

report

Suitability and validity of welders qualification certificates

Suitability of welding procedure specification

Identity of parent material

Identity of welding consumables

Joint preparation (e.g. Shape and dimensions)

Fit-up, jigging and tacking

Special requirements in the welding procedure specification (e.g. Prevention of distortion)

Arrangement for any production test

Suitability of working conditions for welding, including environment

Tests during welding operations

Preheating / interpass temperature

Welding parameters Cleaning and shape of runs and layers of weld metal;

Back gouging;

Welding sequence;

Correct use and handling of welding consumables;

Control of distortion;

Dimensional check

Tests after welding operations

Compliance with acceptance criteria for Visual Testing

Compliance with acceptance criteria for other NDT examinations (e.g. Radiographic or Ultrasonic Testing)

Compliance for destructive testing (when applicable)

Results and records of post-welding operations (e.g. PWHT)

Dimensional checking.

Template for testing and inspection chart.

Survey of specific weld imperfections and their cause (B5) The main national and European norms and standards that can be applied for establishing the level of acceptance of the imperfections, depending on the used control process, are synthetically presented below. Following will be presented the possible causes of imperfections’ appearance, in relation with the welding process that was used:

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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111 - SMAW troubleshooting

PROBLEM PROBABLE CAUSE REMEDY

1. Arc weak, difficult to strike

a. Insufficient Amperage a. Faulty connection

a. Increase amp setting a. Check and secure all connections including work (ground) clamp

2. Electrode sticks to the plate

b. Insufficient Amperage c. Improper technique

b. Increase amp setting c. Review how to strike the arc

3. Lack of fusion d. Insufficient Amperage e. Travel speed too high

d. Increase amp settings e. Reduce travel speed

4. Burn-through f. Excessive Amperage g. Arc length too short h. Travel speed to slow i. Root opening too wide

f. Reduce amp setting g. Maintain 1/16-in. arc length h. Increase travel speed i. Reduce root opening, use a backup material

5. Inclusions j. Insufficient Amperage k. Excessive arc length l. Uneven oscillations and/or travel speed m. Dirty plate

j. Increase amp settings k. Maintain 1/16-in. arc length l. Move electrode uniformly m. Remove rust, grease, paint, etc.

6. Porosity m. Dirty plate n. Excessive amperage o. Excessive arc length

m. Remove rust, grease, paint, etc. n. Lower amp setting o. Maintain 1/16-in. arc length

7. Undercut q. Excessive arc length r. Improper electrode angle s. Travel speed too high t. Excessive amperage

q. Maintain 1/16-in. arc length r. Direct electrode more into area of undercut s. Reduce travel speed t. Lower amp setting

8. Overlap u. Improper electrode angle v. Travel speed too slow

u. Lower electrode angle v. Increase travel speed

9. Cracking w. Bend too small or too concave x. Failure to fill craters y. Wet or dirty plate z. Wet or dirty electrode

w. Reduce travel speed x. Circle electrode at end of bead, re-strike to fill as required y. Dry or clean plate as needed z. Use only dry and clean electrodes

10. Excess spatter aa. Excessive amperage (fine sized spatter) bb. Excessive arc length (large sized spatter)

aa. Lower amp setting bb. Maintain 1/16-in. arc length

11. Rough appearance

cc. Oscillations spaced too far apart dd. Improper travel angle

cc. Use more oscillations per inch of travel dd. Reduce travel angle

12. Arc blow ee. Work (ground) clamp improperly located ff. Direct current

ee. Move clamp to different place relative to weld ff. Use ac if possible

13. Finger nailing (of flux)

gg. Flux coating cracked or chipped hh. Flux coating not concentric with rod

gg. Use undamaged electrode hh. Exchange for quality electrode

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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141 - TIG welding Discontinuities and defects Discontinuities are interruptions in the typical structure of a weldment, and they may occur in the base metal, weld metal, and heat-affected zones. Discontinuities in a weldment that do not satisfy the requirements of an applicable fabrication code or specification are classified as defects, and are required to be removed because they could impair the performance of that weldment in service.

Problems and corrections Tungsten Inclusions One discontinuity found only in gas tungsten arc welds is tungsten inclusions. Particles of tungsten from the electrode can be embedded in weld when improper welding procedure is used with 141 - TIG process. Typical causes are the following: •contact of electrode tip with molten weld pool •contact of filler metal wit hot tip of electrode •contamination of electrode tip by spatter from the weld pool •exceeding the current limit for a given electrode size or type •extension of electrodes beyond their normal distances from the collet (as with long nozzles) resulting in overheating of the electrode •inadequate tightening of the holding collet or electrode chuck •inadequate shielding gas flow rates or excessive wind drafts resulting in oxidation of the electrode tip •defects such as splits or cracks in the electrode •use of improper shielding gases such as argon-oxygen or argon-CO2 mixtures that are used for gas metal arc welding •corrective steps are obvious once the causes are recognized and the welder is adequately trained.

Lack of Shielding Discontinuities related to the loss of inert gas shielding are tungsten inclusions previously described, porosity, oxide films and inclusions, incomplete fusion, and cracking. The extent to which they occur is strongly related to the characteristics of the metal being welded. In addition, the mechanical properties of titanium, aluminum, nickel, and high-strength alloys can be seriously impaired with loss of inert gas shielding. Gas shielding effectiveness can often be evaluated prior to production welding by making a spot weld and continuing gas flow until the weld has cooled to a low temperature. A bright, silvery spot will be evident if shielding is effective. Welding Problems and Remedies Numerous welding problems may develop while setting up or operating a 141 - TIG operation. Their solution will require careful evaluation of the material, the fixturing, the welding equipment, and the procedures. Some problems that may be encountered and possible remedies are listed in the following table:

PROBLEM PROBABLE CAUSE REMEDY 1. Porosity a. Entrapped gas impurities

(hydrogen, nitrogen, air, water vapor a. Defective gas hose or loose hose connections a. Oil film on base metal

a. Blow out air from all lines before striking arc; remove condensed moisture from lines; use welding grade (99.99%) inert gas a. Check hose and connections

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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for leaks a. Clean with chemical cleaner not prone to break up in arc; DO NOT WELD WHILE BASE METAL IS WET

2. Tungsten contamination of workpiece

Contact starting with electrode Electrode melting and alloying with base metal Touching tungsten to molten pool

Use high frequency starter; use copper striker plate Use less current or larger electrode; use thoriated or zirconium-tungsten electrode Keep tungsten out of molten pool

131/135 MIG/MAG Hydrogen Embrittlement An awareness of the potential problems of hydrogen embrittlement is important, even though it is less likely to occur with 131/135 MIG/MAG, since no hygroscopic flux or coating is used. However other hydrogen sources must be considered. For example, shielding gas must be sufficiently low in moisture content. This should be well controlled by the gas supplier, but may need to be checked. Oil, grease, and drawing compounds on the electrode or the base metal may become potential sources for hydrogen pick-up in the weld metal. Electrode manufacturers are aware of the need for cleanliness and normally take special care to provide a clean electrode. Contaminants may be introduced during handling in the user’s facility. Users who are aware of such possibilities take steps to avoid serous problems, particularly in welding hardenable steels. The same awareness is necessary in welding aluminum, except that the potential problem is porosity caused by relatively low solubility of hydrogen in solidified aluminum, rather than hydrogen embrittlement. Oxygen and Nitrogen Contamination Oxygen and Nitrogen Contamination are potentially greater problems than hydrogen in the 131/135 MIG/MAG process. If the shielding gas is not completely inert or adequately protective, these elements may be readily absorbed from the atmosphere. Both oxides and nitrides can reduce weld metal notch toughness. Weld metal deposited by 131/135 MIG/MAG is not tough as weld metal deposited by gas tungsten arc welding. It should be noted here, however, that oxygen in percentages of up to 5 percent and more can be added to the shielding gas without adversely affecting weld quality. Cleanliness Base metal cleanliness when using 131/135 MIG/MAG is more critical than with 111 - SMAW or submerged arc welding (121 SAW). The fluxing compounds present is 111 - SMAW and 121 SAW scavenge and cleanse the molten weld deposit of oxides and gas-forming compounds. Such fluxing slags are not present in 131/135 MIG/MAG. This places a premium on doing a thorough job of preweld and interpass cleaning. This is particularly true for aluminum, where elaborate procedures for chemical cleaning or mechanical removal of metallic oxides, or both, are applied. Incomplete fusion The reduced heat input common to the short-circuiting mode of 131/135 MIG/MAG results in low penetration into the base metal. This desirable on thin gauge materials and for out-of-position

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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welding. However, an improper welding technique may result in incomplete fusion, especially in root areas or longer groove faces.

Weld Discontinuities Some of the more common weld discontinuities that may occur with the 131/135 MIG/MAG process are listed in the following paragraphs.

Undercutting The following are possible causes of undercutting and their corrective actions:

POSSIBLE CAUSES CORRECTIVE ACTIONS 1. Travel speed to high Use slower travel speed 2. Welding voltage too high Reduce the voltage 3. Excessive welding current Reduce wire feed speed 4. Insufficient dwell Increase dwell at edge of molten weld puddle 5. Torch angle Change angle so arc force can aid in metal

placement

Porosity The following are the possible causes of porosity and their corrective actions:

POSSIBLE CAUSES CORRECTIVE ACTIONS 1. Inadequate shielding gas coverage Optimize the gas flow. Increase gas flow to

displace all air from the weld zone. Decrease excessive gas flow to avoid turbulence and the entrapment of air in the weld zone. Eliminate any leaks in the gas line. Eliminate drafts (from fans, open doors, etc.) blowing into the welding arc. Eliminate frozen (clogged) regulators in CO2 welding by using heaters. Reduce travel speed. Reduce nozzle-to-work distance. Hold gun at the end of weld until molten metal solidifies.

2. Gas contamination Use welding grade shielding gas. 3. Electrode contamination Use only clean and dry electrode. 4. Workpiece contamination Remove all grease, oil, moisture, rust, paint, and

dirt from work surface before welding. Use more highly deoxidizing electrode.

5. Arc voltage too high Reduce voltage 6. Excess contact tube-to-work distance

Reduce stick-out

Incomplete fusion The following are the possible causes of incomplete fusion and their corrective actions:

POSSIBLE CAUSES CORRECTIVE ACTIONS 1. Weld zone surfaces not free of film or excessive oxides

Clean all groove faces and weld zone surfaces of any mill scale impurities prior to welding.

2. Insufficient heat input Increase the wire feed speed and the arc voltage. Reduce electrode extension.

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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3. Too large a weld puddle Minimize excessive weaving to produce a more controllable weld puddle. Increase the travel speed.

4. Improper weld technique When using a weaving technique, dwell momentarily on the sidewalls of the groove. Provide improved access at root of joints. Keep electrode directed at the leading edge of puddle.

5. Improper joint design Use angle groove large enough to allow access to bottom of the groove and sidewalls with proper electrode extension, or use a “J” or “U” groove.

6. Excessive travel speed Reduce travel speed.

Incomplete joint penetration Possible causes of incomplete joint penetration and their corrective actions are:

POSSIBLE CAUSES CORRECTIVE ACTIONS 1. Improper joint preparation Joint design must provide proper access to the

bottom of the groove while maintaining proper electrode extension. Reduce excessively large root gap in butt joints, and increase depth of back gouge.

2. Improper weld technique Maintain electrode angle normal to work surface to achieve maximum penetration. Keep arc on leading edge of the puddle.

3. Inadequate welding current Increase the wire feed speed (welding current). Excessive Melt-Through

The following are possible causes of excessive melt-through and their corrective actions:

POSSIBLE CAUSES CORRECTIVE ACTIONS 1. Excessive heat input Reduce wire feed speed (welding current) and the

voltage. Increase the travel speed. 2. Improper joint penetration Reduce root opening. Increase root face

dimension. Weld Metal Cracks

The following are possible causes of weld metal cracks and their corrective actions:

POSSIBLE CAUSES CORRECTIVE ACTIONS 1. Improper joint design Maintain proper groove dimensions to allow

deposition of adequate filler metal or weld cross section to overcome restraint conditions.

2. Too high a weld depth-to width ratio Either increase arc voltage or decrease the current or both to widen the weld bead or decrease the penetration.

3. Too small a weld bead (particularly fillet and root beads)

Decrease travel speed to increase cross section of deposit.

4. Heat input too high, causing excessive shrinkage and distortion

Reduce either current or voltage, or both. Increase travel speed.

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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5. Hot-shortness Use electrode with higher manganese content (use shorter arc length to minimize loss of manganese across the arc). Adjust the groove angle to allow adequate percentage of filler metal addition. Adjust pass sequence to reduce restrain on weld during cooling. Change to another filler metal providing desired characteristics.

6. High restraint of the joint members Use preheat to reduce magnitude of residual stresses. Adjust welding sequence to reduce restraint conditions.

7. Rapid cooling in the crater at the en of the joint

Eliminate craters by backstepping technique.

Heat-Affected Zone Cracks

Cracking in HAZ is almost always associated with hardenable steels.

POSSIBLE CAUSES CORRECTIVE ACTIONS 1. Hardening in the heat-affected zone Preheat to retard cooling rate. 2. Residual stresses too high Use stress relief heat treatment. 3. Hydrogen embrittlement Use clean electrode and dry shielding gas. Remove

contaminants from the base metal. Hold weld at elevated temperatures for several hours before cooling (temperature and time required to diffuse hydrogen are dependent on base metal type).

Flux Cored Arc Welding (136 - FCAW) Troubleshooting

PROBLEM PROBABLE CAUSE REMEDY 1. Porosity a. Low gas flow Increase gas flowmeter setting clean

spatter clogged nozzle.

b. High gas flow Decrease to eliminate turbulence c. Excessive wind drafts Shield weld zone from draft/wind d. Contaminated gas Check gas source

Check for leak in hoses/fittings e. Contaminated base metal Clean weld joint faces f. Contaminated filler wire Remove drawing compound on wire

Clean oil from rollers Avoid shop dirt Rebake filler wire

g. Insufficient flux in core Change electrode h. Excessive voltage Reset voltage i. Excess electrode stick out Reset stickout & balance current j. Insufficient electrode stick

out (self-shielded electrodes) Reset stickout & balance current

k. Excessive travel speed Adjust speed 2. Incomplete fusion or penetration

l. Improper manipulation Direct electrode to the joint root

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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m. Improper parameters Increase current Reduce travel speed Decrease stickout Reduce wire size Increase travel speed (self-shielded electrodes)

n. Improper joint design Increase root opening Increase root face

3. Cracking o. Excessive joint restrain Reduce restraint Preheat Use more ductile weld metal Employ peening

p. Improper electrode Check formulation and content of the flux

q. Insufficient deoxidizers or inconsistent flux fill in core

Check formulation and content of the flux

111 - SMAW Porosity problems Submerged arc deposited weld metal is usually clean and free of injurious porosity because of the excellent protection offered by the blanket of molten slag. When porosity does occur, it may be found on the weld bead surface or beneath a sound surface. Various factors that may cause porosity are the following: •contaminants in the joint •electrode contamination •contaminants in the flux •insufficient flux coverage •entrapped flux at the bottom of the joint •segregation of constituents in the weld metal •excessive travel speed •slag residue from tack welds made with covered electrodes As with other welding processes, the base metal and electrode must be clean and dry. High travel speeds and associated fast weld metal solidification do not provide time for gas to escape from the molten weld metal. The travel speed can be reduced, but other solutions should be investigated first to avoid higher welding costs. Porosity from covered electrode tack welds can be avoided by using electrodes that will not leave a porosity-causing residue. Cracking Problems Cracking of welds in steel is usually associated with liquid metal cracking (hot cracking). This cause may be traced to the joint geometry, welding variables, or stresses at the point where the weld metal is solidifying. This problem can occur in both butt welds and fillet welds, including grooves and fillet welds simultaneously welded from two sides. One solution to this problem is to keep the depth of the weld bead less than or equal to the width of the face of the weld. Weld bead dimensions may best be measured by sectioning and etching a sample weld. To correct the problem, the welding variables or the joint geometry must be changed. To decrease the depth of penetration compared to the width of the face of the joint, the welding

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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travel speed as well as the welding current can be reduced. Cracking in the weld metal or the heat-affected zone may be caused by diffusible hydrogen in the weld metal. The hydrogen may enter the molten weld pool from the following sources: flux, grease or dirt on the electrode or base metal. Cracking due to diffusible hydrogen in the weld metal is usually associated with low alloy steels and with increasing tensile and yield strengths. It sometimes can occur in carbon steels. There is always some hydrogen present in deposited weld metal, but it must be limited to relatively small amounts. As tensile strength increases, the amount of diffusible hydrogen that can be tolerated in the deposited weld decreases. Cracking due to excessive hydrogen in the weld is called delayed cracking; it usually occurs several hours, up to approximately 72 hours, after the weld has cooled to ambient temperature. It is at ambient temperatures that hydrogen accumulated at small defects in the weld metal or base metal results in cracking. To keep the hydrogen content of the weld metal low: •remove moisture from the flux by baking in an oven (follow the manufacturer’s recommendations). •remove oil, grease, or dirt from the electrode and base material. •increase the work temperature to allow more hydrogen to escape during the welding operation. This may be done by preheating or by post heating the weld joint.

Electroslag troubleshooting

LOCATION PROBLEM CAUSES REMEDY

1. Porosity 1. Insufficient slag depth 1. Moisture, oil, or rust 1. Contaminated or wet flux

1. Increase flux additions 1. Dry or clean workpiece 1. Dry or replace flux

2. Cracking 2. Excessive welding speed 3. Poor form factor 4. Excessive center-to-center distance between electrodes or guide tubes

2. Slow electrode feed rate 3. Reduce current; raise voltage; decrease oscillation speed 4. Decrease spacing between electrodes or guide tubes

Weld

3.Nonmetallic inclusions

5. Rough plate surface 6. Unfused nonmetallics from plate lamination

5.Grind plate surfaces 6. Use better quality plate

4. Lack of fusion

7. Low voltage 8. Excessive welding speed 9. Excessive slag depth 10. Misaligned electrodes or guide tubes 11. Inadequate dwell time 12. Excessive oscillation speed 13. Excessive electrode to shoe distance

7. Increase voltage 8. Decrease electrode feed rate 9. Decrease flux addition; allow slag to overflow 10. Realign electrodes or guide tubes 11. Increase dwell time 12. Slow oscillation speed 13. Increase oscillation width or add another electrode 14. Decrease spacing between electrodes

Fusion line

5. Undercut 14. Too slow welding speed 15. Excessive voltage

15. Increase electrode feed rate 16. Decrease voltage

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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16. Excessive dwell time 17. Inadequate cooling of shoes 18. Poor shoe design 19. Poor fit-up

17. Decrease dwell time 18. Increase cooling water flow to shoes or use larger shoe 19. Redesign groove in shoe 20. Improve fit-up; seal gap with refractory cement dam

Heat-affected zone

6. Cracking 20. High restraint 21. Crack-sensitive material 22. Excessive inclusions in plate

21. Modify fixturing 22. Determine cause of cracking 23. Use better quality plate

Oxyfuel gas welding

Weld quality The appearance of a weld does not necessarily indicate its quality. It discontinuities exist in a weld, they can be grouped into two broad classifications: those that are apparent to visual inspection and those that are not. Visual examination of the underside of a weld will determine whether there is complete penetration and whether there are excessive globules of metal. Inadequate joint penetration may be due to insufficient beveling of the edges, too thick a root face, too high a welding speed, or poor torch and welding rod manipulation. Oversized and undersized welds can be observed readily. Weld gages are available to determine whether a weld has excessive or insufficient reinforcement. Undercut or overlap at the sides of the welds can usually be detected by visual examination. Although other discontinuities, such as incomplete fusion, porosity, and cracking, may not be externally apparent, excessive grain growth and the presence of hard spots cannot be determined visually. Incomplete fusion may be caused by insufficient heating of the base metal, too rapid weld travel, or gas or dirt inclusions. Porosity is a result of entrapped gases, usually carbon monoxide, which may be avoided by careful flame manipulation and adequate fluxing where needed. Hard spots and cracking are result of metallurgical characteristics of the weldment.

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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MODULE 8 Introduction to ISO 14731 Welding Coordination (B9) The tasks and responsibilities of personnel involved in welding coordination activities, shall to be clearly defined because each single activity can be associated with a number of tasks and responsibilities such as: - specification and preparation, - coordination, - control, - inspection, check or witnessing. Where welding coordination is carried out by more than one person, the tasks and responsibilities shall be clearly allocated. Welding coordination is the sole responsibility of the manufacturer. The manufacturer shall appoint at least one responsible welding coordinator. The responsible welding coordinator may delegate specific welding coordination tasks. Welding coordination may be subcontracted. A clear identification of the assigned welding coordinator shall exist in respect to: - position in the manufacturing organization and responsibilities. - the extent of authorization to accept by signing on behalf of the manufacturing organization for e.g. procedure specification, supervision reports, as needed in order to fulfill the assigned tasks. - the extent of authorization to carry out the assigned tasks. For all tasks assigned the welding coordinators shall be able to demonstrate adequate technical knowledge to enable such tasks to be performed satisfactorily. The following factors should be considered: - general technical knowledge; - specialized technical knowledge in welding and related processes relevant to the assigned tasks. Responsible welding coordination personnel should usually have: Comprehensive technical knowledge Welding coordination personnel with full technical knowledge for planning, executing, supervisory and testing of all tasks and responsibilities in welding fabrication. Specific technical knowledge Welding coordination personnel where technical knowledge is sufficient for planning, executing, supervisory and testing of the tasks and responsibilities in welding fabrication within a selective or limited technical field. Basic technical knowledge Welding coordination personnel where technical knowledge is sufficient for planning, executing, supervisory and testing of the tasks and responsibilities within a limited technical field involving only simple welded constructions. Welding related tasks of the welding coordinator Requirements review a) The product standard to be used, together with any supplementary requirements; b) the capability of the manufacturer to meet the prescribed requirements. Technical review a) Parent material(s) specification and welded joint properties;

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b) joint location with relation to the design requirements; c) quality and acceptance requirements for welds; d) location, accessibility and sequence of welds including accessibility for inspection and NDT; e) other welding requirements, e.g. batch testing of consumables, ferrite content of weld metal, ageing, hydrogen content, weld profile; f) dimensions and details of joint preparation and completed weld. Sub-contracting Suitability of any sub-contractor for welding fabrication. Welding personnel Qualification of welders and welding operators, brazers and brazing operators. Equipment a) suitability of welding and associated equipment; b) auxiliaries and equipment supply, identification and handling; c) personal protective equipment and other safety equipment, directly associated with the applicable manufacturing process d) equipment maintenance. Production planning a) reference to the appropriate procedure specifications for welding and allied processes; b) sequence in which the welds are to be made; c) environment conditions (e.g. protection from wind, temperature and rain); d) allocation of qualified personnel; e) equipment for preheating and post-heat treatment including temperature indicator. Qualification of the welding procedures Method and range of qualification. Welding procedure specifications Range of qualification. Work instructions Issue and use of work instruction. Welding consumables a) compatibility; b) delivery conditions; c) any supplementary requirements in welding consumable purchasing specifications including the type of welding consumables certificate; d) storage and handling of welding consumables. Materials a) any supplementary requirements in the material purchasing specifications including the type of material certificate; b) storage and handling of parent material; c) traceability. Inspection and testing before welding a) suitability and validity of welders qualification certificates; b) suitability of welding procedure specification; c) identity of parent material; d) identity of welding consumables; e) joint preparation (e.g. shape and dimensions); f) fit-up, jigging and tacking; g) any special requirements in the welding procedure specification (e.g. prevention of distortion); h) arrangement for any production test;

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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i) suitability of working conditions for welding, including environment. Inspection and testing during welding a) Essential welding parameters (e.g. welding current, arc voltage and travel speed); b) preheating/interpass temperature; c) cleaning and shape of runs and layers of weld metal; d) back gouging; e) welding sequence; f) correct use and handling of welding consumables; g) control of distortion; h) any intermediate examination (e.g. checking dimensions). Inspection and testing after welding a) by visual inspection (completeness of welding, weld dimensions, shape); b) by non-destructive testing; c) by destructive testing; d) form, shape, tolerance and dimensions of the construction; e) results and records of post-operations (e.g. post-weld heat treatment, ageing). Post weld heat treatment Performance in accordance with the specification. Non-conformance and corrective actions Necessary measures and actions (weld repairs, re-assessment of repaired welds, corrective action). Calibration and validation of measuring, inspection and testing equipment Necessary methods and actions. Identification and traceability a) identification of production plans; b) identification of routing cards; c) identification of weld locations in construction; d) identification of non-destructive testing procedures and personnel; e) identification of welding consumable (e.g. designation, trade name, manufacturer of consumables and batch or cast numbers); f) identification and/or traceability of parent material (e.g. type, cast number); g) identification of location of repairs; h) identification of location of temporary attachments; i) traceability for fully mechanized and automatic weld-equipment to specific welds; j) traceability of welder and welding operators to specific welds; k) traceability of welding procedure specification to specific welds. Quality records Preparation and maintenance of the necessary records (including subcontracted activities). Surface inspection on cracks and other surface imperfections by visual testing (B8) Visual examination is a simple, accessible low - cost inspection method, and it is an excellent process-control tool to help avoid subsequent fabrication problems and evaluate workmanship. Visual inspection only identifies surface discontinuities. Consequently, any conscientious quality control program should include a sequence of examinations performed during all phases of fabrication. Visual Inspection is performed in three phases. I. Prior to Welding. II. During Welding.

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III. After Welding. I. Prior to Welding. Some typical action items requiring attention should include the followings: i. Groove angle. ii. Root openings. iii. Joint alignment. iv. Backing. v. Consumable insert. vi. Joint cleanliness. vii. Tack welds viii. Preheat (if required) II. During Welding. Some typical action items requiring attention by those responsible for weld quality should include the followings: a. Check preheat and interpass temperatures. b. Check conformance to Welding Procedure Specification or Weld Schedule. c. Examine weld root pass. d. Examine weld layers. e. Examine second side prior to welding Any of these factors, if ignored could result in discontinuities that could cause serious degradation. III. After Welding. Following welding, some typical action items requiring attention by the visual inspector should include followings: a. Examination of weld surface quality. The typical discontinuities found at the surface are as:

xi. Porosity xii. Lack of fusion xiii. Incomplete joint penetration xiv. Undercut xv. Underfill xvi. Overlap xvii. Cracks xviii. Metallic and non-metallic inclusions xix. Excessive and negative reinforcement xx. Off set xxi. Arc Strikes xxii. Suck back xxiii. Overlay xxiv. Burn thru xxv. Discoloration

b. Verifying weld dimensions c. Verifying dimensional accuracy d. Reviewing subsequent requirements

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This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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Non destructive evaluation of welded joints The application of non-destructive testing is highly dependent on the geometrical conditions of the component, the configuration and accessibility of the joint. This is particularly true for volumetric methods, radiographic and ultrasonic testing. The methods for surface testing visual, magnetic particle, penetrant and eddy current are primarily dependent on the surface conditions and accessibility. This document shows examples for general non destructive evaluation of welded joints in table 1. More specific examples for the evaluation of different weld types representing various applications are shown in table. The examples are intended to give guidance when planning for non-destructive testing during design and fabrication. Each serial number starts with a joint configuration, a) showing the least acceptable configuration for testing, and b) a better joint configuration for testing, and c) the best configuration. The following conventions are also used: + implies that the method is applicable and that the results will satisfy ordinary requirements; (+) implies that the method has a limited application. The method should be supplemented with another method; - implies that the method cannot be used or that the results are not sufficient. General evaluation of welded

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joints:

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Evaluation of specific examples of welded joints

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Welders qualification and qualification standards

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The testing of a welder's skill in accordance with EN 287-1 standard depends on welding techniques and conditions used in which uniform rules are complied with, and standard test pieces are used. The principle of EN 287-1 standard is that a qualification test qualifies the welder not only for the conditions used in the test, but also for all joints which are considered to weld easier on the presumption that the welder has received a particular training and/or has industrial practice within the range of qualification. The qualification test can be used to qualify a welding procedure and a welder provided that all the relevant requirements, e.g. test piece dimensions, are satisfied. Accredited and none-accredited certification Within the European system, there are a number of standards (EN 45000 series) that include regulations for testing the ability of inspection organs to act as third party Body. Its aim is to ensure that the inspection organs acting in Europe carry out equivalent assessments so that the results can be approved by all the member countries. The inspection organs that are approved according to these requirements become accredited for a certain certification task. A Manufacturer may be certified by a Accredited or a non-accredited Certification Body (national or international). Both accreditations are valid but the certification realized by an Accredited Certification Body has a much larger recognition. Maintenance and prolongation of certificates The welder's qualification test certificate issued is valid for a period of two years. This is providing that the welding coordinator or the responsible personnel of the employer can confirm that the welder has been working within the initial range of qualification. This shall be confirmed every six months. Welder's qualification test certificates according to EN 287-1 standard can be prolonged every two years by an examiner/examining body. Before prolongation of the certification takes place, 9.2 needs to be satisfied and also the following conditions need to be confirmed: a) All records and evidence used to support prolongation are traceable to the welder and identifies the WPS that have been used in production; b) Evidence used to support prolongation shall be of a volumetric nature (radiographic testing or ultrasonic testing) or for destructive testing (fracture or bends) made on two welds during the previous six months. Evidence relating to prolongation needs to be retained for a minimum of two years; c) The welds satisfy the acceptance levels for imperfections as specified in clause 7;

d) The test results shall demonstrate that the welder has reproduced the original test conditions, except for thickness and outside pipe diameter.

Essential variables for the certificates The qualification of welders is based on essential variables. For each essential variable a range of qualification is defined. All test pieces shall be welded using the essential variables independently. If the welder has to weld outside the range of qualification a new qualification test is required. The essential variables are: - welding process, - product type (plate and pipe), - type of weld (butt and fillet), - material group, - welding consumable, - dimension (material thickness and outside pipe diameter),

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- welding position, - weld detail (backing, single side welding, both side welding, single layer, multi layer, leftward welding, rightward welding).

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MODULE 9

Delivery of the product. Manufacturing processes such as fusion welding are widely used to produce many products, and for some companies, these are the key production features. Products may range from simple to complex; examples include pressure vessels, domestic and agricultural equipment, cranes, bridges, transport vehicles and other items. These processes exert a profound influence on the cost of manufacture and on the quality of the product. It is therefore important to ensure that these processes are carried out in the most effective way and that appropriate control is exercised over all aspects of the operation. In general, ISO 9001 standard has been developed in order to apply a consistent Quality Management System. However, surface coating, painting, composite manufacture, welding and brazing are considered as “special processes” because the quality of the manufactured product cannot be readily verified by final inspection. In the case of welded products, quality cannot be inspected directly in the product, but has to be built in during fabrication, as even the most extensive and sophisticated non-destructive testing does not improve the quality of the product.

For this reason quality management systems alone may be insufficient to provide adequate assurance that these processes have been carried out correctly. Special controls and requirements are usually needed, which require adequate competence control before, during and after operation. For products to be free from serious problems during production and in service, it is necessary to provide controls from the design phase through material selection, into manufacture and subsequent inspection. For example, poor design may create serious and costly difficulties in the workshop, on site, or in service; incorrect material selection may result in problems, such as cracking in welded joints.

To ensure sound and effective manufacturing, the management needs to understand and appreciate the sources of potential problems and to implement appropriate procedures for their control.

All these considerations lead to the development of specific standards, EN ISO 3834.

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For long a number of people have thought that a defined level of quality, could have primarily been reached, through the implementation of "a manual and several documented procedures", considering the specific technical knowledge, over the fabrication process applied, a matter of secondary interest. Getting the "substantial quality" is quite easy: to recognise a first priority to the specific technical competence on the fabrication process. According to that, the European trend in quality management is clearly moving from a system approach to a process/product approach, claiming for Manufactures to show an evidenced competence. The European Product Directives and their referring European standards, claiming for the fulfilment of specific technical requirements, are exhaustive examples of that. The European Welded Product Directives. The European Directives, have the dual purpose of:

- ensuring the free movement of goods through a technical harmonization and - guaranteeing a high level of public interest protection.

Innovative features of this legislation, addressed to the introduction of CE marking, include:

- the definition of mandatory essential requirements and

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- the setting up of appropriate conformity assessment procedures. The Manufacturer assumes the responsibility of designing and performing a product, bound to be placed on the Community market, retaining the overall control along the whole fabrication course. For that the Manufacturer must give clear evidence of having the necessary competence. Consistently with this responsibility, the Manufacturer is due to ensure that the conformity of his product is assessed to the essential requirements of the applicable Directives. Where a Directive requires products and/or systems to be independently assessed, this must be done by a "Notified Body". However, even if the Notified Body is involved, the responsibility of the product conformity, is primarily on the Manufacturer. The most important European Directives, concerning welded products, are shown in the table:

87/404/EEC Simple Pressure Vessel Directive SPVD 97/23/EC Pressure Equipment Directive PED 99/36/EC Transportable Pressure Equipment Directive TPED 89/106/EEC Construction Product Directive CPD 01/16/EC Conventional Rail System Directive CRSD 96/48/EC High Speed Rail Directive HSRD

The European Welded Product Standards It is up to the Manufacturer to decide which way to go through to fulfil the Directives’ essential requirements, giving evidence of such a fulfilment. The simplest way, often from contractual point of view, is that of the European standards, either harmonised or not. The European harmonised standards, provide a direct presumption of conformity to the corresponding Directives’ essential requirements. The European non harmonised standards, are however an agreed tool that can assure transparency and common understanding; consequently they are becoming a more and more applied reference in manufacturing contracts. The most important applicable European standards, dealing with welding fabrication, are shown in the table:

Directive Product Standard Standard Title

87/404/EEC (SPVD)

EN 286 Simple unfired pressure vessels designed to contain air or nitrogen

97/23/EC (PED)

EN 13445 EN 13480 EN 12952 EN 12953

Unfired Pressure Vessels Metallic Industrial Piping Water-Tube Boilers and Auxiliary Installations Shell Boilers

99/36/EC (TPED)

EN 13530 EN 14025

Cryogenic Vessels – Large transportable vacuum insulated vessels Tanks for transport of dangerous goods

89/106/EEC (CPD)

pr EN 1090 Execution of steel and aluminium structures

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01/16/EC (CRSD) 96/48/EC (HSRD)

pr EN 15085 Welding of railway vehicles and components

All these standards, when facing the welding fabrication process control, mention directly or indirectly the EN ISO 3834.

Example of a pressure vessel. The EN ISO 3834 Stated that the Manufacturer, is fully responsible for his product conformity, an effective control of the whole fabrication course is a non ignorable matter, particularly when a “special process” like welding, with its ancillary activities (e.g.: PWHT, NDT, etc), is involved.

This control over the whole fabrication course is: - not only the correct way to face the responsibility duties,

- but also the best route to fulfil the contractual and regulatory requirements of the marketed product without any waste or extra costs.

On the other hand, it is well known that any new technological innovation or any new regulatory reference applied impacts on the organisational system, which is at the basis of the industrial profit

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making process. The EN ISO 3834 is made of five parts, whose headlines are self-explaining;

- Part 1: Criteria for the selection of the appropriate levels of quality requirements; - Part 2: Comprehensive quality requirements;

- Part 3: Standard quality requirements; - Part 4: Elementary quality requirements;

- Part 5: Applicable documents.

The main criteria, by means of which, the Manufacturer can select the Part of EN ISO 3834 convenient to his fabrication process, are:

- the critical state of the product from safety point of view; - the manufacturing complexity of the product;

- the range of materials used; - the possible metallurgical problems that can arise;

- the welding processes adopted and their level of automation; - the significance, with respect to the expected service, of possible manufacturing defects.

All reported above means that the correct Part of EN ISO 3834 to be chosen is not necessarily depending on the demanded quality of the product, but rather on the real need for the specific fabrication process to be controlled in order to systematically guarantee the fulfilment of the contractual and regulatory requirements. In other words it is the typology of the specific fabrication process the driving parameter for the selection of the correct EN ISO 3834 Part to be consistent with. As already said, all phases of the welding fabrication process are taken into consideration by the EN ISO 3834, that is:

- Contractual and regulatory requirement review;

- Technical requirement review; - Sub-contracting;

- Welding personnel; - Inspection and testing personnel;

- Equipment; - NDT personnel;

- Welding and ancillary activities; - Welding consumables;

- Storage of parent metals; - Post weld heat treatments;

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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- Inspection and testing;

- Non-conformance and corrective actions; - Calibration and validation;

- Identification and traceability; - Quality records.

Being a management standard, the EN ISO 3834 refers to other specific standards, dealing with particular topics or operations concerning the welding fabrication process (e.g.: personnel or procedure qualification, NDT, PWHT, etc.). The EN ISO 3834,is more process oriented and attentive to the technical aspects; in fact:

- not only the quality manual is unneeded as before, - but even the unwritten praxis, rooted on a specific technical competence, tend often to

replace, with an equal value, the documented procedures. Even the non-conformances appear to be primarily evaluated depending on whether they affect or not (and if yes, in what extent) the product real quality (instead of to be only a breach to the quality system), leading therefore to a process oriented assessment.

Identification and traceability Identification of pieces and parts, and the possibility to retrace their position during the manufacturing stages and when delivered to the customer is one of the most effective way to achieve quality of the product and to have feedback about its functionality.

However, it shall be noted that identification and traceability can imply expensive procedures and are therefore not required by the ISO 3834 standard. However, they can be required by standards, fabrication codes or by the customer himself.

Whenever required, it shall be maintained during the manufacturing process, which means that for every piece or component it shall be possible to retrieve its history by marking the parts and controlling the relevant documentation. Documented systems to ensure identification and traceability of the welding operations shall include:

- identification of production plans; - identification of routing cards; - identification of weld locations in construction; - identification of non-destructive testing procedures and personnel; - identification of welding consumable (e.g. designation, trade name, Manufacturer of

consumables and batch or cast numbers); - identification and/or traceability of parent material (e.g. type, cast number); - identification of location of repairs; - identification of location of temporary attachments; - traceability for fully mechanised and automatic weld-equipment for specific welds; - traceability of welder and welding operators of specific welds; - traceability of welding procedure specification of specific welds.

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

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Quality records Quality records shall be retained for a minimum period of five years in the absence of any other specified requirements. Quality records shall include, when applicable:

- record of requirement/technical review; - material certificates; - welding consumable certificates; - welding procedure specifications; - equipment maintenance records; - welding procedure approval records (WPAR); - welder or welding operator qualification certificates; - production plan; - non-destructive testing personnel certificates; - heat treatment procedure specification and records; - non-destructive testing and destructive testing procedures and reports; - dimensional reports; - records of repairs and non-conformance reports.

This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.