PWHT editable document

BASICS OF PWHT

Volume

1

Cameron PWHT Operator’s Guide

Operator’s PWHT Guide

Vol: 1

1

CAMERON PWHT OPERATOR’S GUIDE

Operator’s PWHT Guide Vol: 1

2015Donald K. Robinson

3007 • Hwy.182Bayou Vista, LA 70380

Personal Phone 337-940-1290Email: [email protected]

Table of ContentsContents

What is a Personal Plan of Action?.....................................2Filling out the required Paperwork..............................................4

About the required paperwork:..........................................4Section A, Breakdown of DI-163 Rev. A02:........................4Section B, ASME Section IX:..............................................6Section C, Data & location Maps:.......................................6Section D, PWHT TC Mapping:..........................................7Section E, Contact Information:.........................................9Section F, Quarter Hourly Temperatures:........................10

WS-1684 Rev.01 in a nutshell....................................................11Interpretation of Specifications:.......................................11Requirements for Heating Elements:...............................11Similar or Dissimilar:........................................................13

WS-1991-01in a nutshell............................................................13The main differences between WS-1684, and WS-1991-01:14

Before starting the layout:..................................................................15Acquiring the Proper Specs:...............................................................16

Things to consider before setting up:....................................17Other Considerations:.........................................................17

Laying Out the PWHT:......................................................................19Laying out for pipe 4.0”in. to 16”in diameter:.......................19

Similar thickness welds 4.0”in to 16”in Diameter:....................................19Dissimilar thickness welds 4.0”in to 16”in Diameter:................................20

Layout for dissimilar thickness welds type #1:......................20Layout for dissimilar thickness welds type #2 (ID Heat):.......21

Layout for Pipe with 16”in Diameter or greater:......................................2216”in. or greater diameter:..................................................22

Similar Thickness Weldments over 16”in Diameter..................................22Laying out for similar thickness weldments 16”in. or greater diameter: 22Layout #1 WS-1684 for 16”in or greater diameter pipe:........22

Layout #2 WS-1991 only, with ID thermocouples for 16”in or greater diameter pipe:...................................................................................23Layout #3 WS-1991 only, with ID thermocouples for 16”in or greater diameter pipe:...................................................................................24

Dissimilar Thickness Weldments over 16”in Diameter:.............................25Layout #1 WS-1684 & WS-1991-01 for dissimilar thickness weldments 16”in. or greater diameter:................................................................25Layout #2 WS-1991-01 only, for dissimilar thickness weldments 16”in. or greater diameter:................................................................26

Special Architectures and Non-standard PWHT Layouts:..........................28Layout #1 WS-1991-01 for Non-Tubular or Non-Standard Architectures: 28

Filling out the required Paperwork.......................................................29About the required paperwork:............................................29

Items Not Covered in the Previous Sections:............................31Other Qualified Layouts:...................................................31Basic rules of thumb:........................................................32Non-standard PWHT Case in Point:..................................33

Qualification of PWHT:.....................................................................33Qualification Authority:....................................................33Qualification Requirements (basic):.................................34

What now?....................................................................................40

P R E P A R A T I O N A N D C A M E R O N R E Q U I R E M E N T S

Preparing the part for PWHT

Before each PWHT process it is important to make the sure that the part is properly prepped before laying out the thermocouple locations. Part preparation is one of the most important steps of PWHT. This is the first point of contact you will have with the part. This is also the point when your personal plan of action will come into play.

he first step in prepping for PWHT is making sure that the part has all required traceability. Make sure the stencils have been applied per the routing, with the correct revision number.T

I C O N K E Y

Valuable information Procedure reviewThe next step is to insure that the part is prepared as per section 5.0 of WS-001684 Rev.01 as follows:

5.0 PREPARATION

5.1 The entire area to be heated shall be cleaned of paint, grease, plastic coating or other carbonaceous material or residue, prior to the heat cycle. Carbonaceous materials can contaminate the surface of the metal during the heat cycle and adversely affect the composition of the metal.

5.2 No weldment that has a surface treatment containing lead, cadmium, tantalum or other poisonous material shall be subjected to a post weld heat treatment. Fumes from such materials are TOXIC! Use the same precautions that would be used for welding of such materials.

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Section

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5.3 Contrasting paints made specifically for use with magnetic particle inspection may be left on during the post weld heat treatment cycle provided they are shown by testing to be harmless or the manufacturers literature specifically states that paint can be left on during heat treatment.

Make sure that the part is supported correctly as per section 6.0 of WS-001684 Rev.01

6.0 PHYSICAL SUPPORT

6.1 All weldments shall be physically supported adjacent to each side of the heat zone as well as at reasonable intervals along the length of the structure.

6.2 Support structures shall be able to compensate for linear and circumferential expansion and contraction of the weldment during the heating and cooling cycle without causing stress to the weldment.

6.3 Support structures used shall be able to withstand any temperature and/or pressure related stress that may be created during the heating cycle, without degradation.

Personal Plan of Action

Part preparation is one of the most important steps of PWHT. This is the first point of contact you will have with the part. This is also the point when your personal plan of action will come into play.

What is a Personal Plan of Action?

Your personal plan of action is a list of steps that you take in order to insure that the job is done in an efficient and timely manner.

It is prioritizing and mapping common tasks.

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It is personal quality control.

he course of action you take while working through any process greatly affects the outcome, in speed and quality, of that process.T

Knowing what to do, and in what order things should be done gives you an edge over unskilled labor, and is the proof that you have become proficient in your prescribed tasks.

In part preparation the basic steps are as follows:

Stencil the part per the routing.

o Verify that the stencil is in the right location on the correct part.

Verify the part numbers against the BOM.

◘ Sign off of the stencil operation, and do the log.

Dope/Protect all seals and threaded holes.

Verify grinding details, and do grinding operation

o Have the grinding verified by a Leaderman.

LP the welds per procedure.

◘ Have Leaderman verify LP

Sign operation and do the log.

Clean grease and paint from all areas to be heated.

Blow grinding dust out of the pipe

Notice that stenciling is always first on the list.

At this point the part should be ready to set up for PWHT.

Make your plan and stick to it.

This applies to every step of every process.

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It will make you a more proficient technician.

Filling out the required PaperworkBefore PWHT, departments and vendors that perform the Post Weld Heat Treatment process will be required to document data using the Post Weld Heat Treatment Form.

About the required paperwork:

Department managers/supervisors, vendor representatives, and Post Weld Heat Treatment technicians are responsible for communicating and implementing the requirements of DI-163 Rev. A02 (this is the departmental instruction put in place for all PWHT performed on parts from the Berwick facility).

Section A, Breakdown of DI-163 Rev. A02:Form-226 Rev A03: Section A Procedure

Form-226 Rev A03 Section A must be documented before the setup and before the heating process is started.

All information pertinent to the process used for “section A” shall be completed by the responsible parties involved. This means that the technician is required to fill out “section A” before laying out the PWHT.

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The date must reflect the date at the start of the PWHT process.

Mark the appropriate Process (Local, Oven, Hydrogen Bake Out, Vendor Local, or Vendor Oven) With an X.

Vendor sections will be filled out by your leadsmen.

Work Order, Part Number, & Serial Number shall be documented in the appropriate fields.

Weight of the part must be documented in the weight field.

The dimensions of the part (OD X ID & pipe wall thickness shall be entered into the dimensions field.

The name of the customer and a description of the part must be placed in the Part Description field.

Weld Map #’s are the weld numbers given to weldments during initial mapping procedures on the attached print of the weld data information.

The WPS used for welding shall be documented on the form whether the PWHT is done by a vendor, or completed locally at our facility. In addition to the WPS, the Local PWHT specification (the WS) shall be documented for all PWHT done in-house.

Section B, ASME Section IX:

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Form-226 Rev A03: Section B Post Weld Heat Treat to ASME Section IX

All fields of section B must be documented before the setup and before the heating process is started, except for; Actual Soak Temperature, Actual Soak Time, & Chart Speed per Hour

Actual Soak Temperature, Actual Soak Time, & Chart Speed per Hour shall be documented after the PWHT process has been completed.

In accordance with the WPS, Minimum, Maximum, and Target soak temperatures as well as the Soak Period Range shall be documented before starting PWHT.

The heating and cooling rate of ascent and descent shall be documented in accordance with the appropriate WPS.

Section C, Data & location Maps:

Form-226 Rev A03: Section C TC Data map / Location map.

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Section C must be documented during the PWHT setup phase. All TC’s must be mapped, and all used TC connections must be designated in sections C & D by the technician during the setup process of PWHT.

Thermocouples used must be designated by color or number, and mapped on the circle maps on section D.

The function of the thermocouples shall be determined as either a control or monitor and entered into the proper fields of section C, and also on the chart on section D.

The location of each thermocouple shall be designated in section C by the weld number in relation to the weld map made by the welding department during the weld process, and exact location in relation to the weldment.

Section D, PWHT TC Mapping:

Form-226 Rev A03: Section D PWHT Mapping.

Section D is designed for the PWHT technician to generate a detailed PWHT map, and must be documented during setup, before starting the heating process.

The map outline shall be generated from the proper Cameron drawing, and imported to the form in section D as shown below. Leaderman shall provide prints for this section as needed.

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In addition to providing a PWHT Chart, the Operator shall generate a PWHT Map clearly identifying placement of all Controlling and Monitoring thermocouples (TCs) both External and Internal (when internal applies).

o The map shall show (at a minimum) two (2) views:

1) A circumferential placement of TCs around the part and

2) A "cut away" view that shows the weld and adjoining parts shape and dimensions including an accurate placement of TCs and Pads

Any additional notes or comments concerning the PWHT performed shall be entered into this section. These Include:

o Any anomalies which may have occurred, and how they were fixed.

o Any pertinent information needed in determining the validity of the PWHT.

o And any dispositions given by the Leaderman pertaining to information needed by engineering for explanations of any non-conformance issues.

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Additional pages may be needed for full documentation with notes.

Section E, Contact Information:

Form-226 Rev A03: Section E Contact InformationSection E is designed for entry of contact information for the primary

Leaderman, Primary technician, and vendor representative.

The Leaderman in charge of PWHT must be entered into the primary contact field along with the contact’s phone number and email address.

o This will be the contact for any additional information needed pertaining to the PWHT process concerning the part/welds listed in section A of Form-226 Rev A03

The Cameron representative field must be signed and dated immediately following the PWHT process and when all appropriate information has been collected

o This field must be signed by the authority that supervised the PWHT regardless of whether the PWHT was In-House or Vended to a third party company.

A representative signature is required for any type of PWHT performed, whether it is by local electrical resistance with ceramic pads, or by oven. (vendor or in-house).

If the PWHT is done by a vendor, the production planner field can be filled out, signed, and dated along with the required Cameron Representative field.

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o This field is not mandatory, but rather helps in tracking the process steps from start to finish.

If vendor supplied labor or equipment is used, the vendor representative field must be signed and dated by the attending technician.

o This must only be signed and dated after a Cameron representative has collected, and reviewed all of the required vendor supplied documentation.

Section F, Quarter Hourly Temperatures:

Form-226 Rev A03: Section F Quarter Hourly Temperatures

Section F is to be documented during the heating process and cooling process. This section will be documented by the Post Weld Heat Treatment technician.

Data must be recorded in increments of fifteen minutes.

o Temperatures must be recorded from the start of PWHT to the end of the cool down period when the part cools to below 800°F.

o The Post Weld Heat Treatment technician must write down the time, the minimum thermocouple temperature, and the maximum thermocouple temperature in relation to the equipment being used.

This is MANDATORY for all PWHT procedures done at the Cameron facilities at Patterson and Berwick.

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WS-1684 Rev.01 in a nutshell

The most common WS used at the Cameron Patterson and Berwick facilities is 1684 Rev.01.this specification is to be used by all of Cameron Corporation personnel and their suppliers who are responsible for the performance and quality control of localized PWHT.

The specification is written for the use of ceramic heating elements in the performance of PWHT on “Drilling Riser Tubular Weldments”.

Interpretation of Specifications:

Interpretation of PWHT Specifications

Questions regarding the intent and/or practice of this specification shall be brought to your immediate supervisory authority.

If your immediate supervisor is unable to rectify the query, it is up to supervisory discretion for course of action up to and including contacting Cameron welding engineering department for determination.

Requirements for Heating Elements:

The dimensions of the pads and their placement are main keys to a successful PWHT process. It is for this reason that basic rules have been

provided to insure proper heating of the weldment and adjacent material.

7.1 Flexible ceramic heating elements (pads) shall cover the entire surface area to be heated with no gaps between heaters over 1” (one inch).

o If a gap is larger than 1” it allows for a greater gradient heat loss through the unheated material.

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WS-1684 Rev.01: Section 2.0 Interpretation of

PWHT Processes. Quarter Hourly

Temperatures

WS-1684 Rev.01: Section 7.0 Requirements

for Heating Elements. Quarter Hourly

Temperatures


It also causes a scenario wherein the material is heated unevenly allowing welding stresses to remain in the joined materials.

o Since boosters are normally secondary to the main area to be heated, allowances are made concerning gaps, pad sizes, and temperature requirements.

7.2 Heater elements shall extend beyond the center of the weld cap by no less than five (5) inches on each side.

o The hottest part of the heater element is in the center of each pad, therefore by extending the width of the pad you create a larger optimal heating area.

The more pads you use the more even, stable, and controllable the PWHT will be.

7.3 No overlap or folding of heaters is allowed.

o Overlapping/folding heaters will cause heat to build up in the areas where the fold or overlap exists. This will put more stress on the wiring of the pads resulting in uneven heating, and possibly blowing the heating elements.

If the pads chosen will overlap or need to be folded in order to conform to section 7.1, the technician shall reconfigure (under direction of the supervisory authority,) the pad sizes, placements, or numbers to allow for full conformance to the WS.

7.4 The heating elements cannot exceed 120 In² on an 80-volt PWHT machine, or 60 In² on a 40-volt machine.

o This is the most efficient configuration for a ceramic heating element.

Qualified operations allow for other configurations cleared by welding engineering as dictated to the technicians by supervisory authority.

7.5 support heaters (boosters) can be used when required to better control heat loss through pipe sections, or flanges, and large diameter or thick wall sections.

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o These are also recommended for any section in which a large heat sink is present.

Placement of boosters can be ascertained by either consulting a qualified PWHT of similar architecture, or by the supervisory authority as needed.

7.6 Each heating element must have its own control circuit.

o Splitters are disallowed by Cameron Berwick PWHT supervisory authority, and will not be used.

7.7 Primary heating elements in vicinity of large heat sinks, or disproportionately dissimilar thicknesses shall be shifted to provide adequate heat to the thicker side of the architecture while not overpowering the thinner member.

o Monitoring TC’s must be located no less than 2 times the thickness of the weldment area from the toe of the weld on both sides.

7.8 Heating elements must be secured by tie wire, or metal banding to prevent shifting during the PWHT process.

o Use of fiber tape, plastic or rubber strapping, or any other material that can degrade during the PWHT process is not allowed for securing of heating elements.

7.9 A minimum of 2 pads must be used for pipe diameters 4.0 inches or above.

Similar or Dissimilar:

How to tell if a joint is similar or dissimilar.WHEN FIGURING WHETHER A WELDMENT IS SIMILAR OR

DISSIMILAR USE THIS RULE OF THUMB.

a. If the change in thickness of the material is less than ¼ of the thinner material’s thickness, then the weld is always a similar thickness joint

b. If the change in thickness is more than ¼ of the thinner material’s thickness it is a dissimilar thickness joint, unless the change in thickness is located 4 times the thickness of the thinner material or more away from the weld toe.

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WS-1991-01in a nutshellThe second most common WS used at the Cameron Patterson and Berwick facilities is 1991-01.this specification is to be used by all of Cameron Corporation personnel and their suppliers who are responsible for the performance and quality control of localized PWHT, and Here at the Berwick facility for any pipes from 16” OD and above. This specification is also used for PWHT of structural repairs on Pad Eyes, Gussets, and similar structures.

The main differences between WS-1684, and WS-1991-01:

Section 6.1.5 of WS-1991-01 requires that thermocouples be attached on the opposite side of the main heater placement whenever possible to verify that the entire thickness of the weld reaches and holds the soak temperature. (OD & ID Thermocouples)

6.2.1 part b. If TC’s can be placed on the inside of the pipe, the 2T TC’s are not required. In this case, for each heating element, one TC shall be placed on the OD surface within ¼ inch from the weld, and one TC per element on the ID near the bead when the joint is of similar thickness.

6.3.2 OD TC’s placement will be 1” from the center of the weld on both sides, and on the ID ½ inch from the bead on both sides for any dissimilar weld joint.

6.3.3 If ID thermocouples cannot be used on a dissimilar joint; then in addition to the TC’s located near the edge of the weld, a monitoring TC will be placed 2T of the thicker material from the edge of the weld on the thicker side.

7.1 Wherever possible, heating elements must be placed on the OD and ID

Before starting the layout:

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Section

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Before starting any part layout, there are steps that need to be taken to insure that the technician has full understanding of the process to be used.

What you need to begin PWHThe first step that any technician should take when preparing to layout for the PWHT process is to consult the supervisory authority.T

Your immediate supervisor will most certainly have information concerning the stress operation that is not available through the routing or WS.

He/she will provide you with valuable information concerning the architecture of the part to be stressed, as well as information specifically suited to making a successful PWHT run.

What is supervisory authority?

Simply put, your supervisory authority at any Cameron job is the person/people who are responsible for making sure that the PWHT is run by Cameron required standards.

This will be the Cameron Primary Contact listed in section E of the required Form-226 Rev.A03 or the Cameron representative overseeing PWHT operations at the facility.

Vendor supervisory authority is secondary to the Cameron Representative authority.

The specifications for PWHT at Cameron Patterson/Berwick are non-negotiable aspects of our requirements, and the Cameron Representative is well versed in the Cameron policies.

o DI-163 Rev. A02 Requires that all vendor work done for Cameron Patterson/Berwick comply with the same mandatory standards adhered to by Cameron technicians.

o Cameron requires a quality of service that is (at a minimum) equal to the quality offered by our own PWHT department, including but not limited to

Documentation

Standardization of process

Adherence to departmental instructions

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Supervisory Authority What it is and

what it effects Quarter Hourly

Temperatures


Safety awareness

Attention to details

Reliability

Accountability

The supervisory authority is the individual who holds the position of accountability between the PWHT department and Cameron engineering.

Acquiring the Proper Specs:

It is the technician’s responsibility to be sure that the proper specifications are being used during the PWHT process.

Therefore, the PWHT technician is required to contact the supervisory authority to obtain all pertinent information before starting work on any production parts.

In the case of a vendor PWHT, the vendor technician must contact the Cameron Representative in charge of PWHT. The representative will provide all needed information before any work begins on production parts.

efore you start you will need to obtain Form-226 Rev.A3 from the supervisory authority and verify the information contained therein.B

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Before Layout Requirements to meet before the layout process. Quarter Hourly

Temperatures


Form-226 will be partially filled out for you with a cutaway print of the work-piece for use in mapping your layout. This form is required by Cameron Patterson/Berwick, and must be filled out and submitted back to Cameron when the PWHT is completed.

This would be a good time to discuss the requirements for the layout with the supervisory authority.

Things to consider before setting up:

Many variables must be considered when heat treating tubular weldments not the least of which are:

Circumference of the inner diameter of the weldment for pad selection

Circumference of the outer diameter of the weldment for pad selection

The thickness of the material to be stress relieved

The location of heat sinks, boxes, stabs, flanges, rises, or thickness changes and their proximities in relation to the weldments

The ambient temperature

The humidity

etc.

Other Considerations:

What machines will be needed, and how many

o Cameron uses both 12 & 24 bank 80-volt units

o Typical PWHT requirements dictate more heating elements than typical stress relief operations used at other facilities.

o All controls and monitors must be charted

What consumables will be required for the job

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o Cameron Patterson/Berwick departmental requirements state that all thermocouple wiring must be terminated with the proper connectors (no twisting together, or bunny ears)

These standards are for facility PWHT crews and all 3rd party vendor technicians performing PWHT at the Patterson and Berwick facilities.

o There must be no less than 14” of total heat band on welds of 1”in to 2“in thickness, with no less than 38” inches of insulation cover when heated from one side

o There must be no less than 7”in of total heat band on welds up to 2”in thick, with 24” inches of insulation cover when heated from both sides

o Fiber tape for insulation attachment

Do you have banding or tie wire for securing heating elements to the work-piece? (tape cannot be used to secure pads to the material, nor anything that will carbonize or degrade during the PWHT process.

Do you have enough heating pads, and pads of proper sizes for the stress operation? (Cameron will not supply heating elements to 3rd party vendors)

What WS & WPS will be used

Is there a qualified procedure? (qualified procedures will be provided by Cameron PWHT supervisory authority at the time of briefing)

Are there any extra considerations due to architecture of the part or the position of the areas to be stress relieved? (Heat sinks, dissimilar thicknesses, etc.)

All of these considerations are important to address before starting the layout process because you are a professional, and are expected to be prepared for the job at hand.

Laying Out the PWHT:

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Now that you are ready to begin, Step back and make sure the area is safe for work Do a walk around, and remove any hazards from the surrounding area. (Step back 5 X 5.)

You may now start the Layout process.

Laying out for pipe 4.0”in. to 16”in diameter:

Similar thickness welds 4.0”in to 16”in Diameter:

The most common architecture for weld joints are welds joining material of similar thicknesses

2T=two times the thickness of the weld joint

Pipes of these diameters use WS-1684 requiring one controlling thermocouple per pad, attached within ¼ inch of the weld toe.

o In addition to the controlling TC, there must also be a monitoring thermocouple per pad, attached no less than 2T from the weld toe

The pad must be centered on the controlling TC

o A minimum of 2 pads must be used per weld (one on top and one on the bottom) with no gaps larger than 1”, and no overlapping or folding of the pads

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PWHT layout Requirements for placement of heating elements and thermocouples.

Quarter Hourly Temperatures


Dissimilar thickness welds 4.0”in to 16”in Diameter:

Parts with an architecture where materials of markedly different thicknesses are in close proximity to the weld joint require a more aggressive monitoring layout than those of a similar thickness.

Due to the amount of gradient heat loss through the materials, weldments that are located near heat sinks must be monitored on both sides of the weld face.

Heating elements must have a separate controlling thermocouple from the monitors, and all thermocouples (besides the controlling thermocouple for booster heating elements,) must reach and hold the soak temperature for the required soak period as dictated by the WS.

Layout for dissimilar thickness welds type #1:

2T= 2 times the thickness of the material at the weld joint.

Pipes of this type of architecture require one controlling thermocouple located within ¼ inch of the weld toe, and monitoring TC’s located 2T from the toe of the weld on both sides (as shown above).

o In addition to the controlling and monitoring TC’s, booster heating elements may be required in order to reduce the gradient heat loss through the “heat Sink”/ thicker material, through the length of the pipe section, or both

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Heating elements must be adjusted to allow for proper heating of the thicker material without overpowering the thinner side


Layout for dissimilar thickness welds type #2 (ID Heat):



o In addition to the controlling and monitoring TC’s, booster heating elements may be required in order to reduce the gradient heat loss through the (“Heat Sink”) thicker material, through the length of the pipe section, or both

A booster element has been added to the ID portion of the above part (labeled “B”) and a controlling thermocouple has been attached. This configuration is used whenever access to the ID allows for the proper attachment of a controlling thermocouple to the ID of the heat sink


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Layout for Pipe with 16”in Diameter or greater:

16”in. or greater diameter:When working with pipes of larger diameters, changes

must be made in the process to insure the

integrity of the PWHT. That is why the following layout information has been provided.

Similar Thickness Weldments over 16”in Diameter

Laying out for similar thickness weldments 16”in. or greater diameter:

Layout #1 WS-1684 for 16”in or greater diameter pipe:


Pipes larger than 16”in diameter have many layout options. When using WS-1684, all welds of similar thickness must be laid out in the standard format (as shown above).

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Laying out large diameter tubular weldments:

Requirements for pipe over 16” Dia. Quarter Hourly

Temperatures


One controlling thermocouple must be attached within ¼”in of the weld toe with a monitoring TC located 2T from the toe of the weld

o In addition to the controlling and monitoring TC’s, booster heating elements may be required in order to reduce the gradient heat loss through the length of the pipe section when using this layout format

Notice that no booster has been added to this layout

o A minimum of one heating element in each quadrant of the pipe must be used to insure proper heating of the entire weldment (as shown on the circle map)

Please note that adding heating elements or thermocouples to the ID of the weld using WS-1684 does not change the TC requirements

Layout #2 WS-1991 only, with ID thermocouples for 16”in or greater diameter pipe:

2T thermocouples are not required.

When using WS-1991-01, on welds of similar thickness, the above layout is acceptable per section 6.2.1 paragraph B

One controlling thermocouple must be attached within ¼”in of the weld toe with monitoring TC’s located 2T from the toe of the weld on both sides

o In addition to the controlling and monitoring TC’s, booster heating elements are required (wherever possible) in order to reduce the gradient heat loss through the length of the pipe section when using this layout format

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o A minimum of one heating element in each quadrant of the pipe must be used to insure proper heating of the entire weldment

Please note that wherever possible, heating elements must be added to the ID with minimum heat band requirements from the list in section 7.5

o The addition of heating elements to the ID will not change the layout for WS-1991-01, but will guarantee less gradated readings between the attached TC’s

Layout #3 WS-1991, with no ID thermocouples for 16”in or greater diameter pipe:

In this case 2T thermocouples are required

When using WS-1991-01, on welds of similar thickness, the above layout is also acceptable per section 6.2.1 with no ID thermocouples

One controlling thermocouple must be attached within ¼ ”in of the weld toe with monitoring TC’s located 2T from the toe of the weld

o In addition to the controlling and monitoring TC’s, booster heating elements may be required in order to reduce the gradient heat loss through the length of the pipe section when using this layout format


o A minimum of one heating element in each quadrant of the pipe must be used to insure proper heating of the entire weldment

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Dissimilar Thickness Weldments over 16”in Diameter:When laying out larger diameter tubular weldments that join materials of dissimilar thicknesses, new focus must

be made concerning heat loss and the displacement of heat through the materials. For PWHT this means that any layout used must account for the full

soak temperature throughout the joint and adjacent material.

Layout #1 WS-1684 & WS-1991-01 for dissimilar thickness weldments 16”in. or greater diameter:

In this case 2T thermocouples are required


The heating elements must be adjusted for best control of material temperatures

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o In addition to the controlling and monitoring TC’s, booster heating elements will be required in order to reduce the gradient heat loss through the “heat Sink”, thicker material, through the length of the pipe section, or both

A booster element has been added to the OD portion of the above part (labeled “B”) and a controlling thermocouple has been attached. This configuration is used whenever access to the ID is not possible

WS-1684 makes no adjustments for PWHT with added TC’s or Heating elements on the ID of the weldment


o A minimum of 4 pads must be used per weld (located in each quadrant of the circumference) with no gaps larger than 1”, and no overlapping or folding of the pads

o TC’s can in no case be attached in excess of 24”in from each other, or in excess of ¼ of the OD circumference, whichever is smallest

The controlling and monitoring thermocouples must reach and hold soak temperature and all range temperatures must remain in tolerance for the full duration required by the WPS

1 degree temperature or more above or below the required soak range is nonconformance, and must be noted and addressed immediately

Layout #2 WS-1991-01 only, for dissimilar thickness weldments 16”in. or greater diameter:

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In the case where ID TC’s can be added, 2T thermocouples are not required

Pipes of this type of architecture require one controlling thermocouple located within 1”in of the weld center, and one monitoring TC located 1”in from the center of the weld on the opposite side of the OD and 2 thermocouples located adjacent from the OD TC’s attached to the ID (as shown above).

The heating elements must be adjusted for best control of material temperatures

o In addition to the controlling and monitoring TC’s, booster heating elements may be required in order to reduce the gradient heat loss through the “heat Sink”, thicker material, through the length of the pipe section, or both

This configuration is used whether or not adding heating elements to the ID is possible

WS-1991-01 requires ID heating elements to be added wherever possible


o A minimum of 4 pads must be used per weld (located in each quadrant of the circumference) with no gaps larger than 1”, and no overlapping or folding of the pads

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Booster pads can be added here to help control gradient heat dispersion.

The addition of heating elements on the ID is required wherever possible.


o TC’s can in no case be attached in excess of 24”in from each other, or in excess of ¼ of the OD circumference, whichever is smallest

The controlling and monitoring thermocouples must reach and hold soak temperature and all range temperatures must remain in tolerance for the full duration required by the WPS

1 degree temperature or more above or below the required soak range is nonconformance, and must be noted and addressed immediately

Special Architectures and Non-standard PWHT Layouts:Layout #1 WS-1991-01 for Non-Tubular or Non-Standard Architectures:

There are many cases when technicians will be required to layout PWHT on parts that are more structural in design, or parts that are impossible to stress using a standard layout.

In these cases, there are some rules that help to insure the integrity of the post weld heat treating process.

The layout must be configured in such a way as to insure that the entire weld area has reached and held soak for the time required by the WPS

o As with all layouts, heating element controls located at the weld must show the actual temperature at the weld, and must be within the range and duration required by the WPS

o Monitoring thermocouples must show that the entire heat band has reached and held soak temperature for the full duration required by the WPS, and must remain within the allowed range

Even 1.0°F degrees above the maximum or below the minimum required soak temperature is unacceptable, and must be reported on the PWHT log with the name of the operator, time of the occurrence, nature of the problem, and how it was fixed

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Any time overages or shortages must be reported on the PWHT log with the name of the operator, and the reason for the shortage/overage

The layout must be accepted by the Cameron Supervisory Authority before the wrapping and heating processes

When planning the PWHT layout, Cameron Supervisory Authority overrides all other supervisory input.

You must layout according to the input given by the Cameron Representative. Failure to do so could forfeit your ability to work on Cameron production parts.

If there are any logistical conflicts between any third party vendor’s supervisor and the Cameron Supervisory Authority concerning the layout of any PWHT, authority goes to the Cameron Representative

Failure to adhere to Cameron policy or departmental instructions concerning PWHT will result in an official query of all technicians/operators, supervisors, charts, and traceability reporting material by Cameron QA and Welding Engineering

o If the resulting findings show negligence, damages may be charged against the purchase order in the amount required to rectify the issue, repair the damages, or replace the part (whichever is required for the best outcome for the aftermarket customer)

o In any case of negligence, the technician/operator, and/or supervisor will be re-evaluated, and actions will be taken to reduce the likelihood of such action being repeated including possible dismissal/banning from the Cameron facility, and/or a statement of demerit added to their record of employment

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Filling out the required PaperworkBefore PWHT, departments and vendors that perform the Post Weld Heat Treatment process will be required to document data using the Post Weld Heat Treatment Form.

About the required paperwork:Department managers/supervisors, vendor representatives, and Post Weld Heat Treatment technicians are responsible for communicating and implementing the requirements of DI-163 Rev. A02 (this is the departmental instruction put in place for all PWHT performed on parts from the Berwick facility).

This paperwork is required for every job, every day.

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Items Not Covered in the Previous Sections:So far we have covered Pre-PWHT and Post weld heat treatment basic layouts. Sometimes parts have an architecture that will not allow for a standard layout of pads, insulation, or thermocouples.

In these cases there are a few rules that must be followed.

Other Qualified Layouts:

here are many times when the layout of a particular WS will be impossible due to factors ranging from T

a welded area being too small

a weld joining a vastly dissimilar thickness material

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The short flange neck of this termination spool looks to be a standard PWHT layout part. What is not readily apparent is the rubber flex gasket located at the arrow.The highest temperature allowed for the rubber is 300°F and the temperature at the weld must reach and hold a temperature of 1180°F. It must also hold that

Section

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a weld located near to material with a markedly different tempering temperature

a destructible material within the intended HAZ that cannot be disassembled or moved

Spot repairs, etc.

Basic rules of thumb:

In these cases, several rules apply:

The entire area of the weld must reach and hold soak temperature for the full duration of time required by the WPS used for the welding process (whether using WS-1684 or WS-1991-01)

TC placements must account for the temperatures of the weld and adjacent material (whether using WS-1684 or WS-1991-01)

Wherever possible TC’s must be placed on the opposite side of the weld to insure full penetration of heat through the entire weldment and adjacent material. (whether using WS-1684 or WS-1991-01)

Wherever possible heating elements must be added to the opposite side of the weldment and correlate with the pad and TC placement on the weld face (whether using WS-1684 or WS-1991-01)

Any weldment with less than 2T of face material on each side of the weldment must have TC’s placed at the farthest limit of the face material, and those TC’s must reach and hold soak temperature for the full duration time required by the WPS used for the welding procedure (whether using WS-1684 or WS-1991-01)

o If ID heat can be added, The layout of the TC’s shall, as a minimum, conform to the WS as written

Insulation placement and amounts must conform to the WS as written unless qualified by Welding Engineering

o Insulation is not a second thought. It is a qualified variable written in detail for each WS

Welding Engineering must be contacted for any architecture that does not fully conform to the required WS for the PWHT, and Engineering must make any final decision on the validity of any proposed layout for which

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there is no qualified PWHT procedure (whether using WS-1684 or WS-1991-01)

Please notice that regardless of which WS is used, the same rules apply. The entire area to be treated must be validated to insure proper relief of stresses caused by uneven heating during the welding process.

Non-standard PWHT Case in Point:

In the case of the Flex King weldment (shown at the top of this section), there is a rubber ring located in close proximity to the weldment that must be kept at a temperature less than 300°F.

Therefore, the PWHT requires that monitoring thermocouples be attached at the edge of the rubber at no less than 4 points on the OD and ID. (Equidistance placement and positions related to the hottest area of each heating element.)

Air circulation must also be added to the process in order to keep the metal at the rubber under the maximum allowed temperature of 300°F.

Air is added at 4 positions on the OD, blowing in a circular pattern to remove excess heat from the rubber side of the material.

An air horn is also added to the ID in order to keep the adjacent material at the rubber below the maximum temperature allowed for that material.

The required band of insulation is reduced to keep heat from gradating toward the rubber flex area.

In addition to the specialized layout, monitoring of the gradient heat zone must continue through the cool down phase until the monitors at the rubber do not rise when the air flow is removed.

As you can see, there are quite a few specialized requirements for this part.This illustrates how even a standard layout can require special considerations in order to insure compliance with the WPS, especially with uncommon architectures.

Qualification of PWHT:As stated earlier, there will be times when 2T thermocouples will be impossible to place on the face of the working material. In these cases engineering is the failsafe.

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Qualification Authority:The supervisory authority, as required by Cameron Welding Engineering, WS-1684, and WS-1991-01 may require that a stress relief procedure be “Qualified” before performing PWHT on a production part. Engineering also has the authority to request a qualification test to be run on any architecture at any time, with or without any physical appraisal of the item being questioned.

In those cases it is the responsibility of Welding Engineering to create a test procedure based on the proper WS, and submit it (in writing with the appropriate layout mapping) to the immediate PWHT supervisory authority.

It is then the responsibility of the PWHT department to carry out the procedure before continuing forward with any layout on the production part.

Qualification Requirements (basic):As per section 13.3 of WS-1684, “a capability test shall be conducted to demonstrate the effectiveness of the PWHT procedure.”

13.3.1 requires that a mockup part be made to represent the diameter, wall thickness, and architecture of the production part to be qualified, and must provide sufficient mass to simulate the heat sink of the production part.

An actual weld is not required, but the maximum anticipated widths of the weldment must be marked on the part (OD and ID when possible) to simulate the presence of a weld.

13.3.2 Additional TC’s are required in the following locations:

Centerline of the OD weld at the same circumferential locations as the other OD thermocouples.

On the ID pipe surface at least ½ in. from the toe of the weld at the same circumferential locations as the OD thermocouples (wherever possible).

13.3.3 Engineering or the supervisory authority may require that TC’s be attached at other locations in order to obtain additional information.

All TC’s must be monitored and charted, and all qualifications must be verified by no less than 2 full PWHT runs without failure (to prove conformity to the WS & WPS for the part.)

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A qualification test may be performed by PWHT technicians at the request of Cameron Engineering, and/or the immediate supervisory authority when a need for such a test is suspected.

Layout for PWHT Qualification:When laying out a project for Qualification, many variables must be considered to insure the validity of the proposed process.

Stringent adherence to the guidelines put forth in the WS is always the baseline for any PWHT operation and must be the first consideration during the qualification process.

Qualification Layout Requirements (Limiting Factors):

Before beginning the qualification layout, all architectural aspects of the part must be addressed, TC placements assessed, heat bands and insulation requirements considered in relation to the limiting factors, if any.

Limiting factors consist of any existing circumstances that might disallow adherence to the minimum requirements of the WS.

Elements that may disallow full adherence to a WS include:

Weldments coupled to a material that is disproportionately thicker than the joining material

Joints which do not have sufficient adjacent surface areas to allow for placement of 2T thermocouples.

Parts with architectures that will not allow for heating elements of the proper width to be used

Weldments or repairs, on or near seal areas

Parts with coatings near the area to be heated that cannot be harmed during the PWHT process (Xylan™ etc.)

Parts with rubberized seals or gaskets which cannot be removed prior to the PWHT process, that are located within or near the area to be heated

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As you can see, there are many factors that may come into play which could disallow the placement of pads, thermocouples, or insulation per the specifications of the WS.

In each of these cases, Welding Engineering is the only department with the authority to adjust the proposed procedure.

In any case in which the minimum requirements of the WS cannot be met, the immediate supervisory authority is required to disclose all pertinent information to Welding Engineering in person, or in writing with a full explanation of the factors in question.

It is also required that suggestions for a remedy be submitted at this time, with a proposed mapping of an alternative PWHT layout for perusal by the engineering authorities.

Qualification Layout Requirements (Methodology):

For the PWHT technician, the method used in the qualification process is as follows:

Research and compare procedures performed on objects of a similar architecture

o Note any similarities and dissimilarities between those parts

Use a notebook while doing your research

Include details and maps of the procedures researched

Remember to show TC placements, pad sizes with their placements, and ramp speed (include PWHT charts if available)

Make a supposition/hypothesis about the most viable means to insure that the proper temperatures will be reached, and the proper hold times will be met

In the case of a production part:

o Do not guess (this might work.)

o Do not make a decision based on information alone, or a similar PWHT(this should work)

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o Do not use a process that may have worked on other material, but has not been qualified for your particular part (this works, can we adjust it to match our requirements?)

o Do have engineering consider your gathered information when you submit your layout proposal

o Do not stress relieve the part until engineering approves the process

Design the layout based on your research, and the proposed “viable means” made during the suppositional stage, and map a proposed outcome.

o Mark all required items on your map clearly and accurately

Submit all proposals and information to Welding Engineering with a layout map, and a process deposition (why you believe the process will work)

Engineering will submit a full layout to you based on all available information, and their expertise.

Setup and run the PWHT according to the designed “viable means”

If the layout was successful accept the design

o Run the same layout again to prove the process

If the layout was not successful, report the failure to Welding Engineering.

Use the information gleaned from the research, supposition, design, and run stages to adjust any failed portions of the PWHT toward compliance with the requirements

o Submit the adjusted layout to Welding Engineering

Run again and compare

o If the new layout is successful, run the same layout again to prove the process.

Turn all maps and information into Welding Engineering for final acceptance of the process

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At this point, the PWHT technician is done with the qualification process.

All that remains is the disclosure process. It is at this time that engineering may require more information from the technician to finalize the details of the PWHT runs

What parts are covered by a qualified procedure?

Welding Engineering may apply the same qualified procedure across a wide range of part numbers depending on their similarities, and may also disallow a procedure based on any dissimilarity between parts within the same genre or specifications.

Generally speaking, any qualified process is cleared for application on a “part by part” basis. The accepted process must be applied equally across all part numbers for which the qualified treatment has been assigned.

This means that many parts can be covered by a single qualified procedure.

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The parts that may be covered by a single PWHT procedure are:

Parts with an architecture that allows for a layout that exactly mimics the architecture of an existing qualified procedure

o These will have a thickness that is not more than 10% more or 10% less than the part qualified in the procedure

o They will use the same number of heating elements

o They will use the same size heating elements

o The pad arrangement will not be altered

o There will not be an increase in the width of the weldment of more than .25”in. or ½ T of the thinner member being joined

o There will be no decrease in the distance of the monitoring thermocouples from the edge of the weld

o There will be no change in the insulation type

o There will be no change in the thickness or placement of the insulation

o There will be no change in the output voltage of the power supply used of more than 10%

o There will be no increase in the qualified temperature of more than 50°F

If all of these requirements are met, the “qualified” procedure is acceptable per section 13.4 for Essential Variables in WS-1684.

(Check with Welding Engineering before proceeding with PWHT on any production part for which there is no assigned qualified procedure.)

THE FINAL WORDThe moment you step foot on a Cameron facility, you become much more than a representative of your own personal work ethic. You become part of a team.

Everyone at Cameron has made it their goal to be the best of the best at everything they do, and it shows. They prove it with their quality of work, with

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their production, and their attention to detail.

As part of the team, help will always be available for you regardless of your status. Whether you are a helper just starting out as contract labor, a 3rd party vendor, a new hire, or even just a visitor you are seen as part of a larger picture, and we want that picture to be a masterpiece.

In PWHT, you are elite. The skills involved in what you do are not easy to master, and we will make it our goal to help you to master the processes required by our department.

What now?Wrap tight, layout accurately, map with attention to detail, and never neglect to do your job.

Your job requires that all aspects of the PWHT process are monitored, and validated with detailed traceability. This means that you are responsible for making sure every PWHT you do is done according to the Cameron required procedures.

Bottom line is Do your job, Do it well, Ask questions, and never give any less than your best effort.

Welcome to Cameron.

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Documents

PWHT editable document