114
U V PATEL COLLEGE OF ENGINEERING Page 1 DESIGN AND ANALYSIS OF PRESSURE VESSEL BY JIMIT VYAS AND MAHAVIR SOLANKI GUIDED BY : MR BHAVESH PATEL

Pressure Vessel Design Handbook

Embed Size (px)

DESCRIPTION

All about pressure vessel design.

Citation preview

Page 1: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 1 

DESIGN AND ANALYSIS OF

PRESSURE VESSEL

BY JIMIT VYAS AND MAHAVIR SOLANKI

GUIDED BY : MR BHAVESH PATEL

Page 2: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 2 

ACKNOWLEDGEMENT Certainly, help and encouragement from others are always appreciated, but in

different times, such magnanimity is valued even more. This said, this

Dissertation would never have been completed without the generous help and

support that I received from numerous people along the way.

I wish to express my deepest thanks and gratitude to my elite guide Mr Bhavesh

P Patel, Mechanical Engineering Dept., U.V. Patel College of Engg., Mehsana, for

his invaluable guidance and advice, without that the Dissertation would not

have appear in present shape. He also motivated me at every moment during

entire dissertation.

I also hearty thankful and express deep sense of gratitude to Mr. Bhavesh

Prajapati, senior manager at GMM Pflauder, for giving opportunity to undertake

a dissertation in the industry and furnishing the details and help.

Special thanks to Mr. Ankit Prajapati, Design Engineer, at GMM Pflauder, for

his keen interest and guidance in carrying out the work.

I wish to thank the principal Dr. J. L. Juneja and all the staff members of

Mechatronics & Mechanical Dept., U. V. Patel College of Engg., especially to ,

Prof. J. M. Prajapati, Prof. J. P. Patel, Prof. V. B. Patel, for their co-operation,

guidance and support during the work.

Jimit Vyas & Mahavir Solanki

Page 3: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 3 

ASTRACT The significance of the title of the project comes to front with designing structure of the

pressure vessel for static loading and its assessment by Ansys , is basically a project

concerned with design of different pressure vessel elements such as shell, Dish end

,operating manhole ,support leg based on standards and codes ; and evolution of shell and

dish end analysed by means of ansys .The key feature included in the project is to check

the behaviour of pressure vessel in case of fluctuating load .The [procedural step includes

various aspects such as selecting the material based on ASME codes ,and then designing

on the standards procedures with referring standard manuals based on ASME .Further we

have included the different manufacturing methods practice by the industries and

different aspects of it . And step by step approaches to the NTD method practice by the

industries followed with standards and also included within the report work. This will be

making a clear picture f this method among the reader .

conclusively, this modus operandi of design based on technical standard and

codes ., can be employed on practical design of pressure vessel as per required by the

industry or the problem statement given associated to the field of pressure vessel.

Page 4: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 4 

INTRODUTION: The pressure vessels (i.e. cylinder or tanks) are used to store fluids under pressure. The

fluid being stored may undergo a change of state inside the pressure vessel as in case of

steam boilers or it may combine with other reagents as in a chemical plant. The pressure

vessels are designed with great care because rupture of pressure vessels means an explosion

which may cause loss of life and property. The material of pressure vessels may be brittle

such that cast iron or ductile such as mild steel.

Cylindrical or spherical pressure vessels (e.g., hydraulic cylinders, gun barrels, pipes,

boilers and tanks) are commonly used in industry to carry both liquids and gases under

pressure. When the pressure vessel is exposed to this pressure, the material comprising the

vessel is subjected to pressure loading, and hence stresses, from all directions. The normal

stresses resulting from this pressure are functions of the radius of the element under

consideration, the shape of the pressure vessel (i.e., open ended cylinder, closed end cylinder,

or sphere) as well as the applied pressure.

Two types of analysis are commonly applied to pressure vessels. The most

common method is based on a simple mechanics approach and is applicable to “thin wall”

pressure vessels which by definition have a ratio of inner radius, r, to wall thickness, t, of

r/t≥10. The second method is based on elasticity solution and is always applicable regardless

of the r/t ratio and can be referred to as the solution for “thick wall” pressure vessels. Both

types of analysis are discussed here, although for most engineering applications, the thin wall

pressure vessel can be used.

Page 5: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 5 

Classification of Pressure Vessels

Unfired Cylindrical Pressure Vessels (Classification Based on IS 2825-1969)

a) Class 1 :

Vessels that are to contain lethal or toxic substances.

Vessels designed for the operation below -20 C and

Vessels intended for any other operation not stipulated in the code.

b) Class 2:

vessels which do not fall in the scope of clas1 and class 3 are to be termed as

class2 vessels. The maximum thickness of shell is limited to 38 mm.

c) class 3:

there are vessels for relatively light duties having plate thickness not in excess of

16 mm,

and they are built for working pressures at temperatures not exceeding 250 c and

unfired .

class3 vessels are not recommended for services at temperatutre below 0c.

Page 6: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 6 

Categories Of Welded Joints The term categories specifies the location of the joint in a vessels, but not the

type of joint. These categories are intended for specifying the special requirements

regarding the joint type and degree of inspection. IS-2825 specifies 4 categories of welds.

(Refer fig.)

a) category A: longitudinal welded joints within the main sheet, communicating

chambers ,nozzles and any welded joints within a formed or flat head.

b) Category B: circumferential welded joints with in the main shell, communicating

chambers, nozzles and transitions in diameter including joints between the

transtations and a cylinder at either the large of small end, circumferential welded

joints connecting from heads to main shells to nozzles and to communicating

chambers.

c) Category c: welded joints connecting flanges, tubes sheets and flat heads to main

shells , to formed heads , to nozzles or to communicating chambers and any

welded joints connecting one side plate to another side plate of a flat sided vessel.

d) Category d: welded joints connecting communicating chambers or nozzles to

main sheels ,to heads and to flat sided vessels and those joints connecting nozzles

to communicating chambers.

Page 7: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 7 

STRESS Types of Stresses Tensile

Compressive Shear

Bending Bearing

Axial Discontinuity

Membrane Tensile

Principal Thermal

Tangential Load induced

Strain induced Circumferential

Longitudinal Radial

Normal

Classes of stress Primary Stress

General:

Primary general membrane stress Pm

Primary general bending stress Pb

Primary local stress, PL

Secondary stress:

Secondary membrane stress. Qm

Secondary bending stress Qb

Peak stress. F

Definition and Examples PRIMARY GENERAL STRESS:

These stress act over a full cross section of the vessel. Primary stress are

generally due to internal or external pressure or produced by sustained external

forces and moments. Primary general stress are divided into membrane and

Page 8: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 8 

bending stresses. Calculated value of a primary bending stress may be allowed to

go higher than that of a primary membrane stress.

Primary general membrane stress, Pm

Circumferential and longitudinal stress due to pressure.

Compressive and tensile axial stresses due to wind.

Longitudinal stress due to the bending of the horizontal vessel over the saddles.

Membrane stress in the centre of the flat head.

Membrane stress in the nozzle wall within the area of reinforcement due to

pressure or external loads.

Axial compression due to weight.

Primary general bending stress, Pb

Bending stress in the centre of a flat head or crown of a dished head.

Bending stress in a shallow conical head.

Bending stress in the ligaments of closely spaced openings.

LOCAL PRIMARY MEMBRANE STESS, PL Pm+ membrane stress at local discontinuities:

Head-shell juncture

Cone-cylinder juncture

Nozzle-shell juncture

Shell-flange juncture

Head-skirt juncture

Shell-stiffening ring juncture

Pm+ membrane stresses from local sustained loads:

Support legs

Nozzle loads

Beam supports

Major attachments

SECONDARY STRESS Secondary membrane stress Qm

Axial stress at the juncture of a flange and the hub of the flange

Thermal stresses.

Page 9: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 9 

Membrane stress in the knuckle area of the head.

Membrane stress due to local relenting loads.

Secondary bending stress, Qb

Bending stress at the gross structural discontinuity: nozzle, lugs, etc., (relenting

loadings only).

The nonuniform portion of the stress distribution in a thick-walled vessels due to

internal pressure.

The stress variation of the radial stress due to internal pressure in thick-walled

vessels.

Discontinuity stresses at stiffening or support ring.

Peak Stress F

Stress at the corner of discontinuity.

Thermal stress in a wall caused by a sudden change in the surface temperature.

Thermal stresses in cladding or weld overlay.

Stress due to notch effect. (stress concentration).

LOADINGS Loadings or forces are the “causes” of stress in pressure vessels. Loadings may be

applied over a large portion (general area) of the vessel or over a local area of the

vessel. General and local loads can produce membrane and bending stresses.

These stresses are additive and define the overall state of stress in the vessel or

component.

The stresses applied more or less continuously and uniformly across an entire

section of the vessel are primary stresses.

The stresses due to pressure and wind are primary membrane stresses.

O the other hand, the stresses from the inward radial load could be either a

primary local stress or secondary stress. It is primary local stress if it is produced

from an unrelenting load or a secondary stress if produced by a relenting load.

Page 10: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 10 

If it is a primary stress, the stress will be redistributed; if it is a secondary stress,

the load will relax once slight deformation occurs.

Basically each combination of stresses ( stress categories will have different

allowables, i.e.,

Primary stress: Pm < SE

Primary membrane local (PL):

PL=Pm+ PL <1.5 SE

PL=Pm+Qm< 1.5SE

Primary membrane + secondary (Q):

Pm+Q< 3SE

Loading can be outlined as follows:

Categories of loadings

General loads—Applied more or less continuously across a vessel section.

Pressure loads—Internal or external pressure (design, operating,

hydrotest, and hydrostatic head of liquid).

Moment loads—Due to wind, seismic, erection, transportation.

Compressive/tensile loads—Due to dead weight, installed

equipment, ladders, platforms, piping and vessel contents.

Thermal loads—Hot box design of skirt-head attachment.

Local loads—Due to reactions from supports, internal, attached

Piping, attached equipment, i.e., platforms, mixers, etc.

a. Radial load—Inward or Outward.

b. Shear load—Longitudinal or circumferential.

c. Torsional load.

d. Tangential load.

e. Moment load—Longitudinal or circumferential.

f. Thermal load.

Page 11: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 11 

Types of Loadings 1) Steady loads—Long-term duration, continuous.

a. Internal/external

pressure.

b. Dead weight.

c. Vessel contents.

d. Loading due to attached

piping and equipment.

e. Loadings to and from vessel

supports.

f. Thermal loads.

g. Wind Loads

Types of Loadings 1) Non-steady loads- Short-term duration, Variable.

Shop and field hydro-test

Earthquake

Erection

Transportation

Upset, emergency

Thermal Loads

Startup, shut down

FAILURE IN PRESSURE VESSELS Categories of Failures: Material--Improper Selection of materials; defects in material.

Design—Incorrect design data; inaccurate or incorrect design methods;

inadequate shop testing.

Fabrication – Poor quality control; improper or insufficient fabrication procedures

including welding; heat treatment or forming methods.

Page 12: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 12 

Service—Change of service condition by the user; inexperienced operations or

maintenance personnel; upset conditions. Some types of services which requires

special attention both for selection of materials, design details, and fabrication

methods are as follows:

Lethal

Fatigue (cyclic)

Brittle (low temperature)

High Temperature

High shock or vibration

Vessel contents

Hydrogen

Ammonia

Compressed air

Caustic

Chlorides

TYPES OF FAILURES Elastic deformation—Elastic instability or elastic buckling, vessel geometry, and

stiffness as well as properties of materials are protecting against buckling.

Brittle fracture—Can occur at low or intermediate temperature. Brittle fractures

have occurred in vessels made of low carbon steel in the 40-50 F range during

hydrotest where minor flaws exist.

Excessive plastic deformation—The primary and secondary stress limits as

outlined in ASME Section VIII, Division 2, are intended to prevent excessive

plastic deformation and incremental collapse.

Stress rupture—Creep deformation as a result of fatigue or cyclic loading, i.e.,

progressive fracture. Creep is a time-dependent phenomenon, whereas fatigue is a

cyclic-dependent phenomenon

o TYPES OF FAILURES o Plastic instability—Incremental collapse; incremental collapse is cyclic strain

accumulation or cumulative cyclic deformation. Cumulative damage leads to

instability of vessel by plastic deformation.

Page 13: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 13 

o High Strain—Low cyclic fatigue is strain-governed and occurs mainly in lower-

strength/high-ductile materials.

o Stress corrosion—It is well know that chlorides cause stress corrosion cracking in

stainless steels; likewise caustic service can cause stress corrosion cracking in

carbon steel. Materials selection is critical in these services.

o Corrosion fatigue—Occurs when corrosive and fatigue effects occur

simultaneously. Corrosion can reduce fatigue life by pitting the surface and

propagating cracks. Material selection and fatigue properties are the major

considerations.

SPECIAL PROBLEMS Thick Walled Pressure Vessels

Mono-bloc- Solid vessel wall.

Multilayer—Begins with a core about ½ in. thick and successive layers are

applied. Each layer is vented (except the core) and welded individually with no

overlapping welds.

Multi-wall—Begins with a core about ½ in. to 2 in. thick. Outer layers about the

same thickness are successive “ shrunk fit” over the core. This creates

compressive stress in the core, which is relaxed during pressurization. The process

of compressing layers is called auto-frettage from the French word meaning “self-

hooping.”

Multilayer auto-frettage—Begins with a core about ½ in. thick. Bands or forged

rings are slipped outside and then the core is expanded hydraulically. The core is

stressed into plastic range but below ultimate strength. The outer rings are

maintained at a margin below yield strength. The elastic deformation residual in

Page 14: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 14 

the outer bands induces compressive stress in the core, which is relaxed during

pressurization.

Wire wrapped vessels: Begin with inner core of thickness less than required for

pressure. Core is wrapped with steel cables in tension until the desired auto-

frettage is achieved.

Coil wrapped vessels: Begin with a core that is subsequently wrapped or coiled

with a thin steel sheet until the desired thickness is obtained. Only two

longitudinal welds are used, one attaching the sheet to the core and the final

closures weld. Vessels 5 to 6 ft in diameter for pressure up to 5000psi have been

made in this manner.

THERMAL STRESS Whenever the expansion or contraction that would occur normally as a result of

heating or cooling an object is prevented, thermal stresses are developed. The

stress is always caused by some form of mechanical restrain.

Thermal stresses are “secondary stresses” because they are self-limiting. Thermal

stresses will not cause failure by rupture. They can however, cause failure due to

excessive deformations.

DISCONTINUITY STRESSES Vessel sections of different thickness, material, diameter and change in directions

would all have different displacements if allowed to expand freely. However, since they

are connected in a continuous structure, they must deflect and rotate together. The

stresses in the respective parts at or near the juncture are called discontinuity stresses.

Discontinuity stresses are “ secondary stresses” and are self-limiting.

Discontinuity stresses do become an important factor in fatigue design where

cyclic loading is a consideration.

FATIGUE ANALYSIS When a vessel is subject to repeated loading that could cause failure by the

development of a progressive fracture, the vessel is in cyclic service.

Fatigue analysis can also be a result of thermal vibrations as well as other

loadings.

Page 15: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 15 

In fatigue service the localized stresses at abrupt changes in section, such as at a

head junction or nozzle opening, misalignment, defects in construction, and

thermal gradients are the significant stresses.

NOZZLE REINFORCEMENT

Fig : nozzle reinforcement

Limits.

a. No reinforcement other than that inherent in the construction is required for

nozzles.

3-in. pipe size and smaller in vessel walls 3/8 in. and less.

2-in. pipe size and smaller in vessel walls greater than 3/8 in.

b. Normal reinforcement methods apply to

Page 16: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 16 

Vessels 60-in. diameter and less-1/2 the vessel diameter but not to exceed 20 in.

Vessels greater than 60-in. diameter-1/3 the vessel

diameter but not to exceed 40.in

a. 1b, reinforcement shall be in accordance with para. 1-7 of ASME Code.

2. Strength

It is advisable but not mandatory for reinforcing pad material to be the same as the

vessel material.

a. If a higher strength material is used, either in the pad or in the nozzle neck, no

additional credit may be taken for the higher strength.

3. Thickness

It is recommended that pad be not less then 75% nor more than 150% of the part to

which they are attached.

4. Width

While no minimum is stated, it is recommended that re-pads be atleast 2in wide.

5. Forming:

Reinforcing pads should be formed as closely to the contour of the vessel as

possible. While normally put on the outside of the vessel, re-pads can also be put

inside providing they do not interfere with the vessel’s operation.

8. Openings in flat heads:

Reinforcements for the openings in the flats heads and blind flanges shall be as

follows

a. Openings < ½ head diameter- area to be replaced equals 0.5(tr), or thickness of

head or flange may be increased by:

Doubling C value

Using C=0.75

Increasing head thickness by 1.414

b. Openings>1/2 head diameter –shall be designed as a bolted flange connection.

9. Openings in torispherical heads.

Page 17: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 17 

When a nozzle openings and all its reinforcement fall within the dished portion,

the required thickness of head for reinforcement purpose shall be computed using

M=1

10. Openings in elliptical heads

When a nozzle openings and all its reinforcement fall within 0.8 D of an elliptical

head, the required thickness of the head for reinforcement purpose shall be equal to the

thickness required for a seamless sphere of radius K(D).

11. General

Reinforcement should be calculated in the corroded condition assuming maximum

tolerance (minimum t)

12. Openings through seams.

a. Openings that have been reinforcement may located in a welded joint. ASME

code, division 1, does not allow a welded joint to have two different weld joint

efficiencies

13. Re-pads over seams

If at all possible, pads should not cover weld seams. When unavoidable, the seam

should be ground flush before attaching the pad.

14. Openings near seams

Small nozzles ( for which the code does not require, the reinforcement to be checked)

shall not be located closer than ½ in. to the edge of a main seam.

15. External pressures.

Reinforcement required for openings subject to external pressure only or when

longitudinal compression governs shall only be 50 % of that required for internal pressure

and tr, is thickness required for external pressure

16. Ligaments

When there is a series of closely spaced openings in a vessel shell and it is

impractical to reinforce each opening, the construction is acceptable, provided the

efficiency of the ligaments between the holes is acceptable.

17. Multiple openings:

Page 18: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 18 

a. For two openings closer than 2 times the average diameters and where limits of

reinforcement overlap, the area between the openings shall meet the following

1. Must have a combined area equal to the sum of the two areas

2. No portion of the cross-section shall apply to more than one openings.

3. Any overlap area shall be proportional between the two openings by the ratio of

the diameters.

b. When more than two openings are to be provided with combined reinforcement:

17 b. When more than two openings are to be provided with combined reinforcement:

1. The minimum distance between the two centers is 1 1/3 the average diameters.

2. The area of reinforcement between the two nozzle shall be atleast 50% of the area

required for the two openings.

c. Multiple openings may be reinforced s an opening equal in diameter to that of a

circle circumscribing the multiple openings.

18. Plane of reinforcement.

A correction factor f may be used for “ integrally reinforced” nozzle to compensate

for differences in stress from longitudinal to circumferential axis of the vessel. Value of f

vary from 1.0 for the longitudinal axis to 0.5 for circumferential.

Page 19: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 19 

CHAPTER 2

ENGINEERING GUIDELINES FOR

DESIGN OF PRESSURE VESSELS

Page 20: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 20 

Engineering Design Guidelines For Pressure Vessels

1.0 SCOPE This specification covers the design basis for following equipment:

- Vessels

- Columns

- Reactors

- Spheres

- Storage Tanks

- Steel silos, Bins. Hoppers

- Steel Flare Stacks

2.0 CODES AND STANDARDS The following codes and standards shall be followed unless otherwise specified:

ASME SEC. VIII DIV.1 / For Pressure vessels

IS: 2825

ASME SEC. VIII DIV.2 For Pressure vessels (Selectively for high

pressure / high thickness / critical service)

ASME SEC. VIII DIV.2 For Storage Spheres

ASME SEC. VIII DIV.3 For Pressure vessels (Selectively for high pressure)

API 650 / IS: 803 For Storage Tanks.

API 620 For Low Pressure Storage Tanks,

Page 21: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 21 

API 620 / BS 7777 Cryogenic Storage Tanks (Double Wall)

ASME SEC. VIIIDIV.1 For workmanship of Vessels not categorized under

any other code.

ISO R831/ IBR For Steam producing, steam storage catch water

vessels, condensate flash drums and similar vessels

IS: 9178 / DIN 1055 For Silos Hoppers and Bins

BS: 4994 / ASME SEC X FRP vessels / tanks.`

ASME: B 96.1 Welded Aluminium Alloy Storage Tanks.

ASME SEC.II For material specification

ASTM / IS For material specification (Tanks)

IS: 875 / SITE DATA For wind load consideration

IS: 1893 / SITE DATA For seismic design consideration

ASME SEC. IX For welding.

WRC BULLETIN#

107, 297 / PD 5500 For Local load / stress analysis

3.0 DESIGN CRITERIA Equipment shall be designed in compliance with the latest design code requirements, and

applicable standards/ Specifications.

Page 22: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 22 

4.0 MINIMUM SHELL/HEAD THICKNESS

Minimum thickness shall be as given below

a) For carbon and low alloy steel vessels- 6mm (Including corrosion allowance not

exceeding 3.0mm), but not less than that calculated as per following:

FOR DIAMETERS LESS THAN 2400mm

Wall thickness = Dia/1000 +1.5 + Corrosion Allowance

FOR DIAMETERS 2400mm AND ABOVE

Wall thickness = Dia/1000 +2.5 + Corrosion Allowance

All dimension are in mm.

b) For stainless steel vessel and high alloy vessels -3 mm, but not less than that

calculated as per following for diameter more than 1500mm.

Wall thickness (mm) = Dia/1000 + 2.5

Corrosion Allowance, if any shall be added to minimum thickness.

c) Tangent to Tangent height (H) to Diameter (D) ratio (H/D) greater than 5 shall be

considered as column and designed accordingly.

d) For carbon and low alloy steel columns / towers -8mm (including corrosion allowance

not exceeding 3.0mm.

e) For stainless steel and high alloy columns / towers -5mm.

Corrosion allowance, if any, shall be added to minimum thickness.

Page 23: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 23 

5.0 GENERAL CONSIDERATIONS

5.1 Vessel sizing All Columns Based on inside diameter

All Clad/Lined Vessels Based on inside diameter

Vessels (Thickness>50mm) Based on inside diameter

All Other Vessels Based on outside diameter

Tanks & Spheres Based on inside diameter

5.2 Vessel End Closures : - Unless otherwise specified Deep Torispherical Dished End or 2:1 Ellipsoidal Dished

End as per IS - 4049 shall be used for pressure vessels. Seamless dished end shall be used

for specific services whenever specified by process licensor.

- Hemispherical Ends shall be considered when the thickness of shell exceeds 70mm.

- Flat Covers may be used for atmospheric vessels

- Pipe Caps may be used for vessels diameter < 600mm having no internals.

- Flanged Covers shall be used for Vessels /Columns of Diameter < 900mm having

internals.

- All columns below 900mm shall be provided with intermediate body flanges. Numbers

of Intermediate flanges shall be decided based on column height and type of internals

5.3 Pressure Pressure for each vessel shall be specified in the following manner:

5.3.1 Operating Pressure Maximum pressure likely to occur any time during the lifetime of the vessel

5.3.2 Design Pressure a) When operating pressure is up to 70 Kg./cm2 g , Design pressure shall be equal to

operating pressure plus 10% ( minimum 1Kg./cm2 g ).

Page 24: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 24 

b) When operating pressure is over 70 Kg./cm2 g , Design pressure shall be equal to

operating pressure plus 5% ( minimum 7 Kg./cm2g).

c) Design pressure calculated above shall be at the top of vertical vessel or at the highest

point of horizontal vessel.

d) The design pressure at any lower point is to be determined by adding the maximum

operating liquid head and any pressure gradient within the vessel.

e) Vessels operating under vacuum / partial vacuum shall be designed for an external

pressure of 1.055 Kg./cm2 g.

f) Vessels shall be designed for steam out conditions if specified on process data sheet.

5.3.3 Test Pressure a) Pressure Vessels shall be hydrostatically tested in the fabricators shop to 1.5 /1.3/ 1.25

(depending on design code) times the design pressure corrected for temperature.

b) In addition, all vertical vessels / columns shall be designed so as to permit site testing

of the vessel at a pressure of 1.5/ 1.3 / 1.25 (depending on design code) times the design

pressure measured at the top with the vessel in the vertical position and completely filled

with water. The design shall be based on fully corroded condition.

c) Vessels open to atmosphere shall be tested by filling with water to the top.

d) 1. Pressure Chambers of combination units that have been designed to operate

independently shall be hydrostatically tested to code test pressure as separate vessels i.e.

each chamber shall be tested without pressure in the adjacent chamber.

2. When pressure chambers of combination units have their common elements

designed for maximum differential pressure the common elements shall be subjected to

1.5/ 1.3 times the differential pressure.

3. Coils shall be tested separately to code test pressure.

e) Unless otherwise specified in applicable design code allowable stress during hydro test

in tension shall not exceed 90% of yield point.

f) Storage tanks shall be tested as per applicable code and specifications.

Page 25: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 25 

5.4 Temperature Temperature for each vessel shall be specified in the following manner:

5.4.1 Operating Temperature Maximum / minimum temperature likely to occur any during the lifetime of vessel.

5.4.2 Design temperature a) For vessels operating at 0C and over:

Design temperature shall be equal to maximum operating temperature plus 15 0C.

b) For Vessels operating below 0C:

Design temperature shall be equal to lowest operating temperature.

c) Minimum Design Metal Temperature (MDMT) shall be lower of minimum

atmospheric temperature and minimum operating temperature.

5.5 Corrosion allowance : Unless otherwise specified by Process Licensor, minimum corrosion allowance shall be

considered as follows :

- Carbon Steel, low alloy steel column, Vessels, Spheres : 1.5 mm

- Clad / Lined vessel: Nil

- Storage Tank, shell and bottom : 1.5 mm

- Storage tank, Fixed roof / Floating Roof : Nil

For alloy lined or clad vessels, no corrosion allowance is required on the base metal. The

cladding or lining material (in no case less than 1.5 mm thickness) shall be considered for

corrosion allowance.

Cladding or lining thickness shall not be included in strength calculations.

Corrosion allowance for flange faces of Girth / Body flanges shall be considered equal to

that specified for vessel.

Page 26: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 26 

5.6 Wind Consideration Wind load shall be calculated on the basis of IS : 875 / site data.

a) Drag coefficient for cylindrical vessels shall be 0.7 minimum.

b) Drag coefficient for spherical vessel shall be 0.6 minimum.

5.7 Earthquake Consideration : Earthquake load shall be calculated in accordance with IS : 1893 / site data if specially

developed and available

5.8 Capacity

5.8.1 Tank Capacity shall be specified as Nominal capacity and stored capacity

Nominal capacity for fixed roof tanks be volume of cylindrical shell.

Nominal capacity for floating roof tanks shall be volume of cylindrical shell minus free

board volume.

Stored capacity shall be 90% of Nominal capacity.

5.8.2 Sphere Stored capacity shall be 85% of nominal capacity.

5.9 Manholes : a) Vessels and columns with diameter between 900 and 1000 mm shall be

provided with 450 NB manhole. Vessels and columns with diameter greater than

1000mm shall be provided with 500 NB manhole. However, if required vessels and

columns with diameter 1200mm and above may be provided with 600NB manhole.

b) For storage tanks minimum number of manholes (Size 500mm) shall be as

follows:

Tank Diameter Shell Roof

Dia. < 8m 1 1

Page 27: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 27 

> 8m dia. < 36 dia 2 2

Dia. > 36m 4 2

Floating roofs (pontoon or double deck type) shall be provided with manholes to inspect

the entire interior of the roofs. Size of manhole shall be 500 mm minimum.

5.10 Floating Roof :

5.10.1 Unless otherwise specified floating roof shall be of following construction.

Tank Diameter Type of Roof

12 M < Double Deck Type

>12 M < 60M Pontoon Type

> 60M Double Deck Type

5.10.2 Floating roof design shall be in fabricators scope having proven track record.

Foam seal of proven make shall be provided unless otherwise specified.

5.11 Nozzle size : Unless otherwise specified

- Minimum nozzle Size : 40 NB

- Minimum Nozzle Size, Column : 50 NB

- Safety Valve Nozzle : Based on I.D.

- Self Reinforced Nozzle Neck : Based on I.D.

5.11.1 a) All nozzles and man-ways including self-reinforced type shall be 'set in' type

and attached to vessel with full penetration welds.

b) Self reinforced nozzles up to 80mm NB may be 'set on' type.

5.12 Flanges

Page 28: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 28 

5.12.1 Unless otherwise specified nozzle flanges up to 600NB shall be as per ASME

/ANSI B16.5 and above 600 NB shall be as per ASME /ANSI B 16.47 (SERIES

'B')

5.12.2 For nozzles 100 NB and below, only weld neck flange shall be used. Slip on

flanges may be used for nozzles above 100NB in Class 150 rating only. All

flanges above Class 150 rating shall be weld neck type

5.12.3 Slip on flanges shall not be used in Lethal, Hydrogen, caustic, severe cyclic

service and corrosive service (where corrosion allowance is in excess of 3mm).

5.13 Internals : Removable internals shall be bolted type and bolting shall be stainless steel Type 304,

unless specified otherwise.

5.14 Spares : Gaskets : Two sets for each installed gasket.

Fasteners: 10 % (Minimum two in each size) of installed fasteners.

Sight/Light Glass: 4 sets for each installed glass.

5.15 Vent/Drain Connections: Vessel shall be provided with one number each, vent/drain connection as per following :

VESSEL VOLUME, m3 VENT SIZE, NB (mm) DRAIN SIZE, NB

(mm)

6.0 and smaller 40 40

6.0 to 17.0 40 50

17.0 to 71.0 50 80

71.0 and larger 80 100

Page 29: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 29 

5.16 Pipe Davit : Vertical Vessel / Column having safety valve size > 80 NB and or having internals, shall

be provided with pipe davit per relevant standard.

6.0 INSULATION THICKNESS : As indicated on process data sheet by process licensor

7.0 PAINTING As per Standard Specification, unless otherwise stated.

8.0 MATERIAL SELECTION : Material of various parts of equipment shall be selected per process data sheet guidelines

and proper care shall be taken for the points as given in Annexure- I or as specified.

9.0 SPECIAL CONSIDERATION FOR TALL COLUMN DESIGN

Mechanical design of self supporting Tall Column / Tower shall be carried out for

various load combinations as per Annexure-II

10.0 STATUTORY PROVISIONS :

National laws and statutory provisions together with any local byelaws for the state shall

be complied with.

Annexure : I

1. PRESSURE VESSEL STEEL PLATES ARE PURCHASED TO THE

REQUIREMENT OF THE STANDARD ASME SA-20, WHICH REQUIRES

TESTING OF INDIVIDUAL PLATES FOR LOW TEMPERATURE SERVICE.

CARBON STEEL MATERIAL IS ORDERED TO MEET THE IMPACT

REQUIREMENTS OF SUPPLEMENT OF STANDARD ASME SA 20. TYPICAL

Page 30: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 30 

MATERIAL SPECIFICATION IS AS FOLLOWS SA 516 GR.60. NORMALISED TO

MEET IMPACT REQUIREMENTS PER SUPPLEMENT SS OF SA 20 AT-50F

2. ALL PERMANENT ATTACHMENTS WELDED DIRECTLY TO 9 %

NICKEL STEEL SHOULD BE OF THE SAME MATERIAL OR OF AN AUSTENTIC

STAINLESS STEEL TYPE WHICH CANNOT BE HARDENED BY HEAT

TREATMENT.

3. CHECK FOR IMPACT TESTING REQUIREMENT AS PER UCS-66 FOR

COINCIDENT TEMPERATURE AND PART THICKNESS.

4. SELECTION OF STAINLESS STEEL MATERIAL SHALL BE BASED ON

PROCESS RECOMMENDATION/PROCESS LICENSOR.

5. ATMOSPHERIC/LOW PRESSURE STORAGE TANKS. MATERIAL SHALL

BE SELECTED AS PER API 650 /API 620 AS APPLICABLE.

6. MATERIALS FOR CAUSTIC SERVICE SOUR SERVICE OR SOUR + HIC

SHALL BE SELECTED BASED ON SPECIFIC RECOMMENDATION OF PROCESS

LICENSOR.

7. MATERIAL FOR PRESSURE VESSELS DESIGNED ACCORDING TO

ASME SECTION VIII DIVISION 2 SHALL BE GIVEN SPECIAL CONSIDERATION

AS PER CODE.

8. ALL PIPES SHALL BE OF SEAMLESS CONSTRUCTION.

9. NONFERROUS MATERIAL AND SUPER ALLOYS SHALL BE SELECTED

BASED ON SPECIFIC RECOMMENDATION.

Page 31: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 31 

10. MATERIAL FOR VESSEL /COLUMN SKIRT SHALL BE THE SAME

MATERIAL AS OF VESSEL/ COLUMN SHELL FOR THE UPPER PART WITH A

MINIMUM OF 500MM.

Annexure -II

DESIGN PHILOSOPHY OF TALL COLUMNS

Mechanical design of self-supporting tall column and its anchorage block shall be carried

out considering combination of various loads.

1.0 Loadings

The loadings to be considered in designing a self-supporting tall column/tower shall

include:

1.1 Internal and or external design pressure specified on process data sheets.

1.2 Self weight of column inclusive of piping, platforms, ladders, manholes, nozzles,

trays, welded and removable attachments, insulation and operating liquid etc. The

weight of attachments to be considered shall be as per Table -1 enclosed

Other loading as specified in UG-22 of ASME Code Sec, VIII Div.1. wherever

applicable.

1.3 Seismic forces and moments shall be computed in accordance with IS 1893 (latest

edition). Unless otherwise specified importance factor and damping coefficient

shall be considered as 2 and 2% respectively.

1.4 Basic wind pressure and wind velocity (including that due to winds of short

duration as in squalls) for the computation of forces / moments and dynamic

analysis respectively shall be in accordance with IS 875 (latest edition).

Additional wind loading on column due to external attachments like platforms,

ladders piping and attached equipment should be given due consideration.

1.5 Loadings resulting in localised and gross stresses due to attachment or mounting

of reflux / reboiler / condenser etc.

Page 32: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 32 

2.0 Loading Condition

Analysis shall be carries out for following conditions :

2.1 Erection Condition: Column (un-corroded) erected on foundation without

insulation, platforms, trays etc. but with welded attachments plus full wind on

column.

2.2 Operation Condition: Column (in corroded condition) under design pressure,

including welded items, trays removable internals, piping, platforms, ladder,

reboiler mounted on column, insulating and operating liquid etc. plus full wind on

insulated column with all other projections open to wind, or earthquake force.

2.3 Test Condition: Column (in corroded condition) under test pressure filled with

water plus 33% of specified wind load on uninsulated column considered.

2.4 EARTHQUAKE AND WIND SHALL BE CONSIDERED NOT ACTING

CONCURRENTLY

3.0 Deflection of Column

Maximum allowable deflection at top of column shall be equal to height of the column

divided by 200.

3.1 If the deflection of column exceeds the above allowable limit the thickness of

skirt shall be increased as first trial up to a maximum value equal to the column

thickness and this exercise shall be stopped if the deflection falls within allowable

limit.

3.2 If the above step is inadequate, skirt shall be gradually flared to reduce the

deflection. Flaring of skirt shall be stopped if the deflection falls within limits or

half angle of cone reaches maximum limit of 9 deg.

3.3 If the above two steps prove inadequate in limiting the deflection within

allowable limits, the thickness of shell courses shall be increased one starting

from bottom course above skirt and proceeding upwards till the deflection falls

within allowable limits.

Page 33: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 33 

4.0 Stress Limits

The stresses due to pressure weight wind / seismic loads shall be combined using

maximum principle stress theory for ASME Section VIII Div. I. Thicknesses are

accordingly chosen to keep the within limits as per Table-2.

5.0 Skirt Support Base

Base supporting including base plate, anchor chairs compression ring, foundation bolting

etc. shall be designed based on overturning moment (greater of seismic or wind). A

minimum number of 8 foundation bolts shall be provided. Numbers of foundation bolts

shall be in multiple of four.

6.0 Minimum Hydrotest Pressure

Minimum Hydrotest Pressure (in Horizontal position) shall be equal to 1.3 x design

pressure x temperature correction factor as specified in ASME Code Section VIII Div. I

(Clause UG-99) at top of column.

7.0 Dynamic Analysis

Dynamic analysis of each column shall be carried out for stability under transverse wind

induced vibrations as per standard design practice. The recommended magnification

amplitude shall be limited to tower diameter divided by five.

TABLE-1

DETAILS AND WEIGHT OF COLUMN ATTACHMENT

1. Shape factor for shell (for wind force calculation) : 0.7

2. Weight of trays (with liquid) to be considered. : 120 Kg./m2

3. Weight of plain Ladder: 15 Kg./m

4. Weight of caged ladder: 37 Kg./m

5 Equivalent projection to be considered for wind load on caged ladder : 300 mm

6. Distance of platform below each manhole : Approx. 1000 mm

Page 34: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 34 

7. Maximum distance between consecutive platform : 5000 mm

8. Projection of Platform : 900mm up to 1meter dia. column; 1200 mm for column

dia.> 1 meter, from column insulation surface.

9. Equivalent height of platform (for wind load computation) : 1000 mm

10. Weight of platforms : 170 Kg./m2.

11. Platform shall be considered all around

TABLE -2

ALLOWABLE STRESSES FOR COMBINED LOADING

VESSEL CONDITION / TEMP./ CONDITIONS

TYPE OF STRESSES ERECTION

OPERATING TEST

NEW OR CORRODED NEW CORRODED

CORRODED

TEMPERATURE AMBIENT DESIGN

AMBIENT

LONGITUDINAL KxSxE KxSxE

0.90xY.PxE

LONGITUDINAL COMPRESSIVE

STRESS KxB KxB B

Where

S = Basic allowable Tensile Stress as per Clause UG 23 (a) of ASME Code Sec. VIII

Div.1.

B = 'B' value calculated as per Clause UG-23 (b).

E = Weld joint efficiency of circumferential weld, depending on extent of radiography.

Page 35: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 35 

K = Factor for increasing basic allowable value when wind or seismic load is present, 1.2

as per ASME Sec VIII Div 1.

Note : Allowable stresses in skirt to shell joint shall be as per following :

a) 0.49S, if joint is shear type.

b) 0.70S, if joint is compression type.

Page 36: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 36 

CHAPTER 3

DESIGN PROCEDURE AND

CALUCULATION

Page 37: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 37 

DESIGN THEORY

Circumferential or Hoop Stress A tensile stress acting in a direction tangential to the circumference is called

Circumferential or Hoop Stress. In other words, it is on longitudinal section(or on the

cylinder walls).

Let,

p = Intensity of internal pressure,

d = Internal diameter of the cylinder shell,

l = length of cylinder,

t = Thickness of the shell, and

t1σ = hoop stress for the material of the cylinder.

Now,

We know that total force on a longitudinal section of the shell

= Intensity of pressure × projected Area = p × d × l …..i

and the total resisting force acting on the cylinder walls

= t1σ × 2t × l ….(Q of two section)

…ii

From equation (i) and (ii) , we have

Page 38: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 38 

t1σ × 2t × l = p × d × l or t1σ = p d2t× or t =

t1

p d2×σ

…..ii

Longitudinal Stress A tensile stress acting in a direction of the axis is called longitudinal stress. In

other words, it is a tensile stress acting on the transverse or circumferential section.

Fig of Longitudinal stress

Let t 2σ = Longitudinal stress.

In this case, the total force acting on the transverse section

= Intensity of pressure × Cross- sectional Area

= p × 4π (d)² ………i

and total resisting force = t 2σ × πd.t ………ii

From equation (i) and (ii), we have

t 2σ × πd.t = p × 4π (d) ²

t 2σ = p d4t× or t =

t 2

p d4×σ

Page 39: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 39 

Design of Shell Due to Internal Pressure As discussed in article on thin vessel are cylindrical pressure vessel is subjected to

tangential ( tσ ) and longitudinal ( Lσ ) stresses.

2

i it

P Dt

σ ×= and

4i i

LP D

tσ ×

= where D= mean diameter

= iD + t

Rule The design pressure is taken as 5% to 10% more than internal pressure, where as

the test pressure is taken as 30% more than internal pressure.

Considering the joint efficiency,

The thickness of shell can be found by following procedure,

( )2

i iP D tt

η σ × +× =

2 ( )i it P D tη σ× × = × +

2( )

i i

i

P DtPη σ

×=

× −

Design of Elliptical Head: Elliptical heads are suitable for cylinders subjected to pressures over 1.5 MPa. The

shallow forming reduces manufacturing cost. It’s thickness can be calculated by the

following equation:

Page 40: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 40 

t = 2i ip d W

where,

id = Major axis of ellipse

W= Stress intensification factor

21 (2 )6

W k= +

Where , k = Major Axis DiameterMajor Axis Diameter

= i0.5dc

Rule > Generally, k = 2 ( how ever k should not be greater than 2.6)

21 (2 2 )6

W = +

= 1

2

Pi di WtJσ

⋅ ⋅=

⋅ ⋅

Design of Manhole Let,

id = internal dia. Of nozzle

d = id + 2 CA

where, CA = corrosion Allowance in mm

t = Actual thickness of shell in mm

tr = require thickness as per calculation in mm.

tn = Actual thickness of nozzle

trn = Required thickness as per calculation in mm

2rn

Pi DiPit σ η

×=

× × −

Page 41: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 41 

1actualh = Height of the nozzle above the shell in mm

2actualh = Height of the nozzle below the shell in mm

1h = Height till where the effect of the nozzle persists above the shell in mm

2h = Height till where the effect of the nozzle persists below the shell in mm

To calculate 1h and 2h consider a term ‘h’

h = 2.5 ( t – CA) or h = 2.5 ( tn – CA) (whichever is smaller)

1h = h or 1actualh (whichever is smaller)

2h = h or 2actualh (whichever is smaller)

X = Distance where the effect of the nozzle persists in mm on each side of the

centre line

X = d.

or X = id2

+ t + tn -3CA (whichever is maximum)

opd = outer dia. Of Reinforcing Pad in mm

ipd = inner dia. Of Reinforcing Pad in mm

pt = Thickness of Reinforcing Pad in mm

Page 42: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 42 

Area Calculation Area pertaining to material removed, A = d × tr

Excess area in the Shell, A1 = (2X – d ) ( t – tr –CA)

Excess area in the Nozzle, A2 = 2h1(tn – trn – CA)

Excess area in the nozzle inside the shell A3 = 2 h2 (tn – 2CA)

Area Required, rA = ( opd - ipd ) pt

Area required, Ar = A – ( A1 + A2 + A3)

When Ar = 0 or negative, no reinforcement is necessary as the vessel thickness self

compensates.

Design of Leg:

A) Legs support

In certain cases, legs can be made detachable to the vessel. These legs can

be bolted to plates. The design for leg supports is similar to that for bracket support. If

the legs are welded to the shell, then the shear stresses in the weld will be given by:

22 1 22

0.707W oW W

Ww P KPH D mmt L n

τ ∑= =

× × ×

0.707WW W

Wt L n

τ ∑=

× × ×

Where, Wt = Weld Height

WL = Weld Length.

These types of supports are suitable only for small vessels as there is a concentrated

local stress at the joint.

B) Wind Load

Wind load can be estimated as :

w1P = K P1 H oD

This equation is valid for heights upto 20m. Beyond 20m, the wind pressure is

higher and hence for heights above 20m.

2 2 2w oP KP H D=

Generally, 1P lies between 400 N/ 2mm and 2P may be upto 2000 N/ 2m .

Therefore, the bending moment due to wind at the base will be

Page 43: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 43 

(IF H ≤ 20 m) wM = w1 1P h2

(IF H> 20m) wM = w1 1P h2

+ w 2P ( 1h + 2h2

)

Therefore, bending stress will be,

bwσ = wMz

Where Z= section Modulus

The wind load would create tensile stress on the wind side and compressive on the other

side.

Page 44: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 44 

Design Calculation 1) Thickness of cylinder

Given data Internal pressure (P) = 0.588 MPa

Internal Diameter (Di) = 496mm

Corrosion Allowance (CA) = Nil.

Joint Efficiency for shell = 1.

As per Equation,

2

Pi DitPiσ η

×=

× × − + CA

(0.588) (496)2 137 1 0.588

t ×=

× × − (Q CA is NIL)

= 1.066

∴ t = 1.066mm

2) Elliptical Head

21 (2 )6

W k= +

where ,

k = Major Axis DiameterMajor Axis Diameter

= i0.5dc

k = 2

Rule > Generally, k = 2 ( how ever k should not be greater than 2.6)

21 (2 2 )6

W = +

= 1

2

Pi di WtJσ

⋅ ⋅=

⋅ ⋅

where,

Page 45: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 45 

di = Major axis of ellipse = 496mm

W = Stress intensification factor = 1

2

Pi di WtJσ

⋅ ⋅=

⋅ ⋅

0.588 496 12 137 1

t × ×=

× ×

= 1.06 mm

∴ t = 1.06 mm

3) Design Of Manhole INLET NOZZLE (N1)

GIVEN DATA

Internal pressure (Pi) = 0.588 N/ 2mm

Internal diameter (Di) = 496 mm

Thickness (t) = 6 mm.

CA = NIL

Joint Efficiency (η ) = 1

Internal diameter of nozzle (di) = 254.51 mm

d = di + CA = 254.51 mm.

tr = require thickness = 1.066 mm.

tn = Actual thickness of nozzle = 9.27 mm.

trn = Required thickness as per calculation in mm.

1

0.588 254.512 137 1 0.588A ×

=× × − 2rn

Pi DiPit σ η

×=

× × −

0.588 254.512 137 1 0.588rnt ×

=× × −

Page 46: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 46 

= 0.547 mm.

rnt = 0.547 mm.

Area Calculation Area Pertaining to material removed, A = d × tr

= 254.51× 1.066

= 271.3 2mm

Excess area in the shell, A1 = (2X – d ) ( t – tr –CA)

Generally,

X = d = 254.51 mm.

X = di + t + tn -3CA

2

= 254.51 + 6 +9.27 – 0

2

= 142.52 mm.

( Take X whichever maximum)

Therefore,

A = (2×254.51-254.51)(6-1.066-0)

= 1255.75 2mm

Excess area in the nozzle, A2 = 2h1(tn – trn – CA)

h = 2.5 ( t – CA) or h = 2.5 ( tn – CA)

= 2.5 ×6 = 2.5 (9.27)

= 15mm = 23.175 mm

( Take X whichever smaller)

h1 = h2 = h = 15 mm.

Therefore,

A2 = 2×15 ( 9.27 – 0.547 – 0)

= 261.69 2mm

Excess area in the nozzle inside the shell A3 = 2 h2 (tn – 2CA)

= 2× 15 ( 9.27-0)

Page 47: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 47 

= 278.1 2mm

Area required Ar = A – ( A1 + A2 + A3)

= -1524.24

As Ar is –ve or zero reinforcement is not necessary.

4) Design of leg

Wind load Here ,

K = Coefficient depending on shape factor = 0.7

P1= Wind pressure = 730 N/ 2mm

H = Height of the vessel above foundation =2413 mm

oD = Outer Diameter Of Vessels

Wind load can be estimated as :

w1P = K P1 H oD

= 0.7×730×2.413×0.508

= 626.38 N

(IF H ≤ 20 m) wM = w1 1P h2

(IF H> 20m) wM = w1 1P h2

+ w 2P ( 1h + 2h2

)

Here we use ,

wM = w1 1P h2

= 626.38 × 1206.47

= 755.41 N.m

Here we use I- Section,

Therefore, Z = section Modulus

Z = 3 3

1 1bh b h6h−

Page 48: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 48 

= 3 34t(5t) 3t(3t)6(5t)−

= 13.96 3t

Therefore, Bending Stress will be ,

bwσ = wMz

(as bwσ = 350 N/mm²)

350× 610 = 3

755.4113.96t

t = 5.36 × 310− m

∴ L = 1233

+ 1233

+ 1834

= 1916 mm

Page 49: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 49 

SUMMARY

   INTERNAL DIAMETER (Di)  496mm   SHELL  LENGTH (L)  1734mm       THICKNESS (t)  6mm   HEAD   THICKNESS (t)                                   6mm      HEIGHT (h)                              173mm   MAN HOLE  DIAMETER OF OPENING (di)  254.51      THICKNESS OF NOZZLE (tn)  9.27   

REINFORCEMENT AS AREA CALCULATED IS   ‐ve     RF PAD IS NOT REQUIRED     

PAD                   

LEG   THICKNESS OF LEGS                          5 .36mm                     

Page 50: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 50 

DESIGN APPROCH 2 BY ASME

CODES

Page 51: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 51 

DESIGN THEORY

PPRREESSSSUURREE VVEESSSSEELL HHEEAADD DDEESSIIGGNN UUNNDDEERR IINNTTEERRNNAALL PPRREESSSSUURREE

THICKNESS OF HEADS/ CLOSURES:

ELLIPSOIDAL HEAD: t = P.Di / (2SE- 0.2P) + CA

OTHERS;

t = P.K.Di/ (2SE-0.2P) + CA

K =CONSTANT BASED ON THE RATIO OF

MAJOR & MINOR AXIS (D/2H)

““VVAALLUUEESS OOFF FFAACCTTOORR KK””

D/2H 3.0 2.8 2.6 2.5 2.4 2.2 2.1 2.0

K 1.83 1.64 1.46 1.37 1.29 1.14 1.07 1.00

D/2H 1.8 1.6 1.5 1.4 1.2 1.0

K 0.87 0.76 0.71 0.66 0.57 0.50

TORISPHERICAL HEAD: t = 0.885 PL/ (SE-0.1P) + CA

FOR KNUCKLE RADIUS, r = 6% OF CROWN RADIUS (L)

t =PLM/ (2S.E- 0.2P) + CA

where L=CROWN RADIUS

M=CONSTANT BASED ON RATIO OF CROWN AND KNUCLE

RADIUS(L/r)

Page 52: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 52 

““VVAALLUUEESS OOFF FFAACCTTOORR MM””

L/r 1.0 1.50 2.00 2.50 3.00 3.50 4.0

M 1.00 1.06 1.10 1.15 1.18 1.22 1.25

L/r 5.0 6.0 7.0 8.0 9.0 10.0 11.0

M 1.31 1.36 1.41 1.46 1.50 1.54 1.58

L/r 12.0 13.0 14.0 15.0 16.0 16.67

M 1.62 1.65 1.69 1.72 1.75 1.77

(USE NEAREST VALUE OF L/r; INTERPOLATION UNNECESSARY)

NOTE:

– MAXIMUM RATIO ALLOWED BY UG-32 (j) WHEN L EQUALS THE

OUTSIDE DIAMETER OF THE SKIRT OF THE HEAD. KNUCKLE

RADIUS, r SHALL NOT BE LESS THAN 3t.

CONICAL HEAD: t = PDi/ 2 COS α (SE-0.6P) + CA

α = half apex angle

HEMISPHERICAL HEAD: t = P.Ri/ (2SE- 0.2P) + CA

FLAT HEADS & COVERS (UG- 34) CIRCULAR COVER/ HEADS

t = Di * SQRT(CP/SE) + CA

Where C = Factor, dependent on joint geometry of head cover to shell (range 0.1

– 0.33)

OBROUND/ NON-CIRCULAR HEADS (INCLUDING SQUARE/ RECTANGULAR)

Page 53: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 53 

t = Di * SQRT(Z*CP/SE) + CA

where Z = 3.4 - (2.4 d / D)

PPRREESSSSUURREE VVEESSSSEELL SSHHEELLLL CCOOMMPPOONNEENNTT DDEESSIIGGNN UUNNDDEERR

IINNTTEERRNNAALL PPRREESSSSUURREE

Pressure Vessel Definition: – Containers of Pressure

Internal

External

– Pressure Source

External

Application of Heat

Code Coverage: – Subsections

Rule, Guidelines, Specifications

– Mandatory Appendices

Specific Important Subjects to Supplement Subsections

– Non-Mandatory Appendices

Additional Information, Suggested Good Practices Inclusions:

– Unfired Steam Boilers/ Generators

Evaporators

Heat Exchangers

– Direct Fired Vessels

Gas Fired Jacketed Steam Kettles(Jacket Pressure less than 50

PSI)

Additional Interpretation:

Page 54: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 54 

– The code rules may not cover all designs & constructions procedures.

Such additional design & construction procedure may be

adopted which are safe and acceptable.

– Field fabrication are acceptable.

– Other standards for components are acceptable

Guidelines for Designed Thickness (To be adopted): – (1/16)” excluding corrosion allowance for shell & head (Min.)

– The above will not apply to heat transfer surface

– (1/4)” min. for unfired steam boiler shell

– (3/32)” min. excluding corrosion allowance for compressed air/ steam/

water service(for CS/AS)

– Corrosion allowance shall be based on experience/ field data(No

value/ code recommended).

THICKNESS CALCULATIONS

UNDER INTERNAL PRESSURE, CYLINDRICAL SHELL:

Circumferential stress:

t = P.Ri / (SE- 0.6P) + CA

Longitudinal stress:

t = P.Ri / (2SE+0.4P) + CA

SPHERICAL SHELL:

t = P.Ri / (2SE- 0.2P) + CA

CONICAL SECTION: (INTERNAL PRESSURE) t =P.Di/ 2COSα(SE- 0.6P) + CA

Stress Calculation UNDER INTERNAL PRESSURE,

CYLINDRICAL SHELL:

Circumferential stress:

Page 55: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 55 

Sc = P (Ri + 0.6t)/ Et

Longitudinal stress:

Sl = P (Ri - 0.4t)/ 2Et

SPHERICAL SHELL:

Sc = P (Ri + 0.2t)/ 2Et

CONICAL SHELL SECTION:

Sc =P (Di + 1.2 tCOSα)/2Et COSα Sl =P (Di – 0.8tCOSα)/4Et COSα

Page 56: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 56 

ANALYSIS OF PRESSURE VESSEL

Project Author

jimit and mahavir

Subject

shell analysis

Prepared For

project report

Project Created

Sunday, May 25, 2008 at 10:04:27 PM

Project Last Modified

Sunday, May 25, 2008 at 10:04:27 PM

Page 57: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 57 

1 Introduction

The ANSYS CAE (Computer-Aided Engineering) software program was used in conjunction with 3D CAD (Computer-Aided Design) solid geometry to simulate the behavior of mechanical bodies under thermal/structural loading conditions. ANSYS automated FEA (Finite Element Analysis) technologies from ANSYS, Inc. to generate the results listed in this report.

Each scenario presented below represents one complete engineering simulation. The definition of a simulation includes known factors about a design such as material properties per body, contact behavior between bodies (in an assembly), and types and magnitudes of loading conditions. The results of a simulation provide insight into how the bodies may perform and how the design might be improved. Multiple scenarios allow comparison of results given different loading conditions, materials or geometric configurations.

Convergence and alert criteria may be defined for any of the results and can serve as guides for evaluating the quality of calculated results and the acceptability of values in the context of known design requirements.

Solution history provides a means of assessing the quality of results by examining how values change during successive iterations of solution refinement. Convergence criteria sets a specific limit on the allowable change in a result between iterations. A result meeting this criteria is said to be "converged".

Alert criteria define "allowable" ranges for result values. Alert ranges typically represent known aspects of the design specification.

All values are presented in the "SI Metric (m, kg, N, °C, s, V, A)" unit system.

Notice

Do not accept or reject a design based solely on the data presented in this report. Evaluate designs by considering this information in conjunction with experimental test data and the practical experience of design engineers and analysts. A quality approach to engineering design usually mandates physical testing as the final means of validating structural integrity to a measured precision.

Page 58: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 58 

2. Scenario 1

2.1. "Model" "Model" obtains geometry from the Pro/ENGINEER® part "H:\shaell and cylinder\SHEEL.PRT.2".

The bounding box for the model measures 1.73 by 0.52 by 0.52 m along the global x, y and z axes, respectively. The model has a total mass of 109.69 kg. The model has a total volume of 1.4×10-2 m³.

Table 2.1.1. Bodies

Name Material Nonlinear Material Effects Bounding Box(m) Mass (kg) Volume (m³) Nodes Elements

"SHEEL" "Structural Steel" Yes 1.73, 0.52, 0.52 109.69 1.4×10-2 4968 684

2.1.1. Mesh

"Mesh", associated with "Model" has an overall relevance of 0. "Mesh" contains 4968 nodes and 684 elements.

No mesh controls specified.

2.2. "Environment" Simulation Type is set to Static

Analysis Type is set to Static Structural

"Environment" contains all loading conditions defined for "Model" in this scenario.

2.2.1. Structural Loading Table 3.2.1.1. Structural Loads

Name Type Magnitude Vector Reaction Force

Reaction Force Vector

Reaction Moment

Reaction Moment Vector

"Pressure" Pressure 600,000.0 Pa N/A N/A N/A N/A N/A

2.2.2. Structural Supports Table 3.2.2.1. Structural Supports

Name Type Reaction Force Reaction Force Vector Reaction

Moment Reaction Moment Vector

"Fixed Support"

Fixed Surface 1.71×10-3 N [-1.71×10-3 N x, 1.16×10-7 N y,

3.67×10-9 N z] 1.81×10-5 N·m [1.81×10-5 N·m x, 3.16×10-9 N·m y, 1.06×10-7 N·m z]

Page 59: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 59 

2.3. "Solution" Solver Type is set to Program Controlled

Weak Springs is set to Program Controlled

Large Deflection is set to Off

"Solution" contains the calculated response for "Model" given loading conditions defined in "Environment".

Thermal expansion calculations use a constant reference temperature of 22.0 °C for "SHEEL". Theoretically, at a uniform temperature of 22.0 °C no strain results from thermal expansion or contraction.

2.3.1. Structural Results Table 3.3.1.1. Values

Name Figure Scope Minimum Maximum Minimum Occurs On

Maximum Occurs On

Alert Criteria

"Equivalent Stress" A1.1 "Model" 8.6×106 Pa 3.5×107 Pa SHEEL SHEEL None

"Maximum Shear Stress" None "Model" 4.96×106 Pa 1.87×107 Pa SHEEL SHEEL None

"Total Deformation" A1.2 "Model" 0.0 m 4.27×10-5 m SHEEL SHEEL None

Convergence tracking not enabled.

2.3.2. Equivalent Stress Safety Table 3.3.2.1. Definition

Name Stress Limit

"Stress Tool" Yield strength per material.

Table 3.3.2.2. Results

Name Scope Type Minimum Alert Criteria

"Stress Tool" "Model" Safety Factor 7.13 None

"Stress Tool" "Model" Safety Margin 6.13 None

Convergence tracking not enabled.

2.3.3. Shear Stress Safety Table 3.3.3.1. Definition

Name Shear Limit Shear Factor

Page 60: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 60 

"Stress Tool 2" Yield strength per material. 0.5

Table 3.3.3.2. Results

Name Scope Type Minimum Alert Criteria

"Stress Tool 2" "Model" Safety Factor 6.69 None

"Stress Tool 2" "Model" Safety Margin 5.69 None

Convergence tracking not enabled.

stress

Figure A1.1. "Equivalent Stress" Contours

Page 61: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 61 

Scenario 1 Figures deformation Figure A1.2. "Total Deformation" Contours

Page 62: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 62 

AppendicesA1.

A2. Definition of "Structural Steel"

Table A2.1. "Structural Steel" Constant Properties

Name Value

Compressive Ultimate Strength 0.0 Pa

Compressive Yield Strength 2.5×108 Pa

Density 7,850.0 kg/m³

Poisson's Ratio 0.3

Tensile Yield Strength 2.5×108 Pa

Tensile Ultimate Strength 4.6×108 Pa

Young's Modulus 2.0×1011 Pa

Thermal Expansion 1.2×10-5 1/°C

Specific Heat 434.0 J/kg·°C

Thermal Conductivity 60.5 W/m·°C

Relative Permeability 10,000.0

Resistivity 1.7×10-7 Ohm·m

Table A2.2. Alternating Stress

Page 63: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 63 

Mean Value 0.0

Table A2.3. "Alternating Stress"

Cycles Alternating Stress

10.0 4.0×109 Pa

20.0 2.83×109 Pa

50.0 1.9×109 Pa

100.0 1.41×109 Pa

200.0 1.07×109 Pa

2,000.0 4.41×108 Pa

10,000.0 2.62×108 Pa

20,000.0 2.14×108 Pa

100,000.0 1.38×108 Pa

200,000.0 1.14×108 Pa

1,000,000.0 8.62×107 Pa

Table A2.4. Strain-Life Parameters

Table A2.5. "Strain-Life Parameters"

Strength Coefficient 9.2×108 Pa

Strength Exponent -0.11

Ductility Coefficient 0.21

Page 64: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 64 

Ductility Exponent -0.47

Cyclic Strength Coefficient 1.0×109 Pa

Cyclic Strain Hardening Exponent 0.2

Page 65: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 65 

Project

Author Jimit vyas and mahavir solankiSubject Ellipsoidal dish end Prepared for project analysis First Saved Sunday, May 25, 2008 Last Saved Sunday, May 25, 2008 Product Version 11.0 Release

Page 66: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 66 

Contents • Model

o Geometry ELIPTICALHEAD

o Mesh CFX-Mesh Method

o Static Structural Analysis Settings Loads Solution

Solution Information Results Max Equivalent Stress

Results Max Shear Stress

Results • Material Data

o Structural Steel

Units TABLE 1

Unit System Metric (m, kg, N, °C, s, V, A)Angle Degrees Rotational Velocity rad/s

Model

Geometry

TABLE 3 Model > Geometry > Parts

Object Name ELIPTICALHEADState Meshed Graphics Properties Visible Yes Transparency 1 Definition Suppressed No Material Structural Steel Stiffness Behavior Flexible Nonlinear Material Effects Yes Bounding Box Length X 0.508 m Length Y 0.508 m Length Z 0.173 m

Page 67: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 67 

Properties Volume 1.9271e-003 m³ Mass 15.128 kg Centroid X -8.1168e-017 m Centroid Y 1.0962e-017 m Centroid Z -3.7996e-002 m Moment of Inertia Ip1 0.34417 kg·m² Moment of Inertia Ip2 0.343 kg·m² Moment of Inertia Ip3 0.6178 kg·m² Statistics Nodes 2289 Elements 6232

Mesh

TABLE 4 Model > Mesh

Object Name Mesh State Solved Defaults Physics Preference CFD Relevance 0 Advanced Relevance Center Fine Element Size Default Shape Checking CFD Solid Element Midside Nodes Dropped Straight Sided Elements Initial Size Seed Active AssemblySmoothing Medium Transition Slow Statistics Nodes 2289 Elements 6232

TABLE 5 Model > Mesh > Mesh Controls

Object Name CFX-Mesh MethodState Fully Defined Scope Scoping Method Geometry SelectionGeometry 1 Body Definition Suppressed No Method CFX-Mesh Element Midside Nodes Dropped

Static Structural

Page 68: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 68 

TABLE 6 Model > Analysis

Object Name Static StructuralState Fully Defined Definition Physics Type Structural Analysis Type Static StructuralOptions Reference Temp 22. °C

TABLE 8 Model > Static Structural > Loads

Object Name Pressure Fixed Support 2State Fully Defined Scope Scoping Method Geometry Selection Geometry 4 Faces 1 Face Definition Define By Normal To Type Pressure Fixed Support Magnitude 6.e+005 Pa (ramped) Suppressed No

FIGURE 1 Model > Static Structural > Pressure

Page 69: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 69 

Solution

TABLE 9 Model > Static Structural > Solution

Object Name SolutionState Solved Adaptive Mesh Refinement Max Refinement Loops 1. Refinement Depth 2.

TABLE 10 Model > Static Structural > Solution > Solution Information

Object Name Solution InformationState Solved Solution Information Solution Output Solver Output Newton-Raphson Residuals 0 Update Interval 2.5 s Display Points All

TABLE 11 Model > Static Structural > Solution > Results

Object Name Equivalent Stress Maximum Shear Stress Total DeformationState Solved Scope Geometry All Bodies Definition Type Equivalent (von-Mises) Stress Maximum Shear Stress Total DeformationDisplay Time End Time Results Minimum 3.101e+006 Pa 1.6131e+006 Pa 0. m Maximum 3.1378e+007 Pa 1.6963e+007 Pa 4.1032e-005 m Information Time 1. s Load Step 1 Substep 1 Iteration Number 1

FIGURE 2 Model > Static Structural > Solution > Equivalent Stress > Figure equivalent stress

Page 70: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 70 

FIGURE 3 Model > Static Structural > Solution > Maximum Shear Stress > Figure maximum shear stress

Page 71: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 71 

TABLE 12 Model > Static Structural > Solution > Stress Safety Tools

Object Name Max Equivalent Stress State Solved Definition Theory Max Equivalent Stress Stress Limit Type Tensile Yield Per Material

TABLE 13 Model > Static Structural > Solution > Max Equivalent Stress > Results

Object Name Safety Factor Safety MarginState Solved Scope Geometry All Bodies Definition Type Safety Factor Safety MarginDisplay Time End Time Results Minimum 7.9674 6.9674

Page 72: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 72 

Information Time 1. s Load Step 1 Substep 1 Iteration Number 1

TABLE 14 Model > Static Structural > Solution > Stress Safety Tools

Object Name Max Shear Stress State Solved Definition Theory Max Shear Stress Factor 0.5 Stress Limit Type Tensile Yield Per Material

TABLE 15 Model > Static Structural > Solution > Max Shear Stress > Results

Object Name Safety Factor Safety MarginState Solved Scope Geometry All Bodies Definition Type Safety Factor Safety MarginDisplay Time End Time Results Minimum 7.369 6.369 Information Time 1. s Load Step 1 Substep 1 Iteration Number 1

Material Data

Structural Steel

TABLE 16 Structural Steel > Constants

Structural Young's Modulus 2.e+011 Pa Poisson's Ratio 0.3 Density 7850. kg/m³ Thermal Expansion 1.2e-005 1/°C Tensile Yield Strength 2.5e+008 Pa Compressive Yield Strength 2.5e+008 Pa Tensile Ultimate Strength 4.6e+008 Pa Compressive Ultimate Strength 0. Pa Thermal

Page 73: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 73 

Thermal Conductivity 60.5 W/m·°C Specific Heat 434. J/kg·°C Electromagnetics Relative Permeability 10000 Resistivity 1.7e-007 Ohm·m

FIGURE 4 Structural Steel > Alternating Stress

TABLE 17 Structural Steel > Alternating Stress > Property Attributes

Interpolation Log-Log Mean Curve Type Mean Stress

TABLE 18 Structural Steel > Alternating Stress > Alternating Stress Curve Data

Mean Value Pa0.

TABLE 19 Structural Steel > Alternating Stress > Alternating Stress vs. Cycles

Cycles Alternating Stress Pa10. 3.999e+009 20. 2.827e+009 50. 1.896e+009 100. 1.413e+009

Page 74: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 74 

200. 1.069e+009 2000. 4.41e+008 10000 2.62e+008 20000 2.14e+008 1.e+005 1.38e+008 2.e+005 1.14e+008 1.e+006 8.62e+007

FIGURE 5 Structural Steel > Strain-Life Parameters

TABLE 20 Structural Steel > Strain-Life Parameters > Property Attributes

Display Curve Type Strain-Life

TABLE 21 Structural Steel > Strain-Life Parameters > Strain-Life Parameters

Strength Coefficient Pa 9.2e+008Strength Exponent -0.106 Ductility Coefficient 0.213 Ductility Exponent -0.47 Cyclic Strength Coefficient Pa 1.e+009 Cyclic Strain Hardening Exponent 0.2

Page 75: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 75 

FATIGUE ANALYSIS

Project

Author JIMIT AND MAHAVIR

Subject FATIGUE ANALYSIS

Prepared for DESIGN AND ANALYSIS OF PRESSURE VESSEL

First Saved Monday, March 17, 2008

Last Saved Tuesday, March 18, 2008

Product Version 11.0 Release

Page 76: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 76 

Contents

• Model o Geometry

FATIGUEANALYSIS o Mesh o Static Structural

Analysis Settings Loads

Solution Solution Information Results Max Equivalent Stress

Results Max Shear Stress

Results Fatigue Tool

Results Result Charts

goodman stress life rl Results

• Material Data o Structural Steel 2

Units

TABLE 1

Unit System Metric (m, kg, N, °C, s, V, A)

Angle Degrees

Rotational Velocity rad/s

Page 77: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 77 

Model

Geometry

TABLE

Model > Geometry

Object Name Geometry

State Fully Defined

Definition

Source D:\pressurevesselanalysis\fatigueanalysis\FATIGUEANALYSIS.PRT.3

Type ProEngineer

Length Unit Millimeters

Element Control Program Controlled

Display Style Part Color

Bounding Box

Length X 0.762 m

Length Y 0.782 m

Length Z 2.08 m

Properties

Volume 0.30847 m³

Mass 2421.5 kg

Statistics

Bodies 1

Active Bodies 1

Nodes 12181

Elements 6191

TABLE

Model > Geometry > Parts

Object Name FATIGUEANALYSIS

State Meshed

Page 78: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 78 

Graphics Properties

Visible Yes

Transparency 1

Definition

Suppressed No

Material Structural Steel 2

Stiffness Behavior Flexible

Nonlinear Material Effects Yes

Bounding Box

Length X 0.762 m

Length Y 0.782 m

Length Z 2.08 m

Properties

Volume 0.30847 m³

Mass 2421.5 kg

Centroid X -2.3696e-003 m

Centroid Y 2.1709e-003 m

Centroid Z -8.3295e-004 m

Moment of Inertia Ip1 522.75 kg·m²

Moment of Inertia Ip2 522.8 kg·m²

Moment of Inertia Ip3 80.459 kg·m²

Statistics

Nodes 12181

Elements 6191

Common Decisions to Both Types of Fatigue Analysis

Once the decision on which type of fatigue analysis to perform, Stress Life or Strain Life,

there are 4 other topics upon which your fatigue results are dependent upon. Input decisions

that are common to both types of fatigue analyses are listed below:

• Loading Type

• Mean Stress Effects

Page 79: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 79 

• Multiaxial Stress Correction

• Fatigue Modification Factor

Within Mean Stress Effects, the available options are quite different. In the following

ections, we will explore all of these additional decisions. These input decision trees for

both Stress Life and Strain Life are outlined in Figures 1 and 2. fatigue analysis in both

predicted life and types of post processing available. We will look at each of these choices

in detail below.

Mesh

TABLE

Model > Mesh

Object Name Mesh

State Solved

Defaults

Physics Preference Mechanical

Relevance 0

Advanced

Relevance Center Coarse

Element Size Default

Shape Checking Standard Mechanical

Solid Element Midside Nodes Program Controlled

Straight Sided Elements No

Initial Size Seed Active Assembly

Smoothing Low

Transition Fast

Statistics

Nodes 12181

Elements 6191

Page 80: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 80 

Static Structural

TABLE

Model > Analysis

Object Name Static Structural

State Fully Defined

Definition

Physics Type Structural

Analysis Type Static Structural

Options

Reference Temp 22. °C

TABLE

Model > Static Structural > Analysis Settings

Object Name Analysis Settings

State Fully Defined

Step Controls

Number Of Steps 1.

Current Step Number 1.

Step End Time 1. s

Program Controlled

TABLE

Model > Static Structural > Loads

Object Name Pressure Fixed Support

State Fully Defined

Scope

Scoping Method Geometry Selection

Geometry 10 Faces 2 Faces

Definition

Define By Normal To

Type Pressure Fixed Support

Magnitude -6.e+005 Pa (ramped)

Suppressed No

Page 81: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 81 

FIGURE

Model > Static Structural > Pressure

Solution

TABLE

Model > Static Structural > Solution

Object Name Solution

State Obsolete

Adaptive Mesh Refinement

Max Refinement Loops 1.

Refinement Depth 2.

TABLE

Model > Static Structural > Solution > Solution Information

Object Name Solution Information

State Not Solved

Solution Information

Solution Output Solver Output

Page 82: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 82 

Newton-Raphson Residuals 0

Update Interval 2.5 s

Display Points All

TABLE

Model > Static Structural > Solution > Results

Object Name Equivalent Stress Maximum Shear Stress Total Deformation

State Solved

Scope

Geometry All Bodies

Definition

Type Equivalent (von-Mises) Stress Maximum Shear Stress Total Deformation

Display Time End Time

Results

Minimum 4.7782 Pa 2.757 Pa 0. m

Maximum 6.4722e+007 Pa 3.5341e+007 Pa 4.4133e-004 m

Information

Time 1. s

Load Step 1

Substep 1

Iteration Number 1

TABLE

Model > Static Structural > Solution > Stress Safety Tools

Object Name Max Equivalent Stress

State Solved

Definition

Theory Max Equivalent Stress

Stress Limit Type Tensile Yield Per Material

TABLE

Model > Static Structural > Solution > Max Equivalent Stress > Results

Object Name Safety Factor Safety Margin

State Solved

Scope

Page 83: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 83 

Geometry All Bodies

Definition

Type Safety Factor Safety Margin

Display Time End Time

Results

Minimum 3.8627 2.8627

Information

Time 1. s

Load Step 1

Substep 1

Iteration Number 1

TABLE

Model > Static Structural > Solution > Stress Safety Tools

Object Name Max Shear Stress

State Solved

Definition

Theory Max Shear Stress

Factor 0.5

Stress Limit Type Tensile Yield Per Material

TABLE

Model > Static Structural > Solution > Max Shear Stress > Results

Object Name Safety Factor Safety Margin

State Solved

Scope

Geometry All Bodies

Definition

Type Safety Factor Safety Margin

Display Time End Time

Results

Minimum 3.537 2.537

Information

Time 1. s

Page 84: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 84 

Load Step 1

Substep 1

Iteration Number 1

TABLE

Model > Static Structural > Solution > Fatigue Tools

Object Name Fatigue Tool

State Solved

Materials

Fatigue Strength

Factor (Kf) 1.

Loading

Type History Data

History Data

Location

C:\Program Files\Ansys Inc\v110\AISOL\CommonFiles\Language\en-

us\EngineeringData\Load Histories\sampleHistory2.dat

Scale Factor 5.e-003

Definition

Display Time End Time

Options

Analysis Type Stress Life

Mean Stress Theory Goodman

Stress Component Equivalent (Von Mises)

Bin Size 32

Use Quick Rainflow

Counting Yes

Infinite Life 1.e+009 cycles

Maximum Data

Points To Plot 5000.

Life Units

Units Name cycles

1 block is equal to 1.e+006 cycles

Non-constant amplitude, Proportional Loading

Page 85: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 85 

Non-constant amplitude, proportional loading also needs only one set of FE results. But

instead of using a single load ratio to calculate alternating and mean values, the load ratio

varies over time. Think of this as coupling an FE analysis with strain-gauge results

collected over a given time interval. Since loading is proportional, the critical fatigue

location can be found by looking at a single set of FE results. However, the fatigue

loading which causes the maximum damage cannot easily be seen. Thus, cumulative

damage calculations (including cycle counting such as Rainflow and damage summation

such as Miner’s rule) need to be done to determine the total amount of fatigue damage and

which cycle combinations cause thatdamage. Cycle counting is a means to reduce a

complex load history into a number of events, which can be compared to the available

constant amplitude test data. Non-constantAmplitude, proportional loading within the

ANSYS Fatigue Module uses a “quick counting” technique to substantially reduce runtime

and memory. In quick counting, alternating andmean stresses are sorted into bins before

partial damage is calculated. Without quick counting, data is not sorted into bins until after

partial damages are found. The accuracy of quick

counting is usually very good if a proper number of bins are used when counting. The bin

size defines how many divisions the cycle counting history should be organized into for the

history data loading type. Strictly speaking, bin size specifies the number of divisions of the

rainflow matrix. A larger bin size has greater precision but will take longer to solve and use

more memory. Bin size defaults to 32, meaning that the Rainflow Matrix is 32 x 32 in

dimension.

For Stress Life, another available option when conducting a variable amplitude fatigue

analysis is the ability to set the value used for infinite life. In constant amplitude loading,

if the alternating stress is lower than the lowest alternating stress on the fatigue curve, the

fatigue tool will use the life at the last point. This provides for an added level of safety

because many materials do not exhibit an endurance limit. However, in non-constant

amplitude loading, cycles with very small alternating stresses may be present and may

incorrectly predict too much damage if the number of the small stress cycles is high

enough. To help control this, the user can set the infinite life value that will be used if the

alternating stress is beyond the limit of the SN curve. Setting a higher value will make

small stress cycles less damaging if they occur many times. The Rainflow and damage

Page 86: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 86 

matrix results can be helpful in determining the effects of small stress cycles in your

loading history.

FIGURE

Model > Static Structural > Solution > Fatigue Tool

FIGURE

Model > Static Structural > Solution > Fatigue Tool

Page 87: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 87 

TABLE

Model > Static Structural > Solution > Fatigue Tool > Results

Object Name Life Safety Factor Damage

State Solved

Scope

Geometry All Bodies

Definition

Type Life Safety Factor Damage

Design Life 1.e+009 cycles

Results

Minimum 2.e+007 cycles 0.

Maximum 50.

TABLE

Model > Static Structural > Solution > Fatigue Tool > Result Charts

Page 88: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 88 

Object Name Rainflow Matrix Damage Matrix

State Solved

Scope

Geometry All Bodies

Options

Chart Viewing Style Three Dimensional

Results

Minimum Range 0. Pa

Maximum Range 1.9246e+008 Pa

Minimum Mean -3.2328e+008 Pa

Maximum Mean 6.1628e+007 Pa

Definition

Design Life 1.e+009 cycles

FIGURE

Model > Static Structural > Solution > Fatigue Tool > Rainflow Matrix

Rainflow Matrix Chart Rainflow Matrix Chart is a plot of the rainflow matrix at the

critical location. This result is onlyapplicable for non-constant amplitude loading where

rainflow counting is needed. This result may be scoped. In this 3-D histogram,

alternating and mean stress is divided into bins and plotted. The Z-axis corresponds

to the number of counts for a given alternating and mean stress bin. This result gives

the user a measure of the composition of a loading history. (Such as if most of the

alternating stress cycles occur at a negative mean stress.) From the rainflow matrix

figure, the user can see that most of the alternating stresses have a positive mean

stress and that in this case the majority of alternating stresses are quite low.

Page 89: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 89 

FIGURE

Model > Static Structural > Solution > Fatigue Tool > Damage Matrix

Damage Matrix Chart

Damage Matrix Chart is a plot of the damage matrix at the critical location on the

model. This result is only applicable for non-constant amplitude loading where

rainflow counting is needed. This result may be scoped. This result is similar to the

rainflow matrix except that the percent damage that each of the Rainflow bin cause is

plotted as the Z-axis. As can be seen from the \corresponding damage matrix for the

above rainflow matrix, in this particular case although most of the counts occur at the

lower stress amplitudes, most of the damage occurs at the higher stress amplitudes.

Page 90: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 90 

TABLE

Model > Static Structural > Solution > Fatigue Tools

Object Name goodman stress life rl

State Solved

Materials

Fatigue Strength Factor (Kf) 1.

Loading

Type Fully Reversed

Scale Factor 1.

Definition

Display Time End Time

Options

Analysis Type Stress Life

Mean Stress Theory Goodman

Page 91: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 91 

Stress Component Equivalent (Von Mises)

Life Units

Units Name cycles

1 cycle is equal to 1.e+006 cycles

Types of Cyclic Loading

Unlike static stress, which is analyzed with calculations for a single stress state, fatigue

damage occurs when stress at a point changes over time. There are essentially four classes

of fatigue loading, with the ANSYS Fatigue Module currently supporting the first three:

• Constant amplitude, proportional loading

• Constant amplitude, non-proportional loading

• Non-constant amplitude, proportional loading

• Non-constant amplitude, non-proportional loading

In the above descriptions, the amplitude identifier is readily understood.

Is the loading a variant of a sine wave with a single load ratio or does the

loading vary perhaps erratically, with the load ratio changing with time?

The second identifier, proportionality, describes whether the changing

load causes the principal stress axes to change. If the principal stress

axes do not change, then it is proportional loading. If the principal stress

axes do change, then the cycles cannot be

counted simply and it is non-proportional loading.

Constant amplitude, Proportional Loading

Constant amplitude, proportional loading is the classic, “back of the envelope”

calculation describing whether the load has a constant maximum value or continually

varies with time. Loading is of constant amplitude because only one set of FE stress

results along with a loading ratio is required to calculate the alternating and mean values.

Page 92: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 92 

The loading ratio is defined as the ratio of the second load to the first load (LR = L2/L1).

Loading is proportional since only one set of FE results are needed (principal stress axes

do not change over time). Common types of constant amplitude loading are fully reversed

(apply a load, then apply an equal and opposite load; a load ratio of -1) and zero-based

(apply a load then remove it; a load ratio of 0). Since loading is proportional, looking at a

single set of FE results can identify critical fatigue locations. Likewise, since there are

only two loadings, no cycle counting or cumulative damage calculations need to be done.

FIGURE

Model > Static Structural > Solution > goodman stress life rl

Value of Infinite Life

Another available option when conducting a variable amplitude fatigue analysis is the

ability to set the value used for infinite life. In constant amplitude loading, if the

alternating stress is lower than the lowest alternating stress on the fatigue curve, the

Page 93: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 93 

fatigue tool will use the life at the last point. This provides for an added level of safety

because many materials do not exhibit an endurance limit. However, in non-constant

amplitude loading, cycles with very small alternating stresses may be present and may

incorrectly predict too much damage if the number of the small stress cycles is high

enough. To help control this, the user can set the infinite life value that will be used if

the alternating stress is beyond the limit of the SN curve. Setting a higher value will

make small stress cycles less damaging if they occur many times. The rainflow and

damage matrix results can be helpful in determining the effects of small stress cycles in

your loading history. The rainflow and damage matrices shown in Figure 13 illustrates

the possible effects of infinite life. Both damage matrices came from the same loading

(and thus same rainflow matrix), but the first damage matrix was calculated with an

infinite life if 1e6 cycles and the second was calculated with an infinite life of 1e9

cycles.

FIGURE

Model > Static Structural > Solution > goodman stress life rl

TABLE

Model > Static Structural > Solution > goodman stress life rl > Results

Object Name Life Damage Safety Factor Equivalent Alternating Stress

State Solved

Scope

Geometry All Bodies

Definition

Type Life Damage Safety Factor Equivalent Alternating Stress

Design Life 1.e+009 cycles

Page 94: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 94 

Results

Minimum 1.e+012 cycles 8.895 4.7782 Pa

Maximum 1.e-003 6.4722e+007 Pa

Material Data

Structural Steel 2

TABLE

Structural Steel 2 > Constants

Structural

Young's Modulus 2.e+011 Pa

Poisson's Ratio 0.3

Density 7850. kg/m³

Thermal Expansion 1.2e-005 1/°C

Tensile Yield Strength 2.5e+008 Pa

Compressive Yield Strength 2.5e+008 Pa

Tensile Ultimate Strength 4.6e+008 Pa

Compressive Ultimate Strength 0. Pa

Thermal

Thermal Conductivity 60.5 W/m·°C

Specific Heat 434. J/kg·°C

Electromagnetics

Relative Permeability 10000

Resistivity 1.7e-007 Ohm·m

Page 95: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 95 

FIGURE

Structural Steel 2 > Alternating Stress

TABLE

Structural Steel 2 > Alternating Stress > Property Attributes

Interpolation Log-Log

Mean Curve Type Mean Stress

Page 96: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 96 

TABLE

Structural Steel 2 > Alternating Stress > Alternating Stress vs. Cycles

Cycles Alternating Stress Pa

10. 3.999e+009

20. 2.827e+009

50. 1.896e+009

100. 1.413e+009

200. 1.069e+009

2000. 4.41e+008

10000 2.62e+008

20000 2.14e+008

1.e+005 1.38e+008

2.e+005 1.14e+008

1.e+006 8.62e+007

FIGURE Structural Steel 2 > Strain-Life Parameters

Page 97: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 97 

TABLE

Structural Steel 2 > Strain-Life Parameters > Property Attributes

Display Curve Type Strain-Life

TABLE

Structural Steel 2 > Strain-Life Parameters > Strain-Life Parameters

Strength Coefficient Pa 9.2e+008

Strength Exponent -0.106

Ductility Coefficient 0.213

Ductility Exponent -0.47

Cyclic Strength Coefficient Pa 1.e+009

Cyclic Strain Hardening Exponent 0.2

Page 98: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 98 

Wind analysis

Contents 1. File Report Table 1 File Information for windanalysiscfx11_001 2. Mesh Report Table 2 Mesh Information for windanalysiscfx11_001 3. Physics Report Table 3 Domain Physics for windanalysiscfx11_001 Table 4 Boundary Physics for windanalysiscfx11_001 4. Solution Report Table 5 Boundary Flows for windanalysiscfx11_001 5. User Data Figure 2 Figure 3 Figure 4

Fig: Wind analysis

Page 99: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 99 

1. File Report Table 1. File Information for windanalysiscfx11_001

Case windanalysiscfx11_001 File Path D:/pressurevesselanalysis/windanalysiscfx11_001.resFile Date 15 March 2008 File Time 03:46:08 PM File Type CFX5 File Version 11.0 Fluids Air at 25 C Solids None Particles None

Figure 2. pressure distributation on face of vessel

Page 100: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 100 

2. Mesh Report Table 2. Mesh Information for windanalysiscfx11_001

Domain Nodes Elements pressurevessel 7338 28308

Figure 3. streamline and pressure representation

Page 101: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 101 

3. Physics Report Table 3. Domain Physics for windanalysiscfx11_001

Name Location Type Materials Models

pressurevessel B4 Fluid Air at 25 C

Heat Transfer Model = Isothermal Turbulence Model = SST Turbulent Wall Functions = Automatic Buoyancy Model = Non Buoyant Domain Motion = Stationary

Table 4. Boundary Physics for windanalysiscfx11_001

Domain Name Location Type Settings

pressurevessel inlet inlet Inlet

Flow Regime = SubsonicNormal Speed = 47 [m s^-1]Mass And Momentum = Normal Speed Eddy Length Scale = 0.1 [m]Fractional Intensity = 0.05Turbulence = Intensity and Length Scale

pressurevessel outlet outlet Outlet

Flow Regime = SubsonicMass And Momentum = Static Pressure Relative Pressure = 0 [Pa]

pressurevessel symp symp Symmetry

pressurevessel body body Wall Wall Influence On Flow = No Slip

pressurevessel freewalls freewalls Wall Wall Influence On Flow = Free Slip

pressurevessel pressurevessel Default

F41.4, F45.4 Wall Wall Influence On Flow = No

Slip

Page 102: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 102 

4. Solution Report Table 5. Boundary Flows for windanalysiscfx11_001

Momentum Location Type Mass Flow

X Y Z body Boundary 0.0000e+00 -1.7561e+03 2.7605e+02 -8.3776e+01freewalls Boundary 0.0000e+00 -1.4953e+02 0.0000e+00 0.0000e+00 inlet Boundary 1.7405e+02 -5.1811e-07 -8.5229e+03 1.5579e-06 outlet Boundary -1.7405e+02 1.3129e+01 8.1929e+03 -2.3151e+00pressurevessel Default Boundary 0.0000e+00 -1.9325e-02 5.4447e+01 8.5967e+01 symp Boundary 0.0000e+00 1.8922e+03 0.0000e+00 0.0000e+00

By interpolation we get: for 41 m/s of

wind speed the wind pressure is 730

N/ 2m and from the standard wind

load table we compare the result

which is very accurate.

Page 103: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 103 

INTRODUCTION TO GLASS LINING

Introduction of Glass lining (Glasteel) In recent years, because of the expansion of the chemical process and pharmaceutical

industries world-wide and increased concerns for safety and quality control, Pfaudler

began investigating new approaches in glass development that would lead to a glass

composition that could be made available to all users of glass-lined equipment.

Page 104: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 104 

Together with the chemical process industry and with the co-operation of Pfaudler

divisions around the world, Pfaudler established the criteria for a new composition:

A non-crystalline structure.

Increased resistance to acid and alkali corrosion.

High resistance to impact.

High resistance to thermally induced stresses.

A formulation that could be easily produced by all Pfaudler manufacturing plants.

The result is Glasteel 9100®, Pfaudler's first "international glass", offering an unmatched

combination of corrosion resistance, impact strength, thermal shock resistance, non-

adherence and heat transfer efficiency.

Now GMM Pfaudler customers, regardless of where their processing operations are

located, can purchase a single glass system and be assured of getting the same high

quality worldwide. With Glasteel 9100 ®, GMM Pfaudler sets a standard the world can

depend on.

glass. However, these are very recipe sensitive and general statements cannot usually be

made. An exception to this are chemistries that involve the element silicon (Si),

especially when ionised, e.g. Si, SiO. Relatively small amounts of dissolved SiO can be

highly effective in reducing the corrosion rate of the Glasteel 9100 system, thereby

greatly extending its usage range. It has also been shown that colloidal silica additions to

recipes containing the highly corrosive fluorine ion (F-) can drastically reduce the

corrosive rate.

Page 105: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 105 

Water Pure Water

Pure water in the liquid phase is not very aggressive. Its behaviour resembles highly

diluted acid and corrodes only the surface layer of the glass ("ion exchange process"). At

170°C, a corrosion rate of 0.1 mm/year can be expected.

But because this water is an unbuffered, pH-unstable system, even a slight alkalization

can change the situation. If there is a shift toward higher pH values, the isocorrosion

curves for diluted alkaline solutions have to be consulted for orientation purposes.

Glasteel 9100 ® is highly resistant to condensing water vapour. However, to counter the

possible danger of the condensate shifting to an alkaline pH, it is recommended that the

vessel contents be slightly acidified with a volatile acid, e.g. hydrochloric or acetic acid.

It is also highly recommended that the unjacketed top head be insulated or heat traced to

reduce condensation formation.

Agueous Neutral pHMedia

With these type media, e.g. tap water, salt solutions, corrosion rate depends greatly on the

type and quantity of the dissolved substance. Carbonates and phosphates usually increase

the rate while alcohols and some ionic species, e.g. A13+, Zn2+ Ca2+, may reduce it.

Alkalis As alkali concentration rises, corrosion rate increases. Also, the temperature gradient for

alkaline glass corrosion, is steeper. The result is that concentrated alkalis require a more

definite setting of the temperature limits.

The corrosion rate of concentrated alkaline solutions cannot be expressed by the pH value

alone. For aqueous solutions of alkaline materials with a pH value of 14, the particular

concentration must also be considered to establish appropriate operating temperatures.

Other factors affecting alkaline corrosion are the specific reaction and the dissolving

ability of the chemical, the influence of the nature and amount of other dissolved

substances and agitation.

Page 106: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 106 

Isocorrosion curves for sodium hydroxide, potassium hydroxide, sodium carbonate and

ammonia take into account technically relevant parameters influencing the rate of

corrosion; for example, the volume/ surface area ratio, inhibition effects by calcium ions,

alkaline concentration and temperature.

Under actual operating conditions, even very slight contamination (tap water in sodium

hydroxide, for example) can cause major changes in the rate of corrosion. Other factors,

such as product velocity and splash zone, can affect the corrosion rate as well. Due to

these interactive complexities, meaningful testing is strongly advised.

To eliminate the influence of the testing equipment on the rate of corrosion, procedures

are carried out in polypropylene bottles. For solutions above the boiling point, autoclaves

with PTFE inserts were used. By comparing the results with control experiments, it is

proven that the testing equipment does not have an inhibiting effect.

Pfaudler Ultra-Glas 6500 ®

1 . Extends the range of Glasteel® applications.

2. Allows safe and easy handling of high temperature processes

never before approved for Glasteel equipment.

3. Provides potential for reduced cycle time compared to conventional

vessel glass.

4. Provides extended thermal shock protection for faster heating

and cooling.

5. Provides increased operating safety margin through its enhanced

thermal protection.

6. Is ideal for the higher temperatures required by today's chemical

process applications.

Page 107: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 107 

The features of GMM Pfaudler Ultra-Glas 6500 ® are the result of changes in glass

composition and material preparation, altered applications and firing procedures, as well

as changes in equipment design and materials of construction. These changes permit

trouble-free application of the required high-stress coating and provide the highly

corrosive-resistant glass-lined surface for which Pfaudler has been respected for years.

Technical details of corrosion rates in common chemicals and thermal operation limits

are available on request.

Temperature Limits

Although Ultra-Glas 6500 ® has a high degree of helpful compressive stress in the glass

layer there are definite limits to the level of thermal stress which the glass can withstand

without incurring damage:

Only two thermal conditions must be considered when determining the temperature

limits:

A. Introduction of media into a vessel.

B. Introduction of media into a jacket.

CAUTION: "Safe" operating temperatures vary with conditions. Because so many

variables are involved, temperature ranges are given only as a guide. Where in practical,

operation below the maximum and above the minimum is recommended. Contact

Pfaudler for details.

Type 4300 Glass Coatings

Type 4300 ® glass coatings represent a new aspect of this tradition and are designed to

bridge a perceived gap in the application range. GMM Pfaudler Type 4300 ® glass is still

an acidic type of glass, but its primary application is based on improved alkali resistance.

Type 4300 glass coatings are advisable wherever alkaline conditions prevail during the

Page 108: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 108 

cycle, or as a result of concentration and temperature, or where concentration and/or

temperature conditions exceed permissible limits for conventional glass.

In addition, Type 4300 ® glass coatings are advisable where any of the following

conditions exist:

Protection of alkaline products against metal contamination.

Danger of discoloration of alkaline products due to incorporation of metals.

Stabilization of high-molecular alkalis sensitive to metal contact.

Inadequate redox stability of the vessel material in the alkaline range.

Compared to our world renowned standard glass, Type 4300 ® has three times better

alkali resistance. This means that higher process temperatures can be used, or that, under

otherwise equal conditions, these glass coatings will have three times the life

expectations.

The Type 4300 ® glass does make a slight concession in the area of acid resistance.

Although it is adequate for mild service, it is not recommended for aggressive acid

conditions.

Corrosion Resistance For pure acids and bases most commonly used in the chemical industry , technically

relevant parameters influencing the rate of corrosion (for example, the volume/surface

area ratio, inhibition effects, concentration, and temperature) are considered.

In practical operation these materials are always encountered with liquid additives,

dissolved substances or gases which may have positive or negative effects on resistance.

We therefore recommend performing corrosion tests or contacting a Pfaudler consultant

to assure material suitability for individual processes.

The Need For PPG

Page 109: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 109 

When the requirements of the Bulk Drug industry were studied recently, in context of the

stringent requirements of GMP and FDA, the need for a different glass was evident. Two

of the requirements of the pharmaceutical industry are increased purity in order to comply

with the FDA and GMP requirements and alternating alkali/acid operation.

The process equipment of the chemical and pharmaceutical industries has so far been

very similar - especially in terms of glasslined reactors and components. In light of the

survey, Pfaudler's response was a novel glass tailored to the needs of manufacturing

pharmaceutical products, vitamins and fine chemicals.

Page 110: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 110 

Appendix

Page 111: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 111 

Page 112: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 112 

Page 113: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 113 

Page 114: Pressure Vessel Design Handbook

 

U V PATEL COLLEGE OF ENGINEERING  Page 114 

BIBLOGRAPHY Dennis Moss

Hiadri Farzdak

C.S Sharma

Somnath chatopadhay

For Ansys :

Tutorials of cfx 11.0