1 IntroductionVessels, tanks and pipelines that carry, store or receive fluids are called Pressure vessel.A pressure vessel is defined as a container with a pressure differential between inside and outside. The inside pressure is usually higher than the outside, except for some isolated situationsThe fluid inside the vessel may undergo a change in state as in case of steam boilers, or may combine with other reagents as in case of a chemical reactor.Pressure vessels often have a combination of high pressures together with high temperatures, and in some cases flammable fluids or highly radioactive materials.Because of such hazards it is imperative that the design be such that no leakage occurs and these vessels have to be designed carefully to cope with the operating temperature and pressure.

2 Applications of Pressure vessel in IndustriesPressure vessels are used in a number of industries

Power generation industry for fossils Nuclear power Petrochemical industry for storing and processing crude petroleum oil in tank farms as well

as storing gasoline in service station Chemical Industry Industry plants for storage and manufacturing process

3 Pressure vessel classification

3.1 Based on manufacturing methods Welded vessels Forged vessels Multi wall vessels Multi wrapped vessels Band wrapped vessels

3.2 Based on manufacturing materials Steel vessels Non ferrous vessels Non metallic vessels

3.3 Based on geometric shapes Cylindrical vessels Spherical vessels Rectangular vessels Combined vessels

3.4 Based on installation methods Horizontal vessels Vertical vessels

3.5 Based on pressure bearing situation Internal pressure vessels External pressure vessels

3.6 Based on wall thickness Thin wall vessels Thick wall vessels

3.7 Based on technological processes Heat exchanger vessel Separation vessel Reaction vessel Storage container vessel

3.8 Based on operating temperatures Low temperature vessels (less than or equal to -20oC) Normal temperature vessels (between -20oC to 150oC) Medium temperature vessels (between 150oC to 450oC) High temperature vessels (more than or equal to 450oC)

3.9 Based on design pressure Low pressure vessel (0.1 MPa to 1.6 MPa) Medium pressure vessel (1.6 MPa to 10 MPa) High pressure vessel (10 MPa to 100 MPa) Ultra high pressure vessel (More than 100 MPa)

3.10 Based on usage mode Fixed pressure vessel Mobile pressure vessel

4 Pressure vessel types

4.1 Horizontal Pressure vessel

4.2 Vertical Pressure vessel

4.3 Tower (Column)

4.4 ReactorReactors are used where chemical reactions of process fluids are required.

4.5 Spherical tankSpherical tanks are usually used for gas storage under high pressure

5 Components of Pressure Vessel

5.1 ShellThe shell is the primary component that contains the pressure. Pressure vessel shells are welded together to form a structure that has a common rotational axis.

There are two different classes of shell Thick shell Thin shell

A shell is called thin if the maximum valve of the ratio t/r (where r is the radius of the curvature of the middle surface) can be neglected in comparison with unity.

Max(t/r) ≤ 1/20

Shells for which this inequality is violated are referred to as thick shell.

5.2 HeadAll pressure vessel shells must be closed at the ends by heads (or another shell section). Heads are typically curved rather than flat. Curved configurations are stronger and allow the heads to be thinner, lighter, and less expensive than flat heads. Heads can also be used inside a vessel. These “intermediate heads” separate sections of the pressure vessel to permit different design conditions in each section.

5.2.1 EllipsoidalThis is also called a 2:1 elliptical head. The shape of this head is more economical, because the height of the head is just a quarter of the diameter. Its radius varies between the major and minor axis.

5.2.2 Torispherical A Torispherical (or flanged and dished) head is typically somewhat flatter than an elliptical head and can be the same thickness as an elliptical head for identical design conditions and diameter. The minimum permitted knuckle radius of a Torispherical head is 6% of the maximum inside crown radius. The maximum inside crown radius equals the outside diameter of the head.

5.2.3 HemisphericalA sphere is the ideal shape for a head, because the pressure in the vessel is divided equally across the surface of the head. The radius (r) of the head equals the radius of the cylindrical part of the vessel. The required thickness of a hemispherical head is normally one-half the thickness of an elliptical or Torispherical head for the same design conditions, material, and diameter. Hemispherical heads are normally fabricated from segmented sections that are welded together, spun, or pressed.

5.2.4 ConicalTall towers may have sections with different diameters along their length. The transition between the different diameters is made in a conical section. The most common design for a conical transition does not have formed knuckles at the ends of the cone. The cylindrical sections of different diameter are welded to each end of the cone. Formed knuckles are sometimes used at the cone-to-cylinder transition in order to reduce localized stresses. When knuckles are used, the transition is called Toriconical. The use of knuckles is 106 mandatory when the cone half-apex angle exceeds 30°. Knuckles are also sometimes used for smaller angles when there is concern about potentially high local stresses at the cone-to-cylinder junction. The ASME Code has design procedures for Toriconical sections.

5.3 NozzleA nozzle is a cylindrical component that penetrates the shell or heads of a pressure vessel. The nozzle ends are usually flanged to allow for the necessary connections and to permit easy disassembly for maintenance or access. Nozzles are used for the following applications: ·

Attach piping for flow into or out of the vessel. · Attach instrument connections, (e.g., level gauges, thermo-wells, or pressure gauges). Provide access to the vessel interior at man-ways. · Provide for direct attachment of other equipment items, (e.g., a heat exchanger or mixer).

Nozzles are also sometimes extended into the vessel interior for some applications, such as for inlet flow distribution or to permit the entry of thermo-wells.

5.4 Support5.4.1 SkirtMost common methods of supporting vertical pressure vessels are by means of a rolled cylindrical or conical shell called a skirt. The skirt can be either lap fillet or butt welded directly to the vessel.This method of support is attractive from the designer’s stand point because it minimizes the local stresses at the point of attachment, and the direct load is uniformly distributed over the entire circumference.

The critical line in the skirt support is the weld attaching the vessel to the skirt

5.4.2 LegA wide variety of vessels, bins, tanks, and hoppers may be supported on legs. Leg supports should be equally spaced around the circumference.

Leg supports may be braced or unbraced. Braced legs are those which are reinforced with either cross bracing or sway bracing. Sway braces are the diagonal members which transfer the horizontal loads, but unlike cross braces, they operate in tension only. Cross braces are tension and compression members. Cross braces can be pinned at the centre or unpinned, and transfer their loads to the legs via wing plated or can be directly welded to the legs.Bracing is used to reduce the number or size of the legs required by eliminating bending in legs.

5.4.3 SaddleHorizontal pressure vessels and tanks are supported on two vertical cradles called saddles. A saddle support spreads the weight load over a large area of the shell to prevent an excessive local stress in the shell at the support points. The width of the saddle, among other design details, is determined by the specific size and design conditions of the pressure vessel. The use of more than two saddles should be avoided. The reason for not using is that it creates an indeterminate structure, both theoretically and practically. Saddle itself as various parts: the web, base plate, ribs and wears plate. The saddle itself is normally bolted to a foundation via anchor bolts. The other support is normally free to permit unrestrained longitudinal thermal expansion of the drum

Saddles may be steel or concrete.

5.4.4 LugLugs that are welded to the pressure vessel shell may also be used to support vertical pressure vessels. The use of lugs is typically limited to vessels of small to medium diameter (1 to 10 ft.) and moderate height-to-diameter ratios in the range of 2:1 to 5:1. Lug supports are often used for vessels of this size that are located above grade within structural steel. The lugs are typically bolted to horizontal structural members to provide stability against overturning loads; however, the bolt holes are often slotted to permit free radial thermal expansion of the pressure vessel.

Lugs offer one of the least expensive and most direct ways of supporting pressure vessels. They can readily absorb diametric expansion by sliding over greased or bronzed plates, are easily attached to the vessel by minimum amounts of welding, and are easily levelled in the field.

Since lugs are eccentric supports they induce compressive, tensile, and shear forces in the shell wall.

Two or four lug systems are normally used.

6 Design conditions & loadingThe mechanical design of a pressure vessel begins with specification of the design pressure and design temperature. Pressure imposes loads that must be withstood by the individual vessel components. Temperature affects material strength and, thus, its allowable stress, regardless of the design pressure. Some pressure vessels have multiple sets of design conditions that correspond to different modes of operation. For example, during its operating cycle, a reactor may have a high pressure and moderate temperature during normal operation, but it may operate at a much lower pressure and a very high temperature during catalyst regeneration. Both sets of design conditions must be specified because either one or the other may govern the mechanical design. All pressure vessels must be designed for the most severe conditions of coincident pressure and temperature that are expected during normal service.

Normal service includes conditions that are associated with Startup Normal operation Deviations from normal operation that can be anticipated (e.g., catalyst regeneration or

process upsets) Shutdown

6.1 Different types of loads acting on pressure vessel

6.1.1 Pressure

6.1.1.1 Operating PressureThe operating pressure must be set based on the maximum internal or external pressure that the pressure vessel may encounter. The following factors must be considered:

Ambient temperature effects. Normal operational variations. · Pressure variations due to changes in the vapour pressure of the contained fluid. Pump or compressor shut-off pressure. · Static head due to the liquid level in the vessel. System pressure drop. Normal pre-start-up activities or other operating conditions that may occur (e.g., vacuum),

that should be considered in the design.

6.1.1.2 Design Pressure Generally, design pressure is the maximum internal pressure (in psig), that is used in the

mechanical design of a pressure vessel. For full or partial vacuum conditions, the design pressure is applied externally and is the

maximum pressure difference that can occur between the atmosphere and the inside of the pressure vessel.

Some pressure vessels may experience both internal and external pressure conditions at different times during their operation. The mechanical design of the pressure vessel in this case is based on which of these is the more severe design condition.

The specified design pressure is based on the maximum operating pressure at the top of the vessel, plus the margin that the process design engineer determines is suitable for the particular application.

The hydrostatic pressure that is exerted by the liquid must be considered in the design of vessel components upon which it acts. Therefore, the pressure that is used to design a vessel component is equal to the design pressure at the top of the vessel, plus the hydrostatic pressure of the liquid in the vessel that is above the point being designed

6.1.2 Temperature

6.1.2.1 Operating TemperatureThe operating temperature must be set based on the maximum and minimum metal temperatures that the pressure vessel may encounter.

6.1.2.2 Design TemperatureThe design temperature of a pressure vessel is the maximum fluid temperature that occurs under normal operating conditions, plus an allowance for variations that occur during operation.

6.1.2.3 Critical Exposure TemperatureThe CET must also be specified for pressure vessel design to ensure that materials that have adequate fracture toughness are selected for construction (i.e., MDMT ≤CET).

6.1.3 Other Design Loadings Internal or external design pressure. Weight of the vessel and its normal contents under operating or test conditions. · Superimposed static reactions from the weight of attached equipment (e.g., motors,

machinery, other vessels, piping, linings, insulation). Loads at attached of internal components or vessel supports. Wind, snow, and seismic reactions. Cyclic and dynamic reactions that are caused by pressure or thermal variations, or by

equipment that is mounted on a vessel, and mechanical loadings. Test pressure combined with hydrostatic weight. Impact reactions such as those that are caused by fluid shock. Temperature gradients within a vessel component and differential thermal expansion

between vessel components.

7 Pressure vessel design codes and standardsThere are standards and codes laid down by approved regulatory bodies for the design, construction, welding, testing, marking, operation, inspection, and repair of any pressure vessel, which provides fundamental safeguards and good safety practices.

ASME Boilers and Pressure Vessel Codes API Standards PD5500 British Standards European Codes and Standards Other International Codes

The standards and codes that are commonly used codes for pressure vessels are: ASME Boiler and pressure vessel code: Section VIII, div 1 and div2 ASME B16.9 Factory made wrought steel butt welding fittings : 1978 ASME B16.11 Forged steel fittings socket-welded and threaded : 1980 ASME Boiler and Pressure Code Part X, Fiberglass Reinforced Plastic Pressure Vessels (1992). BS 1500: 1958 - Fusion Welded Pressure Vessels for General Purposes.

BS 5500 replaced this conventional code in the UK in 1976. BS 1515: 1965 - Fusion Welded Pressure Vessels for Use in the Chemical, Petroleum and Allied

Industries. BS 5500 : Specification for Unfired Fusion Welded pressure Vessels BS EN 286-1:1991. Simple unfired pressure vessels designed to contain air or nitrogen. BS 1501: 1970 - Steels for Pressure Purposes:

Part 1 (1990) - Specification for carbon and carbon manganese steelsPart 2 (1988) - Specification for alloy steelsPart 3 (1990) - Specification for corrosion and heat resisting steels

BS 1502: 1990 - Specification for steels for fired and unfired pressure vessels: sections and bars BS 1503: 1989 - Specification for steel forgings for pressure purposes BS 1504: 1984 - Specification for steel castings for pressure purposes BS 1506: 1990 - Specification for carbon, low alloy and stainless bars and billets for bolting material to

be used in pressure retaining applications. BS 2594: 1975 - Specification for carbon steel welded horizontal cylindrical storage tanks. BS 2654: 1989 - Specification for vertical steel welded non-refrigerated storage tanks with butt-

welded shells for the petroleum industry BS 2790: 1992 - Specification for design and manufacture of shell boilers of welded construction BS 5276: 1977 - Pressure Vessel details (dimensions) BS 5387: 1976 - Specification for vertical cylindrical welded steel storage tanks for low temperature

service: double wall tanks for temperatures down to -196°C. BS 4994: 1987 - Specification for Design and Construction of Vessels and Tanks in Reinforced Plastics. BS 6374: 1984 - Lining of equipment with polymeric materials for the process industries. API 510 Pressure vessel inspection code: Maintenance inspection, rating, repair, and alteration API RP 572 Inspection of pressure vessels API Standard 653 Tank inspection, repair, alteration and reconstruction. API RP 520 Sizing, selection, and installation of pressure relieving devices in refineries ISO R831: Recommendations for Stationary Boilers which is applicable to pressure vessels. Pressure Vessels: Non-metallic materials of construction ASTM D 4021-86 Standard Specification for Contact Moulded Glass-fiber-reinforced Thermosetting

Resin Underground Petroleum Storage Tanks. ASTM D 4097-88 Standard Specification for Contact Moulded Glass-fiber-reinforced Thermosetting

Resin Chemical Resistant Tanks.

Other Vessels (including Storage Tanks) API Std 620 Design and construction of large, welded, low-pressure storage tanks, American

Petroleum Institute, 1990. API Std 650 Welded steel tanks for oil storage, American Petroleum Institute, 1988. API Std 653 Tank inspection, repair, alteration, and reconstruction, American Petroleum Institute,

1991. API 12B - Bolted Production Tanks. API 12D - Large Welded Production Tanks.

API 12F - Small Welded Production Tanks. API Std 2000 venting atmospheric and low pressure storage tanks: Nonrefrigerated and

refrigerated, American Petroleum Institute, 1998.

Heat Exchangers BS 3274: 1960- Tubular Heat Exchangers for General Purposes. American Tubular Heat Exchanger Manufacturers Association (TEMA standards). The TEMA standards cover three classes of heat exchanger:

Class R - generally severe duties in the petroleum and related industries; Class C - moderate duties in commercial and general process applications; Class B - exchangers for use in the chemical process industries.

API Standard 660: 1987 - `Shell and Tube heat Exchangers for General Refinery Services' supplements both the TEMA standards and the ASME code.

API Standard 661: 1992 - Air Cooled Heat Exchangers for General Refinery Services.

8 Pressure Vessel failureIt is important to identify the potential failure modes and mechanism in the pressure vessel. Different failure modes should be related to possible safety and economic consequences. It is necessary to focus evaluation on those failure scenarios which are having highest rate of occurrence.

The failure modes are identified below.

Small crack Local corrosion/Wall thinning Excessive distortion Leaking through wall Through wall corrosion Excessive leakage Fracture rupture

Degradation if not detected and repaired will ultimately lead to catastrophic failure.

In some cases, concerns may be limited to catastrophic ruptures that would present the greatest threat to workers or to the general public. In other cases, evaluations may have a broader objective that considers unexpected degradation (corrosion, cracking, etc.) that would require repairs or replacements of components and thereby have an economic impact associated with repair costs and/or the loss of the productive use of the component. The consequences of small leaks can be very different depending on the situation. For a water storage vessel, the loss of a small volume of water could be of little concern; whereas, small leaks in vessels containing toxic or flammable materials could result in a large number of fatalities.

Small Crack – Degradation is sometimes detected in the form of a crack that does not fully penetrate the wall of the vessel or piping component.

Local Corrosion and Wall Thinning – While design methods usually specify a wall thickness that includes some allowance for corrosion over the life of the vessel, the actual operating conditions may produce local rates of corrosion that exceed the expected rates.

Excessive Distortion – A failure mode of concern may not involve penetration of the component wall, but may rather degrade the function of the component because of excessive deflection or distortion. For example, seating surfaces may become sufficiently misaligned to the degree that gasket leakage results.

Leaking Through-Wall Crack – In some cases, even a small amount of leakage can have significant safety consequences, especially if the leaking fluid is highly toxic or flammable. In other cases, the release of otherwise non-hazardous fluids could impact the operation of nearby critical equipment by causing corrosion or electrical malfunctions.

Through-Wall Corrosion/Wall Thinning – As for cracking, leakage even at relatively small rates can present significant safety or economic consequences.

Excessive Leakage – Leakage rates can over time increase to levels that impact the function of a system or component. For example, a leak could eventually depressurize a critical system to the extent that it could no longer perform its intended function. In other cases, the leakage could create a water spray that could cause damage in the area adjacent to the leak

Fracture/Catastrophic Rupture – This most severe of consequences comes from sudden fracture or ruptures, which can occur without any prior leakage to give any warning of impending failure. The consequences of concern can be related to loss of function of the rupture component itself (e.g., loss of cooling water to process equipment) or can come from the extreme energy of the rupture event (e.g., high velocity missiles, blast waves, release of hot fluids, etc)

Rupture Cracking

Local buckling & Crack Vacuum Hazard

Failure Mechanisms

Many failures come from gradual material degradation (e.g., corrosion, fatigue cracking, wear, etc.) that occurs over time spans of many years before it advances to a stage sufficient to cause a structural failure (leak or rupture event). Metal fatigue is one common failure mechanism. Small-diameter piping is often subject to vibration stresses that cause cracking. Fatigue failures of larger sizes of vessels and piping are more likely to come from cyclic thermal stresses such as at locations exposed to cyclic exposures to hot and cold fluids. Corrosion mechanisms are a particularly common cause of failures both in the form of widespread loss material (wall thinning) or as local attack such as pitting or cracking. In other cases, a single short-term event (e.g., overpressure, extreme overheating, water hammer, etc.) can cause a sudden failure. Some loading events are natural occurrences such as earthquake loadings; whereas, other events come from human errors in operating and maintaining the facility such as from improper repairs and operation at pressures or temperatures over design limits. Pressurized systems are usually protected from excess pressures and temperatures by safety devices, but these devices can fail to function due to time-related degradation or improper installation or maintenance.

The main causes of failure of a pressure vessel are as follows: Faulty Design Operator error or poor maintenance Operation above max allowable working pressures Change of service condition Over temperature Safety valve Improper installation Corrosion Cracking Welding problems Erosion Fatigue Stress Improper selection of materials or defects Low –water condition Improper repair of leakage Burner failure Fabrication error Over pressurisation Failure to inspect frequently enough Erosion Creep Embrittlement Unsafe modifications or alteration Unknown or under investigation

9 Pressure vessel qualification: Design by analysis (finite element analysis)

Before 1963, all Pressure Vessels were designed using a systematic Design by Formula Approach which was based on experience and simple mechanics. What was mostly described was how to keep hoop stress low with respect to yield and how to use ductile material to accommodate local peak stresses.

In the Design by formula, the vessel geometry and major dimensions such as radius, length, etc. are specified and the required thickness is then calculated for a given load using equations and graphical data. With the development of the nuclear technology in the 1950s, pressure vessel design requirements needed to be improved in order to permit the use of higher allowable stresses without reduction in Safety.

This required changing the philosophy of Code design by formula. It is also worth to note that advances in mechanics theory and analysis methods provided new and more scientific methods for the pressure vessel design.

In 1963, ASME published the B&PV Code Section III: Nuclear Vessels based on the principles of limit analysis (Shakedown analysis, Fatigue Analysis) and Stress Analysis was used to determine higher allowable loads and more consistent margins of safety.

This New code permitted two approaches for design:

Improved design by formula, providing more accurate formula for sizing common components and higher allowable stresses, was intended for standard configurations

Design by Analysis, in which designer performs stress analysis and evaluates results against code limits, was intended for configurations not covered by the Design By Formula

The main guidelines of the Design by Analysis are to prevent the gross plastic deformation or ductile burst under static load, the incremental plastic collapse under repeated or cyclic load and the fatigue under cyclic load. Elastic buckling, creep, brittle fracture, stress corrosion, etc. also have to be considered…

10 Case studies

10.1 Case study 1: Qualification of mounted butane storage bullet of 2053MT capacity by PD5500, EEMUA-190 using finite element analysis

10.1.1 IntroductionThe mounded bullets are used to store highly inflammable, toxic and pressurized gases such as Butane/Propane/LPG & it is of prime challenging task and there is a need to design storage facilities for such gases with safety of the personal in and around, the locations, where it is situated. The safety is of prime importance, because it not only leads to the loss to the industry but also to the lives of the people.

10.1.2 ObjectiveThe objective of this is “Design validation of Mounded Butane storage bullet as per PD-5500, EEMUA-190”

10.1.3 Sequence of activities 3D cad model generation Discretization

FRS generation

0 20 40 60 80 100 1200

0.5

1

1.5

2

2.5

3

Material modelling Applying loads & Boundary conditions

o Loads & load combinations as per PD 5500 FE Analysis Post processing the results Qualification of the mounded bullets using PD5500 Report & Documentation Approval from customer

10.1.4 Complexities involved Identification of SCL locations Calculation of Pressure due to mound at Dome & Shell region of the Mounded Bullet Calculation of Elastic foundation stiffness Understanding the requirement of “UNEVEN” supports i.e. Midsoft & End soft conditions FRS generation. Stress categorization

10.1.5 Approach to resolve complexities SCL locations are identified based on the critical regions of the component & on the

previous experience. Pressure due to mound is calculated as per A.4.2.5 of EEMUA-190. Elastic foundation stiffness is calculated as per EEMUA-190 ProSIM has previous experience of generating FRS using IS-1893. This helped us to

generate the FRS for this project. Good understanding of PD5500 standard helped us to categorize the stress based on the

code annexure.

10.1.6 Qualification criteria & Results The accountable stresses on the components meshed with solid elements shall be

extracted from stress linearization method. Since for shell elements we shall get the membrane and bending

The qualification of components is based on the membrane and Membrane + Bending stresses.

Stress categorization is mandatory requirement to qualify the component as per PD 5500

SCL

Results: Membrane and membrane + bending stresses are calculated. The stresses are compared with allowable as mentioned in the PD5500.

10.1.7

Benefits to customer The expertise of ProSIM in both finite element analysis and code understanding helped the

customer to validate his equipment and get qualified by the approval authority. The simulation of the equipment helped the customer to understand the stressed regions. The simulation also helped to understand the factor of safety (FOS) for different components

and regions, which will help him in optimize the equipment – strength the region of lesser FOS and save the material in the region of higher FOS.

10.2 Case study 2: Qualification of blow egg vessel of 22m3 capacity by ASME sec VIII, Div2, using finite element analysis

10.2.1 Introduction

10.2.2 ObjectiveThe objective was to validate the blow egg vessel as per ASME sec VIII div 2. The scope of work involves qualification of blow egg vessel by performing stress and fatigue analysis. The ASME sec VII I div 2 needs the vessel to be qualified based on the stresses generated and the fatigue life of the equipment.

10.2.3 Sequence of activities 3D cad model generation

Discretization

Material modelling Applying loads & Boundary conditions

o Loads & load combinations as per ASME sec VIII div 2 FE Analysis Post processing the results

Fatigue analysis Post processing the results Qualification of the blow egg vessel using ASME sec VIII div 2 Report & Documentation Approval from customer

10.2.4 Complexities involved The geometry of the blow egg vessel was intricate. The discretization became complex because of the geometry. The hexahedral meshing involves detailed planning and approach towards the discretization and also the quality to be maintained.

Identifying the Stress Classification Lines (SCL) locations

To extract stresses at SCL locations, the mesh needs to as much as possible symmetric in nature and also have defined mesh flow. To have this in such a complicated model was a challenge.

Identifying zero pressure height and reference pressure height in the assembly to analyze the vessel for hydrotest analysis

10.2.5 Approach to resolve complexitiesThe detailed approach note was defined as how to mesh the model and an experience engineer who has worked on similar complex project was assigned the work.

Well established methods to mesh the complex equipments helped us to maintain the desired quality parameters and criteria’s.

The understanding of ASME section VIII, div 2 helped us to identify the stress classification lines (SCL).

10.2.6 Qualification criteria & Results The accountable stresses on the components meshed with solid elements shall be

extracted from stress linearization method. Since for shell elements we shall get the membrane and bending

The qualification of components is based on the membrane and Membrane + Bending stresses.

Stress categorization is mandatory requirement to qualify the component as per PD 5500

SCL

Results: Membrane and membrane + bending stresses are calculated. The stresses are compared with allowable as mentioned in the ASME section VIII, Div 2. The fatigue life calculations were performed using FESAFE software and compared with the life calculations using ASME sec VIII, Div 2.

10.2.7 Benefits to customer The equipment was not qualifying as per ASME sec VIII, div 2. ProSIM expertise in design

analysis helped customer in providing the engineering solution and made sure the equipment satisfies all the criteria’s as per ASME sec VIII, div 2.

The expertise of ProSIM in both finite element analysis and code understanding helped the customer to validate his equipment and get qualified by the approval authority.

The simulation of the equipment helped the customer to understand the stressed regions. The simulation also helped to understand the factor of safety (FOS) for different components

and regions, which will help him in optimize the equipment – strength the region of lesser FOS and save the material in the region of higher FOS.