LOAD CASE

1. WW+HP HYD

b. Operating case: When operation starts working fluid will flow through the piping at a temperature and pressure. So accordingly our operating load cases will be as mentioned below:

2. W+T1+P1 OPE for operating temperature case3. W+T2+P1 OPE for maximum system temperature case4. W+T3+P1 OPE for minimum system temperature case

c. Sustained Case: Sustained loads will exist throughout the plant operation. Weight and pressure are known as sustained loads. So our sustained load case will be as follows:

5. W+P1 SUS

d. Occasional Cases: Piping may be subjected to occassional wind and seismic forces. So to check stresses in those situations we have to build thefollowing load cases:

6. W+T1+P1+WIN1 OPE Considering wind from +X direction7. W+T1+P1+WIN2 OPE Considering wind from -X direction8. W+T1+P1+WIN3 OPE Considering wind from +Z direction9. W+T1+P1+WIN4 OPE Considering wind from -Z direction10. W+T1+P1+U1 OPE

Considering seismic from +X direction11. W+T1+P1-U1 OPE Considering seismic from -X direction12 W+T1+P1+U2 OPE Considering seismic from +Z direction13 W+T1+P1-U2 OPE Considering seismic from -Z direction

While stress analysis the above load cases form load case 6 to load case 13 is generated only to check loads at node points.

To find occasional stresses we need to add pure occassional cases with sustained load and then compare with code allowable values. Following sets of load cases are built for that purpose.

14. L6-L2 OCC Pure wind from +X direction15. L7-L2 OCC Pure wind from -X direction16. L8-L2 OCC Pure wind from +Z direction17. L9-L2 OCC Pure wind from -Z direction18. L10-L2 OCC Pure seismic from +X direction19. L11-L2 OCC Pure seismic from -X direction20. L12-L2 OCC Pure seismic from +Z direction21. L13-L2 OCC Pure seismic from

-Z direction22. L14+L5 OCC Pure wind+Sustained23. L15+L5 OCC Pure wind+Sustained24. L16+L5 OCC Pure wind+Sustained26. L18+L5 OCC Pure seismic+Sustained27. L19+L5 OCC Pure seismic+Sustained28. L20+L5 OCC Pure seismic+Sustained29. L21+L5 OCC Pure seismic+Sustained

Load cases from 22 to 29 will be used for checking occasional stresses with respect to code B 31.3 allowable (=1.33 times Sh value from code). Use scalar combination for load cases 22 to 29 above and algebraic combination for others as shown in figure attached below:

e. Expansion Case: Following load cases are required for checking expansion stress range as per code

30. L2-L5 EXP31. L3-L5 EXP32. L4-L5 EXP33. L3-L4 EXP

The above load cases (from 30 to 33) are used to check expansion stress

The above mentioned load cases are minimum required load cases to analysis any stress system. Out of the above load cases the load cases mentioned in point number 1, 5, and 22-33 are used for stress check. And load cases mentioned in point number 1 to 13 are used for checking restraint forces, displacements and nozzle load checking.

Few additional load cases may be required for PSV connected systems, Rotary equipment connected systems.

Seismic and Wind analysis may not be required every time. So those load cases can be deleted if the piping system does not fall under the purview of seismic and wind analysis by project specification. However to perform wind and seismic analysis proper related data must have to be entered in Caesar II spreadsheet (Will be discussed in my future posts).

If the stress system involves use of imposed displacements (D) and forces (F) then those have to be added with the above load cases in the form of D1, D2 or F1, F2 as applicable.

It is a better practice to keep

1. Hydro and sustained stresses below 60% of code allowable

2. Expansion and occasional stresses below 80% of code allowable

3. Sustained sagging below 10 mm for process lines and below 3 mm for steam, two phase and flare lines

4. Design/Maximum displacement below 75 mm for unit piping and below 200 mm in rack piping.

Basic Load Cases used for Piping Stress AnalysisFollowing steps shall be carried for Piping Stress Analysis of any system,1. Identify the Critical lines from the P&ID based on the criteria mentioned in

the Piping Stress Analysis Design Basis.

2. Prepare a Stress Critical Line list

3. Categorize the lines as Category-1 (Extensive computer analysis required), Category-2 (Visual Analysis or by Nomo graphs, etc.) and Category-3 (Non-critical lines)

4. Segregate the Category-1 lines and identify Stress systems. Segregation should be made in such a way that proper boundary conditions can be defined for those lines. Also lines which can affect the behavior of the system significantly should be selected. Depending on the configurations Category-2 and Category-3 lines may also be included in the Piping system

5. Select a system for the analysis based on the priority or project requirement

6. List down the lines to be included in the system

7. Check if all the parameters of the lines are available,

1. Maximum Design Temperature & Pressure

2. Operating Temperature & Pressure

3. Minimum Design Temperature & Pressure

4. Test Pressure

8. Check if any Occasional loading is applicable for the selected system,

1. Wind Loading

2. Seismic Loading

3. PSV reaction forces

9. Note down environmental Data of the project,

1. Ambient Temperature

10. Once the modeling of the system is done in the Caesar-II using all the above data, next important activity is to formulate the load cases for which the system is to be analyzed

11. List down all the possible conditions the selected system may experience.

12. Load Cases for a piping system is given below,

CASE: 1 Basic parameters and no occasional loading

Following parameters will be used for formulating the load cases,WW = Water filled weightHP = Hydro test PressureW = Dead weight of the Piping systemP1 = Maximum Design PressureP2 = Operating PressureP3 = Minimum Design PressureT1 = Maximum Design TemperatureT2 = Operating TemperatureT3 = Minimum Design Temperature

Case No. Load Case Stress Type

L1 WW+HP HYDRO

L2 W+T1+P1 OPE

L3 W+T2+P2 (P1 can be used in this case) OPE

L4 W+T3+P3 (P1 can be used in this case) OPE

L5 W+P1 SUS

L6 L2-L5 EXP

L7 L3-L5 EXP

L8 L4-L5 EXP

L9 L2-L4 EXP

CASE: 2 Basic Parameters with Wind loading

Following parameters will be used for formulating the load cases,WW = Water filled weightHP = Hydro test PressureW = Dead weight of the Piping systemP1 = Maximum Design PressureP2 = Operating PressureP3 = Minimum Design PressureT1 = Maximum Design Temperature

T2 = Operating TemperatureT3 = Minimum Design TemperatureWIN1 = Wind Load in +X direction (direction is just for example user can use thisterminology for any other direction as per his ease)WIN2 = Wind Load in –X direction (direction is just for example user can use thisterminology for any other direction as per his ease)WIN3 = Wind Load in +Z direction (direction is just for example user can use thisterminology for any other direction as per his ease)WIN4 = Wind Load in –Z direction (direction is just for example user can use thisterminology for any other direction as per his ease)

Case No. Load Case Stress Type Combination Type

L1 WW+HP HYDRO Algebraic

L2 W+T1+P1 OPE Algebraic

L3 W+T2+P2 (P1 can be used in this case) OPE Algebraic


L5 W+P1 SUS Algebraic

L6 W+T1+P1+WIN1 OPE Algebraic




L10 L6-L2 OCC Algebraic




L14 L5+L10 OCC Scalar




L18 L2-L5 EXP Algebraic




CASE: 3 Basic Parameters with Seismic loading

Following parameters will be used for formulating the load cases,WW = Water filled weightHP = Hydro test PressureW = Dead weight of the Piping systemP1 = Maximum Design PressureP2 = Operating PressureP3 = Minimum Design PressureT1 = Maximum Design TemperatureT2 = Operating TemperatureT3 = Minimum Design TemperatureU1 = Seismic loads also known as Uniform loads in terms of ‘g’ in North-SouthDirection (direction is just for example user can use this terminology for any other direction as per his ease)U2 = Seismic loads also known as Uniform loads in terms of ‘g’ in East-WestDirection (direction is just for example user can use this terminology for any other direction as per his ease)U3 = Seismic loads also known as Uniform loads in terms of ‘g’ in VerticalDirection (direction is just for example user can use this terminology for any other direction as per his ease).Generally vertical load due to seismic is negligible and not included in the Load case formation.







L6 W+T1+P1+U1 OPE Algebraic

L7 W+T1+P1-U1 OPE Algebraic















CASE: 4 Basic Parameters with Wind &Seismic loading

Following parameters will be used for formulating the load cases,WW = Water filled weightHP = Hydro test PressureW = Dead weight of the Piping systemP1 = Maximum Design PressureP2 = Operating PressureP3 = Minimum Design PressureT1 = Maximum Design TemperatureT2 = Operating TemperatureT3 = Minimum Design TemperatureWIN1 = Wind Load in +X direction (direction is just for example user can use thisterminology for any other direction as per his ease)WIN2 = Wind Load in –X direction (direction is just for example user can use thisterminology for any other direction as per his ease)WIN3 = Wind Load in +Z direction (direction is just for example user can use thisterminology for any other direction as per his ease)WIN4 = Wind Load in –Z direction (direction is just for example user can use thisterminology for any other direction as per his ease)

U1 = Seismic loads also known as Uniform loads in terms of ‘g’ in North-SouthDirection (direction is just for example user can use this terminology for any other direction as per his ease)U2 = Seismic loads also known as Uniform loads in terms of ‘g’ in East-WestDirection (direction is just for example user can use this terminology for any other direction as per his ease)U3 = Seismic loads also known as Uniform loads in terms of ‘g’ in VerticalDirection (direction is just for example user can use this terminology for any other direction as per his ease).Generally vertical load due to seismic is negligible and not included in the Load case formation.



































Classification of Pipe Supports Based on Details, Constructions and FunctionsClassification of Pipe Supports

Broadly the pipe supports are classified in three groups as per following details / functions:– General details– Construction details– Functions ie. PurposeThese are described below in brief.

1. Pipe Supports Classification as per General Details:

A pipe line needs to be supported from a foundation or a structure. The piping loads will be acting on these foundations / structures. Since these foundations / structures are built on ground, they will exert an equal and opposite reaction, while supporting the pipe.In a pipe support, there will be some parts of support arrangement which is directly attached to the pipeline and there will be some other parts which shall be directly attached to the foundation / structure supporting the pipe.As per this general detail the support is classified as:

http://www.piping-engineering.com/pipe-supports-classification-based-on-details-constructions-functions.html#functions

http://www.piping-engineering.com/pipe-supports-classification-based-on-details-constructions-functions.html#construction

http://www.piping-engineering.com/pipe-supports-classification-based-on-details-constructions-functions.html#general

1.1 Primary Supports:It is the parts of support assembly which is directly connected to the pipe.1.2 Secondary Supports:It is the parts of support assembly which is directly connected to the foundation / structure and is supporting the primary support attached to the pipe line.

2. Pipe Supports Classification as per Construction:

Based on construction details, pipe supports are broadly classified in three types, as

– RIGID SUPPORTS– ELASTIC SUPPORTS– ADJUSTABLE SUPPORTSThese are described below in brief.2.1 Rigid Supports:This type of support arrangement is generally very simple and has maximum use in piping. It does not have adjustability to the erection tolerances. It will directly rest on foundation or structure which is supporting the pipe. Common type of RIGID SUPPORTS are shoe type (welded), shoe type (with clamp) Trunnion type, valve holder type, support brackets (Secondary Support). These are described under the topic ‘Supports Generally used’.2.2 Elastic Supports:This type of support is commonly used for supporting hot piping. It shall be able to support pipes even when the pipe is moving up or down at support point.Common types of elastic supports are variable type spring supports, constant type spring supports. These are described under the topic ‘Supports generally used ‘.2.3 Adjustable Supports:This type of support is Rigid type in construction but is has few nuts and bolts arrangements for adjusting the supports with respect to the actual erected condition of pipe. The support can be adjusted for the erection tolerances in the piping. These are required for a better supporting need at critical locations of pipe supports.Mostly all type of rigid supports can be modified by using certain type of nuts and bolts arrangement, to make it as an Adjustable support.Only a typical type of adjustable support is described under the topic ‘Supports Generally used.’

http://www.piping-engineering.com/spring-support-piping.html

3. Pipe Supports Classification as per Function (i.e. Purpose)

Pipe support classification as per function. This may change based on project.

Pipe supports classified as per functions are summarized in the Table at FIG.7. These are shown along with its basic construction, the symbols generally used and type of restraints it offers to the piping system.The supports classified as per function are further described as follows:3.1 Loose Support:This is most commonly used support meant for supporting only the pipe weight vertically. It allows pipe to move in axial as well as transverse direction but restricts only the vertical downward movement.3.2 Longitudinal Guide:This type of support is used to restrict the movement of pipe in transverse direction i.e. perpendicular to length of pipe but allow movement in

longitudinal direction. This is also a commonly used type of support. Generally it is used along with Loose support.3.3 Transverse Guide:This type of support is used to restrict the movement of pipe in longitudinal (axial) direction but allows the pipe to move in transverse direction. This is also referred as ‘AXIAL STOP’. This type is less used as compared to above two types. Generally it is used along with Loose support.3.4 Fixed point/Anchor:FIX POINT type of support is used to restrict movements in all three directions. ANCHOR type of support is used to restrict movement in all three directions and rotation also in these three directions.Non-Welded Type (Fix Point):This can be considered as a combination of longitudinal and transverse guide. This type resists only the linear movements in all directions but not the rotational movements. This avoids heavy loading of support as well as pipe. Therefore this type of support is preferred over welded type.Welded Type (Anchor)This type of support prevents total movements i.e. linear as well as rotational. This type of support is used when it is absolutely essential to prevent any moment/force being transferred further. It causes heavy loading on support as well as pipe.3.5 Limit Stop:As name itself indicates it allows pipe movement freely upto a certain limit and restricts any further movement. This is useful when total stops causes excessive loading on piping and support or nozzle.This type of support should be used selectively, because of stringent and complicated requirements of design, erection and operation.3.6 Special Supports:When we need a pipe support whose construction or functional details are different from the available details, then a special support detail sketch is prepared. The functions of this support can be any combination of above functions.

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LOAD CASE