startanalysis pipestress

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Pipingsolutions, IncPipe Stress Analysis

Where Do I Start?This is a step-by-step logic guideline for the data collection effort that shouldoccur prior to beginning to model a piping system for a stress analysis:

TRIFLEXWINDOWSPipingSolutions, Inc.

TRIFLEX WINDOWSTraining Presentation


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Step 1: What do you wish to achieve?a. Calculate stresses in a piping system and compare them with code

allowablesb. Evaluate the loads on rotating equipment nozzles and casingc. Evaluate the loads on nozzles on heat exchangers, pressure vessels

or tanksd. Evaluate the loads on structural anchors

e. Evaluate the loads on pipe supportsf. Evaluate piping movements from thermal expansion or contractiong. Evaluate the effects of wind loads on the piping system and attached

equipmenth. Evaluate the effects earthquake loads on the piping system and

attached equipment

i. Evaluate the effects of wave loads on the piping system and attachedequipment

j. Evaluate the effects of soil resistance to piping system movementsand stresses

k. Evaluate the effects of changes in temperature, pressure and weighton flanged connections to identify possible flange leakages



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Steps 2, 3, & 4:

2. Which Piping Code will govern thedesign of the piping system?

3. Collect all plan and elevation drawings4. Obtain or construct an isometric drawing

align North arrows



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Step 5: Collect the Necessary Physical Propertiesa. Nominal Pipe Diameterb. Pipe Schedule / Wall Thicknessc. Corrosion Allowanced. Specific Gravity of contentse. Insulation Material or Density & Thicknessf. Piping Material or density, modulus of elasticity & coefficient of expansion

g. Operating Temp, Design Temp, Upset Condition Temp & Base or Ambient Temph. Operating Pressure, Design Pressure & Upset Condition Pressurei. Flange Rating & Typej. Valve Rating & Typek. Elbow and/or Bend Radius or Bend Radius Ratio and Fitting Thicknessl. Reducer Length, Inlet & Outlet Diameters, Schedule or Wall Thick, Concentric or

Eccentricm. Branch Connection Typen. Expansion Joint Properties Translation & Rotational Spring Constants, Length of

Bellows, Length of Tie Rods, Pressure Thrust Areao. Structural Member Specifications AISC designation for standard shapes &

dimensional info for non-standard shapes



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Step 6: For All Anchors, Collect the FollowingData:

a. Location

b. Stiffness or Flexibilityc. Movements mostly from thermal growth

d. Origin of thermal growth in Anchor



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Step 7: For all restraints collect the following data:a. Location of each restraintb. Translational Restraints - the axis of action & 1 directional or double actingc. Limit Stops the axis of action, the plus and minus gaps and stiffness when limit is

encounteredd. Imposed Movements - the axis of action & the amount of the movement (+/-).e. Imposed Forces - the axis of action, the amount of the force (+/-) & spring constant,

if applicable

f. Dampers

the axis of actiong. Frictional Resistance to Movement - the plane on which the friction occurs, the static

and dynamic coefficient of frictionh. Existing Spring Hangers - the location, the installed load, the operating load, the

spring constant & the minimum and maximum loads of the spring hanger . It is alsohelpful to know if the spring hanger supports from above or below the pipe

i. New Spring Hangers - the location, the number of spring hangers in that location,

the percentage load variation allowed and whether a hanger or support is mostdesiredj. Rotational Restraints the location and the axis about which rotation is to be

resistedk. Imposed Rotations - the location, the number of degrees of rotation and the

direction of rotationl. Imposed Moments the location, the amount of moment and the direction of action



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Step 8: Special Effects

Special Effects such as Cold Spring:

Cut Short - the location, the axes of

application, the amount of cold spring &whether Cut Short or Cut Long



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Step 9: Special Loading Conditions

a. Wind Loading the piping segments where wind is to beapplied, the orientation of the wind vector, wind speed orpressure per unit length and shape factor

b. Wave Loading the piping segments where wave loading is tobe applied, the orientation of the loading vector, the wave

loading pressure per unit length and shape factorc. Uniform Loads such as Snow and Ice the piping segments

on which the loads are to be applied, the amount of theloading per unit length and the load orientation with regards toW,Y & Z

d. Seismic Loads the method to be used to simulate the

seismic event (RSA or percentage of gravity) and themagnitude of the seismic evente. Soil Interaction the piping segments on which soil restraints

are to be applied, the soil spring constants or the soilproperties



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Steps 10 & 11:10. Orient the Global (X,Y,Z) Axis System on

the Isometric Drawing Y is always Up

11. Now, assign Node Numbers to the pipingisometric drawing in accordance with theguidelines set forth in the next

presentation



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Pipe Stress Analysis

Where Do I Start?For more details please contact:

6219 Brittmoore Road

Houston, Texas 77041-5114 U.S.A.

Voice: 713-849-3366

Fax: 713-849-3806

e-mail: [email protected]


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