Stress Analysis piping chilled water

[BIPVguy]

Dear all,

I have been tasked to do stress analysis of secondary side chilled water piping to determine stress risk on plate heat exchangers (PHEX). Secondary side (flow 5.5C and return 14.5C) piping extends horizontally (from PHEX to risers) and vertically from risers, branches to each FCU on 90m high building.

Any advise, example calculation, link,code, source would be greatly appreciated.
Thanks muchly.

 

[JohnBreen]

To do a structural analysis of a piping system (piping flexibility and stress analysis) you first must determine the Code or Standard to which it must comply. Then you must read that Code or Standard and determine what loading cases must be evaluated and what the limits on primary and secondary stresses are. Also it is necessary to obtain the limits on forces and moments applied to the equipment from the manufacturer of the equipment to which the piping is attached. Then you model the system using Caesar II and evaluate the calculated stresses and loadings on the equipment.

 

[BIPVguy]

Hi JohnBreen,

Thanks for reply. That is my point...what code is applicable? Is there any 'on foot' calculation eclarification in applicable literature or free of charge software that can be used for completing the job?


Thanks.

 

[TGS4]

BIPVguy - you're WAY out of your league on this one. Hire someone (like JohnBreen) who knows what they're doing. There is so much that can go wrong, and not being in compliance with the laws of the land (wherever you are...) can land you in a whole heap of trouble.

If you really want something for free, remember that you always get what you pay for.

 

[JohnBreen]

BIPVguy

I guess the first question that we should ask you is "where are you"? The choice of which Code document to follow will depend upon the jurisdiction in which the piping will be built and operated. Contact your local jurisdiction (the folks who are responsible for the LOCAL building Code) and ask them which piping Code THEY require for the piping system at issue. Then your employer must obtain (buy) a copy of that piping Code and YOU must read it.

The piping Code will provide you with the limits on stresses in the pipe (your design must accommodate these limits). The manufacturer of the equipment should provide you with the limits on the loadings (forces and moments) that your piping can transfer to the equipment. You may have to add some flexibility to the piping system to comply with the limit on the loadings your piping transfers to the equipment. Then you will have to design a pipe support system that will manage (control) the expansion/contraction of the piping such that the system will comply with the equipment manufacturer's limits on piping loadings. In designing the pipe support system you must look for available structures to which your pipe supports can be attached and you will have to assure that the loadings from your piping will not overload these structures.

There are many books in print that describe this procedure. You should use the "search" facility provided by this discussion board (at the top of the page) and look for previous questions on this topic.

Regards, John

 

[simplemath]

Correct me if I am wrong.

1. Use ASHRAE handbook. No ASME piping code will cover.

2. Horizontal support per MSS-SP-58. Rise support per typical arrangement.

3. Use simple calculation book(say, kellog's design of piping system, has examples)to decide equipment load.

4. good luck



--It boils down to simple math--

 

[JohnBreen]

1. Use ASHRAE handbook. No ASME piping code will cover.

If the piping has an internal pressure of 15 psig or greater (or an internal pressure less than atmosphere), the LOCAL building Code will likely require compliance with an ASME B31 Code for Pressure Piping. If it is to be operated in North America it is certain that B31 Code compliance will be required. The local building code has the force of law and therefor any Code or Standards invoked by the local Building Code has the force of law.

 

[BIPVguy]

Thanks muchly.