load combination for piping analysis

[sbnz]

For a pressure piping system in a power plant that we are designing as per B 31.1, the combination of maximum operating plus occassional (cyclonic wind) loads are resulting in excessive nozzle loads for connected equipment.

Is it reasonable to assume a less severe combination (eg, wind loads reduced by a factor when combining with highest operating loads) to compute the nozzle loads? I am looking for procedures/ norms either as per code guidelines or as followed in good engineering practices by piping design engineers.

Would appreciate suggestions by experienced piping engineers.

regards,

 

[stanier]

Hi sbnz,

You may be getting high loads if there are non linear supports in you model. For the code load case pressure + dead load + thermal these are active however for other load cases these may not be active depending upon the software you are using and the set up.

In Algor's Pipepak you need to change the configuration file so that these non linear supports remain active for other code cases. I ma not sure if this is the case for Caesar, Triflex, Autopipe or other packages.

Suggest you check your help file or manual on non linear pipe supports. These include Oneway supports, limit stops etc.