Hello all!! I have a question, p

[carletes]

Hello all!!

I have a question, perhaps too easy for some of you, but it's making me go crazy.

I am calculating a piping system according to Ansi B31.1. As you know, several comprobations must be perfomed: pressure, sustained load and expansion condition. My question refers to sustained load calculations (including piping weight, pressure, insulation and valves weight etc)
In this case, if there are any supports that I know are going to lift during operation due to expansion, must they be considerated in the sustained load case calculations? Becasuse I think ANSI doesn't say anything regarding it, but if I considerate those supporting points or not, my pipe fails or not.
I hope having explained myself "decently" (my English is not that good)

Any help will be really welcomed.

Thanks.


Carletes

 

[ChasBean1]

Apply support for the proper points for weight and for thermal expansion and contraction. The sustained condition you mention will be an opposite reaction force at the throttling point. If your piping takes a 90° bend down to turbine poppets, for example, the piping will want to jump away in the opposite direction from this throttling point. Think of a garden hose run from your spigot to one bend, then another, then another. Only at the point of greatest pressure drop (the nozzle) does the hose want to kick back in the opposite direction... think on that for a moment and let us know what you conclude...

 

[ccfowler]

Code specified values, materials, procedures, etc. must always be observed fully and properly, but observance of these is not the end of any design work. The code requirements must be considered to be minimum requirements. You must always thoroughly consider your specific design's needs and assure that all needed provisions are assured so that your design does not "fail" under any expected circumstance, including transient conditions. This may involve using more (or more elegant) support provisions, seemingly more costly materials, etc.

So called "code minimum" designs are seldom the truly most economical designs even though they may provide a relatively low initial cost. I always like seeing codes that clearly state that a design that merely satisfies the minimum requirements of the code shall be interpreted as being in violation of the that code. Statements such as these serve to remind the users that they must truly understand what they are designing and why they are designing it.