Steel Pipe support 1

[eatapeach]

I always read in the specifications where a hanger is required within 12" of a change of direction on horizontal piping regardless of the pipe size however I have never read this in any of the codes such IMC, IPC or even the MSS-SP-69. Where does this requirement come from?

 

[JohnRBaker]

Common sense ;-)

John R. Baker, P.E. (ret)
EX-'Product Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

 

[eatapeach]

John,
Unfortunately I can't enforce Common Sense as a QC. I was hoping it was stated somewhere in code.

Thanks

 

[MJCronin]

OK, ... Its still morning and my medications are just kicking in ...

It is my understanding that the general rule "put a pipe support near every elbow" is a result of the usage of the ancient "span methodology" used to design and support piping systems. The span methodology broke the system up into a series of simply supported spans and set a maximum stress and deflection for the span....

Under this ancient and venerable set of rules, the designer is to develop maximum piping spans based on the particular piping strength, wall thickness and contents. The construction forces or field engineer can easily locate and support various types of piping systems as long as the piping span was less than the maximum. Both ASME B31.1 and B31.3 permit this methodology.

The spans were different for stainless and carbon steel systems and, obviously, different for Schedule 10S piping than for Schedule 80.

A wise engineering firm did not permit all piping systems to be supported in this manner. Some piping and pipe supports were restricted and called "Engineered systems". A piping stress analysis would be done and individual supports would be designed for Engineered systems.

What made this whole span methodology work was the need to place supports where there was a concentrated weight (valves or risers) AND a support at the elbows. Elbows are a change in direct and a violation of the span assumptions.

Butthole MBAs, project managers and newbie clients have confused this complex issue and, sadly, the final vestiges of these rules only exist as the phrase "put a support at every elbow"...

https://www.geothermal-energy.org/pdf/IGAstandard/WGC/2000/R0258.PDF

Any other geezers out there with strong opinions on this ??

Regards



MJCronin
Sr. Process Engineer

 

[JohnRBaker]

Elbows are a change in direct and a violation of the span assumptions.

So I guess suggesting that it was "Common Sense" wasn't that far off, eh?

John R. Baker, P.E. (ret)
EX-'Product Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

 

[EdStainless]

If they don't have supports at valves and changes in direction (in any plane) then ask to see the engineering calculations for the support system.
You support near elbows so that you only have to worry about normal loads on piping and not torque also.

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