Gas service line support span considering hydro testing

[enggpiping]

Hello All,

I am about to provide an input to civil guys to design a sleeper for a bunch of NG lines & the smallest of which is 20" SCH 80 pipe.

This is inside process plant scenario so ASME B 31.3 is applicable.

I want to know the general way of calculating a pipe support span for a gas service line which will be hydro tested.

WRT the ASME B 31.3 it is mentioned that “345.3.2 Temporary supports. Piping designed for vapor or gas shall be provided with additional temporary supports, if necessary, to support the weight of test liquid."

So how do you guys calculate the support span in this situation?

Option 1)- Is it good to design the sleeper for gas filled spans however the provision for temporary hydro test supports are to be taken care for Hydro test before testing & removed after the test (is it very complicated? or it is a normal practice?)

Or Option 2)- It is better to Design the sleeper for liquid filled spans even if the regular line service is gas? Considering temporary supporting arrangement is way problematic at site & can increase complications?

Looking forward to your inputs on this at the earliest as the civil guy is behind me to get the concerned spans.

Thanks in advance



Regards,
Abhijit
Plant Layouts

 

[BigInch]

It is usual practice to design pipe supports for hydrotest loads. The piping engineer will direct structural engineers to put permanent or temporary supports, anchors and guides wherever they are needed.

you must get smarter than the software you're using.

 

[enggpiping]

Thanks BigInch,

Agreed & implemented as it is very logical approach.



Regards,
Abhijit
Plant Layouts

 

[LittleInch]

I agree. What you sometimes find is that as the hydro load is occasional and not combined with other loads such as temperature effects and in a multi-pipe rack you could also stipulate that only one pipe at one time is tested, the hydrotest load is acceptable with a reduced safety margin compared to operation plus high wind / seismic loads etc. However I also believe it should not need separate supports, mainly because in the future if you ever need to hydro this line again, everyone will have forgotten about the need for temporary supports....

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[enggpiping]

Hi LittleInch,

Thanks for highlighting this important point & to confirm on this I am considering hydro test loads while giving the spans to civil.



Regards,
Abhijit
Plant Layouts