Pipe Supports

[Inchtain]

Good morning,

We have an off gas pipe from the top of a new separator with the following parameters:

4 inch, SMLS Pipe, SCH STD, ASTM A 106 Gr. B, Design pressure 17.6 bar, Working pressure 3 bar, design temperature -28.9 to +37.8 degreed Celsius, working temperature 38 degrees Celsius, insulation no, Fluid: Gas.

The distance between its supports is 9400 mm, do you think this is acceptable? and I wonder how to approve this distance?

We used the Pipe Data Software to verify the supports distances and the maximum span for the 4" STD pipe found to be 9600mm for the empty pipe (carrying gas or air), So, are we in the safe side?

Please see the attached photo

Best regards,

 

[LittleInch]

It's a bit flimsy looking alright.

Your worst case will be hydrotest - just make sure it can handle the weight and the pressure stress without failing and then it's up to you. You won't approach yield in service, but it may "sag" a bit.

The thing I would be more worried out is Vortex induced Vibration (VIV) if you get a constantish wind coming across the pipe at 90 odd degrees. Then it can start to constantly flex and look alarming and may fatigue something out.

I've seen it on long spans of pipe and it's quite odd seeing this pipe vibrate at 2-3 Htz.

But it's difficult to say it won't work unless it fails the hydrotest case when your acceptance stress is basically 100% of SMYS.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[JStephen]

Quite often, customers will have specifications with standard spacing which is less than what you'd calculate- or maybe PIP standards, etc.

 

[IFRs]

Needs a bridge btween the supports, IMHO

 

[dik]

I think it is overspanned, just from appearance. I've never been on a project where 4" pipe is spanning 30'. It's also an end span condition with limited continuity. If the numbers say it's OK, it's your call, but too far for me.

So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[XL83NL]

Concur with dik. Way too far for me.
Also, A106-B, is by definition seamless, so need to call it out twice ;-)

Huub
- You never get what you expect, you only get what you inspect.

 

[dik]

...and if you get 1" of ice on it, the ice just helps add to the strength...

So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik