10 replies to this topic

[farid.k]

Typically, hydrotest pressure for pipeline is 1.5 x process design pressure. My problem is, my process design pressure is 40 barg. Design pressure of my pipe based on pipe spec (piping is 300#) is 50 barg @ 50 deg C. So hydrotest pressure is 1.5 x 40 = 60 barg (above design pressure as in pipe spec). I don't think it is allowed to do hydrotest pressure above design pressure that has been stated in pipe spec. Any comment? Hope my understanding was correct.

[fallah]

farid.k,

 

At first, please specify the design code of the piping system you described...

[farid.k]

I am not sure where to refer that. I did refer to pipe spec but didn't mention. Can we assume any code as example? I just need to know how to determine the hydrotest pressure

Edited by farid.k, 30 May 2016 - 05:54 PM.

[farid.k]

stated at last page of pipe spec, it mention ANSI B31-3B 1991

[fallah]

stated at last page of pipe spec, it mention ANSI B31-3B 1991

 

farid.k,

 

As long as the hydro-test pressure equal to 1.5 times the piping design pressure will produce a stress not to be exceeded than the relevant yield strength at test temperature, there would be no concern about the hydro-test pressure being above design pressure...

[farid.k]

Sorry as I don't really know where to get yield strength at test pressure. Will it be mention in the pipe spec document?

[fallah]

Sorry as I don't really know where to get yield strength at test pressure. Will it be mention in the pipe spec document?

 

farid.k,

 

No, but the allowable stress value by which the pipe thickness has been calculated based on selected design pressure had already been specified such that 1.5 times of design pressure won't result in a stress higher than the mentioned specified allowable stress...
 

[Mahdi1980]

Farid,

 

Although I confirm what Mr. Fallah said, most of the time it is not required to exactly consider the hydrotest pressure 1.5 times the design pressure.

In many case, you can practically test the line with pressure 1.3 times the design. So, if you are sure about not allowing to run above 50 barg, you may hydrotest the line on 50 barg.

 

Mahdi

[farid.k]

Farid,

Although I confirm what Mr. Fallah said, most of the time it is not required to exactly consider the hydrotest pressure 1.5 times the design pressure.
In many case, you can practically test the line with pressure 1.3 times the design. So, if you are sure about not allowing to run above 50 barg, you may hydrotest the line on 50 barg.

Mahdi

Thanks Mahdi for the suggestion. Yea, I just simply put test pressure = 48 barg which is 2 barg below the design pressure stated in the pipe spec and 8 barg above my process design pressure. Just that I deviate what has been suggested from ASME standard which 1.5 x design pressure. Is it OK to deviate? And any basis for the 1.3 x design pressure?

[fallah]

stated at last page of pipe spec, it mention ANSI B31-3B 1991

 

If the design code of the piping is ASME/ANSI B31.3, then you are not allowed to do the hydrotest pressure below 1.5 times of the piping design pressure. Indeed, hydrotest pressure with 1.3 times of design pressure is relevant to pressure vessels mostly being designed based on AMSE Sec.VIII Div.I.
 

[Mahdi1980]

Farid,

 

You can check the below links:

http://www.wermac.or...re_testing.html

https://pgjonline.co...-determination/

 

In addition you can search the topic in "Pipeline rules of thumb handbook". By: McAlister

 

Mahdi