4 replies to this topic

[arkae]

hi everyone...

 

if we know the operating pressure of natural gas in a pipeline, for example if the operating pressure of natural gas is in the range of 30 ~ 50 barg, then how do we select the design pressure to be considered for the pipeline.

 

Is there any code requirement or any reference for considering margin over operating pressure to select the design pressure?

 

Thanks in advance for your replies..

[fallah]

arkae,

 

If the design code is ASME B31.8, attached page well specify the relation between MAOP, test pressure and design pressure...

Attached Files

•  Pages from ASME B31.8.pdf   61.77KB   90 downloads

[arkae]

@falla

 

Thanks for your quick reply.

 

In ASME 31.8 attachment provided by you

 

Test pressure minimum = 1.1 x maximum operating pressure(i.e 1.1 x 50 = 55 barg as per the details provided by me)

 

Test pressure maximum = 1.1 x Design pressure(but design pressure is not known)

 

Maximum allowable pressure = minimum( 1.1 x test pressure , design pressure)

 

Please explain me how the design pressure should be selected as the correlation among test pressure, MAWP and design pressure is not clear.

 

@Nida

 

Thank you for the references provided. I will go through it.

 

But i couldnot open____________ and  _____________. Please check. If you can mail me please mail to my id .

[fallah]

arkae,

 

The design pressure of the gas pipeline has to be calculated as per the formula in ASME B31.8 in which the pipe thickness and allowable stress of the pipe material are the main parameters. Then by using the attached sheet you can specify maximum allowable operating pressure of the pipeline...

Edited by fallah, 01 March 2014 - 11:56 AM.

[Root]

Hi,

Use Barlow equation to determine Design pressure for given pipe class and from your post, you mentioned pressure rage 30-50 barg. Hence you need to select the pipe that can with stand your pressure range + capacity (calculate capacity based on velocity criteria) and after selecting the pipe class you can assign MAOP based on your process requirement or end user. MAWP is 10% more than MAOP but again depend your company standards.

 

Toor

Edited by Toor, 05 March 2014 - 02:04 PM.