5 replies to this topic

[pmunishankar]

Dear Members,

 

I am looking for methodology / correlations to determine the PSLL setting to shut natural gas supply line incase of pipeline rupture.

 

Let me elaborate my problem further:

We are supplying natural gas through by high pressure distribution pipeline network to industrial customers. It was decided during HAZOP and consequently during Safety Integrity level (SIL) review that SDV (of SIL rating 1) should be provided to protect upstream pipeline and block the inventory incase of full bore pipeline rupture. The operating pressure of pipeline is in the range of 850 - 950 psig. 

 

The question here is 'what should be the pressure low setting to shutdown the pipeline?'  

 

Has anyone carried out similar calculations?

Please share the methodology to do this.

 

Thanks and Regards,

Muni Shankar

[Bobby Strain]

I'll bet that you can find some information with Google. Or visit the FERC pipeline safety site (USA).

 

Bobby

Edited by Bobby Strain, 22 April 2013 - 02:38 PM.

[Root]

Use your judgement for psll based on your minimum operating pressure.
Toor

[latexman]

You need to do some "what if" calculations, put all the results in order, and use your engineering judgement.  Where will the PSLL be located?  What if the full bore pipeline rupture is just downstream of the PSLL?  What is the pressure at the PSLL?  What if the full bore pipeline rupture is at the end of the pipeline?  What is the pressure at the PSLL?  What is max. operating pressure at the PSLL?  What is min. operating pressure at the PSLL?  What if the full bore pipeline rupture is just upstream of the PSLL?  What is the pressure at the PSLL?

[neel_avi]

Dear Mr. Munishankar,
 
in the organisation I am working with, SDVs have not been envisaged so far. What ASME 31.8 and PNGRB says is about provision of isolations on basis of location class and thus the sectionalising valves are provided.
 
In pipelines what we have proposed are sectionalising valves at certain intervals of the pipeline which can be closed in case of a low pressure or leak detection system or a possible rupture. Major leaks can be identified from the online leak detection systems.
 
A start permissive for opening the valves have been provided in order to prevent the operator to open the valve and risk the integrity of the valve at high differential pressure.   
 
My post may not be of help w.r.t your query - I just wanted to share my experience here.
 
Please do share if you have arrive at any conclusion. Hope this forum will be able to help you.
 
Regards

Avijit

Edited by neel_avi, 23 April 2013 - 12:01 AM.

[chemsac2]

Munishankar,

 

There is an API 1149 on leak detection system. I think one of the methods works on method of characteristics (MOC) used in water hammer analysis.

 

Standard softwares are also available from vendor for pipeline leak detection based on this standard. I think one paper is available on web for leak detection software selection.

 

Regards,

 

Sachin