7 replies to this topic

[_1angelia23]

Dear engineers

we have HIPPS, upstream of first stage separator in initial oil and gas separation, i am trying to understand which location is better to pressure transmitters PTs, whether upstream of UZVs or downstream. It is a recommandation in HAZOP for a facility to change their location to upstream of UZVs.

Edited by _1angelia23, 10 January 2025 - 07:21 PM.

[Dacs]

Without any sketch, I assume that you have HIPPS at the inlet of your separator. And what is "UZV"?

[_1angelia23]

Dacs, on 12 Jan 2025 - 04:17 AM, said:

Without any sketch, I assume that you have HIPPS at the inlet of your separator. And what is "UZV"?

you can see it attached

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[Dacs]

Hard to tell from the drawing, but I'll make the assumption that UZV-001 is U/S B/L Isolation valve, UZV-003 is a pipeline sectionalizing valve and UZV-004 is D/S B/L Isolation valve.

 

Anyway, you place the PTs in your HIPPS in the location where you want to protect. U/S of UZV-004 is of higher class (600#) and I presume your separator is of lower class 300# from spec break).

 

Based on the info at hand, I cannot see a reason why the PTs needs to be located U/S of UZV-004.

 

Only reason (and I'm speculating here) that you want to relocate this U/S is to avoid surge when UZV-004 is closed. 

 

Can you share the relevant HAZOP worksheet covering this node and action to relocate the PTs?

[_1angelia23]

Dacs, on 13 Jan 2025 - 05:44 AM, said:

Hard to tell from the drawing, but I'll make the assumption that UZV-001 is U/S B/L Isolation valve, UZV-003 is a pipeline sectionalizing valve and UZV-004 is D/S B/L Isolation valve.

 

Anyway, you place the PTs in your HIPPS in the location where you want to protect. U/S of UZV-004 is of higher class (600#) and I presume your separator is of lower class 300# from spec break).

 

Based on the info at hand, I cannot see a reason why the PTs needs to be located U/S of UZV-004.

 

Only reason (and I'm speculating here) that you want to relocate this U/S is to avoid surge when UZV-004 is closed. 

 

Can you share the relevant HAZOP worksheet covering this node and action to relocate the PTs?

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[Dacs]

I'm not sure what CPF means, but I suppose "Central Production Facility" is CPF?

 

Again, the consequence and recommendation does not make any sense to me, given the information you provided.

 

What is this "HIPPS valve trip" in the deviation? I presume the HIPPS isolates the pipeline from CPF, but it's not clear where these are.

[_1angelia23]

Dacs, on 13 Jan 2025 - 12:58 PM, said:

I'm not sure what CPF means, but I suppose "Central Production Facility" is CPF?

Again, the consequence and recommendation does not make any sense to me, given the information you provided.

What is this "HIPPS valve trip" in the deviation? I presume the HIPPS isolates the pipeline from CPF, but it's not clear where these are.

For CPF you are correct, HIPPs is considered as a mechanism to reduce flaring during emergency operating conditions and isolate the facility if overpressure happened due to choke valve failure for instance
Deviation here is no or less flow!as you said before l think the issue is about surge what if Hipps valves is tripped what are the consequences? How does that effect the upstream of hipps valve? in standard API 170 PTs is upstream HIPPs, but im two exisiting facilities in my field , upstream of hipps valves..

[Dacs]

My experience with HIPPS and wellheads is that HIPPS valves are located at the wellhead so if they need to close, you isolate from the wellhead itself.

 

Inadvertent closure of those will obviously cut the supply to CPF obviously, but there's no inherent overpressure that I can see that relocation of the HIPPS PT will solve.

 

As I said, the PTs should be located on the system being protected (300#) and I cannot see any (as far as I can tell) reason on a benefit of relocating those on the 600# side of the pipeline and it certainly won't help in the CPT not getting any feed from the wellhead when the HIPPS valve closes.

 

Were you in the HAZOP when it was done? Maybe there are contexts that were discussed that were not documented in the HAZOP report.