Pig Receiver/Launcher Non Operational State

[Brnmcgn]

Hopefully posted within the correct forum to get the most. Iews, replies and experiences.

I am currently working on a new build on-shore gas processing facility. As part of the build, a large pipeline transporting mainly clean gas with some liquids (c5+)is being attached. It is expected that the pipeline will require to be pigged once a week to ensure liquid slugs are brought through.

Obviously as part of the design we have an appropriate pig receiverbeing installed and this is wheremy question is.

The pig receiver in question is an appropriate rated pressure vessel with a bandlock door seal. Due to the make upof the new facility it is actually located in the middle of the plant (slightly different from other facilites).

In your experiences, in what state would people normally leave the pig receiver? Isolated, Depressurised and inertered or isolated and left at pressure with hydrocarbons?

The current design (as I believe with most pig receivers) does not have a relief valve but is rated for the maximum pipeline pressure. However, a design has been made to fireproof the vessel.

Really appreciate any comments.

 

[BigInch]

That button didn't work.
OK. I was envisioning much more than a few ml "splashing the pipeworks". You painted a much bigger picture.

If it ain't broke, don't fix it. If it's not safe ... make it that way.

 

[zdas04]

Thermal relief is always a tiny fluid volume that if you don't relieve is a major pressure problem.

David Simpson, PE
MuleShoe Engineering

"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.

 

[dcasto]

you do not need a relief valve, you can use a tubing check valve around the block valve that isolates the receiver.

The pig receiver doesn't have to be an ASME vessel, it can be made of pipe and fittings designed to a piping code, most people use B31.8.

 

[zdas04]

dcasto,
I've done the check valve thing and it mostly worked, but the Nanny Society has ripped all of them out because: (1) you can't open a vessel that is only protected by a check valve; and (2) the check on a bypass would have to have a locked-open block valve behind it to protect personnel from (1) above which requires an MOC to remove the lock for every pig run (I'm serious, and the MOC takes 6-9 months to process every time the state changes, weekly for a weekly pig run). I expect the MOC disaster to resolve itself over the next few years, but I don't think that it will never again be easy to shift a lock.

There are states and countries that have overruled ASME B31.8 and mandated that launchers and receivers be code vessels. I expect that nonsense to become more widespread with time.

David Simpson, PE
MuleShoe Engineering

"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.

 

[MortenA]

I would not follow the Shell DP, even if I worked for Shell

enough reason why you would never work for shell ah just kidding but ppl who work for Shell seems to think of the DEP's as if they were handed down to Moses at a certain occation envolving a burning bush etc.

Best regards

Morten

 

[BigInch]

Company men.
Since that DP apparently allows for deviations as I suggested, it turns out that I could follow that one.

If it ain't broke, don't fix it. If it's not safe ... make it that way.

 

[dcasto]

zdas, I understand your pain. We had pig traps that we owned and operated inside chemical plants where we delivered the feedstock to them. The chem plants wanted to force us to do similar things. One time they drew a line in the sand and would not let us use such things or allow us to maintain our pielines. They changed their tune when I hit the shutdown valve via the scada system 100 miles away and shutdown their plant.

We had signage that had operating proceedures much like ones at loading racks. Tell me, how would that plant load out say condensate, LPG, would it require an MOC to open and close the valve? How about a prover? Or proving a dp meter.

you can only dumb down the workforce so much....

Good Luck

 

[zdas04]

If only they would dumb down the workforce. The field guys I work with are as smart as field guys ever were (actually pretty smart), but the Nanny Society trying to eliminate ALL risk through (administrative) processes won't allow them to think. I keep telling companies that field operators in Oil & Gas make over $25/hour. You pay that kind of money for people to think, not to mechanically follow scripts. If you want script followers you can get them for $10/hour. The field guys are so frustrated with crap like an absolute prohibition against unlocking a LO valve without an MOC. Not many of them are so frustrated (yet) to leave a $30/hour job for a sweaty $15/hour job somewhere else, but some are getting close.

David Simpson, PE
MuleShoe Engineering

"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.

 

[dcasto]

I got rid of the stainless steel carseals and went to plastic. During the quarterly LDARS inspection, the gas sniffer verifies the carseal status on those few valves as documentation of no tampering.

If someone needs a carseal open, thats in the work permit for the job.

I remeber the days of serial munbered car seals and keeping the broken ones as proof, proof of what I don't know.