Pig Receiver/Launcher Non Operational State
Pig Receiver/Launcher Non Operational State
(OP)
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.
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.





RE: Pig Receiver/Launcher Non Operational State
Second, there really isn't a standard way to leave receivers, and if you assume one, an operator will figure out a reason to ignore you. I've had good luck with purging the barrel through the bypass line and leaving the barrel isolated at around 1 barg. That way you can check the pressure before starting the process to see if valves are leaking in (i.e., barrel at line pressure) or leaking out (i.e., barrel at atmospheric pressure). Going to the trouble of inerting it is simply a waste of resources, it does not add to safety in any tangible way. A lot of people are happy leaving the barrel vented, but I have a problem with that--if the bypass or barrel-isolation valves leak through then you don't really have any indication.
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.
RE: Pig Receiver/Launcher Non Operational State
You're asking because it doesn't have a thermal relief, correct?
What would you be doing, if you knew that you could not fail? Ans. Gov lobbyist.
RE: Pig Receiver/Launcher Non Operational State
What would you be doing, if you knew that you could not fail? Ans. Gov lobbyist.
RE: Pig Receiver/Launcher Non Operational State
Thanks for the replies.
You are correct it does not have thermal relief as the designer has designed it like they would (i.e it is a pig receiver within a field) others they have designed. The problem it is in the middle of gas plant but it does have a tie in/blow down line to the flare system, manual only. I felt that an operational procedure, stating that it is depressurised and isolated would provide adequate safeguards in case of thermal relief. Thermal relief is only a problem in the event of a pool fire underneath it.
RE: Pig Receiver/Launcher Non Operational State
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.
RE: Pig Receiver/Launcher Non Operational State
What would you be doing, if you knew that you could not fail? Ans. Gov lobbyist.
RE: Pig Receiver/Launcher Non Operational State
A thermal relief valve shall be installed where the shut-in pressure of trapped fluid could
exceed the design pressure as a result of thermal expansion of the static fluid. Thermal
relief valves are not normally required for gas or multiphase pipelines, but should be
considered for liquid pipeline systems. The relief valve capacity and setting shall comply
with the pipeline design code and DEP 80.45.10.11-Gen.
NOTE: Where operating procedures restrict isolation of the pig trap to the period of loading or retrieving pigs,
it may be possible to eliminate the thermal relief valve.
Steve Jones
Materials & Corrosion Engineer
http://www.linkedin.com/pub/8/83b/b04
RE: Pig Receiver/Launcher Non Operational State
If it ain't broke, don't fix it. If it's not safe ... make it that way.
RE: Pig Receiver/Launcher Non Operational State
Steve Jones
Materials & Corrosion Engineer
http://www.linkedin.com/pub/8/83b/b04
RE: Pig Receiver/Launcher Non Operational State
Now, since you brought up this Shell, let's talk about it.
Given the circumstances of this question, specifically directed towards pig launchers and receivers in slug clearing service run once per week, I would not follow the Shell DP, even if I worked for Shell. While I would agree that a relief valve might not be needed on a pipeline in gas or multiphase service, this case is not discussing the pipeline, it is a localized bottle-tight device that could easily be full of liquids. Furthermore it is not way out on the edge of a plant or on the pipeline somewhere, it is in the MIDDLE of the plant. If there is anywhere you would want to have a relief valve on any part, or component, of a gas or multiphase pipeline, especially on a LAUNCHER/REVEIVER, and even the DP allows for it, I will requote you, "not NORMALLY required", this is one of those cases where it needs to be given a whole lot of thought. IMO, the Shell DP does not give a safe practice in this circumstance. I would not follow it. The B31.8 code is far superior in the degree of safety provided and .... costs relatively nothing. They are handling the liquids in some manner at present anyway.
If it ain't broke, don't fix it. If it's not safe ... make it that way.
RE: Pig Receiver/Launcher Non Operational State
]Whether it is right or not will have to be determined by HAZID, HAZOP and other process safety activities.
Steve Jones
Materials & Corrosion Engineer
http://www.linkedin.com/pub/8/83b/b04
RE: Pig Receiver/Launcher Non Operational State
This may become moot anyway. I am starting to see regulations (starting with Norway, but others are following) that reject the idea that pigging facilities are "pipeline accessories" as defined in B31.8 et al and requiring them to be treated as pressure vessels. I don't agree with this trend, but I understand where it is coming from. If a receiver barrel is a pressure vessel then this whole discussion becomes moot because there is no way to say that thermal relief is not required under the BPVC.
I started noticing 4-5 years ago that the horrible pre-fabricated pigging facilities that you can purchase from folks such as the old Tube Turns (they have changed their name) now have code stamps and include pressure relief on the barrels. This is recent, but it is a response to some pretty dramatic failures.
What you do with the PSV exhaust is another issue. A thermal relief generally dumps a couple of tablespoons of liquid and reseats until next time. Piping that to a flare is a really bad idea. Mostly people don't pipe it at all, and just let it splash the pipeworks. I support that approach, but in the middle of a plant that would probably be seen as wrong. If I had to pipe it somewhere it would be into a sump or waste water collection system.
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.
RE: Pig Receiver/Launcher Non Operational State
In terms of relief route, it will be fed through to our flare which has a liquid knock drum before the actual flare which will be suitable.
Thanks again
RE: Pig Receiver/Launcher Non Operational State
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.
RE: Pig Receiver/Launcher Non Operational State
If it ain't broke, don't fix it. If it's not safe ... make it that way.
RE: Pig Receiver/Launcher Non Operational State
RE: Pig Receiver/Launcher Non Operational State
In a plant (even on the edge) I'll pipe it to a sump of some sort, but putting a stream that will be exclusively water into a flare header is a problem for me.
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.
RE: Pig Receiver/Launcher Non Operational State
If it ain't broke, don't fix it. If it's not safe ... make it that way.
RE: Pig Receiver/Launcher Non Operational State
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.
RE: Pig Receiver/Launcher Non Operational State
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.
RE: Pig Receiver/Launcher Non Operational State
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.
RE: Pig Receiver/Launcher Non Operational State
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.
RE: Pig Receiver/Launcher Non Operational State
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.
RE: Pig Receiver/Launcher Non Operational State
Best regards
Morten
RE: Pig Receiver/Launcher Non Operational State
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.
RE: Pig Receiver/Launcher Non Operational State
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
RE: Pig Receiver/Launcher Non Operational State
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.
RE: Pig Receiver/Launcher Non Operational State
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.