10 replies to this topic

[anamackic]

Pig receiver

Please if some one can help me to find an answer on one question:

How should I design pig receiver as pressure vessel or a pipe. From all my understanding this should be a pressure vessel, but my client is asking from me to design it as a pipe. When you compare the thickness which in these calculations there is a big difference, when I consider Pig Receiver as a pressure vessel I have thickness of 26mm, but when I consider it as a pipe it is 16mm. Let me just say that I feel much safer considering pig receiver as a pipe

Please if someone can help me with his/hers experience

Thank you
Ana

[JoeWong]

Both approaches have been done and both approaches work per my past experiences.

As long as it is designed, fabricated, tested, etc in accordance to code, it is "safe". It is "non-safe" with pipe if you don't design, fabricate and test accordance code.

[anamackic]

Dear Joe Wong,

Thank you for your answer. But as I have wrote, there is a big difference in thickness, i am just wondering even that is the difference biger then 10 mm we are still be safe.

Regards,
Ana

[djack77494]

I believe that pig launchers and receivers MUST be designed as pressure vessels. I fail to see why one would be considered anything else. Unless I am missing something, these vessels meet the criteria spelled out in the ASME codes and therefore must be designed as such. They are vessels and not pipe (even if they are partially constructed of pipe).

[ankur2061]

Ana,

You must surely have heard of 'Shell' which is amongst the top O&G companies in the world. They have their own design standards designated as DEPs (Design Engineering Practices) which are considered by many as amongst the best engineering practices anywhere. There is a DEP for Pig traps with the number and title as: 31.40.10.13-Gen. 'Design of Pipeline Pig Trap Systems'.

The above mentioned engineering practice has clearly mentioned that the entire pig trap system (launcher and receiver) should be designed, constructed and tested according to the same code as the pipeline. It also says that it is assumed that the pipeline on which the pig trap system is provided is designed according to ISO 13623 (Petroleum and natural gas industries -- Pipeline transportation systems).

It also says the following:

quote "For the purpose of code break locations it is also assumed that the piping of the facilities to
which the pipeline/pig trap system is connected is designed in accordance with
ASME B31.3."unquote

Many experienced engineers in the O&G field consider Shell DEPs as some of the best engineering practices and recommend them. I also find them extremely good and have followed their design practices for a lot of my engineering design without any hitch.

I hope this experience helps.

Regards,
Ankur.

[JoeWong]

Doug,
Pig launchers and receivers are just a piece of equipment launche or recieve pig for pipeline pigging.

So some people consider it is PIPE and it can be fabricated and tested on site without going through all the details in procurement. They just procure it under the PIPELINE and PIPING bulk items. From technical perspective, pipeline code may have different wall thickness and the internal diameter. The ID the minor barrel shall be same as pipeline. It may be easire for CONTRACTOR to procure in bulk together with pipeline rather than let the vessel fabricator to source specific ID, correct material and yet it is just a short piece. This tends to increase the cost.

However, some people may consider this is an equipment as it mark as equipment in P&ID. Have not heard or any technical reason why it must be designed to vessel code (as it can be in PIPING / PIPELINE code).

[JoeWong]

Ana,

Something made me curious.

You specify a receiver with a design pressure (said 100 barg). Then your mechanical engineer can design to vessel code or pipeline code. Using vessel code, you got 26mm. Using pipeline code, you got 16mm (just an example). From safety perspective, both are having design pressure of 100 barg. Why one is safer than the other ?

Personally i would think there are other requirements bind to the code that you use i.e. formula, design margin, testing procedure, welding requirement, etc. It is possible to have 2 different thickness with same design condition but same level of safety.

[Qalander (Chem)]

Ana,

Something made me curious.

You specify a receiver with a design pressure (said 100 barg). Then your mechanical engineer can designed to vessel code or pipeline code. Using vessel code, you got 26mm. Using pipeline code, you got 16mm (just an example). From safety perspective, both are having design pressure of 100 barg. Why one is safer than the other.

Personally i would think there are other requirement binded to the code that you use i.e. formula use, design margin, testing procedure, welding requirement, etc. It is possible to have 2 different thickness with same design condition but same level of safety.

Although

Design pressure may be the same(as indicated 100 barg)

but the connected background,perspective scenarios for each(Vessel) and(Pipeline segment) case would greatly vary.

Some of the more Code(s), Standard(s) conversant forum stalwarts

will guide us for correct situation/position.

I believe for each case.

Hope this proves helpful.

[anamackic]

Thank you all for your answers. My client is asking to make design as a pipe and i will do it like that. This is my first time that i need to design the pig receiver/launcher as a pipe, previously my college was designing couple of them as pressure vessels. So I was little bit confused.
Thank you all for your clarification
Ana

[djack77494]

Ana,
Best of luck to you. I maintain that Launchers and Receivers must be designed as pressure vessels. They fall into ASME code requirements for vessels due to their design pressures and their volumes. Therefore, I don't believe you can arbitrarily exclude them from PV code requirements. My general approach might be to design these devices using the more stringent of the possibly governing codes - never the less stringent. That is unless I know for certain that the more stringent requirement does not apply. Better to err on the side of safety.

[anamackic]

Ana,
Best of luck to you. I maintain that Launchers and Receivers must be designed as pressure vessels. They fall into ASME code requirements for vessels due to their design pressures and their volumes. Therefore, I don't believe you can arbitrarily exclude them from PV code requirements. My general approach might be to design these devices using the more stringent of the possibly governing codes - never the less stringent. That is unless I know for certain that the more stringent requirement does not apply. Better to err on the side of safety.

Dear djack77494,
Because I was conserned for safty i have asked this question. At the end client needs to decide what they want to do.
Thank you again on your comment