Design Code for Pipeline Pig Traps

[DD88]

Dear Guys,

Most of the Client documents are having design standard for Pig Trap as ASME 31.4/31.8 and End closure with ASME Sec VIII. But my client is asking to design the traps from ASME B31.3 for Above ground pipeline which is designed from ASME B31.3. Is it right approach to keep the design code ASME 31.3? If anyone can enlighten on this.

Thanks in advance for support.

 

[LittleInch]

Well IMHO, an above ground pipeline designed to ASME 31.3 is in fact a piece of piping...

AFAIK, B 31.3 doesn't have a specific section on pig traps and usually you don't do it due to different wall thicknesses between the two different codes.

I can't see any reason why you can't set it to 31.3 and it would make sense, but why is this being designated as a pipeline?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[1503-44]

It is correct according to the scope of the 31.4 & 8 codes (see section 1.0) to design pig traps, pump and compressor stations with these codes. In the US CFRs and PHMSA agree that the pipeline codes do cover pig traps, pump stations, compressor stations and pipeline components located on offshore pipelines. Note that a 0.4, 0.5 or 0.6 design factor is required, 0.5 if it is inside a compressor, pump Station, or offshore platform, or other area in those respective class locations.
If you are outside the USA, you may also have a specific country code requirement.

I would think that if you design to B31.3, it will probably meet 4 and 8, but that may depend on the exact materials and the class location, in which case you might be able to easily certify it for any code and alleviate your concerns. If there are no applicable local country requirements, just do as the client says, provided that you are happy that the resulting design is safe.

Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

 

[r6155]

Ask your client why B31.3

Regards

 

[1503-44]

It's usually because the engineers only have refinery experience.

Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

 

[LittleInch]

It's also above ground which neither B31.4 or .8 really like. Plus no idea of fluids or design temps which sometimes send you to 31.3

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[1503-44]

I have never thought it to be any problem at all.

Lot of the Alaska Pipeline is above ground.

Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

 

[GBTorpenhow]

Pig traps/launchers would be subject to the same code as the pipeline, as they are functionally part of the pipeline.

Pig traps are usually designed to a pipeline code probably because only pipelines regularly need pig traps. I would be curious how your subject pipeline, above ground or not, falls under the scope of B31.3.

You see clients want to define things certain ways for various reasons but IMO the intended scope of the codes involved is pretty clear: if its function is to transmit or transport from one place to another it's a pipeline and B31.4/8 would apply, if the function is to convey to/from some sort of process equipment then B31.3 would apply.

 

[Krausen]

I've worked in both pipeline & refining for years and have never seen a pipeline pig trap designed to B31.3. There should be no need for that. All pipeline pig traps I've done were designed to B31.4 and often had trap end closures designed to ASME Section VIII-1. Most pipeline companies have specific preferences for pig trap end closure make & models.

Whether it's above or below ground pipeline system/pig trap, B31.4 still applies. Most pig traps are completely above ground, especially newer ones built nowadays. Many newer pipeline facilities now are all 100% above ground too, designed under B31.4. I believe the max design temperature limitation in B31.4 is 450F, which I've never seen exceeded in any pipeline system.

 

[1503-44]

B31.3 is used for pig traps quite a lot, especially in the mideast. It used to be more common than it is now. Saudi Aramco has changed their spec to 31.4 & .8, but only onshore. Offshore traps are still b31.3

https://www.scribd.com/document/550825376/02-SAMSS-009

B31.4 Temperature Scope is -20 to 250F

B331.8 Temperatùre Scope is -20 to 450F, but be aware of ...
Table 841.1.8-1 Temperature Derating Factor,
T, for Steel Pipe
Temperature Derating
Temperature, °F (°C) Factor, T
250 (121) or lower 1.000
300 (149) 0.967
350 (177) 0.933
400 (204) 0.900
450 (232) 0.867

Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

 

[LittleInch]

I've had to battle a few times when some idiot drew the code demarcation line at the fence line or somewhere not including the pig traps and the piping guys insisted on using 31.3 for the end of a 31.4 or 31.8 pipeline.

I usually won, but one which escaped ended up with about a 10% reduction in ID in the minor barrel because of the different material strengths....

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[1503-44]

Ah yes. The Magical fence.

Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

 

[LittleInch]

Worst one I even saw the idiot then designed all the pipeline inside the fence to B31.3 and ended up so thick they needed to bring in PWHT equipment.

And I think needed to fly in some transition pieces as the bends were thicker than the pipe.

Lunacy.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[1503-44]

Just to give the pigs that extra bump going around the bend.
Mixing codes is never a good idea, for a lot of reasons.

Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

 

[DD88]

Thank you all for replies.

I am trying to Convince Client to go with design Code ASME B Sec VIII. I think this will be ok if they agree on it.

 

[1503-44]

It is not necessary according to B31.8 to design a trap to ASME BPV 8.
It is not necessary 15 Feb 23 15:08 to have a closure with BPV 8 stamp.
However many companies prefer to have a BPV 8 stamped closure, some prefer both.

Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

 

[LittleInch]

What exactly is ASME B section VIII?

If you mean you're designing the whole thing as a pressure vessel that is a bad idea IMHO.

It will cost you loads more, be thicker than even b31.3 and then you'll need to inspect it every 5 years or so to the BPV inspection code.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[1503-44]

Yeah. Boiler & Pressure Vessel.
That's why I warned him again.

Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

 

[Rubje]

@1503-44
"B31.4 Temperature Scope is -20 to 250F"

What code should be used if temperatures are above 250F? I imagine b31.3 but what if the temperature is above B31.3's temperature limit?

 

[LittleInch]

Don't hijack a thread.

Start a new one please.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.