ANSI/ASME B31.8, para 802.1 b(6) Desing of flowline 1

[Mechnain Baba]

ANSI/ASME B31.8 para 802.1 (b)(6) State that this code does not apply to flow lines Between wellhead and trap or separator, What is the intent of this exclusion ?
IF B31.8 is not appropriate code for flow line design, then what is?

 

[LittleInch]

HA,

The intent is that B31.8 only applies to single phase gas, not 3 phase well fluids.

In reality it is used widely for "gas" Wells flowlines, but you could use B31.3 or another pipeline code which covers all fluids like ISO 13623 or BS PD 8010 or similar.

What does your country do?

Look over the fence at other systems.

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

 

[1503-44]

I believe that the intent of B31.8 NOT applying to flow lines is to allow for conditions that are not typically found in GAS Pipeline transportation scenarios, ie. much higher pressures and temperatures as well as the many extraneous provisions of the pipeline codes that only apply to pipelines, much of which is related to different design factors for Area classes, inspection and reporting requirements, Pipeline warning signs, cathodic protection and much more. No point in subjecting lease piping to all of that.

B31.8 applies to all phases. Mostly due to Area Class Location Design Factors.
It is B31.4 that does not apply to 2 or 3-phase fluid streams, unless one of n-1 is water.

CFR PART 195—TRANSPORTATION OF HAZARDOUS LIQUIDS BY PIPELINE applies to liquid pipelines (low vapor pressure products) and can be used for liquid stream pipelines (not flow lines) after passing through the oil/gas seperators.

https://www.ecfr.gov/current/title-49/subtitle-B/chapter-I/subchapter-D/part-195

Note: (b-1)
"This Part does not apply to any of the following:
(1) Transportation of a hazardous liquid transported in a gaseous state"

The USA convention as defined in CFRs is ...paraphrased ... You should use B31.3 (not specifically stated, but there is no other choice possible) from well to the seperators, or production pad limit, if no separators. After that you can continue with B31.3, EXCEPT you must change to CFR 192 GAS (basically=B31.8) if you enter public land, or privately owned lands (any land not owned by the company), or cross a public road, or find yourself downstream of a gas processing facility.

CFR 192 GAS TRANSPORTATION
Text is here

https://www.ecfr.gov/current/title-...subchapter-D/part-192/subpart-A/section-192.1

Exceptions do not apply to those parts of an unregulated system that have control and safety functions or have control implications that extend to regulated pipelines.

See also discussion here,

https://www.eng-tips.com/viewthread.cfm?qid=502539

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

 

[LittleInch]

CFR just buggers everything up.

Look at interpretation 16-13 in the attached.



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

 

[1503-44]

I don't see how the interpretation buggered up anything.

That appears to be consistent with both of our recommendations to use B31.3 for flowlines, as B31.8 does exclude flow injection lines, between inj fac & inj wells and it also excludes flow lines between production wells and gas separation facilities, so use B31.3 for all flow and injection lines. The CFRs only make a change when they become pipelines, by virtue of entering "PHMSA pipeline space". As I said above, IN USA, B31.8 must be used if the flow line crosses a road, or enters public lands, or a production facility, as then the flow line ends and it becomes a transportation pipeline. It has entered the pipeline safety act territory, so it must conform to pipeline safety, requirements, class location factors, inspection and reporting requirements.

Let's check and make sure that the newer editions of ASME B31.8 have in fact remained consistent with that 2007/11 interpretation, or have been additionally clarified. Or maybe they now include public safety space criteria. I don't have the latest edition.


Note: B31.4 is not excluded from "flow lines" from oil wells to oil production facilities, but obviously those pipelines should not contain high pressure gas. Pressures from vaporizing fluids (from fluids normally transported in the pipeline in a liquid state) are permitted, as vaporisation would occur only at pressures below the pipeline design pressure needed for transport of that fluid in a liquid state, or otherwise somebody is adding a lot of heat, which should probably be done with process piping anyway.

--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 meant CFR messes things up by magically turning a "flowline" with three phase fluid into a "pipeline" which then mandates B31.8....

Madness.

In reality people just design to b31.8, use 0.6 DF min and stick on a decent corrosion allowance...



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

 

[1503-44]

0.5 within the platform and station/plant zones.
And then, ignoring pipeline requirements, you pretty much have B31.3, but they are just saying you can't ignore pipeline stuff. You have to let the safety agencies do their thing.

Has the new code revision kept the same wording?


--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'll have a look next week...

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

 

[LittleInch]

The latest one I have is 2018 and that still doesn't over flowlines form the well.

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

 

[1503-44]

Thanks. I didn't think it would change, but nice to know that it did not.


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