B31.3 or B31.4? 1

[Ilovescience]

Hello,

I work at a gas treating facility. We have production wells as well as the actually treating facilities.

We are looking at installing some piping for an upcoming project and we would like to ensure we are using the correct B31 code.

There are 2 lines we are interested in constructing:

-We having a water treating facility onsite that treats the waste water. We want to run a 3" line (2200#, 140F) to an injection well. The injection well is outside of the water treatment facility approximately 300 feet away.

-On our gas production lines from the wells, we have drip legs. We are installing a new drip leg and we want to run the water piping to our water treatment facility. We suspect this fluid is 95% water at least with some hydrocarbon.

I've skimmed the B31.3 and B31.4 code books and I'm a bit confused. While B31.3 mentions it is used for water piping i notice it uses the phrase "process piping". The B31.4 diagrams seems like these piping fall under that code but it doesn't mention water in the code itself.

ALSO regulatory and government agencies in this area does not provide direction on which specific piping code to use

With the information provided above, should these lines be constructed to B31.3 or B31.4?

Also, I read on these forums all piping underground is B31.4. I skimmed the code and I can't find this information either. Is this true?

 

[1503-44]

I feel your pain. It is confusing. Here is my take on the current federal requirements. I don't guarantee if this is totally correct, but it should at least give you some reasoning behind the madness, or a few good points of arguement. Some officials may have different interpretations, but I think you will be able to support the following with due diligence reading of the CFRs, Title 49, Part 192 and 195, gas and oil pipeline laws, respectively.

If you are not doing any separation at the well sites themselves, basically running the well stream of some combination of gas, oil and water straight to the processing facility, its not a B31.4 pipeline, its all basically a production pipeline, so use 31.3

B31.3 is also commonly used for the waste water lines too, I figure mostly because it may be salty, carry some corrosive traces of gas, CO2, H2S, etc, and have trace amounts of oil, although if its going from well separators to injection wells, B31.4 can be used and I believe must be used if they are crossing public lands.

The extra twist and exception on those B31.3 practices above is, if the pioeline cross public lands. B31.3 can be used on the well site piping itself, but on public land both a gas or a production well stream pipeline fall within B31.8, due to the fact that the CFRs governing pipelines on public land will require B31.8 there and afterwards. B31.8/CFR 192 (gas pipelines) is used because of the potential to have gas in any well stream production pipeline and of course there will always be gas in a gas pipeline coming from a seperator anyway.

B31.4/CFR TITLE 49 PART 195 oil pipeline design is (mostly) only used for an oil stream coming from a well site separator which is nearly 100% oil only that crosses public lands, or not. It could include small amounts of gas, as does most live oil coming from a well, but ONLY at low pressure, so any gas content should be very small percentage. Such lines usually also include a small pump station located at the well site, but that may not be a defining factor. Exception: water injection lines are B31.4 on public land.

If your API gravity is over say 50 coming from a separator, its not really oil in the classic sense, it's condensate. You will have a lot of high vapor pressure condensates, which will vsporize if leaked from a pipeline, essentially making it a gas pipeline design. It can be B31.3 on the well site, but if crossing public land, switch to B31.8/ CFR TITLE 49 part 192 and stay with that until inside the treating plant.

My Summary is ...

use B31.3 for flow lines (no separator) until you enter public land. When entering public land switch to B31.8 and stay with that until you are inside the treating plant. Inside the treating plant, it's B31.3 again.

If no public land, use B31.3 for all flow lines, or B31.8 if the pipeline comes from a well site separator and stay with that until reaching the treating plant.

Injection water lines can be B31.3 or 4 on the well site, B31.4 on public land and thereafter.
Waste water going to a tank on the well site to await disposal, I'd stick with B31.3

You will probably not use 31.4 at all, unless you have a low API oil and maybe a well site pump station.

Note: I assumed your well site is inside the USA, and not offshore. Are you in contact with your state's oil and gas pipeline regulatory authority? Have they told you that you may need permits to operate pipelines, or are they considering your site as all oilfield, no public crossing permits needed? In Texas that would be the Texas Railroad Commission.

The federal regulations, also followed by all states except Alaska (I think) are Code of Federal Regulations, of which those pretaining to oil and gas are CFR Title 49 Parts 192 for gas transportation by pipeline and Part 195 for oil transportation by pipeline. Those regulations mostly follow ASME b31.4 oil pipelines and B31.8 gas pipelines, but not their current editions. CFRs are based on 2002 code editions. There are some differences. If you are in the USA, be sure you follow the CFRs, they have precedence over ASME B31.4 or 8.

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

 

[r6155]

B31.3 Process PIPING
B31.4 PIPELINE Transportation
B31.8 Gas.......
PIPING is not PIPELINE.

You are in B31.3

Regards

 

[Krausen]

If you’re not clearly under DOT jurisdiction for regulated pipeline transportation, then you aren’t subject to B31.4. Echoing r6155, B31.3 should be applicable here.

 

[1503-44]

I read the question as they do not know if the pipelines to be constructed are regulated or not. Otherwise there would be no question if 31.3 applies, or not.

Read the CFRs
Gas and gathering pipelines
192.8 How are onshore gathering pipelines and regulated onshore gathering pipelines determined?
And
Oil pipelines
§ 195.1 Which pipelines are covered by this Part?

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

 

[1503-44]

BTW, piping under B31.1, 31.3, 31.4, 31.8 can all be above, or below ground.

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

 

[Ilovescience]

Thank you everyone for the input

@1503-44:

"If you are not doing any separation at the well sites themselves, basically running the well stream of some combination of gas, oil and water straight to the processing facility, its not a B31.4 pipeline, its all basically a production pipeline, so use 31.3"

Can't one argue this line is being used for transportation hence B31.3 (process piping) does not apply?

@r6155

How is this not considered a pipeline? The definition provided in B31.4 and CFR 192 are not too clear to me.

 

[1503-44]

Nothing upstream of a gas liquid separation plant or a central processing facility can be a transportation pipeline. It has to be a flowline, hence, B31.3, or if it is on public land B31.8

B31.4 can only be after a seperator where only the possibility of oil can be flowing. Usually that will be a full central processing facility, as opposed to a well pad separator.

A transportation pipeline is never connected to a well.

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

 

[Ilovescience]

Thank you 1503-44 i appreciate this wealth of info.

My last question has to do with condensate.

B31.4 section 400a states that pipelines transporting condensate can be included.

Your responses seem to indicate that only oil is considered for B31.4. Am I missing understanding you?

 

[r6155]

@ Ilovescience
See

https://www.eng-tips.com/viewthread.cfm?qid=219349

Search the forum for more reading.

The pipeline can cross several countries.

Regards

 

[1503-44]

If you can design a B31.4 pipeline to accommodate unusual and abnormal conditions that might be created by your condensate, I'd say it would be OK to do so, but there are reasons we have liquid and gas pipelines.

These are some of those reasons. Not all inclusive.
If others want to add more to this list, that would be great.

How you will handle tank storage, atm tanks, or spheres.
How you will meet emission targets. Vapor recovery systems.
Will you lose too much produce value to atmosphere without pressure storage tanks.
Will you put too much methane into the atmosphere.
How you will handle potentially higher pressures, but perhaps more importantly low pressures in your system.

Possible operation near the vapor pressure is not recommended.
Operating below vapor pressure creates gas pockets that may "vapor lock" your system, interfere with pressure regulation, cause large rapid swings in pressure on vapor pocket collapse, (water hammer) during two phase slug flow and cause wide swings in flow rates. Surge can be excessive. Is surge prevention equipment needed? Flow Measurement at lower pressures is difficult or impossible. Leak detection models crash.

Pumping becomes inefficient at high gas contents, so you will have to maintain minimum pressure above vapor pressure. With high methane, butane and Propane content, efficiency will suffer if pressure drops below 150 psig. Maintaining NPSH will be difficult.

How do you depressurize a liquid/gas pipeline, slug flow and low, cold blowdown temperatures.
Downstream handling, loading into railcars, barges, pressure limits.

Pipeline public Safety: What explosion radaii are created at breaks and leaks and maintaining safety distances.

What will your downstream pipeline accept? Crude is generally limited to 100 kPa. Over that and you get into NGLs. No methane can be in NGL, nor much oil. Some only accept crude, some only NGL, some only gas.

Not the least of which could be marketing concerns, price and treating. What price can you get for crude with Vapor Pressure limits < 14.55 psia, crude-condensate with > VP, vs separating into crude and NGLs. Is separation and treating a better ROI.

All in all, I am not a fan of B31.4 when VOC are concerned, but if you want to install bullet tanks instead of atm tanks, why not. Just pay attention to public safety, hazard distances. I don't thing mixing atm tanks with bullets and spheres is good practice, but it can be done.

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

 

[1503-44]

Typical crude pool limits

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

 

[Ilovescience]

@1503-44

This is a lot of good information you provided. I will bookmark this page as I know i will be revisiting this information again.

Thanks again!

 

[1503-44]

You have an archive here. Save it there.
Click on "Add thread to your archive".
You can access your archived threads through the menu.

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

 

[Grade 70]

@r6155
@1503-44

Respectfully, I disagree that b31.4 is for pipelines only

Figure 400.1.1-1 in b31.4 states the word piping and clearly shows that piping that is outside of a process unit is b31.4 if it contains those hydrocarbon products

Am I misunderstanding that ?

 

[1503-44]

Yes. Probably a misunderstanding of some sort, but it might depend on what you call a process unit and what you think a transportation pipeline is and does. Some people erroneously think a compressor or pump station is some sort of process unit and a liquid knockout drum, or similar piece of equipment often a part of a pipeline compressor or pump station is a process vessel. But yes, basically B31.4 only applies to "transportation pipeline systems" and usually only for hydrocarbons, although anhydrous ammonia (no carbon) and CO2 (no hydrogen) technically are not hydrocarbons.

Give us a PFD, or PID, circle your "process piping" in red, tell us what it is carrying, what the purpose of the unit is and where it is in the piping system and we will see if we disagree or not and why.

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

 

[Rubje]

@Ilovescience

Good question, I had similar questions in my mind. Glad I'm not the only one

@Grade 70

I never knew about this!

@1503-44

I have a a situation that is similar to the OP, @Ilovescience, above.

I will check with legal to see if I'm allow to share the P&IDs.

With the schematic Grade 70 is referring to above, does that change your conclusions for the following two lines in the OP?

"-We having a water treating facility onsite that treats the waste water. We want to run a 3" line (2200#, 140F) to an injection well. The injection well is outside of the water treatment facility approximately 300 feet away.

-On our gas production lines from the wells, we have drip legs. We are installing a new drip leg and we want to run the water piping to our water treatment facility. We suspect this fluid is 95% water at least with some hydrocarbon."

The first one above clearly seems to be process piping.

The second one I'm not 100% sure. Since the line contains liquid that was removed in a drip leg, I would also think that is considered "process piping" hence B31.3 shall apply?

 

[r6155]

In large companies for ECM (Engineering and Construction Management), piping and pipeline are different departments.
Pipeline management requires special skills.
Regards

 

[1503-44]

Water pipeline from well site separation/treatment unit to injection well is B31.4 as all gas has been essentially removed by that point.

Gas production lines from a well are B31.3, if it is NOT crossing public land.
If it crosses public land, it MUST be B31.8
The percentage of liquid water running in any portion of production piping is not a factor in that determination.

A drip and the piping of water to treatment facility would continue with the same B31.3 code (as production piping), until it crosses public land, in which case it would change to B31.8
If production piping was going to cross public land at any point, I would propose that it be designed in its entirety as B31.8

The reason that B31.8 should be used is that B31.3 is only concerned with pipe design, whereas B31.8 has many additional provisions which apply to pipelines and public safety such as area classification design factors, burial depths, operating pressures, corrosion monitoring, material testing and routine inspection and record keeping and reporting requirements that persist during the operating lifetime, none of which are addressed by B31.3. B31.8 is a far more comprehensive code in that respect.

Additionally, in the USA, B31.4 and 8 codes have a legal counterpart, CFR Title 49 part 192 and 194. Those CFR parts are the actual legal requirements, no matter what is said in the B31.4 or 8 ASME version. Read the CFRs. There are some differences.

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