Liquid Ammonia Pipeline

[PipelineDeptTME]

We are currently designing a liquid Ammonia Pipeline System. ASME B31.4 suggests that it is applicable only to anhydrous Ammonia. Is the design code applicable to liquid ammonia as well? If not what is the alternative. Is there anything in particular that we should take care of while designing these pipelines.

 

[LittleInch]

IMHO, no, B 31.4 does not cover any other ammonia other than anhydrous ( i.e. without water) ammonia.

There are other alternative pipeline codes such as ISO 13623 which covers all fluids, but this code and others categorises ammonia as a Cat E fluid. This requires different calculations and treatment than something like A Cat B fluid such as gasoline or diesel.

B 31.3 could be used, but is generally unsuitable for a long distance buried pipeline - it's designed for above ground plant piping.

Liquid ammonia is a corrosive toxic fluid with significant issues if it escapes. Therefore it needs great care to prevent any leaks or ruptures.

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

 

[Latexman]

Though it is rightfully called "anhydrous", at least 0.2% by weight water is added to inhibit corrosion of the carbon steel pipeline.

Good luck,
Latexman

To a ChE, the glass is always full - 1/2 air and 1/2 water.

 

[BigInch]

B31.4 can be used for liquid ammonia. I don't see any of that as a problem, because I've done it before, providing you do your pipe testing at lower than the lowest temperature ammonia you will have in the pipeline. Use low temperature ASTM A333 pipe by the way. I certainly have used B31.4 to design a liquid ammonia pipeline. You must take into consideration that the lowest temperature provision of B31.4 will be exceeded. Liquid ammonia boils (at -33.3[°]C) a few degrees below the declared B31.4 low limit temperature. The good thing is that B31.4 also does not say it can't be used for lower temperatures, it just says it specifically doesn't cover lower temperatures, which in that case the engineer must make sure that he does. With that said and the owner's written permission, I can say that B31,4 has been allowed many times in the past.

Rest of that story
Not sure about the alternative fuel and other stuff he says there, just needed to show the map of the ammonia pipeline delivery system (making a lot of money) in the USA.

Liquid ammonia will be below the freezing point of water, so you need to dry it out as much as possible in any case, otherwise it will all freeze out at the last point where the ammonia crossed 0C. Latexman, am I mistaken in that thought? Insulation will be needed.

Pipe stress and expansion contraction loops of cold pipe works out better than hot pipe. Cold pipe is placed in tension, which being on the same side of Mohr's circle as the tensile hoop stress, makes the maximum shear stress much less than for hot pipe.

The other good thing about cold pipelines is that water contact induced exterior corrosion below the anti-corrosion coating is nearly, if not totally, eliminated. Water touching the pipeline freezes and no corrosion is possible after that. And there is no free water inside.

But at that low temperature, contraction will be extreme. Although at first I thought the pipeline should be buried in a tunnel structure, when I realized that water will have no effect and the pipe will be locked into the soil, direct burial, even at that low temperature, was possible with the right insulation coating. PermaTherm has some recommenadations and I think they supplied the insulation coating we used an HDPE (or was it PVC) overcoating for direct burial. There was some talk at the time that the insulation, being completely or nearly so, closed cell, could have been buried directly in contact with earth. You might want to think about that. I'm leery about freeze cracking of the insulation from any water that might come in contact with the insulation freeze zone. Test is worth a thousand words.

Ammonia stress corrosion cracking can also affect carbon steel equipment, but unlike the cracking mechanism on brass which occurs in an aqueous solution, the cracking of steel equipment occurs in anhydrous ammonia. Proper PWHT is essential. Storage vessels are hot spots for SCC. See thread367-362662
Also see hydrogen embrittlement effects,

https://en.wikipedia.org/wiki/Hydrogen_embrittlement

The explicit danger of liquid ammonia after leaking is that it gasifies, and being toxic and heavier than air, it takes a long time to dissipate, making it extremely dangerous to approach any leaking ammonia pipeline to close valves, or otherwise closely investigate what might be going wrong. Emergency responders need to bring along the right PPE.
farmer-died-as-he-investigated-source
(Although I have also heard that he was drilling into the pipe himself at the time)
Rest of that story (have you seen Breaking Bad?)

An ammonia pipeline leak in Kansas (2004).

Cause attributed to a farmer plowing field damaged pipeline a number of years before this incident.

It cam definitely be touchy stuff,
MN link

Do you think it is a coincidence that ASTM number A333 is nearly the same number as ammonia's liquification temperature -33.3C? (yes, I think so)

 

[BigInch]

Is this for Egypt?

Technology is stealing American jobs. Stop H1-Bs for robots.

 

[Latexman]

Our pipeline (Dixie - back in 2006-2010) on Texas Gulf Coast (Freeport) was not insulated. It was ambient temperature, not cold. The source was miles away. Only a rapid decompression (large leak) would have gotten to -33.3 C.

Good luck,
Latexman

To a ChE, the glass is always full - 1/2 air and 1/2 water.

 

[PipelineDeptTME]

Thanks All for the valuable opinions.
Rounding up on the discussions we have had so far, Conventional piping material LTCS A333 shall be used for designing pipelines. However, as for relevant wall thickness calculations design code ASME B31.4 will be used. Additional recommendation from ISO 13623 will be applicable as it classifies liquid ammonia as a Category E fluid.
@BigInch "providing you do your pipe testing at lower than the lowest temperature ammonia you will have in the pipeline"
I see your point. However, our pipe material is A 333; As mentioned in ISO 13623, we do not need an impact energy value above 27J if the SMYS is below 360 MPa.

 

[LittleInch]

Interesting.

I know B 31.4 can be used, the question was did it officially cover it. The key phrase in BI's very informative post to me was "... and the owner's written permission,...".

Might also depend on where you are and what the certifying authority has to say about it. There are clearly safety issues and studies and low temperature issues to contend with which typically don't fall into the happy arms of B 31.4, but are more closely defined in codes which include for toxic gases.

So some additional elements from other codes need to be applied IMHO to B 31.4 for such a fluid.

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

 

[BigInch]

You might also consider that in 2002 the name of B31.4 was "ANSI/ASME Standard B31.4, Standard for Liquid Transportation Systems for Hydrocarbons, Liquid Petroleum Gas, Anhydrous Ammonia, and Alcohols. 2002. New York City: ANSI/ASME". Remembering that the 2002 edition of B31.4 is still the code referenced by the US CFR Title 49, which technically makes it the legal code for ammonia pipeline design in the USA.
B31.4 says it does not apply
if pipe is above 15 psi (1 bar) gage pressure if design temperature is below minus 20°F (-30°C) or above 250°F (120°C)
and that is even though the phase diagram for ammonia indicates it would quickly be in the gasous phase at pressures higher than 15 psig while at temps immediately above 20°F (-30°C). Perhaps because it is a gas only at relatively lower pressures, the liquid code was thought to be more appropriate then B31.8, since the pipeline is normally operating at higher pressures in the liquid phase.

If the ammonia remains liquid today, IMO B31.4 would still be fine to use if low temperature provisions are applied, however should the owner-engineer consider it prudent to additionally apply B31.8, or any other company design criteria to places where it is more conservative then B31.4, or use the class location design factors of B31.8 because it might gas up some day, I certainly would not argue about that. Level of risk tolerance between owner-engineers can vary considerably.

 

[BigInch]

Deleted Post
Thanks All for the valuable opinions.
Rounding up on the discussions we have had so far, Conventional piping material LTCS A333 shall be used for designing pipelines. However, as for relevant wall thickness calculations design code ASME B31.4 will be used. Additional recommendation from ISO 13623 will be applicable as it classifies liquid ammonia as a Category E fluid.
@BigInch "providing you do your pipe testing at lower than the lowest temperature ammonia you will have in the pipeline"
I see your point. However, our pipe material is A 333; As mentioned in ISO 13623, we do not need an impact energy value above 27J if the SMYS is below 360 MPa.

Could you please reply on this ?

Yes, but I didn't know that you were going to use A333 at the time AND
YOU CANNOT CHERRY PICK THE BEST PROVISIONS FROM EACH CODE. You must choose one code and design to ALL its requirements. If you want to add additional provisions from other codes and/or company standards, personal preferences, etc. then add those on top of the provisions of the design code that you are officially using.

Technology is stealing American jobs. Stop visas for robots.

 

[BigInch]

OK let's simplify the discussion of which code applies.
I'm always saying "READ THE SCOPE, it's the first paragraph in the code", and here I didn't think to read the scope. Actually I didn't think my answer would be so easily proven.

Quote of B31.4-2012

400 GENERAL STATEMENTS
(a) This pipeline transportation systems Code is one of several sections of The American Society of Mechanical Engineers Code for Pressure Piping, ASME B31, and it is the responsibility of the user of this Code to select the applicable Section. This Section is published as a separate document for convenience. This Code applies to hydrocarbons, liquid petroleum gas, anhydrous ammonia , alcohols, and carbon dioxide. Throughout this Code, these systems will be referred to as liquid pipeline systems.

Technology is stealing American jobs. Stop visas for robots.

 

[PipelineDeptTME]

since our liquid ammonia will have water content and it will not be anymore anhydrous. Is ASME B31.4 still applicable?

 

[BigInch]

Water is normally a liquid at typical temperature, so yes to that, but when ammonia is at liquid temperatures, the water will be solid ice deposited maybe on the pipe wall or the first crystalization point after wherever the ammonia liquification system crosses the 0[°] temperature isotherm. So will you have any water making it into the pipeline, no, or surely not very much. Maybe some "snow".

Technology is stealing American jobs. Stop visas for robots.