Fluid service of natural gas B31.3 5

I understand that natural gas is normal fluid service in B31.3.

Fluid Service is one of the items which is specified by the owner within the guidelines of the piping code. In Alberta sour gas is not even treated as lethal but it gets comparable inspection. The radiography is typically reviewed to the severe cyclic criteria. I guess nobody wants to admit how nasty the stuff is.

I don't think that I have ever seen anything called lethal service.

EJL

I worked a project where lethal was in the project name. H2S rich acid gas is lethal. Perhaps lethal would describe super-sour-gas.

Thanks, after 30 years in the industry, some junior Safety guy slapped the "Safety Card" down and demanded to see "industry engineering standard interpertations......"

Hello,

I think that the first thing to remember is that there is NO SUCH THING as a category "M" Fluid. The B31.3 Fluid Service concept considers the fluid contained within the pipe and the particular set of operating circumstances as well as the safeguards that will be in place (see B31.3, Appendix "G").

Natural gas is not TOXIC (albeit, breathing it to exclude oxygen would be harmful), and exposure to very small quantities of natural gas due to leakage cannot result in irreversible harm. Therefor a piping system conveying natural gas should not be determined by the owner to be a category M piping system.

If you look at the logic flow chart (Figure M300, Guide to Classifying Fluid Services)provided by B31.3 in Appendix "M", you will see a clear path of logic in determining that a "Toxic" fluid may be contained in a piping system that is classified "Normal Fluid Service". You will find that there is about the same amount of ("true")category M fluid service piping as there is lethal service pressure vessels - not very much.

Other references in print simply represent the opinions of the writers. The determining factor is clear - "The Owner is also responsible for designating piping in certain fluid services and for determining if a certain Quality Service is to be Employed" (Paragraph 300(b) et. al.).

Best regards, John.

John, et al.....

Although this is (slightly) off topic, I still feel that it would be both useful and informative for someone to devlop a list of commonly transported chemicals that can resonably be designated ASME B31.1 Category "M" fluid service.

For example, phosgene gas is deadly, tiny amounts can cause immediate respratory failure and it is used in the process chmeical industry...

A candidate for a new Category M "deadly list"....of course

The US federal government maintains a list of commonly used, yet toxic chemicals... The Title III SARA list

"In 1986, Congress passed the Superfund Amendments and Reauthorization Act (SARA) as a response to the chemical accident in Bhopal, India. This was the incident in which a toxic gas, methyl isocyanate, escaped from an industrial plant and killed or injured more than 1,000 people. Title III of SARA, also known as the Emergency Planning and Community Right to Know Act, establishes the public's right to know what chemicals are stored in their communities."


It would be reasonable to have such a list and not allow/promote a detailed, and yes somewhat subjective evaluation of each piping system by a never ending crop of new engineers.

Would such a system work in all cases... no, of course not...

Would such a system prevent the endless repetition of the same questions and answers such as the one above ?

Of course.......

My opinion only

-MJC

An older, but similar discussion...


Some ASME people seem to love this chart,I don't..... I still think things could be made simpler......

As the current crop of geezer engineers shuffle toward the nursing home and applesauce afternoon snacks, I feel that things should be made simpler for our young latino and middle eastern replacements...

My feelings and opinions only....

-MJC

MJCronin (Mechanical) & JohnBreen (Mechanical)

Did Piping: MIC methyl isocyanate fall in ASME B31.1 Category "M" fluid service at UC institute facilities?

1986 I know only of five (5) item that were ASME B31.1 Category "M" fluid service!.

Stephen
Leonard Stephen Thill

Leonard and all,

I think that Mike Cronin’s point is well made – there can be materials contained in the piping that make the piping systems CANDIDATES for Category M fluid service but the fluid alone will not be the determining factor in determining the piping system to be Category M.

As an example, let us take a piping system that contains (in the true sense of that word) methyl isocyanate.


Entering the logic chart in Figure M300 of B31.3 Appendix M, we get to column 3 “Is the fluid toxic”? Well, yes methyl isocyanate is truly toxic so we move down column 3 where we see the next question: “Can a single exposure, CAUSED BY LEAKAGE, to a VERY SMALL QUANTITY of the fluid, produce serious IRREVERSIBLE HARM as defined under Category M fluid service? (see fluid service paragraph 300.2).

First of all the exposure must be due to leakage in the piping system of a very small quantity. The question would be “is the exposure due to leakage in the piping system”? The next question would be “would the exposure to this very small amount cause irreversible harm”? The key words here are “small” and “irreversible”. Will a teaspoon of methyl isocyanate cause irreversible harm. The harm might not be irreversible if timely medical care is received (the owner might have counter measures on site to treat exposures). A negative answer to either one of these questions would “bump” us over to Column 4 and send us to the Base Code for design. But let us assume for this example that the owner answers in the affirmative and continue down to the next “box” in column 3.

“Considering EXPERIENCE, SERVICE CONDITIONS, and LOCATION INVOLVED, will design per the Base Code or Chapter VII sufficiently protect personnel from exposure to very small quantities of the fluid in the environment”? The point here is that piping systems may be designed by applying the rules of the Base Code to protect against leakage of small amounts of fluid. Also, if the service conditions are similar (in say, pressure and temperature) to Category D service conditions the Base Code might (by the owner’s experience) provide adequate protection. Significant benefits can be realized by safeguarding in accordance with Appendix G. “Safeguarding by Plant Layout and Operation” (Appendix G, paragraph G300.2) can result in an operating location where personnel are generally not present (restricted). Isolating operating areas by including buffer zones can also be effective.

These are all considerations that must be evaluated when the owner determines if a piping system that contains methyl isocyanate is to be classified as a Category M piping system. Again, it is not the contained fluid by itself that determines the category. And again, the is NO SUCH THING as a Category M fluid.

Regards, John.

MJCronin (Mechanical) & JohnBreen (Mechanical)

I total agree you MJCronin (Mechanical) & JohnBreen (Mechanical), John, thank you for your detail example.

I do remember MIC methyl isocyanate B31.3 piping; [Been their, did that].

The second part of the question pertained to reciprocating compressors being severe cyclic service. I doubt if it is still done but Southwest Research used to perform analog computer simulations of recip compressor piping systems. Some recip installations experienced severe vibration. Perhaps this related to multiple engine driven recips running at different speeds and the suction and discharge piping manifolds. Perhaps some other geezer can clarify the severe cyclic issue.

JLSeagull (Electrical)

Regards to The second part of the question pertained to reciprocating compressors being severe cyclic service. Beside Southwest Research, Also Paulin Research Group
Paulin Research Group BOS FLUIDS Version 4.111 Released September 25, 2003
Chapter 4
Section 1-Recipocation Compressor Pulsation and Mechanical Analysis
Section 2-BOS Fluids and API 618
Section 3-API 618 Compliance for Reciprocating Compressor – Summary
Section 4 BOS Fluids API 674 Compliance
Section 5 Reciprocating Equipment Notes.

Contact Tony Paulin, Perhaps some other geezer can clarify the severe cyclic issue.

Regards
Stephen
Leonard Stephen Thill

John,

Agreed except for the following. I don't see how it is possible to consider any extenuating conditions (anything beyond a method incorporating a means actually stated) to be of benefit to a particular case when examining possible consequences as the ultimate criteria, such as "if timely medical care is received (the owner might have counter measures on site to treat exposures)".

Is it a good idea to have coral snakes as pets, as long as you have the anitvenom in the bathroom medicine chest?

Other than that, a great discussion.

All,

If you have access to the new Section XII (Transport Tanks) there may be a bit more guidance there. If memory serves the criterial for requiring full radioraphy and specific joint details (exactly like lethal service in the vessel code) is directly related the UN dangerous goods packing number. In this case they have taken a step forward (my opinion only) of calling for and equivalent to lethal service if it is to be transported. The fact that transport brings it closer to the general public may have been the reasoning but that is also another discussion for a later time.

EJL