Periodic Functional Test of Anhydrous Ammonia PRV?

[MAPower]

Are there any codes that dictate periodic functional testing of anhydrous ammonia pressure relief valves? I have checked ANSI K61.1 and the only requirement is for visual inspection. The vendor (Anderson Greenwood) also does not have a recommendation. The valves will be replaced every 5 years. Thanks

 

[pipehead]

why would you replace at five years?

I recommend a risked based inspection (functional test and inspection for problems) every 1/2 to 5 years depending on criteria similar that in API risk based inspection of piping and vessels. If the PSV is on a storage tank, then every five years, if its on a pump or compressor about every 1 year.

 

[MAPower]

pipehead, thanks for the post, I'll take a look at that API code.

Well the ANSI K61.1 requires you to replace PRVs at the manufacturers specified date, if none is given then that equals five years. If I read it to the letter it only applies to "containers," so in certain cases it would not apply. I have multiple PRVs, some on piping system and some on storage tank. We do have a visual inspection based mechanical initegrity check monthly. The question was raised during an OSHA PSM hazard review, so I have to take a look at it and determine if it is necessary and if so how frequently.

 

[pipehead]

There are some ammonia terminal codes by other groups that reference ASME and API, I believe NFPA has something. I don't use the NFPA 58 for all of our proprane because the basis for it is commercial type uses which tend to be more stringent or non risk based approach. Remember OSHA allows risk based analysis in its parts.

 

[stookeyfpe]

You are mixing codes.

A NH3 refrigeration system does not require 5 year certification of pressure relief devices. These are governed by ANSI/IIAR (Institute of Ammonia Refrigeration) ANSI/IIAR 2.

For bulk storage of NH3, ANSI/CGA K61.3 governs and it requires evaluation of the pressure relief devices.

NFPA 58 remains silent. Appendix E of NFPA 58 makes reference to the API standard but the Appendix is nonmandatory. The NFPA 58 committee believes (while I served on it) that internal pressure relief devices were adequately lubricated by the LPG that relief valve maintenance is not required.

 

[Latexman]

For bulk storage of NH3, ANSI/CGA K61.3 governs and it requires evaluation of the pressure relief devices.

OSHA 29 CFR 1910.111, Storage and Handling of Anhydrous Ammonia, applies too but I don't believe it speaks to periodic testing of PSVs. Here's a link:

http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=9757

Good luck,
Latexman

 

[MAPower]

I've never heard of K61.3 nor can I find it on the internet??? What I have is not refrigeration by no means, it is ammonia supply for power plant selective catalytic reduction. I also highly doubt it is considered bulk storage, all we have is a 2000 gallon tank.

 

[dcasto]

2000 gallons is bulk, at that size it would become a PSM regulated quanity (10,000 pounds).

When all else fails, ask the PSV supplyer or REGO who makes specialized ammonia valves.

 

[Latexman]

MAPower,

K61.3 is incorrect.

The OSHA reg incorporates by reference the American National Standard for the Storage and Handling of Anhydrous Ammonia, K61.1, and the Fertilizer Institute Standards for the Storage and Handling of Agricultural Anhydrous Ammonia, M-1.


Good luck,
Latexman

 

[MAPower]

Thanks for all the post guys, based on the information you guys have provided, I am going to recommend annual functional testing of the process pressure relief valves and replace after five years per ANSI K61.1. Although there are no requirements for process (piping) relief valves, I will air on the conservative side. Thanks

 

[danthemeterman]

OK, great to read all these answers. I would like to follow up by sayng that no manufacture I know of (especially Rego) make allowance for periodic testing of pressure relief devices. You may be jeoperdizing your liability insurance and testing beyond the original manufacturers specs. They don't tell you, bcause they have no provisions or certifications, outside of the factory. "Just a caution", nothing more.
Does any one know if there is any written regulaions for installing pullaway devices on bulk transfer of NH3, Ahydrous Ammonia. we have the manufactures installation and operation manual, just hoping to find more info. Wisconsin codes only go to '04.

 

[dcasto]

I cannot believe any organization would require someone to through away a PSV after five years of service unless they made the valve and needed more money. If you believe you must test a relief valve every year, buy a better one that will hold up to the service.

 

[unclesyd]

As part of our process we fly wheeled tons of Anhydrous Ammonia around our site. We received it by barges, stored it in Horton Spheres, process wise used it at pressures from 10" water to 6500 psig, and recovered the excess vapor from all the processes to the Anhydrous form. It this system there were numerous relief valves, mostly paired with a three way. These ranged from about 1" to 6" inlet flanges.
Once a year everyone of these valves was pulled, shopped to be dismantled, inspected, reassembled, and tested all on site.

There was never any question about using this approach on the Ammonia relief valves.