Help with H2S certification.

[jraef]

I am being asked to provide the following information, quoted from a CE specification review on our 5kV class Metal Enclosed Switchgear: ..."certification of H2S withstand with respect to being suitable for use in H2S concentrations per OSHA regulations for continuous worker exposure".

Aside from getting the OSHA concentration limits, does anyone have experience in obtaining said "certification"? As in who does it, an Electrical PE or a Chemical Engineer, or an Environmental company? This project is for the Sate of New York.

Yes, I know I posted this in the "Switchboards" forum, but that one is not as widely read as this so I am cross posting because I need help ASAP.

"Venditori de oleum-vipera non vigere excordis populi"

 

[dicksewerrat]

Are you talking about a UL cert for a hazardous environment? As in Explosive Class I,or II?

 

[jraef]

No, H2S (hydrogen sulfide) is a corrosive element, not explosive. Were it explosive, UL or FM would be the answer. I just can't think of any 3rd party agency like them who would certify for corrosion protection.

"Venditori de oleum-vipera non vigere excordis populi"

 

[alehman]

H2S is extremely poisonous. You probably need an industrial hygienist or chemical engineer.

http://www.vngas.com/pdf/g94.pdf

 

[jraef]

Thanks alehman, that gave me the OSHA limits, 20PPM.

What strikes me as funny is, if someone prints a MSDS on it, that means that someone SELLS it! Seems like the rest of the world is trying to get rid of it. Oh well, it just proves that one man's trash is another's treasure.

"Venditori de oleum-vipera non vigere excordis populi"

 

[alehman]

Funny point about "one man's trash", since H2S is commonly found in sewer systems (where it is a considerable hazard).

 

[dicksewerrat]

You may have to do some tests on the switch gear and enclosure to see the effect of a corrosive environment. Ask the State to see the documentaion from a previous project. It is public record. If it has never been done before then the State should have some idea on what has to be done.

 

[corrosivo]

jraef

As you said this gas is corrosive, especially to the copper wires and bars. I recall working in a Hydroelectric plant that the air in the whole area smelled like rotten eggs due to decaying organic matter in the lake. After several years this gas was corroding everything made of copper inside the plant, the control wires inside the control panel crumbled to the touch, they were corroded inside the insulating cover!!! This wiring was inside the air conditioned control room. The bus bars, power cables, ground busses etc. everything was corroding due to this gas, the only equipment that was not affected was coated with some kind of varnish after installation.
Check with specialty switchgear manufacturers if they provide this kind of certification for equipment they fabricate. Maybe the chemical or petroleum folks might work with a certifying body you are looking for, as the ambient air in a refinery or chemical plant can be very aggressive.
Regards

 

[buzzp]

I have not heard of any such certifications. I just don't think there is any such certifications since copper, steel, and most everything else will be corroded. The only real way to eliminate the problem is to change materials (highly unlikely) or to eliminate the gas.
I worked in the oil field for a time. In the area I worked, H2S was a major concern. All the downhole cables were ran through J-boxes to allow the H2S to dissipate because the gas would migrate up the cables. Then the cables ran to the switchgear. I do not recall any discussions on certifying the equipment for such an application. Maybe this will help a little. Good luck.

 

[sjvanhecke]

It is not only corrosive, but it creates a steel wool type substance on any silver plated surface. We had some 480V breakers in a paper mill that would blow up a breaker weekly because the silver plating would peel off in a steel wool type form and short phase to phase. The only solution to the problem was to coat all the bus connections that were silver plated with a glyptol paint and plate the breaker parts with a different material. Tin was considered, but the conductivity is not as good as silver so the breaker would have to be degraded, we even thought about gold, but it was too expensive. I think we used nickle and degraded the breaker slightly.

 

[jraef]

Just a brief follow-up.
We submitted our plans to address the situation in our design, but insisted that they (the consultant) provide additional information as to who would do "certification" and how it would be done. We have no answer as of yet.

"Venditori de oleum-vipera non vigere excordis populi"

 

[corrosivo]

jraef
There is an interesting technical paper that describes what sjvanhecke described in his post.
Mrs. Bella (the author) have worked in this area and maybe she can help You. I pasted the information below.

http://nepp.nasa.gov/whisker/refere...ovsky2002-paper-silver-corrosion-whiskers.pdf

Bella H. Chudnovsky
Staff Engineer
Schneider Electric North America/Square D
9870 Crescent Park Drive
West Chester, OH 45069
chudnovb@squared.com

Regards

 

[jraef]

Fascinating article corrosivo, thanks for that. The phenomenon is bizzare to say the least and the photographs are excellent. It will be interesting to be at a jobsite some day in the future, see that wolly silver, and be able to knowingly declare the cause. I would have never thought of that since it looks at first glance to be the result of some sort of mechanical abrasive action.

Thanks again to everyone else who responded. It has all been helpfull.

"Venditori de oleum-vipera non vigere excordis populi"

 

[mc5w]

Hydrogen sulfide will kill you faster than hydrogen cyanide. Please be very careful!

 

[jsummerfield]

I see some misinformation posted about H2S in this thread. Lots of data is avialable on the web. Lots of industries include H2S exposure.

NACE MR0175 certification is required pressure containment components within a piping system. This would not apply to power distribution equipment.

Many industrial process generate or remove H2S. H2S typically exists with other components such as methane. In the oil and gas industry H2S is the key component if you hear about sour oil or sour gas. If H2S is a component of sour gas, THE MIXTURE IS EXPLOSIVE. This is applicable in the pulp and paper business too. Combustion of H2S results in sulfur dioxide, another toxic gas that combines with water to form sulfuric acid.

H2S is extremely corrosive especially regarding copper compounds.

H2S and HCN are toxic. Study health data for details. Some examples follow:

OSHA Permissible Exposure Limits
Hydrogen Sulfide (Final Rule Limits):
10 ppm (Time Weighted Average)
15 ppm (Short-Term Exposure Limit)


Hydrogen Sulfide
(Transitional Limits):
20 ppm (Ceiling)
50 ppm (Peak - 10 Min Exposure

NIOSH Other human data: It has been reported that 170 to 300 ppm is the maximum concentration that can be endured for 1 hour without serious consequences [Henderson and Haggard 1943] and that olfactory fatigue occurs at 100 ppm [Poda 1966]. It has also been reported that 50 to 100 ppm causes mild conjunctivitis and respiratory irritation after 1 hour; 500 to 700 ppm may be dangerous in 0.5 to 1 hour; 700 to 1,000 ppm results in rapid unconsciousness, cessation of respiration, and death; and 1,000 to 2,000 ppm results in unconsciousness, cessation of respiration, and death in a few minutes [Yant 1930].

Contrast this to the following Hydrogen Cyanide Exposure Limits:

* OSHA PEL

The current Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL) for hydrogen cyanide is 10 ppm (11 milligrams per cubic meter (mg/m(3))) as an 8-hour time-weighted average (TWA) concentration. The OSHA PEL also bears a "Skin" notation, which indicates that the cutaneous route of exposure (including mucous membranes and eyes) contributes to overall exposure [29 CFR 1910.1000, Table Z-1].
* NIOSH REL

The National Institute for Occupational Safety and Health (NIOSH) has established a recommended exposure limit (REL) for hydrogen cyanide of 4.7 ppm (5 mg/m(3)) as a STEL. NIOSH also assigns a "Skin" notation to hydrogen cyanide [NIOSH 1992].
* ACGIH TLV

The American Conference of Governmental Industrial Hygienists (ACGIH) has assigned hydrogen cyanide a ceiling limit value of 4.7 ppm (5 mg/m(3)), which should not be exceeded during any part of the working exposure. The ACGIH also assigns a "Skin" notation to hydrogen cyanide [ACGIH 1994, p. 23].
* Rationale for Limits

The NIOSH limit is based on the risk of thyroid, blood, and respiratory effects [NIOSH 1992].


John

 

[jraef]

Thanks jsummerfield,

I just noticed that nowhere in my posting in this forum, nor in my cross posting in "Switchboards", did I mention that this was a Wastewater Treatment Plant! I had also posted this query in the "Corrosion" forum and mentioned it there, so in my flawed brain cells I was under the mistaken impression that I had done that in all 3 postings. My applolgies.

From my understanding, the H2S will be present in very low concentrations, hence the specifiers inclusion of OSHA exposure limits for workers as the defining criteria.

Another good reason to avoid cross posting...

"Venditori de oleum-vipera non vigere excordis populi"

 

[mc5w]

One of my uncles has a PhD in chemistry and works for Pittsburgh Plate Glass as a research chemist. Evidentally, the government and PPG have different opinions about just how dangerous hydrogen sulfide is.

If you have to ask how poisonous something is, you DO NOT want to fool around - you might as well be asking how much a yellow jacket sting hurts. Same thing can be said about explosives and corrosives.

Mike Cole, mc5w@earthlink.net

 

[buzzp]

One thing about H2S, if you can smell it, chances are the levels are not enough to cause damage. Its when you can not smell it that concentrations are high enough to knock you out (and then kill you). (at least based on my oil filed experience)