Who decides whether a service is a lethal service and what is the basis of such decision. 2

[bmoorthy]

Dear experts,

I am conversant with the ASME UW 2 requirements and the definitions given therein including the details in various footnotes (general notes, inside ASME Sec VIII Div 1). Mechanical discipline engineers get the information on the service from the process data sheet, which is expected to reflect the client's/user's decision on whether a particular service is a lethal service. My question is, how does the user decide whether service is a lethal service? Is there a specific CFR clause or OHSA or OSHA (Canadian or American)clause that provides the list of lethal fluids along with the threshold level? Does individual province/state have regulations within Canada/US decide on the lethality? if not does the insurance companies decide on fluid lethality? if so may I request a reference document issued by any one insurance company? or the reference number of the state/provincial provision that delves in this matter that forms as a guideline for deciding whether a particular service is lethal or not? Best Regards, B.Moorthy

 

[SuperSalad]

The definition is vague in that it doesn't quantify the limit of exposure. I believe it is up to the company to define it on a case by case basis based on the "very small amount in air is dangerous to life when inhaled" phrase int he definition. The "very small amount" will vary depending on the IDLH limit of the specific chemical and possibly other properties.

Andrew H.

http://www.mototribology.com

 

[Latexman]

A long time ago in a HUGE megacorp chemical company, I was thinking of specifying a vessel as lethal. I think it was for anhydrous HCL. I learned very quickly from almost everyone I didn't want to do that. In fact, I was told the company didn't want to do that, unless forced to. You can build a regular pressure vessel just like a lethal vessel, without that unwanted label. So, my advice is, do not take this decision lightly.

Good Luck,
Latexman

 

[EdStainless]

It is not that uncommon to see people invoke the LS rules without calling it LS.
The only two that remember as LS were HF and HCN.

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P.E. Metallurgy

 

[TiCl4]

To answer your question, there is no short-list of lethal materials (that I know of, anyways), that companies in the US are required to adhere to. Some states and/or insurance companies require adherence to B31.3, but do not go further and define lethal service materials. In short, it is up to the process owner, and the process owner alone, to determine lethal service.

That being said, "49 CFR § 173.132" provides guidelines for Class 6.1 poisonous materials, and "§ 172.101 Hazardous Material Table" may be used to screen for Class 6.1 materials.

Note that some materials that are widely considered dangerous (H2S, Cl2) are only classified as class 2.3 materials (under 49 CFR § 173.115). Latexman's example of above of HCl anhydrous is likewise only a class 2.3 material. A large chemical company that I have worked for handled large quantities of CL2 and some H2S. Neither were considered lethal service. They also handled phosgene, a class 6.1 material, and that WAS considered lethal service.

If a material is going to be considered lethal service, it will likely be a class 6.1 material. However, I'm not sure if all class 6.1 materials would be considered lethal service. Again, it is up the process owner to define it.