Article 515 question

[megloff11x]

I have a hypothetical bulk storage plant where there are tanks outside, and processing vessels, piping, and pumps both inside and outside. None of the vessels, pipes, or pumps will release vapor or fluid in normal operation. Chemicals are piped in, not poured. The only flammable chemical present is methanol (Class 1 Group D).

The current plan is to locate the control room and a lab to test various samples inside the building with the processing vessels. And the plan is to have doors opening inside to the main plant floor, albeit a good distance from the processing equipment.

My confusion is, the code defines limited zones around tanks that div 1 and div 2, if the tanks are sometimes opened for filling purposes. After some distance, we're unclassified again. It defines these distances whether such a tank is inside or outside.

Then it says in table 515.3 under "tank storage installations inside buildings" (if I'm interpreting correctly) that the presence of a tank that is never vented to the air automatically makes everything inside the building Class 1 Div 2.

If I read table 515.3 correctly, if I can open it up to pour more in, I'm only Class 1 Div 2 for so far away, but if I never open it, if it fills & drains through pipes, I'm class 1 Div 2 wall to wall to floor to ceiling, and class 1 divi 1 if I have a trench below grade.

Why would a tank or vessel that I open and release fluid and vapor from be safer than a tank that I never normally open and never release fluid or vapor from?

Table 515.3 also declares offices and rest rooms unclassified if they don't open to the classified area, or if they do, if the classified area doesn't reach the door. If the classified area reaches the door, by code, you behave as though the wall doesn't exist. This is where the hair splitting on whether the whole inside is class 1 div 2, or just regions so far away from pumps and vessels are class 1 div 2.

If I go by the criteria of opening vessels, the doors can be moved far enough away from the nearest vessel full of flammables. If I go by "tank storage installations inside buildings" the whole inside above floor grade is class 1 div 2. If I go by "indoor equipment installed in accordance with 5.3 of NFPA 30" I have defined distances. Same for my pumps.

What will it be?

Also, the rule on indoor office space and rest rooms specifies distance from openings indoors, not outdoors. Does this mean I can have the door next to a big methanol vessel outside and its zone won't extend into my room due to the door as it would were the door and vessel inside?

At some point the hazardous area must end, and it would be nice if the NEC gave one clear answer.

I can always move the doors outside, but I'd rather not.

How should I interpret this article of the NEC as well as NFPA 30?

 

[rbalex]

Re: Article 515 question

Originally posted by megloff11x:
...
How should I interpret this article of the NEC as well as NFPA 30?

I believe this is a better question than you imagine. It stumped me completely. Unless someone has access to the NFPA 30-May 2000 ROP I think any answer would be strictly speculation.

The reference to Tank storage installations inside buildings in Table 515.3 was added as "copy" of text from NFPA 30 Table 6-2.2.

From NFPA 70 ? May 2001 ROP:

14- 478 - (Table 515-2): Accept
SUBMITTER: Donald R. Cook, Shelby County Building Insp., AL
RECOMMENDATION: Delete existing NEC Table 515-2 and
insert proposed Table 6-2.2 from NFPA 30-May 2000 ROP (page
579-581) as new NEC Table 515-2.

[Insert what became "new" Table 515.3 here]

SUBSTANTIATION: Based on the NFPA 30 Committee accepting
Proposal 30-167 to change this extracted material, this proposal was
developed as part of the work done by a Task Group including
Donny Cook, Fred Walker, Gordon Johnson, Don Zipsi, Mark
Goodman, Kevin Earley, Mark Ode, Bob Benedetti, and Richard
Hild to correlate the two documents. The Task Group was not
balloted on this proposal.
PANEL ACTION: Accept.
NUMBER OF PANEL MEMBERS ELIGIBLE TO VOTE: 14
VOTE ON PANEL ACTION:
AFFIRMATIVE: 11
NEGATIVE: 1
NOT RETURNED: 2 Earley, Saban
EXPLANATION OF NEGATIVE:
COOK: See my Explanation of Negative Vote on Proposal 14-
376a.
COMMENT ON AFFIRMATIVE:
WECHSLER: See my Comment on Affirmative Vote on Proposal
14-13.

I know 5 members of the "Task Group" mentioned in the "Substantiation" personally. I have calls in to two of them to see if I can get the NFPA 30 ROP material that justifed the change. Will post when I get it.

 

[friebel]

Re: Article 515 question

To: rbalex, what you need to determine classifications is the following:
1. An experienced electrical engineer or someone with electrical experience with classified areas.
2. Sometimes a chemist or a chemical engineer for dealing with the chemicals that you are dealing with.
With that said, when you have a classified area of 1-1-D, you cannot go into an adjoining area that is unclassified. It will be 1-2-D for so many feet. Then you can go to the unclassified area.
If you would get NFPA 497, it will give you some information on classify areas. I wish that we were closer, I would like to help you out with classify.
Another thing that needs to be done, is to have a plan print showing the layout of the different classifications, such as 1-1-D for so many feet, and then 1-2-D for so many feet. I do believe that this is mandatory for OSHA compliance.

 

[rbalex]

Re: Article 515 question

Hi fribel,

Actually, I'm fairly familiar with the process.

I served on API's Subcommittee on Electrical Equipment for 13 years and chaired the Contractors and Manufacturers sub-committee for 3 of them. I was a principal author during the last two Editions of API RP-500 and RP-505. I served on CMP 14 for the 2002 NEC. I've authored either directly or through API over 20 accepted proposals in dealing with classified locations.

The issue megloff11x is having is how a line in Table 515.3 appeared and how to interpret it. The only way to correctly answer that is to review the Proposal that originated it or contact someone in the Task Group. I don't have it available to me at the moment - but I will.

 

[rbalex]

Re: Article 515 question

I apologize for not posting this earlier; I've been Internet "connectability challenged" for the last week or so

I received the following email from Bob Benedetti, the NFPA staff liaison for the Flammable and Combustible Liquids Code Committee. I also had the good fortune to work with him, when he was the staff liaison to CMP14. He is uniquely qualified to discuss this.

The files he refers to are too large for me to post; but, should someone actually need them, request them from me via PM. I've reviewed the files, spoken to two other "Task Force" members, and we all concur with his analysis. Note: this is our collective opinion only - none of us, including Mr. Benedetti, are authorized to offer "official" or "formal" NFPA interpretations.

Bob:

I didn't find much useful.

The section on storage tank buildings was added in the 1993 of NFPA 30, Flammable and Combustible Liquids Code, and it included a table with area classification information. The Committee Statement of the proposal that added the section dealt only with generalities, as this was a large addition. Nothing specific was mentioned about the electrical area classification table. The Statement did explain that the Flammable and Combustible Liquids Code Committee formed a Task Group to write the new section to respond in part to situations where small tank farm owner / operators were enclosing their tank farms with walls and a roof to get out from under onerous EPA requirements.

During the development of the 2000 edition of NFPA 30, responsibility for all electrical requirements in NFPA 30 was given to the NFPA 30 Technical Committee on Operations and they instituted a proposal to consolidate all electrical area classification into a single separate chapter. The proposal creating the chapter was more editorial than technical.

I've attached the relevant pages of NFPA 30-1993 and the relevant information from the 2000 Report on Proposals (ROP).

As we discussed, it is clear to me that the intent of the Task Group was that a building whose sole purpose was to house storage tanks would require area classification for the entire building. I do not believe they intended to do the same for a small tank in a much larger inside area. I hope this helps, but call me if you have any further questions. I'm adding this issue to the October agenda of the Flammable and Combustible Liquids Code Committee.

Bob Benedetti

cc FLCOPS/NM

Robert P. Benedetti, CSP, PE
National Fire Protection Association

I'm also preparing coordinated proposals for NFPA 30 and the NEC to clarify this.