Results 1 to 8 of 8

Thread: How to classify outdoor natural gas substation?

  1. #1
    Join Date
    Aug 2018
    Location
    Kentucky
    Posts
    1

    How to classify outdoor natural gas substation?

    My first post, so Hi everyone.

    How would we approach classification of a natural gas substation (fully outdoors, no building or enclosed spaces)? Also, if classified as a hazardous area, how should the boundary distance be determined?

    Thank you for any advice.

  2. #2
    Join Date
    Dec 2011
    Location
    Wisconsin
    Posts
    462
    Look at Article 515

  3. #3
    Join Date
    Apr 2004
    Location
    Mission Viejo, CA
    Posts
    5,238
    NFPA 497 and/or API RP 500 would be better references. Article 515 will cover bulk storage, but not compressors. The American Gas Association also produces a non-ANSI document, AGA XL 1001 that basically mirrors API RP 500.

    None of these Standards are inexpensive.
    "Bob"
    Robert B. Alexander, P.E.
    Answers based on 2014 NEC unless otherwise noted.

  4. #4
    Join Date
    Aug 2011
    Location
    NH
    Posts
    248
    Is this a regulating station off of a transmission or utility distribution system? The transmission company or utility you are connecting to also likely has standards for classification that are based on the standards referenced by rbalex.

  5. #5
    Join Date
    Jun 2014
    Location
    Denver
    Posts
    31
    Quote Originally Posted by rgriggs View Post
    How would we
    This response is certainly no dig on you, rgriggs. I have many people (mostly younger mechanical/process engineers) ask that very similar question for our O&G facilities, but the question alone is enough to know you are in a bit over your head. Not that you're not capable of figuring it out, but there's a bit of a learning curve when it comes to API RP 500, NFPA 497, and all the backup w/in the NEC. I would highly suggest engaging/consulting a EE or Instrumentation Engineer to assist you with your assessment. I wish I could easily lend you some assistance, because I enjoy doing this type of work, but the entire process can involve reviewing general arrangements, ANSI ratings, 3rd party skid arrangements, piping iso's, instrument lists to verify model/make requirements, etc. Again...this is certainly no dig on you and I wish you the best! This group has an amazing wealth of knowledge and you most certainly will find all your answers...and humiliation as I've found out first hand...to all the question you have.

  6. #6
    Join Date
    Mar 2013
    Location
    California, USA
    Posts
    67
    I believe natural gas is a class 1 div 2 group D area, assuming you are using the division method.

    Basic process is to identify all of the potential leak sources, this will include anything with packing/rotating equipment, for the most part, but can vary. These should be called out on a plot plan.

    Then you basically draw a 15' circle around them and use superposition to create one large bubble around the plant. 15' is because natural gas is lighter than air and will tend to dissipate rather quickly.

    If you need an actual drawing I'd recommend hiring an engineering firm with experience. If you are just looking to locate your electrical equipment within a safe distance, and the only process you have is natural gas, go for at least 15' from any process equipment and the dwg can be done later if necessary. any instrumentation inside the plant boundary should be class 1 div 2 group D rated.

  7. #7
    Join Date
    Feb 2003
    Location
    Illinois
    Posts
    23,769
    Quote Originally Posted by MRKN View Post
    I believe natural gas is a class 1 div 2 group D area, assuming you are using the division method. ...
    The product doesn't really have much to do with what division the area will be classified as. The division is based on actual operations and the equipment that is being used and a number of other factors. There are areas that handle natural gas that are Class I, Division 1.
    Don, Illinois
    (All code citations are 2017 unless otherwise noted)

  8. #8
    Join Date
    Mar 2013
    Location
    California, USA
    Posts
    67
    You are correct. My intent was to compare division as opposed to zone classification methods.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •