Announcement

Collapse
No announcement yet.

How to classify outdoor natural gas substation?

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    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
    Look at Article 515

    Comment


      #3
      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 2017 NEC unless otherwise noted.

      Comment


        #4
        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.

        Comment


          #5
          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.

          Comment


            #6
            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.

            Comment


              #7
              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)

              Comment


                #8
                You are correct. My intent was to compare division as opposed to zone classification methods.

                Comment

                Working...
                X