Running RMC in a Class 1 Div 1 using the process piping to support.

M

Mr.TmO

New User
Location
Anchorage AK
Occupation
Electrician
I'm looking to upgrade my tank farm at my new facility, and the existing conduit is currently secured to the process piping. This is causing it to break at the threads in some areas due to the flooding and vibrations. They have a mixture of supports constructed of Unistrut with all-thread wrapping around the process piping and short extensions of Unistrut that are attached to other conduits for support. I also noted that there are no low point drains and was seeing if anyone could help me pin some of these issues out in the code book to aid me in writing a proposal.
 
Sounds like you need some flexible connections see 501.10, and drains 501.15(F)
 
Welcome to the Forum, TmO!

I used to live a bit south of you in Homer. But am in the natural gas business now. I think I would run rigid conduit for food, I enjoy it that much. But there is a time and a place for everything. First, It's bad news to hang conduit off of anything else. It needs to be supported on its own. Second, If rigid is run outside, it's got to be run with drains. And I know the weather up there. Lots of precipitation and large changes of temperature. Both mean water getting into the conduit.

I am guessing this is in a classified (hazardous atmosphere) area? Even though I prefer running rigid, It is hard to beat CLX type cables (Teck90, Okonite, coated MC) in a cable tray.

That's what I suggest. Are you familiar with them?
 
I was picturing a large process pipe with some unistrut clamped to the pipes then the electrical conduit on the unistrut. I am not sure what section would prohibit that, I'll have to admit to doing that.
 
WD40 said:
I was picturing a large process pipe with some unistrut clamped to the pipes then the electrical conduit on the unistrut. I am not sure what section would prohibit that, I'll have to admit to doing that.
Click to expand...
I think you are right. I was thinking about the prohibition against hanging conduit off of other conduit. Then again maybe there is some of that going on, too: "They have a mixture of supports constructed of Unistrut with all-thread wrapping around the process piping and short extensions of Unistrut that are attached to other conduits for support." It sounds like a mess and that makes it hard to describe and to visualize.

I also think of the industrial "standard" of not hanging one trade's piping of another trade's piping. I can really box you in when you need to change electrical conduit when someone has hung pneumatic tubing off of it! DAMHIK
 
Mr.TmO said:
I'm looking to upgrade my tank farm at my new facility, and the existing conduit is currently secured to the process piping. This is causing it to break at the threads in some areas due to the flooding and vibrations. They have a mixture of supports constructed of Unistrut with all-thread wrapping around the process piping and short extensions of Unistrut that are attached to other conduits for support. I also noted that there are no low point drains and was seeing if anyone could help me pin some of these issues out in the code book to aid me in writing a proposal.
Click to expand...
TmO: I apologize for suggesting solutions rather than responding to what you are actually asking for.

"... seeing if anyone could help me pin some of these issues out in the code book to aid me in writing a proposal."

Yes, we could help you pin down some of these issues, but it is likely you would focus on what you notice rather than other possibly more critical items. Believe it or not, your company's insurance carrier may do much for you by sending an inspector, free of charge. I have done so with great results in areas I didn't understand well, such as gas burners.

These references are from NEC 2020. You will need to read them carefully to have a complete understanding. After doing so, it is likely that some things that you didn't realize are a violation of the Code actually are:

Article 344 Rigid Metal Conduit Type RMC

Article 500 Hazardous (Classified) Locations, Classes I, II, and III, Divisions 1 and 2

Article 501 Class I Locations

Not trying to brush you off, guy. Just don't want you to miss important stuff like using sealtite between a device and a seal, just as an example.
 
WD40 said:
I was picturing a large process pipe with some unistrut clamped to the pipes then the electrical conduit on the unistrut. I am not sure what section would prohibit that, I'll have to admit to doing that.
Click to expand...
That was the engineering design on one project I worked on. Two 10" process pipes on pipe supports 20' apart and unistrut supported from the process pipes at the 10' point between the process pipe supports.
 
You must log in or register to reply here.
Top