Protection against corrosion for RMC

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transman2

Senior Member
Location
Brooklet,Ga.
300.6 explains that metal raceways, couplings, and fittings should have an approved electrically conductive, corrosion-resistant compound applied to conduit that is threaded in the field. I am seeing more and more where the EC is not doing this witch was a normal practice when I worked with my tools. I have encountered many that say galvanized spray is equivalent but I cant see that due to it not meeting 300.6 code. Your thoughts!!!
 

Carultch

Senior Member
Location
Massachusetts
300.6 explains that metal raceways, couplings, and fittings should have an approved electrically conductive, corrosion-resistant compound applied to conduit that is threaded in the field. I am seeing more and more where the EC is not doing this witch was a normal practice when I worked with my tools. I have encountered many that say galvanized spray is equivalent but I cant see that due to it not meeting 300.6 code. Your thoughts!!!

I also notice that factory nipples, elbows, and straight sections do not already come with factory-applied corrosion treatments on the manufactured threads. It is very unfortunate when the part sits in the workshop for years, and all your nipples left over after jobs of previous years are corroded away. I'm surprised it hasn't been a requirement to apply corrosion treatment to factory threads.
 
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bphgravity

Senior Member
Location
Florida
There are several products on the market that provide this protection:

1. Zinc-rich paints or similar compounds
2. Tape Wraps / Shrink Wraps
3. Bitumastic Coatings / Epoxy-based Resins

T&B has a product listed for this application. See UL 2419 - Product Code FOIZ
 

Smart $

Esteemed Member
Location
Ohio
Most contractors I've worked for/with use the so-called cold galvanizing spray (i.e. zinc-rich paint mentioned by Bryan). The problem I've always found with that method is no one actually cleans the threads (i.e. removes the threading oil) prior to applying the paint.

That'll hold up for years and years... :happysad:

Some use the copper-particulate version of an anti-seize compound.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
I also notice that factory nipples, elbows, and straight sections do not already come with factory-applied corrosion treatments on the manufactured threads. It is very unfortunate when the part sits in the workshop for years, and all your nipples left over after jobs of previous years are corroded away. I'm surprised it hasn't been a requirement to apply corrosion treatment to factory threads.
I have tried twice to change the code so that 300.6(A) applied to unprotected factory cut threads, without any success. I guess the factory cut threads don't corrode like field cut ones do. (talking about threads on factory 90s and nipples as the factory threads on the conduit itself has protection on the threads)
 

kwired

Electron manager
Location
NE Nebraska
Most contractors I've worked for/with use the so-called cold galvanizing spray (i.e. zinc-rich paint mentioned by Bryan). The problem I've always found with that method is no one actually cleans the threads (i.e. removes the threading oil) prior to applying the paint.

That'll hold up for years and years... :happysad:

Some use the copper-particulate version of an anti-seize compound.
I remove the threading oil - carburetor cleaner works great and evaporates quickly so you can apply the cold galvanizing pretty much right away.
 

Smart $

Esteemed Member
Location
Ohio
I remove the threading oil - carburetor cleaner works great and evaporates quickly so you can apply the cold galvanizing pretty much right away.
You'd be the first to remove the threading oil in my experience... but that's a good thing. :D

It's not that I wouldn't do it, but working for contractors relies on them furnishing the means to remove the threading oil. Usually the best option is an already oily rag... or one that be oily shortly.

Not cleaning the oil off is also effective at preventing corrosion.
That'll depend on the type and extent of the corrosive environment.

And while on that subject, I should note that Code does not require the application of a coating where it is deemed unnecessary.
 

masterinbama

Senior Member
I remove the threading oil - carburetor cleaner works great and evaporates quickly so you can apply the cold galvanizing pretty much right away.


I use carburetor cleaner or brake cleaner, which ever is cheaper.

Brake clean is the choice on PVC coated GRS as it is formulated to not damage rubber and plastics.
 
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