Explosion proof Sealing compound

Fordean

Senior Member
Should you seal Rigid pipe threads with compound. I believe you should. Any answers please. Compound type would help. Is it the same as the Chico and compound? Cut Rethreads should they be repainted as well.? This is indoors.
 

Dsg319

Senior Member
Location
West Virginia
Occupation
Journeyman Electrician
Should you seal Rigid pipe threads with compound. I believe you should. Any answers please. Compound type would help. Is it the same as the Chico and compound? Cut Rethreads should they be repainted as well.? This is indoors.
I’m not exactly sure what you mean by seal the pipe threads. But by doing so you take away the continuity of the conduit system,and the escape path for gasses under the event of an explosion.

We always you stl8 which is like a grease that does not hinder continuity. Nor does it “seal” But from what I’ve researched and heard is you never wanna use pipe tape or anything like that in conduits and fittings. Because the tapered threads are essentially a path for hot gases to cool down before reaching outside, in the event of explosion in the conduit. I could be wrong if so somebody correct me.
 

Dsg319

Senior Member
Location
West Virginia
Occupation
Journeyman Electrician
I’m not exactly sure what you mean by seal the pipe threads. But by doing so you take away the continuity of the conduit system,and the escape path for gasses under the event of an explosion.

We always you stl8 which is like a grease that does not hinder continuity. Nor does it “seal” But from what I’ve researched and heard is you never wanna use pipe tape or anything like that in conduits and fittings. Because the tapered threads are essentially a path for hot gases to cool down before reaching outside, in the event of explosion in the conduit. I could be wrong if so somebody correct me.
 

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rbalex

Moderator
Staff member
Location
Mission Viejo, CA
Occupation
Professional Electrical Engineer
The main text of section 500.8(E) outlines proper "threading" in hazardous locations. It must not hinder continuity since even a slight current arc, whether fault induced or circulating from harmonics could cause an ignition. This is a problem even in Division 2 since harmonic currents could be continuous. Also "plugging" a thread with compound could affect the pressure relief effect at a thread during an internal ignition.

It should also be recognized that corrosion protection coatings, while desirable, does have a specific exception at threaded joints in section 300.(A). Basically, a properly torqued thread is sufficient.
 

Fordean

Senior Member
I’m not exactly sure what you mean by seal the pipe threads. But by doing so you take away the continuity of the conduit system,and the escape path for gasses under the event of an explosion.

We always you stl8 which is like a grease that does not hinder continuity. Nor does it “seal” But from what I’ve researched and heard is you never wanna use pipe tape or anything like that in conduits and fittings. Because the tapered threads are essentially a path for hot gases to cool down before reaching outside, in the event of explosion in the conduit. I could be wrong if so somebody correct me.
I figured the continuity would be Impeded That is why I doubled checked. Thank you
 

Fordean

Senior Member
The main text of section 500.8(E) outlines proper "threading" in hazardous locations. It must not hinder continuity since even a slight current arc, whether fault induced or circulating from harmonics could cause an ignition. This is a problem even in Division 2 since harmonic currents could be continuous. Also "plugging" a thread with compound could affect the pressure relief effect at a thread during an internal ignition.

It should also be recognized that corrosion protection coatings, while desirable, does have a specific exception at threaded joints in section 300.(A). Basically, a properly torqued thread is sufficient.
Thank you always double checking before installs. No matter how long you do electric. I usually go over installs with inspectors as well.
 

Bluegrass Boy

Member
Location
Texas
Occupation
Commercial/ Industrial/ Maintenance Electrician
We did a explosion proof job at a rubber plant owned by Michelin. Seal offs at every building, and we did use a compound on the threads. I don’t remember exactly what it was called, but the brand was “Robroy”. I tried to look it up, and the company has different divisions, and did find a thread compound that was one of theirs, and is conductive. They have other explosion proof stuff as well.
This job was 18 -19 years ago. 2 inch rigid all over the plant. It may have been spec for that job. There were a lot of different chemicals in different areas there. Some highly volatile stuff.


 
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