heat trace on gas line
- Thread starter jusme123
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I'm not sure of a "hard and fast" NEC section that would prohibit the install. At best, unless the gas that you speak of is liquid, I could make an argument that 427 is not applicable.
Perhaps 110.3(B) should be utilized to assure that the heat trace is actually listed for the purpose.
Pete
Perhaps 110.3(B) should be utilized to assure that the heat trace is actually listed for the purpose.
Pete
- Location
- Massachusetts
What would be the electrical safety issue?
The NEC is only concerned with electrical safety issues.
There may be a plumbing code against it but I kind of doubt it for two reasons.
1) I do not see a hazard. (NM can touch gas lines, gas lines already run near sources of ignition like pilot lights)
2) I can't imagine ot comes up often, why the heck would gas line be heat traced.
Are you sure it was heat trace?
I agree, that is as close as the NEC will get to this issue.
[QUOTE=iwire;1216999
Are you sure it was heat trace?
the cable was wrapped around the gas pipe, just below the meter, outside the convenient store with an unplugged extension cord next to it. Hard to believe thats code. I guess a better question would be why would you need heat trace on a gas line to a store located in a large city?
Are you sure it was heat trace?
the cable was wrapped around the gas pipe, just below the meter, outside the convenient store with an unplugged extension cord next to it. Hard to believe thats code. I guess a better question would be why would you need heat trace on a gas line to a store located in a large city?
The large city not withstanding, according to the almighty internet, the temperature at which natural gas freezes is -296.7 degrees F.
So unless this large city is on the dark side of the moon I couldn't begin to know the reason for the heat trace.
Pete
Mgraw
Senior Member
- Location
- Opelousas, Louisiana
- Occupation
- Electrician
Could be the gas line is trapping water.
Heat trace on piping or vessels is a very common practice in refineries and sour gas plants. Extractive gas analyzers also use heat traced tubing bundles to draw sample for analysis. Usually in hazardous locations Class 1 Div1/2.
One item that is occasionally overlooked is NEC 427.22 requiring a EPD circuit breaker, typically available with 30mA trip.
One item that is occasionally overlooked is NEC 427.22 requiring a EPD circuit breaker, typically available with 30mA trip.
Sierrasparky
Senior Member
- Location
- USA
- Occupation
- Electrician ,contractor
Well if it's propane I could see an issue. Propane can turn to liquid and freeze in the line especially near the regulator.
gadfly56
Senior Member
- Location
- New Jersey
- Occupation
- Professional Engineer, Fire & Life Safety
Exactly what I was thinking. Propane remains a liquid at 100 F at a pressure of 177 psig. And it doesn't need to freeze to cause problems. Gas regulators really hate ingesting liquids.
On the other hand, I am not aware of any city-wide distribution systems that use propane. If the natural gas supply line pressure is high enough, I suppose you might get JT cooling effects at high enough flow rates that would liquify a portion of the gas as it exits into the low pressure areas of the regulator and that might cause some equipment problems. Hence the homemade "preheater". This is common in the semiconductor industry where there are some gases (BCl3, NH3)) which need to be vaporized before they are introduced into the regulator assembly of a gas control cabinet.
All that said, I find the circumstances puzzling, especially if the gas feed is in fact natural gas. Convenience stores don't strike me as the kind of facility that would need to preheat their gas.
Sierrasparky
Senior Member
- Location
- USA
- Occupation
- Electrician ,contractor
out here in the rural west of ca and Nev we do not have Natural gas. So there are areas with propane pipelines.
kwired
Electron manager
- Location
- NE Nebraska
we have all heard the myths and snake oil salesmen in the electrical areas maybe this is an attempt at some of this type of thing in the gas industry?
I'm pretty sure the gas meters compensate for temperature and pressure, and you pay for the energy delivered to you and not the actual volume which will change with temperature and pressure.
I'm pretty sure the gas meters compensate for temperature and pressure, and you pay for the energy delivered to you and not the actual volume which will change with temperature and pressure.
Mgraw
Senior Member
- Location
- Opelousas, Louisiana
- Occupation
- Electrician
I still think its water in the line. I've only seen it a few times. Here it doesn't get cold enough to freeze in the lines but in colder climates it could.
kwired
Electron manager
- Location
- NE Nebraska
Where would water be coming from? If it is normal you would see heating cables on it all the time in cold climates, it gets plenty cold here and I have never seen a heat cable on a gas pipe.
Mgraw
Senior Member
- Location
- Opelousas, Louisiana
- Occupation
- Electrician
It is not normal but does happen. A break in the line caused one instance. Water got in and the gas company didn't get it all out. Water filled gas valves all over the neighborhood. They did step up quickly and pay for repairs. Another time the gas was to "wet" (not dehydrated enough) and water condensated in the lines.
billsnuff
Senior Member
- Location
- East of 480sparky
I'm thinking 'locating wire'.
Yes I have seen it I can't think of why you would do it in a convenience store. When we build Gas Turbines or even some Natural Gas Engines they are temperature and pressure requirements of the incoming gas. if your supply can't always meet these requirements we provide aux equipment to meet them. we have talked about using electric gas heaters and have in the past used natural gas gas heaters.
kwired
Electron manager
- Location
- NE Nebraska
You probably need more heat than you will get from simple heat trace that keeps water pipes from freezing in cold weather, those are typically self regulating and will draw less current as the cable gets above freezing point.
There are pipe heating cables that will put out a lot of heat however, but I'm guessing that is not what was installed in the OP case.
kwired
Electron manager
- Location
- NE Nebraska
very good possibility, gas companies around here do not run steel pipe underground anymore (very high pressure lines may be exception I am not around those ever) but to the typical home or business they run a nonmetallic piping of some type and transition to steel pipe when coming out of the ground for physical protection of the exposed portion of the line. The line always has a 12 AWG copper wire wrapped around it that I can see being mistaken for a heat trace, it is buried with the non metallic portion of the line so underground locating equipment can be used to trace the line. Non metallic underground water piping often has a tracer wire installed with it also - at least if connected to municipal water supply.
With all due respect, it is NOT a 'locating wire', it is ,however, heat trace!
weressl
Esteemed Member
Condensates are removed by purging the lines during initial installation. If recurring condensation is expected, you would remove it by traps, similar to steam traps. If sufficient water accumulates it will block a low pressure line anyways. Heat tracing would just keep the line from freezing and rupturing. Sounds like negligent installation to me, the gas supplier should take care of it according to Utility Commission regulations that would specify the allowable moisture content and the required method(s) of eliminating it.
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