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Diesel Generator Exhaust Piping

Diesel Generator Exhaust Piping

Diesel Generator Exhaust Piping

We need to pipe an indoor generator's exhaust about 20 ft or so to the outside wall of a building. So far I have specified welded stainless steel piping but is there any reason I couldn't use Schedule 40 black?
By the way, I have also specified two layers of 1-1/2" calcium silicate insulation per a John's Manville guide.
Thanks in advance.

RE: Diesel Generator Exhaust Piping


Cummins allows black iron Sched 40 on their systems - so it's probably ok. But, I'd check w/the manufacturer of your gen set to verify.



RE: Diesel Generator Exhaust Piping

One word why- corrosion

Exhaust gas is quite corrosive to plain carbon steel.

A lot depends on how this gen set is used. Intermittent use will corrode faster.

A hole in an inside exhaust can kill people.

For 20ft of pipe why take the risk?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Diesel Generator Exhaust Piping

Thank you both for your information, you're awesome.

RE: Diesel Generator Exhaust Piping

Carbonic acid (carbon dioxide + water vapor) in the exhaust can be a problem with black pipe

RE: Diesel Generator Exhaust Piping

Also the sulfur content of the fuel and NOx from combustion will create acids. There is a reason better cars use stainless exhaust, and they may last fewer years than the life of the car. Before stainless steel exhaust was common, exhaust pipe and muffler replacement were common repairs on a car. I wouldn't use carbon steel.

RE: Diesel Generator Exhaust Piping

Black pipe with a properly selected internal coating could be ok.

If you can find a coating that would tolerate the temperature.

RE: Diesel Generator Exhaust Piping

MintJulep: do you know of an actual product? I'm not aware of a coating that can be applied perfectly over the entire inside of the pipe inc. the fittings and survives the cutting and welding etc. Then it needs to survive the hot/acidic/wet/abrasive environment. If that actually exists, I bet using stainless steel will be cheaper and more reliable.

RE: Diesel Generator Exhaust Piping

There are field-applied products that under good conditions can achieve a continuous film for at least "a while".

I don't know if any of them would survive exhaust temperatures.

I would not bet against your cost and reliability guess.

RE: Diesel Generator Exhaust Piping

There are many, many indoor installations of these engines..

As stated above, what does the engine vendor suggest ? .... The additional cost of a 10S SS system is modest and will probably have a mich longer service life than a black CS pipe

This document might be helpful:


Sr. Process Engineer

RE: Diesel Generator Exhaust Piping

LittleInch (Petroleum)
A hole in an inside exhaust can kill people.

For 20ft of pipe why take the risk?
If it was a gasoline engine you would be correct.
Diesel engines have been used in underground mines long before anyone was worried about emissions.
Gasoline engines produce a lot of Co, Diesel engines not so much, though I would tend to think
the ones that use EGR would produce more than the older ones of years past.
The smart thing would be to always vent a room that is to contain an engine.

RE: Diesel Generator Exhaust Piping

There's a lot of difference between a mine where you have active constant ventilation and what we think might be a pretty closed room.

If the room was constantly ventilated then it might be acceptable. But for the cost why bother.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

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