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Old 09-19-2017, 11:03 PM   #8
CaptSteve53
Senior Member
 
City: Subic Bay
Join Date: Aug 2017
Posts: 194
Quote:
Originally Posted by psneeld View Post
Hmmmm, that last turbo picture looks a lot like one on this page....

https://www.honeywell.com/newsroom/m...urs-of-le-mans

Also, something a friend pointed out (he designs exhaust systems for diesels) pointed this out....

'The thermal conductivity of 300 series stainless is 1/3rd to 1/4 that of mild steel ... that means less heat moves through it to the outside. The specific heat (the amount of heat per pound required to raise its temperature 1 degree F - which can be described as how much heat it "holds") is actually less than mild steel, not enough for a boat owner to even measure.

Thermal Properties of Metals, Conductivity, Thermal Expansion, Specific Heat | Engineers Edge

The fact that a stainless exhaust system uses thinner and lighter material than a steel system means that there is less heat retained in the piping and the fact that stainless conducts less heat than mild steel means more of the exhaust heat goes out with the exhaust then with a mild steel system."

Hmmm, you know what the last turbo picture looks like the original post as:

https://www.sbmar.com/articles/propp...exhaust-leaks/

As images are posted on the WWW there's no end to who and how they are used after insertion??????

Perhaps there's just to much book work here, above arguments just prove the point that , What many operators and builders DO NOT understand is the approx 1/3 of the total energy (heat) that comes from the fuel that is consumed by a diesel engine is expelled as heat thru the exhaust system, and this heat must be contained and then exit the vessel safely.


Current REGULATIONS

1) The design of all exhaust systems must ensure minimum risk of injury to personnel. Protection must be provided in compliance with 177.970 : at such locations where persons or equipment might come in contact with an exhaust pipe.(What the original post was about)
2) If it passes through a combustible bulkhead or partition, be kept clear of, and suitably insulated or shielded from, combustible material.

In closing: Dry exhaust systems (especially close to the engine) can run @ 1200 f this means special lagging/insulation needs to added for the protection of people and surrounding area's/structure.This is the biggest area to come to grips with if using a dry or partial dry system.

You can ignore the following as it's only for the Book worms

1)Thermal conductivity is a material’s ability to conduct heat through itself over a temperature gradient (temperature difference). The specific heat is the amount of energy required to change the temperature of a material a specific amount.

2)Stainless steel, has by definition a minimum of 10.5% chromium(normally 18%) added to it which gives it it’s non-corrosive properties. But chromium atoms that are mixed in with the iron have the added effect of making the material worse at conducting heat than mild steel.


Cheers Steve, Chief Marine Eng (I love it when engineers nerd out over such fun things! Fun to read and a nice little metals )
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