Stainless or regular steel for exhaust nipple?

[killarney_sailor]

I have to replace the 1.5" nipple that connects the engine to the exhaust elbow (Westerbeke 58 engine). Does it make sense to use a stainless nipple rather than regular steel? There is a certain amount of heat here but the combination of heat, exhaust gases, and seawater must be very corrosive.

Thanks

[Faster]

We had good luck with a homemade SS one..... YMMV

[fryewe]

If the engine is raw water cooled and the nipple sees seawater, bronze will give you better service life.

[SloopJonB]

Originally Posted by killarney_sailor

I have to replace the 1.5" nipple that connects the engine to the exhaust elbow (Westerbeke 58 engine). Does it make sense to use a stainless nipple rather than regular steel? There is a certain amount of heat here but the combination of heat, exhaust gases, and seawater must be very corrosive.

Thanks

Hot and corrosive is where stainless is needed most.

[downeast450]

If you can, go with ss. I replaced my hot pipe and wl muffler with ss and have no rust on the transom anymore.

Down

[celenoglu]

SS is not a good material for underwater use. It needs oxygen to stay away from rust. Cast iron is the best material, you can also use bronze (not brass)

[tommays]

I would think the engine to elbow would be dry and the water would be injected in and after the elbow no ?

[fryewe]

Stainless steel in a hot salt water environment under tensile stress can fail due to chloride stress corrosion, which is corrosion between the crystal grains. It manifests itself as cracks. Be careful with SS use in raw water exhaust systems.

[SloopJonB]

Originally Posted by fryewe

Stainless steel in a hot salt water environment under tensile stress can fail due to chloride stress corrosion, which is corrosion between the crystal grains. It manifests itself as cracks. Be careful with SS use in raw water exhaust systems.

Interesting - does that mean cast iron would be better (more dependable) and just live with having to replace it every number of years?

[aeventyr60]

Schedule 40 mild steel pipe lasted me 17 years and about 4000 engine hours on a Perkins 4108