Red RTV silicone for exhaust riser assy?

[chris95040]

Hi,

My wet exhaust system is the type of installation that has galvanized pipes (elbows and nipples) that raise the height of water injection elbow.

That run of pipe is super hot - it's dry exhaust at that point, and the pipe is wrapped in fiberglass exhaust tape.

I like to replace that piping every 5 years or so, but I don't remember what I put it together with last time. Red RTV silicone seems marginal for this? I don't want something that will burn up and then allow the assembly to loosen up.

Anyone have any suggestions? Thanks a lot!

[DougR]

My old 4-108 had the same setup, and I think I used #2 permatex and tightened everything up firmly. Worked fine. I don't think red RTV will cut it.

DougR

[Sailmonkey]

I've done the same thing, but of stainless pipe and anti seize on the joints. Tightened properly with a pipe wrench it shouldn't be a problem. Although the antiseize stunk for the first 10 hours or so until the oil burned off of it.


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[a64pilot]

Being that it is pipe thread I don't think anything has to be put on it, but orange silicone is good for 600F.

[GordMay]

Permatex Red RTV Silicone (#81160) is temperature rated from -65ºF to 650ºF (-54°C to 343°C .
ASI (American Sealants) #600 Hi-Temperature Red RTV is designed operating temperatures up to 310°C (600°F).

[MooGroc]

Here's a quote from Mainesail:

For NPT pipe threaded adapters I've been using Hercules Real-Tuff teflon thread sealant for over 20 years in this application. Seals well, does not dry out and parts will come apart easily in the future. Home Depot stocks it. If replacing an exhaust elbow or such I would strongly suggest schedule 80 pipe vs. schedule 40 for any fittings or nipples you may need..

I've come to trust Mainesail's advise and that's what I used. So far so good after one season.

[chris95040]

Thanks, everyone. Does it really stay below 600F right at the exhaust manifold exit? Its a 55hp diesel. I guess 600F is awfully f'ing hot.

Originally Posted by MooGroc

Here's a quote from Mainesail:If replacing an exhaust elbow or such I would strongly suggest schedule 80 pipe vs. schedule 40 for any fittings or nipples you may need..

Hmmph, I thought about that, but when I first got the boat I had a lot of problems with all the weight of the exhaust piping causing various components to break. I finally resolved it by reducing that weight (P.O. had a wacky set of needless reducers, couplings, and nipples) and adding bracing between the upright and the engine... The experience made me gun-shy about bumping up to sched 80....