Mixing Tee Broke Offshore

[Anonymous 121765]

Twice,

Looking at Chris's photo, at first I didn't see the hose for the mixing tee. I looked at the photo enlarged this morning and could make it out.

my goof, sorry folks.
CR

 

[Twice Around]

Like I said, I wasn't trying to bust chops...just making sure we all provide each other with clear & factual info

Cheers!

 

[Anonymous 121765]

Old School,

Great job for finding this info.

I read what the welder stated and in the process he used, i.e. welding, the temperatures far exceeded what normal exhaust temps would be. So I was not surprised by his recount of the off-gas problem.

To tell you the truth, I've never been a lover of galv. pipe as a process piping designer, still in this application it has worked. In wet applications, galv. pipe will corrode from the inside and in many cases, without any outside visual indication. It's use in industrial fields are mostly for costs savings & in many processes, will last a long time.

I do like the fact that you were being thorough in backchecking what you read in the threads. In the 2 years on this site, It's evident we have some very good folks with great knowledge & experience and I applaud all.

CR

 

[jrowan]

Sorry about your leak Ron, I posted recently about my backup leak coming up from my galley sinks. Since U have a 1980 like mine, check your vent loop check valve - if it leaks it can also flood your boat. It's still available as a solid brass U bend with the valave on top - located inside the galley sink cabinet to right. If your engine is still plumbed like the 5411 the thermostat loop is plumbed through this, so I am warning everyone to check this out. It was a big surpsrise when I found water flooding over the sink drains, when the faucet was off & the sillcock sink drain was closed! Also just out of curiosity did U replace your 5411 cause it died, or to try to get better performance? I still have my original 80 motor, which has been rebuilt & still seems to run O.K. Any tips on other C 30 1980 problems you've had?? Cheers, Jeremy Rowan

 

[Old Skool Neil]

The welder's story caught my attention but only served to open up the research. During the years I worked at the boat plants we never installed a hot section constructed from anything but black iron. We were told at the time it was for metallurgic reasons but our cynicism suggested low cost was the overriding factor. Looks like there was more to it than cost.

Of greater importance is the ABYC standard. It and the USCG are the only standards we've got so I tend to adhere to them without question. I'm often curious as to their reasoning but only for my own education. Everything in the standards is there for a reason so that's good enough for me. They say no galvanized for the hot section, then no galvanized it shall be.

 

[rbmcintire]

OK, reboot: no galvanized pipe. After removing the engine flange from the exhaust pipe, I cut some cross-sections with a sawz-all. The exterior of the pipe had serious rust flaking, but in general, the wall thickness did not seem that diminished. As far as I know, it is the original 1984 exhaust pipe. Based on cost, relative positions on the corrosion scale and expected lifecycle, I'm going fo'wrd w/ black iron fittings and the Moyer bronze mixing tee. It's essentially the materials I have in place now and I will try to protect the pipe's exterior with hi-temp exhaust paint. Another effort in that regard will be to add a second layer of insulation and sealing it to prevent air from getting to the surface of the pipe. Right now, I have a soft fabric heat wrap that breathes. I think the additional layer should prevent any condensation from happening there that would start the surface rust going.

Rob

 

[rbmcintire]

I want to add: in my case, the mixing tee failure was the small stub breaking off at its soldered/ brazed connection while I was yanking on it; probably a combination of corrosion and metal fatigue from heat and vibration. The Moyer unit looks to be properly welded like Ron's shop would build it. If one were to go all stainless, it would be the best of solutions.

 

[Anonymous 121765]

RB,

Judging by the picture from Moyer, you can expect at least 10 years of good use. It looked to be heavy walled.
It's also isolated from any kind electrolysis due to location.
live long be happy.........

CR

 

[Twice Around]

Rob, I have some unused new heat wrap I'll send you if you need it. I bought mine from an auto shop and it was probably enough to wrap V-8 headers, so, I have some leftover just sitting around. The stuff isn't cheap, but it is doing me no good in my boat box in the attic. I'd be happy to send it to another C-30 owner.

I'd also recommend wrapping the 1 5/8" hose in between the hull & ice box...it may help that block of ice (for old school guys like me) or the cold plate not work so hard on those hot summer days when the engine runs a lot.