Standpipe Construction

[hanleyclifford]

As Tom has discovered and correctly reported the environment in the hot section indeed all the way back to the flange is anything but chemical vapor free. That is why it is of utmost importance to construct hot sections from materials as closely resembling the manifold as possible. This means black iron is the #1 choice.

[Laker]

"A machinist friend has offered to recreate the original structure , using common black pipe , for next to nothing , and I accepted."

The above is from my thread on Standpipe autopsy. I am feeling rather brilliant this morning. Never mind that I made my choice based on economy; I like to think that it was my inner metallurgist speaking.

[ArtJ]

I own a Tartan 34 and have converted the exhaust system to a Vetus Waterlift. The hot exhaust rises above the waterline and makes a 180 degree turn into the Vetus. Raw water is injected straight down via one leg of a tee which creates the last 90 degree bend in the hot section. I had installed all 316 stainless about 5 years ago and it consisted of a 90 degree ell at the top of the vertical hot section, a 6" nipple horizontally outboard to the "side" leg of the water injection tee, and a 6" nipple down to the hose that connected to the Vetus. All of the hot section was well lagged with 1" thick Calcium Silicate except for the side of the tee away from the "side" leg (I just could not get to it except to apply some fiberglass cloth). I thought I was finished worrying about my exhaust system.

WRONG! Last year I discovered exhaust gasses and steam coming from the cabinetry around the hot exhaust. To my absolute horror, the stainless tee had rotted through the side away from the "side" leg. There was nothing but scale holding it together! The horizontal 6" nipple was not in much better shape. The 90 degree ell was OK. The vertical 6" nipple was OK.

Stainless steel does not like to be in a hot environment with chlorides. If the steel is stressed, either mechanically or thermally, you can quickly get what the metallurgist call Intergranular Stress Corrosion Cracking. I figured I was OK with my design as all of the raw seawater was downstream of the stainless. I think two separate problems came into play. 1) The tee was not uniformly insulated and thus was under a lot of thermal stress when hot (the side leg was much hotter than the opposite side) 2) Chlorides would rise up into the tee and horizontal nipple during cooldown. I think I had assumed that any vapor that rose up out of the Vetus would be just pure water vapor but I was very wrong.

At any rate, I was not about to put stainless back in the system. I went back and forth between schedule 80 steel and schedule 80 brass. I ended up going with the brass. It is not particularly strong at the elevated exhaust temperatures but then again it does not really need to be. I also insulated much better, this time with 1" flexible silica insulation. Time will tell how this holds up. I plan to put a small mirror down through the water injection connection in a year or to see what things look like on the inside.


Tom Stevens - Indigo

Tom

If you still have the original bronze standpipe, maybe you could revert to
it. I had my bronze standpipe cleaned 12 years ago, installed new black
iron pipe, and it has been problem free ever since. I know that you
have a rear exiting exhaust rerouting, would the standpipe still be compatible
with your rerouted exhaust?

Regards

Art

[67c&ccorv]

I own a Tartan 34 and have converted the exhaust system to a Vetus Waterlift. The hot exhaust rises above the waterline and makes a 180 degree turn into the Vetus. Raw water is injected straight down via one leg of a tee which creates the last 90 degree bend in the hot section. I had installed all 316 stainless about 5 years ago and it consisted of a 90 degree ell at the top of the vertical hot section, a 6" nipple horizontally outboard to the "side" leg of the water injection tee, and a 6" nipple down to the hose that connected to the Vetus. All of the hot section was well lagged with 1" thick Calcium Silicate except for the side of the tee away from the "side" leg (I just could not get to it except to apply some fiberglass cloth). I thought I was finished worrying about my exhaust system.

WRONG! Last year I discovered exhaust gasses and steam coming from the cabinetry around the hot exhaust. To my absolute horror, the stainless tee had rotted through the side away from the "side" leg. There was nothing but scale holding it together! The horizontal 6" nipple was not in much better shape. The 90 degree ell was OK. The vertical 6" nipple was OK.

Stainless steel does not like to be in a hot environment with chlorides. If the steel is stressed, either mechanically or thermally, you can quickly get what the metallurgist call Intergranular Stress Corrosion Cracking. I figured I was OK with my design as all of the raw seawater was downstream of the stainless. I think two separate problems came into play. 1) The tee was not uniformly insulated and thus was under a lot of thermal stress when hot (the side leg was much hotter than the opposite side) 2) Chlorides would rise up into the tee and horizontal nipple during cooldown. I think I had assumed that any vapor that rose up out of the Vetus would be just pure water vapor but I was very wrong.

At any rate, I was not about to put stainless back in the system. I went back and forth between schedule 80 steel and schedule 80 brass. I ended up going with the brass. It is not particularly strong at the elevated exhaust temperatures but then again it does not really need to be. I also insulated much better, this time with 1" flexible silica insulation. Time will tell how this holds up. I plan to put a small mirror down through the water injection connection in a year or to see what things look like on the inside.


Tom Stevens - Indigo

Tom, wondering if it was straight 316 or 316(L)?

Also, were there any welded sections in the tee or was it a cast piece?

Cheers!

[arthur]

stand pipe

Our 1969 Pearson 35 still has the copper standpipe which I believe to be original equipment, although our late model A4 is probably not original to the boat. There's a post from late 2008, I think, that diagrams how the standpipe system works. We've had no trouble with it and to my knowledge neither did the PO. Having said that, knock on wood.

mark i also have a 35 p its 76 model is it possible to get a picture of your system so i can try to craft a system like yours mine has a home made exhaust from the broker i bought it thru thanks only if its not to much trouble art.

[joe_db]

Well crap - I was just about to order stainless pipe to make a hot section
Is there any such thing as BRONZE pipe and fittings or is it all brass?

[urchin]

Is this a standpipe????

[ndutton]

Is this a standpipe????

Is what a standpipe? No picture attached.

Aah, there it is. Yes, standpipe.

[ArtJ]

Neil

Standpipes are the type of exhaust used in Tartan 30, 34. See the Moyer
catalog for a picture

[ndutton]

Neil

Standpipes are the type of exhaust used in Tartan 30, 34. See the Moyer
catalog for a picture

Thanks Art. Urchin, did that answer your question??

[urchin]

Thanks, I thought it was just havent seen a ranger 33 with one before, any reasons to make any changes or just replace the hot section.

[ndutton]

As long as there are no breaches internally it's as good as it gets. Be sure to support the upper canister well to relieve stress on the flange bolts.

[romantic comedy]

This is my standpipe and exhaust on my Tartan 34. I just did this today. Now I need to insulate it.

The standpipe is made of copper. Revere is written on it.

[ArtJ]

Be sure and insulate it really well. Two or three wraps of tape. I also
put a piece of stove pipe at the 90 degree elbow and even cut back
some of the wood as it was getting blackened ! That was 10 years
ago, still gets hot, but I keep engine cover off during long runs of several hours and always run the blower with engine.
The original insulation was asbestos plaster.


Best Regards

Art

[romantic comedy]

Finally someone with a T 34 that says the exhaust gets hot. I dont know why no one talks about it. It has made me crazy.

I used 45 elbows instead of 90 to make less restriction. I have thought that the weight and rigid mounting needs improvement. I wonder if anyone has used a flexible connection in the pipe. I also wonder about bending the 1 1/4 pipe, or standard automotive exhaust pipe, or flexible exhaust pipe.

Then there is the question of what material pipe. Stainless sounds no good. Iron pipe works but rusts out. Mine lasted 10 years. Maybe brass or bronze?

I have insulated that pipe with tons of fiberglass insulation. It still gets too hot. I have run with the engine box open and 3 fans blowing on it, when motoring long distance, like the ICW.

I have thought about making a jacketed exhaust, but have not done it yet. At one point, I was going to wrap 1/2 " copper tubing around the insulation, and run the cooling water thru it. I still might.

I cant imagine that the single wrapped exhaust pipe is much cooler then not wrapped.

I am surprised that no boats have caught fire.