Where to buy black iron mixing elbows to build a new riser??

[Ric in Richmond]

I have a Universal M35 with black iron exhaust from the manifold. I think I may have a mixing elbow going bad with a slight streak of rust down the side.

I cleaned it so I can monitor if this is truly a pinhole or just a spot of rust.

Where can you buy black iron mixing elbows with a 45 degree angle?

I'd probably just rebuild the entire thing- if one section is bad the rest will be too. IT is only a couple sections of iron pipe and some elbows. Seems like they would be pretty easy to copy one and build a new one.

Any words of wisdom as to the job or where I can get the parts?

[dmairspotter]

I'm replacing my Volvos custom casting with stainless steel pipe fittings. I'm going to weld a nipple into the elbow for the water injection. I did something like this on my old A4 and it worked fine.

[bcooke]

I think 'black iron' is a term for the ordinary metal pipe found at all hardware stores.

Stainless would be very nice but iron pipe from the hardware store is dirt cheap and easy enough to replace too.

-Britton

[Ric in Richmond]

I can find the regular pipe and elbows. What I need is the specialized piece with the fitting for the water injection.

Or is that a roll your own part??

[Quetzalsailor]

Black iron is, indeed, just nasty old plumbing supply / hardware store pipe. Most of the fittings these days are from red China so the quality is suspect.

I bought the new riser for the A4 in our Morgan 27 (since sold) right from Universal. It was some wierd alloy (Anzac? Zamac?) and the fittings they supplied were brass. That was obviously really dumb for any use other than an object you'd leave on a coffee table so I called around and bought stainless steel pipe fittings.

So, shop around, Google around; you should be able to find a supplier that'll sell you stainless. Easier for 304, tougher for 316. You should be able to make up the whole thing with bought fittings if you don't care how elegant it is; the local watermen do just that. I've seen that someone drilled and tapped the ell for the water injection, rather than weld a nipple. Not much stress on that fitting.

The next boat over from me and I both have 3 cyl Yanmars; both boats have the same non-Yanmar 8" or so nipple to raise the injection elbow up from the engine. Both boats suffered this nipple breaking off in the fitting on the engine. I only mention this because you'd want to buy the best quality pipe so that you could believe that the threads were neatly cut rather than poorly; less chance for fatigue failure.

[dmairspotter]

McMaster has the stainless. I think the elbow you need is roll your own. That's why I went to stainless, I can weld the elbow nipple in and it will last a while. IMO the price was not bad.

[feetup]

It seems that any town with any amount of industry will have a supplier of pipe and fittings, and if they don't have stainless, they would be the ones to tell you who does. The hard part is asking them for what you want, since they won't let you browse, mostly because they probably don't have a show room. The people they deal with know what they want and ask for it by name. Every concievable fitting is made somewhere, the problem is often knowing what to ask for. If your are not a Pipe fitter it might be worth while doing a web search on pipe fittings to see what is available so you can order stuff with authority.

As far as stainless goes, definately go for 316/ 316L(low carbon, more readily welded). 304 has more chromium and less nickel than 316, and chromium is the element that is most susceptible to attack from the chlorides in the salt. 304 is a little stronger but way more likely to suffer from pitting corrosion in a chloride rich environment. If you don't care about cost, and aren't in a hurry to see the pieces you might order 317/L fittings since this is the alloy that will be the best as far as heat AND corrosion. A bit hard to find though. Duplex stainless steels such as 2205 or 2304 will be better yet. If you can, get your pipe pieces in schedule 80 which has a much thicker wall, making it much stronger in the vulnerable areas where the last thread enters the fitting.
I would suggest that any decent fab shop could weld a nipple into an elbow for you. If there is a shop around that is ASME certified then there is a chance you will get a beautiful weld.
If you use stainless pipe fittings in a place where you might want to dissassemble it at a later date then you must use an anti-seize compound, and it should be nickle based such as 'Permatex #77164' . Copper based anti-seize will cause problems where heat and chlorine are present. If you can't get nickel based anti-seize, then use the aluminum stuff, although it won't work nearly as well. Stainless on stainless without anti-seize is VERY sticky and VERY prone to galling and thread pickup.

Well that was exausting!

Feetup

Enjoy life, the alternative isn't as good.