The raw water injection elbow had a very slight leak dribbling out from under the heat wrap. Unwrapping it showed that the elbow was about to fall apart! These really need to be inspected periodically. If it failed the worst possible way water could be pumped right into the engine. Both the original and replacement water injection elbows are Onan generator parts, so there is no quality issue. They just wear out.
The piping components are all plain steel and cast iron right off the hardware store shelf. Avoid galvanized parts, the coating is poisonous as it burns off. The copper colored fitting is a $100+ part from Westerbeke/Universal that I wanted to reuse. A propane torch, Kroil and a 24" wrench got the old street ell off. If that didn't work I could have cut the pipe off flush and machined away the stub from the inside on the mill or lathe. All of the threaded connections are NPT so they seal pretty well alone but I coated everything, including the manifold studs with Permatex 77124 Nickel anti-sieze good for 2400 deg F so it's easier to disassemble in the future.