Brass scupper tubes question

[Bushwacker]

Originally Posted by FLexpat

. . . McMaster has 1-1/4 brass tube but I'm not sure if it is a marine alloy so I decided to add some 316 stainless to a recent buy and try it - maybe several times before I get it right. . .

If you ever get any leaks and the wood block gets wet around a stainless tube, you'll have the perfect conditions for crevice corrosion, due to moisture + lack of oxygen. The stainless might not be much better than brass in that situation!

[gofastsandman]

Originally Posted by riptide

McMaster only sells 260 alloy brass or "yellow brass" in 1 1/4 tubing which is not marine grade and will eventually corrode in salt water.The ones Moeller sells are a special alloy.

Since you sent me a PM...I will explain, and look forward to May. Get marine grade.

Follow the croutons...
Us

[FLexpat]

Originally Posted by Bushwacker

If you ever get any leaks and the wood block gets wet around a stainless tube, you'll have the perfect conditions for crevice corrosion, due to moisture + lack of oxygen. The stainless might not be much better than brass in that situation!

I suspected so - thats why I was looking at passivating the stainless. After checking into it more, that is a PITA for this small of a job and nitric isn't cheap with hazmat shipping. Plan B is looking like using a fiberglass tube through the (soon to be replaced) block and a stainless tube inside of that. Redundancy works for me. Makes more work too - I don't want to finish too fast and have to start enjoying the boat. Should be easier to do since the cap is off for the transom recore.