Through hull fittings

Swimming pool chlorine eats SS, so the chemicals are definitely different from what is in a paper pulp mill.

 

Swimming pools, with far more chlorine than the ocean, use stainless ladders, etc for decades with no corrosion problems. How many boats have anything else but stainless for their prop shafts?
How often do they fall off?
Its quite a stretch to suggest that corrosion that has not happened in 40 years, just may happen.
I've never seen it happen on ss through hulls in over 40 years.\
As for the weld failure, it simply doesn't happen.

 

Stainless steel in swimming pools also get lots of oxygen. When the stainless is buried in wet material in an anoxygenic environment crevice corrosion sets in.

 

Through hulls a foot or so below the water get lots of oxygen. Foam is anything but airtight, so SS in foam gets enough oxygen. This is not the case with SS bolts holding flanges on. There, crevice corrosion is a real risk.

 

BS that's BS..

 

Hi, I have a set of plans here from a well respected NA from USA that is specifiying SS sch40 pipe nipple welded to hull plate. I have been fitting this setup to boats since I started working in 1983. It works well. Mild steel pipe nipples if not looked after crumble when you put a pipe wrench on them to remove valves. Stainless V/V on a S/S pipe nipple wont do that. A 50mm S/S pipe welded to the large surface area of the hull is fine. Keep your zincs up to date and you will be fine. You guys need to stop believing every thing you read on the internet.