William_H
Well-known member
I was given somme "stainless steel" chain about 10 years ago for my swing mooring. It came out of a ceement works kiln. Links 18mm and about 10cm diameter round links. Becuae the buoy I ma obliged to use has stainless steel attachment and built in swivel I fitted 316 ss shackles and this chain down to an iron mass (railway wheel). This cahin worked beautifully for 10 years or more with no signs of wear.
Now the government who control the moorings have mandated a 2 yearly inspectionn of the moorings by a licenced inspector. So though I have cared for my mooring for 30 years I had to pay someone to check and report to the authority. 2 years ago the inspector reuired a new railway wheel mass. I thought the old mass was OK. Anyway inspection time again this different guy reported SS chain rotten. I had some more spare so he changed it. Now I have the rotten bit at home and indeed it is scary. Just one link the top which attached to aa 316ss shackle then the ss loop of the buoy/swivel.
The inside of the 18mm link has been hollowed out for about 90mm the openening and surface damage on the outside of the link. Just as if a worm had got in and eaten the SS. So the rubbing surface where wear occurs is perfect as is the 316 shackle it attached to. All the other links are perfect.
The only thing is that this top part of the chain always had a lot of growth on the bottom part being very shiny from contact with the bottom. It is a 2.5 to 3.5 metre deep mooring. Not much tide.
So leaves me wondering if this is a case of the SS that fails due to lack of oxygen? Or if there was some sort of inclusionj of foreign metal in the link. While I believe the metal is stainless steel is is probably more designed for heat resistance than 316 or similar.
Anyway I am going to stick with the present arrangement. It certainly lasts longer than GI. Especially where it attaches to the SS buoy.
Any metalurgy experts here? sorry gave up on uploading photo. How do you delete existing uploaded files in attachment manager?olewill
Now the government who control the moorings have mandated a 2 yearly inspectionn of the moorings by a licenced inspector. So though I have cared for my mooring for 30 years I had to pay someone to check and report to the authority. 2 years ago the inspector reuired a new railway wheel mass. I thought the old mass was OK. Anyway inspection time again this different guy reported SS chain rotten. I had some more spare so he changed it. Now I have the rotten bit at home and indeed it is scary. Just one link the top which attached to aa 316ss shackle then the ss loop of the buoy/swivel.
The inside of the 18mm link has been hollowed out for about 90mm the openening and surface damage on the outside of the link. Just as if a worm had got in and eaten the SS. So the rubbing surface where wear occurs is perfect as is the 316 shackle it attached to. All the other links are perfect.
The only thing is that this top part of the chain always had a lot of growth on the bottom part being very shiny from contact with the bottom. It is a 2.5 to 3.5 metre deep mooring. Not much tide.
So leaves me wondering if this is a case of the SS that fails due to lack of oxygen? Or if there was some sort of inclusionj of foreign metal in the link. While I believe the metal is stainless steel is is probably more designed for heat resistance than 316 or similar.
Anyway I am going to stick with the present arrangement. It certainly lasts longer than GI. Especially where it attaches to the SS buoy.
Any metalurgy experts here? sorry gave up on uploading photo. How do you delete existing uploaded files in attachment manager?olewill