Oh , you are wise to ask that question about welded chainplate fittings.
Although I am not a rigger, except for my own rig, I have read a number of books about marine DIY surveying, and found it mentioned a number of times, that it is not an approved practice to hang anything structural on a welded fitting.
I have seen it done, even on my former ss bowsprit cranze iron .
It was difficult for me to find out why a ss welded fitting could not be depended on, structurally. From what I could find out, is that when you weld on ss , the molten puddle, boils off some chrome and nickle, thus you don't have a marine grade 18-8 alloy any more , all along that weld .
Some welders said to me, where you can not avoid using a welded ss structural fitting, you can use an "enrichening" filler rod, thus replacing the chrome and nickle that would normally be lost or vaporized to the air in the welding puddle.
I have had this enrichening rod used on my ss welded swim ladder , and I expected to see the normal rusting occur on and around the weld, but the corrosion evidenced by rust, has not appeared yet after 3 years, hurray !
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