Weil McLain Boiler issues

Second Weil McLain boiler in a row with exactly the same corrosion on the TPR fitting, stain at side of casing and deterioration on the exterior of the casing. Does anyone know if this is a common issue with these boilers? One boiler was 1989, second boiler was 1995. Do you suspect the corrosion at the bottom of the casing is from the leak at the TPR fitting or the boiler is leaking?

Just looking at the pic it appears to me the 90 degree fitting at the bottom of the relief valve had leaked and in the other pic it appears to me the relief valve lifted. BTW us old farts were never allowed to use black iron fittings on boiler water or any water for that matter galvanized or copper only