e.alleg wrote:here's what the AHS site says: "Stays are rods that pass through the water wall and are welded to the water wall at each end of the stay. The purpose of stays is to ensure that the water wall remains rigid and does not warp as it is heated. In a non-ASME-code-compliant boiler, we use carbon steel stays and weld over the end of the stays to prevent the carbon steel from oxidizing. The ASME code requires stays to be visible. The purpose of this requirement is so that the inspector can easily see that the stays have been included in the boiler assembly. In ASME-code-compliant boilers, Alternate Heating Systems uses stainless steel stays so that the protruding ends do not oxidize."
I guess the extra $2,000 helps cover the cost of the stainless, seems a little high to me.
Here's my interpretation of what AHS does:
Non-code compliant - Steel stay, welded over end so you can't inspect to see if a stay is present. The purpose of the weld over is to protect the steel stay end. Perhaps it's done with stainless welding rod.
Code compliant - Stainless stay, not welded over but welded so you can see it's present. Protected because the stay is stainless to begin with.
The steel stays must be less expensive than stainless steel ones for this to make any sense.