A Material problem! 1

It is a much stronger stainless steel with similar corrosion resistance as 304. Depending on your environment it may be OK. Chloride resistance will not be as good as 316.

It also isn't austenitic like 316, so welding will be different.

This looks like 17-4 PH double aged condition H1150.

To elaborate on the first two responses, Type 630 stainless steel (also called 17-4 PH) is a precipitation hardening stainless steel, which means that it responds to heat treating-- first a solution heat treatment step and then a precipitation hardening step (also called age hardening). You can obtain more information by using the following links:



ASTM A 564 is a standard specification for ordering age-hardening stainless steel bars. You can obtain this standard from ASTM using the following link:

Type 630 SS (17/4)in leiu of 316 SS is common in the valve industry, particularly in high pressure valves >Class 300. It is usually replaced for stems / shafts and ball components in ball valves where the much higher SMYS of the 17/4 is advantageous. I have also used it for the main body components for the same reasons.