SA 106 Gr B v/s SA 106 Gr.B

As you have noted, Gr B has lower tensile strength. Hence Gr C is used for BFP Discahrge. Gr B can be used for other boiler water services with lower pressures, such as BFP recirculation lines, boiler drains after drain valves etc

The appropriate standard would be ASTM A 192, referencing ASTM A 450, A520; Per note 1 47 ksi min ts 26 ksi min yield and 35% min elongation are assumed.

Be careful about applying cold finished rather than hot finished. if cold finished will need to be heated above 1250F.

milo