Question 447Steam Plants - Assistant Engineer

The correct answer is A) set screw. On a boiler safety valve, the blow down adjusting ring is locked in place by a set screw. This set screw is used to secure the adjusting ring and prevent it from moving, which could affect the valve's performance and safety. The set screw is a common mechanical fastener used for this purpose and is the correct answer according to the regulations governing boiler safety valves. The other options (B, C, and D) are incorrect because they are not the primary method used to lock the blow down adjusting ring in place on a boiler safety valve. A locknut, wire seal, or cotter pin may be used for other purposes on the valve, but the set screw is the specific component that secures the adjusting ring.