Suction Pump Block Valve

Block valve shall be provided on suction and discharge line of pump. The block valve is required for isolation purpose during maintenance. In this posting, we will discuss about the block valve on suction pump. The block valve is not required for suction pump where pump maintenance can be performed without isolating the suction side.

The following drawings are example of application the block valve on suction pump. 

1. Block valve is normally installed for isolating the suction side

2. Where pump maintenance can be performed without isolating the suction side, suction block valve is no longer required

3. For high pressure service, generally consider high rating 900# or more, double block is required.

4. In case using spectacle blind is selected for isolation instead of double block, spectacle blind shall be installed downstream of the valve

5. For pump require “AUTO START” , the suction block valve shall be locked open (LO), for example ; Boiler Feed Water Pump, Surface Condenser Condensate Pump, Compressor Lube Oil Pump etc.

6. For stand by pump, suction valve should be in normally open position. As a standard operating practice/procedure, stand by pump should be in a stand by condition with liquid filled in the pump and with suction valve in open position.

That's all I can share .. Please correct me if I'm wrong (cmiiw)