You are right in questioning the valve arrangement. This is not normal practice. The main reason check valves are provided in the pump discharge is to protect the pumps (operating or standby) from system dynamic or static head pressures. The reason why check valves are not installed above the shut-off/throttling valves is because check valves are prone to leakage. So imagine this, you have a busted check valve (no way of shutting-off the system), the whole system fluid content will be dumping on you..............and your future as a Design Engineer.
It doesn't hurt to ask/clarify with the Senior Project Engineer.......this is your job as an Engineer anyhow(most probably a young draftsman did the P & ID). While you're at it, check the shut-off/throttling valve specs...........butterfly valves are standard practice nowadays for most water applications.
-----Original Message-----
From: Subhendu Mukherjee [mailto:subhendu_mukherjee2001@yahoo.com]
Sent: Friday, May 02, 2003 6:19 AM
To: piping design
Subject: [PipingDesign] Does Gate Valve comes before check valve in
discharge line
Hi friends, I faced a problem while doing layout for a pump suction (8") / discharge (6") line. P & ID showing the gate valve is placed after discharge nozzle before the check valve. This line is connected to a tank nozzle with an isolation valve. It seems to me very confusing considering at the time of back flow ( after the pump is stopped) the thrust exerts by the liquid on the check valve may cause damage to its flap. My question is does gate valve comes before check valve in discharge line at all? Or the P & Id is not correct? Your cooperation is solicitated. Regards, Subhendu
[Non-text portions of this message have been removed]
Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ Received on Fri May 02 09:01:00 2003
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