LPS Globe Valve

[tact]

I am trying to size globe valves for a project and have 4 steam to hot glycol heat exchangers each with a 10" 1/3 (10,683 lb/h)and 12" 2/3 (21688 lb/h) LPS supply (5 psi). Specifications say whenever flow rate requires a valve larger than 2", provide two valves piped in parallel, one of which shall not exceed 2" in size. Can anyone come up with a possible solution? I read this to mean they want 2 valves, one 2" or smaller and the other sized to meet the remaining CV. Any suggestions are appreciated.

 

[ApC2Kp]

tact,
The use of a small bypass valve on large gate or globe valves serves two purposes. First, the small bypass valve helps equalize the downstream pressure across the valve to reduce handwheel effort for opening the large valve. (Not a problem for your LPS case). Second, the small bypass valve allows a slow heat up for the downstream piping. Most valve vendors are able to provide option for a small 3/4" or 1" bypass valve piped to taps on the larger body. After the large main valve has been opened, then the small bypass valve would be shutoff.
Old Crane valve book refers to it as "Built-Up Bypass". A size 2" bypass valve is provided for size 24" gate valve.