RE: Dumb Question about Gate Valves [bcc][faked-from][bayes]

From: <Bruce>
Date: Fri Jan 30 2004 - 09:37:00 EST

Steve:

Might I suggest that the precise valve isn't so important? I propose this because, 1) the plant has run for some time without it, but there is some optimization gained with using it; and 2) the valve, if it was installed and run for years in a partially opened manner, it probably changed over time anyway (erosion, etc.).

Replace the bypass including a gate valve, and install a flanged spoolpiece in which to include (or just allow for) an orifice.

If there is a concern about finding just the right size orifice, use a slide-gate weir in the place of the orifice plate and try a variety of settings on the gate 'til you find the "sweet spot", and design a few orifices with flow characteristics based on the what you found from testing with the slide-gate (all but one as spares) to more permanently install in the bypass.

                ... Bruce D. Bullough ...
                Sebesta Blomberg & Associates
                2381 Rosegate
                Roseville, MN  55113    USA
                651-634-7344 direct
                651-634-7400 FAX
                www.sebesta.com

-----Original Message-----
From: Steve McKenzie [mailto:mechproj@xtra.co.nz] Sent: Friday, January 30, 2004 5:12 AM
To: PipingDesign@yahoogroups.com
Subject: [PipingDesign] Dumb Question about Gate Valves [bcc][faked-from][bayes]

Gents
On a process plant I am looking at, they used to have a 16" gate valve fitted to a bypass valve which normally ran at about 4 turns open according to old logsheets.
The bypass line was deemed unnecessary and it and the valve were pulled out and dumped. Thats all I know about the valve. I reckon the line needs to be reinstated (to improve plant performance), but possibly smaller if I could find out what percentage open the valve was. This is easy to do if I knew how many turns open to closed the original valve required. A similar 12" valve (no name) is fitted elsewhere on the plant and is 12 turns open to closed - two start thread. My guess is that the 16" valve would therefore be somewhere between 12 and 16 turns O to C.
Just wondered if there is a standard or something covering this.

Cheers

Steve

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Your use of Yahoo! Groups is subject to:   http://docs.yahoo.com/info/terms/ Received on Fri Jan 30 09:37:00 2004