Posted by Tarzan on June 20, 2001 at 07:00:18:
In Reply to: standard or recommended practice for piping/valve installation on steam distribution from boiler vessel posted by Wilfred Alexander on June 20, 2001 at 02:01:06:
: my company has installed a 300Hp boiler that delivers steam to a unit 20 metres away. The boiler has been piped from its gate valve which sits on top the boiler to a manifold (in the boileroom )and from the manifold to the process unit 20 metres away with no additional valve. The process unit does have its own steam shutoff valve and other pressure reducing and control items. Is this system okay. Should there be a shutoff valve on the manifold for distribution to the process unit.
The stop valve that sits atop the boiler can be a gate or globe valve. If you have additional boilers installed that supply the same header, you need a 'stop-check' type valve atop each boiler and preferably an additional header isolation valve with a drain valve in between the two... ...any additional valves downstream of that are optional and dictated by plant configuration and local codes....having individual valves located at the manifold make repairs to downstream equipment easier and safer, but also add to your maintenance load...unnecessary stop valves that never get cycled won't work when you need them to anyway....
At any rate just make sure the valve atop the boiler is the correct type and rated for steam service and pressure at of above the MAWP stamped on the boiler, not the pressure you tend to operate at. That valve is considered part of the 'boiler proper' and must meet the requirements of the applicable section of the ASME code associated with your boiler...if your boiler is a steam boiler stamped for pressure over 15 psi, it's gotta meet sect IV of the code...anything downstream of that is subject to section 31.1
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