Double Block and Bleed
Double Block and Bleed
(OP)
Hi Everyone,
Question for you. What's more cost effective for a double block and bleed arrangement. Purchasing and installing a dedicated double block and bleed valve, or purchasing the separate components (two block valves and a drain valve) and fabricating the arrangement as part of your piping fabrication.
Any thoughts?
Thanks, Boomer.
Question for you. What's more cost effective for a double block and bleed arrangement. Purchasing and installing a dedicated double block and bleed valve, or purchasing the separate components (two block valves and a drain valve) and fabricating the arrangement as part of your piping fabrication.
Any thoughts?
Thanks, Boomer.





RE: Double Block and Bleed
Composite single body DBB valves are limited in size, but can be quite effective (two ball valves and a bleed valve in one body).
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Double Block and Bleed
I think installation of dedicated DBB valve is not based on cost effectiveness, but rather requirement of project specs.
What do I mean?
Even if you install single body DBB valve very often you will have another isolation valve before it. I worked in projects where specs split "piping" scope from "instrumentation" scope. When, for instance, you have pressure gauge installed in a line, piping spec requires 1/2" Nom x Sch 80 pipe with gate valve installed at the point. In some cases spec may allow using one end socket weld and the other end threaded gate valve.
After gate valve instrumentation scope starts and they can install DBB with 1/2" male NPT and 1/4" male NPT where pressure gauge is installed.
Regards,
Curtis
RE: Double Block and Bleed
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Double Block and Bleed
In Both Cases, the cost would be the same probably. But, As said by Littleinch,
the selection of DBB is purely depend upon the space provision and piping spec.
In other view, if we put DBB Twin type, how it will be done when it come for
Maintenance or Shut down. You have to replace with Pipe Spool or isolating the
first isolation valve in the same line.
The purpose of DBB is for Double Positive Isolation. It will be good providing
2 Ball Valves & 1 Drain Connection if there is no space constraint.
Regards
Pipingeng1