Double Block and Bleed Valves thread408-48267
Double Block and Bleed Valves thread408-48267
(OP)
In thread408-48267: Double-Block Valves and Double Block and Bleed Valve on 10Mar03, davefitz (Mechanical) posted a comment stating,"double block and bleed is required by code in section I (boiler) service if there are 2 or more boilers interconnected on a common steam line and the boilers have a manway in the steam drum. This is to avoid cooking the maintenance person that enters the steam drum on the idle boiler. A similar philosphy would be prudent for any pressure vessel that a person can enter , if the vessel is interconnected to another active system which has dangerous fluids."
What code is davefitz refering to? I ask this because at our facility we are currently installing a second boiler that will be connected to our existing boiler. I'm not the engineer over this project, but I would like to ensure that no one could potentially be hurt.
What code is davefitz refering to? I ask this because at our facility we are currently installing a second boiler that will be connected to our existing boiler. I'm not the engineer over this project, but I would like to ensure that no one could potentially be hurt.





RE: Double Block and Bleed Valves thread408-48267
See also thread408-94849: Double Block Bleed Valve. If you are in the USA, Federal OSHA probably applies and its in their regulations that you'll find the energy isolation and entry requirements. Individual states and local jurisdictions may impose tighter restrictions. My state generally follows OSHA but is a bit tighter on some particular issues.
jt
RE: Double Block and Bleed Valves thread408-48267
Thanks for your response. I am in the USA, North Carolina, and i'm familiar with OSHA and it's energy isolation requirements.
What I was trying to ask, is there a specific code, standard, or regulation that requires double block and bleed valves when there are 2 or more boilers interconnected on a common steam line or injector system? If so, can you let me know what that code is?
I'm definitely going to encourage the engineer in charge of this project to put double block and bleed valves on the interconnected boilers. Employee don't enter the steam lines because they are only 6" lines. But maintenance employees routinely enter the butterfly valves which is connected to the injector system used to vacuum seal the Vacuum Induction Melt tanks.
Thanks,
KD
RE: Double Block and Bleed Valves thread408-48267
RE: Double Block and Bleed Valves thread408-48267
Rant over.
Mark Hutton
RE: Double Block and Bleed Valves thread408-48267
A double bloc and bleed valve as security to enter would not be acceptable.
Complete isolation, of the concerning recipient, with blinds is the only secure and foolproof working practise.
this is a safety standard and should be implemented in your procedures.
cheers
RE: Double Block and Bleed Valves thread408-48267
I’m looking to find a DDB valve with the following specifications:
-1.00” NPT Inlet and Outlet.
-Rated for 3000 psi / 204 Barg
-¼” Vent
-316SS
I can't find any US manufacturers that make these. Any help inding one?
Thank you,
Justin W. Tweed
RE: Double Block and Bleed Valves thread408-48267
RE: Double Block and Bleed Valves thread408-48267
RE: Double Block and Bleed Valves thread408-48267
RE: Double Block and Bleed Valves thread408-48267
I did find one source for the DB&B valve unfortunately its made over seas and the shipping alone is $500. (Ouch!) I;m trying to find a US manufacturer, however that's not going very well. :(
RE: Double Block and Bleed Valves thread408-48267
RE: Double Block and Bleed Valves thread408-48267
Gotcha. I'll check with the customer if this acceptable.
Thank you.
RE: Double Block and Bleed Valves thread408-48267
If it was me, I would prefer two valves and a bleed, and then a blind flanged before I stick my "behind" on the line, if you get my drift.
"Do not worry about your problems with mathematics, I assure you mine are far greater."
Albert Einstein
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RE: Double Block and Bleed Valves thread408-48267
JWTweed,
I believe you are intend to install the valve you are after upstream of an instrument devise; e.g PT,PIT! Is this right? If so, have you tried Swagelok?
Rgds,
Marcell
RE: Double Block and Bleed Valves thread408-48267
Refered to the above thread, the gentleman has mentioned using gate valves as isolation valves in DB&B configuration; however I do not agree with him entirely on that. I prefer using Ball Valves. What do you think? Your feedbacks are welcome!
Rgds Marcell
RE: Double Block and Bleed Valves thread408-48267
Did you ever find your 1" dbb valve? There are several manufacturers that make this valve for the instrumentation industry. I agree most of these are manufactured overseas, but are represented in the US. You might try going to www.dbb-valves.com and check on Alco Hi-Tek, or to www.valves.co.uk for the Oliver product line.
RE: Double Block and Bleed Valves thread408-48267
There are a few manufacturers out there who make DBB valves. The best know is probab ly Cooper Cameron's General twinseal valve. www.sa
You could also contact Gosco valves. www.goscovalves.com
RE: Double Block and Bleed Valves thread408-48267
My application is two globe valves in series with a short section of pipe off of which a vent valve is taken.
Thanks
Dave
RE: Double Block and Bleed Valves thread408-48267
You should start a new thread.
"Do not worry about your problems with mathematics, I assure you mine are far greater."
Albert Einstein
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