API 6D defines a double-block-and-bleed valve (DBB) as a “single valve with two seating All DBB valves are manufactured to EEMUA latest revision. I have question: when is the double block and bleed valve is must or required, what is the reference API, echecs16.info? I know that for more than. Hi, In our gas processing plant and for many DP cell flow instrument, we frequently experience clogging of instrument DBB valves (double and.
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This post describes the attributes of a double block and bleed valve, its function, and eBooks, Calculators, and More in our Resource Library. PRODUCT OVERVIEW. BFE manufactures the most complete line of quality Double Block & Bleed valves, and can provide the exact Double Block & Bleed. Oliver Valves in the early 80's pioneered the Double Block and Bleed (DBB) concept, which has very much now become a standard world wide. Each Double .
LittleInch Petroleum 13 Nov 13 Please don't double post. You've been on this forum enough times to know it's not allowed. Choose which forum you want then red flag the other post before someone else does I have to ask, "Why are you double block and bleeding an instrument line"? If there is some reason that you need positive energy isolation for an instrument line I can't imagine one, but maybe one exists , it is trivial to shut a valve and remove a piece of tubing you can even cap the process end if you are that nervous about it. You have a line that is a dead leg all year except twice when you calibrate. It is going to collect debris if there is any to collect.
RE: Double block and bleed valve 6 Sep 12 atayto I think you should read Davids posts and dont make very general statements in this subject. Aside form this Hamood should also notice that practise varies and some companies have very stringent policies and other will rely more on engieering.
Both has its more or less obvious disadvantages. Ihave developed a policy myself - but its a part of a total design phlosophy and consideres a number of other practises to be followed as well and may therefore not be right for everybody else.
I will give it anyway Its a little difficult to get the formatting right though: Any process design shall determine whether process isolation is appropriate.
For other systems, positive isolation shall only be applied if the time to establish the positive isolation does not exceed the time required for the actual work to be performed. This process isolation shall be based on the Medium Ranking System, in which the requirement for system isolation is established from an individual risk assessment. The risk score shall be determined from a tab1e based on the media type and system pressure and temperature. The isolation requirements are then determined from another table based on the risk score and activity.
These tables are however impossible to reproduce here. If we need to work on the valve we close the upstream block valve and drain the line. Reduced vibrational stresses. Cost savings with exotic material designs are huge. Oliver Valves in the early 80's pioneered the Double Block and Bleed concept, which has very much now become a standard world wide.
Each Double Block and Bleed has a unique number recording its factory history and we are now way above , of these units in installation worldwide. Our DBB Valves are a smaller unit vs the traditional hook-up, bringing both piping and instrumentation isolation into one unit. To the end user you , you get the advantage of having less weight, which is significant on the top side of a platform when you combine all the pressure instrument take-offs.
Cost saving on site - Our end-users only have to worry about the cost of one factory tested component, as opposed to different piping valves, instrument valves, flanges, connections and flanged seal rings and then the cost to raise purchase orders. On top of that, departments are expected to chase the parts in goods receivable, etc.
Coded welders could be required as well. A lot of this process is completely erased when choosing Oliver's DBB valves.
Safety - including spool pieces the type of valve, i. The cost of which can be excessive.
These documents state that a double block and bleed valve must be used. All these documents stem from the Piper Alpha disaster over 20 years ago and the P36 disaster in Brazil, both of which indicated double block and bleed as a marked improvement for safety.
Block and Bleed A block and bleed manifold with one block valve and one bleed valve is also known as an isolation valve or block and bleed valve; a block and bleed manifold with multiple valves is also known as an isolation manifold. This valve is used in combustionable combustible gas trains in many industrial applications. Block and bleed needle valves are used in hydraulic and pneumatic systems because the needle valve allows for precise flow regulation when there is low flow in a non-hazardous environment.
Double Block and Bleed DBB Valves These valves replace existing traditional techniques employed by pipeline engineers to generate a double block and bleed configuration in the pipeline.
Two block valves and a bleed valve are as a unit, or manifold, to be installed for positive isolation. Applications that use DBB valves include instrument drain, chemical injection connection, chemical seal isolation, and gauge isolation. DBB valves do the work of three separate valves 2 isolations and 1 drain and require less space and have less weight.
It features all the benefits of the single unit DBB valve, with the added benefit of a bespoke face-to-face dimension if required. Single Unit DBB This design also has operational advantages, there are significantly fewer potential leak paths within the double block and bleed section of the pipeline. Because the valves are full bore with an uninterrupted flow orifice they have got a negligible pressure drop across the unit.