{"id":1508,"date":"2022-06-22T02:31:00","date_gmt":"2022-06-22T00:31:00","guid":{"rendered":"https:\/\/as-schneider.blog\/?p=1508"},"modified":"2022-03-18T15:19:28","modified_gmt":"2022-03-18T14:19:28","slug":"how-to-isolate-process-line-from-process-instrument-with-dbb-valve","status":"publish","type":"post","link":"https:\/\/as-schneider.blog\/2022\/06\/22\/how-to-isolate-process-line-from-process-instrument-with-dbb-valve\/","title":{"rendered":"How to isolate a process line from process instrument with a DBB valve"},"content":{"rendered":"\t\t
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How to isolate a process line from process instrument with a DBB valve<\/h1>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Block and Bleed and Double Block & Bleed isolation systems are used in process instrumentation to isolate your instrument from the main process line.<\/p>

The isolation valve(s) stop the flow from the upstream, while the bleed valve removes any pressure or residual product that remains in the downstream section or in the section between the two valves.<\/p>

Use of block and bleed valves is mandatory in many industrial processes for isolating the measuring instrument from the process line. This allows maintenance work to be performed on the instrumentation without the need to shut down the entire operation.<\/p>

There are two approaches to the installation of a block and bleed or a double block and bleed setup. I explain both in more detail in this article.\u00a0<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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Conventional system<\/h2>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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The conventional system connects multiple valves and fittings together to create the block and bleed setup. The figure below shows a conventional, flanged, double block and bleed isolation setup that connects a process line to a pressure transmitter\/gauge.<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

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Such installations are common in many industries including oil refineries.<\/p>

The double block and bleed isolation, for the pressure transmitter\/gauge, is achieved by using three separate valves between the transmitter and the process line.<\/p>

The pressure transmitter is connected to an instrument manifold which is connected to an isolation valve followed in series by another isolation valve to provide Block X Block operation.<\/p>

A third valve, between the two block valves, provides the bleed functionality.<\/p>

As the image above shows, a conventional system produces a very large and bulky setup which takes a lot of time to install, has a large number of potential leak points, and is relatively expensive to install and maintain.<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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Close-coupled installation<\/h2>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Close-coupled installation brings the instrument (transmitter\/gauge) closer to the process by replacing multiple valves and fittings with an integrated instrument mounting product. It creates a direct, minimal link between the process and instrument which helps save installation time and cost in addition to reducing the number of potential leak paths.<\/p>

Choosing a suitable close-coupled installation requires consideration of the application and the process conditions.<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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Process-to-instrument system<\/h3>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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An important part of the close-coupled installation is the process-to-instrument system. It has been designed to replace bulky, multi-component conventional setups, widely used for connecting instruments to process lines.<\/p>

There are two industry standards for an integrated process to instrument product that integrate block, double block, or double block and bleed valve functionality in a monoblock design:<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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Monoflanges <\/h4>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Monoflanges use ball valves on the isolation valve(s) and can either use a ball valve or a needle valve for the vent valve. At AS-Schneider this design is called VariAS-Block while the industry also often names it “DBB Ball Valve”.<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t

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Slimline Monoflanges <\/h4>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Slimline Monoflanges use needle valves on the isolation valve(s) and the vent valve. At AS-Schneider we just use the expression Monoflange.<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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Benefits of using a process-to-instrument system<\/h4>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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General benefits of using a process-to-instrument system in place of a conventional installation include:<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

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