Double Block and Bleed Valves for the Oil Industry

International leaders in double block and bleed technology, Oliver Twinsafe, have seen significant growth in demand for their Cartridge Style Standard Length Double Block and Bleed Valve. This year sees the Cheshire based company celebrating its thirtieth anniversary, twenty five years of which have been dedicated to developing and improving double block and bleed systems.

Oliver Twinsafe CSL Cutaway

"As oil companies turn to new means of extraction such as Floating Production, Storage and Offloading vessels, our Cartridge Style Standard Length product is providing a popular solution for governing flow in installations where space is at a premium," said Deputy Chairman of Oliver Twinsafe, Mark Oliver.

"This is technology that we developed partly in response to the Cullen report over two decades ago but we are still meeting oil companies in emerging markets who haven't encountered this kind of system before."

The patented valve incorporates two ball valves and a bleed valve into one compact cartridge type unit valve thereby replacing traditional techniques employed by pipeline engineers to generate a double block and bleed configuration in a pipeline, consequently saving space and costly installation and testing charges.

"The major benefit of our Cartridge Style Standard Length Double Block and Bleed Valve is that the valve has the same face-to-face dimension as a single block ball valve, as specified in API 6D and ANSI B16.10," said Mr Oliver. "This means the valve can easily be installed into an existing pipeline without the need for any pipeline re-working."

The single unit Double Block and Bleed design also has operational advantages. There are significantly fewer potential leak paths within the double block and bleed section of the pipeline and, because the valves are full bore with an uninterrupted flow orifice, they display a negligible pressure drop across the unit. The pipelines where these valves are installed can also be pigged without any problems.

"Significantly, because all the valve components are housed in a single unit, the space required for the installation is dramatically reduced thus freeing up room for other pieces of essential equipment," said Mr Oliver.

The Oliver Twinsafe Cartridge Style Standard Length (CSL) Double Block and Bleed Valve offers further advantages over the traditional hook up.

"Due to the volume of the cavity between the two balls being so small, the operator is afforded the opportunity to evacuate this space efficiently thereby quickly establishing a safe working environment," said Craig Furnival, Engineering Director.

"Subsequently, the volume of the process media removed from this cavity is much smaller which means less waste, less cost, easier disposal and reduced handling."

There are two types of seats offered, soft seats and metal-to-metal seats for abrasive service. The insert material used for the soft seats varies from PTFE to Peek, the standard material being Devlon. Each of the soft seat materials available offers a 100% tight shut off without the need for any kind of sealant. The metal-to-metal seats are coated with Caboflam H654, a tungsten carbide based coating. A chrome carbide coating is also available. These seats offer a superior seal to that required by API 6D.

As with all Oliver Twinsafe valves, the Cartridge Style Standard Length Double Block and Bleed Valve has been approved by the Lloyd's Register Quality Assurance.

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