Integrated API-rated valves deliver system-level gains for wellhead OEMs

18 June 2013

A new range of API-rated integrated valve assemblies from the Instrumentation Products Division of Parker Hannifin are said to offer wellhead equipment suppliers and operators the ability to make major enhancements to their 'Christmas tree' and related equipment designs.

The integration offered by the new valve assemblies reduces weight by up to 40% compared with double-block-and-bleed configurations using discrete valves, and can reduce space envelopes even further - by as much as 75%. Users can choose from a range of connection styles including flanged, welded, Grayloc hubs and Autoclave cone-and-thread connectors -– to suit the particular installation.

The new range offers integrated process-to-instrument interfacing solutions that reduce weight and size, and is said to eliminate many potential leak paths and risk, when compared with configurations based on discrete valves and connectors.

Parker's Pro-Bloc range of integrated manifolds for interfacing instrumentation to process piping, the Pro-Bloc API range integrates a complete double-block-and-bleed assembly of fire safe isolation and venting valves that is suitable for interfacing process pressure and temperature instruments. The assembly is available in three main forms – with ball valves, needle valves, or high-performance needle valves that can also meet the Class A or Class B ultra-low-emissions levels of the ISO 15848 standard. The new valve assemblies are initially available in three choices of pressure ratings: 5K, 10K and 15K PSI, and have been independently tested for conformance with the API 6A specification for wellhead and Christmas tree equipment.

Traditionally, OEMs and operators producing Christmas tree configurations and wellhead control systems have typically constructed any instrumentation interfacing subsystems required using larger process-sized valves that are rated to the API specifications preferred in this application sector. These systems have not benefited from the substantial size and weight savings – and designed-for-purpose flow paths –typical of the double-block-and-bleed manifolds that are readily available for instrument interfacing in other parts of the process world.

The integrated design also eliminates numerous interconnection joints, each of which is a potential leak path and source of unreliability, and system building cost; this can amount to a reduction of as many as four potential leak points compared to a system built from discrete valves.

The close-coupled flow paths inside Parker's Pro-Bloc API process-to-instrument valve assemblies are ‘purpose-designed’ to support accuracy of measurement. In the case of the ball valve variant of the design, the flow path is completely straight, with a uniform bore. It is not possible to create such a short flow path with a system based on discrete valves, and it can also be very difficult to avoid bends – and sometimes changes of bore sizes – that impact measurement accuracy by generating turbulence.

Parker developed these new integrated process-to-instrument interfacing solutions rated to API 6A after application-specific project experience on wellhead applications, and is now making the technology available to the wider market.

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