Parker helps offshore industry meet pressure demands

Parker Autoclave Engineers’ subsea ball valves facilitate hydraulic control at water depths down to 3,800 metres

As offshore oil production platforms move into deeper waters in their quest for new reserves, the ball valves, tubes and fittings used for subsea hydraulic control systems are coming under increasing pressures – both internally and externally. Manufacturers of equipment intended for subsea use, such as hydraulic manifolds, control panels and ‘Christmas trees’, need to be confident that the performance and integrity of valves and interconnecting pipe work will not be compromised in such an environment, where working (internal) pressures may be as high as 20,000 PSI.

Following its recent acquisition of Autoclave Engineers – a US-based leader in high pressure technology – Parker has extended its portfolio of instrumentation valves and fittings significantly and now offers components capable of handling ultra high working pressures up to 150,000 PSI. Now called Parker Autoclave Engineers, the company also produces a series of 2-way and 3-way ball valves designed specifically for subsea applications. Typically used for isolating or switching the flow of hydraulic control fluid during in situ testing or reconfiguring of subsea Christmas trees, the valves incorporate a number of innovative features for deepwater applications and have undergone extensive performance verification, including third-party validation.

As standard, Parker Autoclave Engineers’ subsea ball valves are manufactured from cold worked 316 stainless steel. They are also available in a wide variety of other materials such as 6Mo, Super Duplex and Inconel 625 – the latter being especially suitable for equipment located at great depths or in areas of very high salinity. Parker’s extensive design and production experience of these types of anti-corrosion materials, backed by secure and fully traceable sourcing arrangements with highly reputable mills in Europe and North America, helps accelerate delivery of standard and custom-engineered products.

The 2-way valves are available with ball orifice sizes up to 1 inch, while the 3-way valves offer a choice up to ½ inch, with all models featuring full port flow paths to minimise pressure drop. Depending on the type and size of tube fittings specified by the user, the valves can accommodate a maximum allowable working pressure (MAWP) as high as 20,000 PSI (1,379 bar).

Nowadays, virtually all subsea instrumentation ball valve connections in deepwater applications are made using coned and threaded fittings. Originally developed by Autoclave Engineers specifically for high pressure applications, these types of fittings employ a metal-to-metal seal to ensure a very high integrity, maintenance-free connection, and are used by the majority of subsea Christmas tree manufacturers for interconnecting small bore tubes and valves. As a result of this heritage, Parker has over 50% share of this specialist fittings market.

Parker Autoclave Engineers’ subsea ball valves are designed to meet or exceed the rigorous qualification test requirements of API 6A-PR2, and their structural integrity and seal capabilities have been confirmed by customer-commissioned independent third-party tests. The valves are equipped with PEEK valve seats in metal retainers, providing excellent resistance to chemicals, heat and abrasion, and with Buna-N O-rings rated at 121˚C (250˚F) maximum. Special materials are optionally available to suit specific process fluids or operating temperatures. The valve’s low friction spring energized PTFE stem seal is graphite filled to maximize cycle life and incorporates double O-rings to prevent seawater ingress. The ball and stem is an innovative one-piece, trunnion-mounted design which eliminates shear failure (a common problem with two-piece designs), extends seat life and allows for excellent bi-directional flow service. The stem is supported by a thrust washer that prevents external pressure from affecting the ball and seat alignment.

All Parker Autoclave Engineers’ subsea ball valves are available in versions designed for control by remote operated vehicles (ROVs). Each valve can be supplied with an optional ‘subsea bucket’, which provides positive stops that limit actuator movement to prevent any overtorque being applied to the valve stem by an ROV in the event of it losing grip of the equipment frame.

First launched in 1998, the valves have proved to be extremely reliable. In 2000, for example, Autoclave Engineers supplied 3/8 inch 2-way ball valves for a deepwater oil exploration project off the coast of Nigeria, where they are used at depths of more than 1,000 metres; there have been no reported problems during their 12-year service history. One particularly rigorous application – where again, the valves have been in use for about 12 years, but at even greater depths – involves emergency ballast systems on ROVs. Here, the valves control the flow of air into and out of accumulators, used for filling ballast bags to recover items from depths in excess of 3,000 metres. Aside from the valves’ ability to operate at these depths, their low torque requirements mean that the ROV manufacturer is able to use very small hydraulic actuators, helping to conserve valuable space. Nowadays, Parker Autoclave Engineers’ subsea ball valves are used by most of the world’s leading oil companies and independent operators for deepwater production projects, including a large number in the Gulf of Mexico, where recoverable reserves are being found at increasing depths.

Steve Hanson of Parker Autoclave Engineers points out that the market for subsea ball valves is substantial, “Worldwide, up to 800 subsea oil distribution structures such as Christmas trees are brought into operation every year. Most of these structures typically require at least 7 ball valves, so the potential market is easily in excess of 5,000 units per annum. However, as production moves into deeper waters, engineers are beginning to demand pressure components that offer a choice of fabrication materials to meet specific operational needs, and are proven to provide reliable, long-term service. Parker Autoclave Engineers’ subsea ball valves meet all these requirements, and are set to gain significant market share.”

Parker Hannifin
Tel: +44 (0) 1271 313131
www.phstock.com

Published: 28th June 2013