Rising-plug valves for contaminated media

Paul Boughton

Parker Instrumentation has developed a novel rising-plug style valve for process instrumentation applications.

The patented design provides users with a highly reliable valve for applications where contaminated media could otherwise lead to premature valve failure.

Called the HRPV series, the rising plug valve's 'straight-through' design supports higher flow rates than needle valves, thereby helping to avoid the build-up of deposits. It additionally allows cleaning to take place by rodding. These features make it suitable for applications involving heavily contaminated media, such as those frequently encountered in oil and gas processing facilities.

A major concern of users of this form of valve is its reliabilityand the high costs associated with in-service failures and down-time says Brian Rice, Parker Instrumentation's oil and gas applications engineer. Our design goals were to increase the typical cycle life and reliability that users can expect from a rising plug valvewhile also creating a cost-effective solution."

To meet this needParker developed a new seat design that reduces the size of the sealing regionallowing a high-integrity seal to be created with less force. This addresses a common failure mode associated with this kind of valveand development testing has demonstrated an extended cycle life compared with similar valves currently available.

The HRPV series valve features an eight-turn actuation cyclewith a rolled spindle thread and smaller sealing area - thereby lowering the torque required when controlling high-pressure fluid flows and providing a long life. Despite the valve's very high pressure capability - it is rated to 10000 psi (689 bar) - a typical actuation torque of just 25 pound-inches (2.82 Nm) is required.

The HRPV valve has a 1/4 inch (6.4mm) orifice with a Cv of 1.8but can be supplied with either 1/4 or 1/2 inch portswith a range of end connections including male and female NPTand twin-ferrule A-LOK compression tube fittings. The latter option is well suited to space- and weight-sensitive applications such as on offshore platformsand can reduce weight and space by around 30 per cent compared with standard threaded versions. Integral end connections also substantially reduce assembly time.

Two types of body are available: an inline two-port designand an inline design with a standard three-port gauge interface at one end. In its smallest 1/4 inch female NPT versionthe overall body length of the compact valve measures just 60.5 mm (2.38 inches).

As standardthe valve is provided with PEEK (polyetherketone) seatswhich allow the valve to operate up to 200 degrees Cand resists wear and damage from the kind of aggressive media encountered in oil and gas processing environments. Seats can be replaced 'in-situ'facilitating the low life-cycle cost goals of many modern process instrumentation designs.

Fabricated from 316 stainless steel as standardthe HRPV series valves can optionally be specified in a wide range of exotic alloys - including titaniumHastelloyalloy 625duplexInconel and Monel - which offer proven properties to combat the corrosive effects of fluids such as sea waterbleaching agentscarbon dioxide and hydrogen sulphide. Fluids like these pose considerable problems in the offshore and onshore petrochemical industriesin many chemical processesand in pulp and paper plants.

Further options include a choice of T-bar or hand-wheel handlesand an anti-tamper locking device to secure a valve's setting.

For more informationvisit www.parker.com/Instrumentation