Application:  Trim Modification for Reactor Water Clean-Up (RWCU) Flow Control Valve

Project Description:  Trim Upgrade of Original Hammel Dahl 4″ 600# Globe Control Valve

Valve Description:  4″ 600# Globe Control Valve with Piston Actuator

Typical Valve Assembly Drawings:  V500L-5, V500L-6

Typical Valve Tag Numbers:  G31-F033, G31-1239, G33-F033

Typical Valve Model Number:  V500NFC92ZZZ9

Typical Actuator Model Number:  A32AJD6FBZ

Drawing of Typical RWCU Valve Trim Modification Kit:  HP1201622

Objectives of Retrofit

  • Address damage to plug and cage due to stroking of valve under high DP flow conditions
  • Maintain original flow characteristics and operational parameters original design
  • Improve internal shutoff capability of valve
  • Reduce susceptibility of valve to seat damage as a result of high DP flow conditions
  • Re-use of existing actuator without any adjustments to established set-up parameters

Features and Benefits of Retrofit Package

  • Replacement of original O-ring Plug Seal with custom-engineered spring-energized UHMWPE Plug Seal
    • Offers improved sealing capability
    • More resistant to damage under high flow conditions
    • Material provides excellent radiation resistance
  • Re-design of Plug profile to incorporate relief area(s) in outer diameter of Plug
    • Creates better pressure balance under dynamic fluid conditions
    • Reduces side-loading on Plug during stroke
    • Reduces frictional drag
    • Reduces risk of galling of Plug and Cage interacting surfaces during stroke
  • Use of case-hardened (i.e. Nitrided) 410 Martensitic Stainless Steel for materials of Plug, Cage, and Seat
    • Increases galling resistance of mated sliding surfaces of Plug and Cage
    • Reduces risk of localized damage to seating surfaces from steam cutting, etc.

Frequently Asked Questions

What is the WTM RWCU Valve Trim Modification?

The WTM RWCU trim modification is an engineered upgrade for certain original Hammel Dahl Reactor Water Cleanup flow-control valves. The published application involves a 4-inch, 600-pound-class globe control valve with a piston actuator.

Why was the RWCU valve trim retrofit developed?

The retrofit was designed to address plug and cage damage associated with valve stroking under high differential-pressure flow conditions while maintaining the intended flow characteristics and operating parameters.

What does the RWCU trim modification do to improve valve shutoff?

The retrofit incorporates an engineered plug-seal design and other trim changes intended to improve sealing capability and internal shutoff performance.

How does the redesigned plug help under high differential-pressure conditions?

The redesigned plug incorporates relief areas intended to improve pressure balance, reduce side loading and frictional drag during travel, and reduce the potential for galling between interacting plug and cage surfaces.

What materials are used in the upgraded RWCU valve trim?

The published retrofit uses case-hardened, or nitrided, 410 martensitic stainless steel for the plug, cage, and seat to improve resistance to galling and localized seating-surface damage.

Can the existing actuator be reused with the RWCU trim modification?

One objective of the published retrofit design is to reuse the existing actuator without requiring changes to established actuator setup parameters, subject to verification for the specific valve and application.

Which original Hammel Dahl valves may be associated with this RWCU modification?

The example published by WTM identifies typical V500L-5 and V500L-6 valve assembly drawings, model V500NFC92ZZZ9, and A32AJD6FBZ piston actuation. Actual applicability should be confirmed by WTM for each installed valve.