Non-Lubricated Plug Valve (NLPV) is a type of quarter-turn valve that uses a plug with a through passage to control flow. Unlike lubricated plug valves, which require sealing grease, non-lubricated designs rely on a sleeve, lining, or elastomeric material around the plug to provide a tight seal and reduce friction.

Description

Construction of Non-Lubricated Plug Valve

Body: Cast or forged steel, stainless steel, bronze, or alloy.
Plug: Tapered or cylindrical, often PTFE-coated or lined with fluoropolymers.
Sleeve / Liner: Made of elastomer, PTFE, or other low-friction polymer, installed inside the body.
Stem: Connected to the plug, providing quarter-turn operation.
Gland & Packing: Provide stem sealing.
End Connections: Flanged (RF/RTJ), butt-welded, socket-welded, or threaded.
Typical design types:
Sleeved Plug Valve (PTFE or composite sleeve)
Lined Plug Valve (PFA, PTFE, or rubber lining for corrosive media)

Applicable Standards of Non-Lubricated Plug Valve

API 599 – Metal Plug Valves
API 6D / ISO 14313 – Pipeline Valves
ASME B16.34 – Valve design and pressure-temperature ratings
ASME B16.5 / B16.25 / B16.10 – Flange dimensions, butt-weld ends, and face-to-face
MSS-SP-78 / MSS-SP-115 – Steel & PTFE-lined plug valves
Fire-safe testing: API 607 / ISO 10497 (if required)

Features of Non Lubricated Plug Valves

Quarter-turn operation (fast shut-off)
Bubble-tight sealing (with PTFE/rubber sleeve)
No lubrication needed → low maintenance
Suitable for corrosive, toxic, or abrasive fluids
Compact and simple design
Reduced operating torque compared to lubricated plug valve
Available in fire-safe and anti-static designs

Applications of Non-Lubricated Plug Valve

Chemical & Petrochemical Plants – acid, alkali, corrosive fluids
Oil & Gas Pipelines – on-off and diversion services
Water & Wastewater Treatment – sludge, slurry, dirty water
Pharmaceutical & Food Industry – hygienic and non-contaminating
Power Plants – steam, condensate, cooling systems

Operation of Non Lubricated Plug Valve

Manual: Operated by hand lever, gear, or wrench (90° rotation).
Automated: Pneumatic, electric, or hydraulic actuator.
Flow is controlled by rotating the plug passage parallel (open) or perpendicular (closed) to the pipeline.

Maintenance Manualof Non-Lubricated Plug Valve

Inspection & Preventive Maintenance

Check stem packing regularly for leakage.
Inspect sleeve/liner condition during shutdown.
Verify smooth operation of plug (no excessive torque).
Ensure body bolts and gland bolts are tight to spec.

Operation Care

Do not force the handle if stuck (indicates sleeve wear or debris).
Use actuator torque settings per manufacturer recommendation.
Avoid rapid operation under high pressure (to reduce shock).

Repair & Replacement

If sleeve or liner is damaged → replace per OEM instructions.
If leakage persists → inspect plug and sleeve alignment.
Lubrication is NOT needed (except stem packing in some cases).

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