Through Conduit Gate Valve

TCGV is short for Through Conduit Gate Valve,it is a type of gate valve designed with a slab or expanding gate that, when opened, creates a full-bore (straight-through) flow path. This minimizes pressure drop and prevents turbulence.

The Through Conduit Gate Valve is a full-bore, piggable isolation valve designed for high-pressure pipelines. It complies with API 6D / API 6A standards, features tight shutoff, low pressure drop, and DBB capability, and is widely used in oil, gas, and petrochemical pipelines. Regular lubrication, seal checks, and proper handling ensure long service life.

1.Structure of Through Conduit Gate Valve

Body: Usually cast or forged steel, designed for high pressure and temperature.
Gate (Slab or Expanding type): A flat plate that moves up/down across the flow path.
Seat Rings: Metal-to-metal or soft seal; spring-loaded or floating design for tight shutoff.
Stem: Connects gate to actuator or handwheel (rising or non-rising).
Bonnet: Pressure-sealed or bolted, allows access for maintenance.
Seals: Elastomers, PTFE, or graphite for stem packing and seat sealing.
Full-bore Through Conduit: When open, bore diameter = pipe diameter → allows pig passage.

2.Standards of Through Conduit Gate Valve

Common design, testing, and manufacturing standards include:
API 6D – Pipeline valves
API 6A – Wellhead and Christmas tree valves (for upstream service)
ASME B16.34 – Valve pressure-temperature ratings
ISO 14313 – Pipeline transportation systems, pipeline valves
NACE MR0175 / ISO 15156 – For sour service material selection

3.Features of Through Conduit Gate Valve

Full-bore opening (no flow restriction, piggable).
Low pressure drop across the valve.
Tight sealing (metal-to-metal or soft seats).
Double Block and Bleed (DBB) capability in many designs.
Fire-safe and anti-blowout stem designs (per API 6FA, ISO 10497).
Bi-directional sealing in most designs.
Available with manual, gear, hydraulic, pneumatic, or electric actuators.

4.Applications of Through Conduit Gate Valve

Crude oil and natural gas transmission pipelines.
Petrochemical plants.
Storage and distribution terminals.
Offshore and onshore pipeline isolation.
Pipeline pigging operations.
High-pressure, large-diameter pipeline service.

5.Operation of Through Conduit Gate Valve

Manual – Operated via a handwheel and gear mechanism.
Actuated – Electric, pneumatic, or hydraulic actuators for remote or automated control.
Opening – The gate retracts into the bonnet cavity, giving full-bore unobstructed flow.
Closing – The gate lowers and presses against seat rings for tight shutoff.

6.Maintenance Manual (General Guidelines)of Through Conduit Gate Valve

Routine Maintenance
Inspect stem packing for leakage → adjust or replace as needed.
Grease stem and seats (if grease fittings provided).
Check actuator/gearbox function and lubrication.
Verify valve operation (full open/close cycle).
Seat & Seal Maintenance
Seats may be renewable (field replaceable).
For leakage, inject sealant (emergency seat sealant system, if equipped).
Major Overhaul
Isolate valve and depressurize pipeline before disassembly.
Remove bonnet and inspect gate, seats, stem, and body cavity.
Clean and replace worn/damaged parts.
Reassemble with proper torque on bonnet bolts and re-pressurize slowly.
Storage & Handling
Store valve in dry, covered area with end caps.
Keep stem in half-open position to avoid seal deformation.
Apply rust preventive oil if stored long-term.