Fully Welded Ball Valve
The NORTECH Fully Welded Ball Valve is a high-performance, heavy-duty pipeline valve engineered for critical oil and natural gas transmission and district-heating distribution networks. Unlike conventional bolted-body valves, the fully welded configuration uses a robust forged steel body joined by an automatic welding process, removing all bolted body joints and the associated risk of external fugitive emissions.
This compact, high-strength structure makes it the industry standard for long-distance trunklines, city gas networks and demanding underground buried applications. It is designed and manufactured to API 6D and ASME B16.34, with materials available to NACE MR0175 / ISO 15156 for sour service.
Fully Welded Forged Body — the automatic-welded forged steel construction eliminates bolted body joints, delivering zero external leakage and maintenance-free reliability for buried, high-pressure pipelines up to Class 1500.
The forged steel body is fully welded by an automatic process, eliminating every bolted body joint and the leakage path that comes with it. The result is high structural integrity at minimum weight, ideal for long-term, maintenance-free operation. Forging materials are ultrasonically examined to ASME non-destructive examination (NDE) requirements, and the butt-weld ends are dye-penetrant inspected, with RT inspection available on request.
Equipped with an extended stem and extended grease and vent lines, the valve can be buried deep underground while the actuator, sealant and maintenance ports remain easily accessible at ground level — the standard execution for cross-country and city-gas buried pipelines.
Compliant with API 6D, the spring-loaded seats seal independently upstream and downstream, allowing the body cavity to be safely vented and drained (double block and bleed). To suit different working conditions, the seat can be configured as DBB, DIB-1 or DIB-2.
A three-layer stem seal ensures reliable tightness and prevents leakage across a wide range of working conditions and pressures.
The stem is engineered to ASME B16.34 with a blow-out-proof design and an anti-static device that maintains a conductive path between ball, stem and body, ensuring maximum operational safety under high-pressure service up to Class 1500.
A corrosion allowance is built into the body wall thickness. The carbon-steel stem, trunnion, ball, seat and seat retainer ring are electroless-nickel plated to ASTM B733 and B656, and a wide range of corrosion-resistant materials is available. On request, materials can be supplied to NACE MR0175 / ISO 15156 or NACE MR0103, with strict quality control to meet sour (sulfide) service conditions.
For butt-weld-end valves, a transition pipe can be welded to the valve during manufacture. The transition pipe can be supplied by the user or by NORTECH on request — please indicate the transition pipe diameter and length A when ordering.
| Design & manufacture | API 6D |
| Body material | Forged carbon steel / stainless steel / alloy steel |
| Nominal diameter | 6″–40″ (DN150–DN1000) |
| End connection | BW / Flanged |
| Pressure rating | Class 150–1500 (PN16–PN320) |
| Operation | Lever / Gearbox / Electric / Pneumatic / Electro-hydraulic / Gas-over-oil actuator |
| Working temperature | -46°C to +200°C |
| 1 | Body |
| 2 | Anti-fire packing |
| 3 | Seat |
| 4 | Seat ring |
| 5 | O-ring |
| 6 | Spring |
| 7 | Bonnet |
| 8 | Sealant injection valve |
| 9 | Check valve |
| 10 | Ball |
| 11 | Thrust gasket |
| 12 | Sliding bearing |
| 13 | Pin |
| 14 | Bearing holder |
| 15 | Seal gland |
| 16 | Thrust bearing |
| 17 | Stem |
| 18 | Flat key |
| 19 | Thrust bearing |
| 20 | Anti-fire gasket |
| 21 | Connection plate |
| 22 | Socket head cap screw |
| 23 | Packing |
| 24 | Packing gland |
| 25 | Anti-static device |
| 26 | Air release valve |
| 27 | Drainage valve |
Long-distance, cross-country gas pipelines and trunklines requiring zero-leakage isolation.
Buried installations in municipal gas networks and metering stations.
Large-scale hot water and steam distribution loops for industrial and urban networks.
Heavy-duty applications demanding absolutely reliable shut-off without structural deflection.
