A long weld neck flange (LWN) does the job of a flange and a nozzle in one piece — the extended neck welds straight into the vessel shell or drum, which is why it is the standard choice for pressure vessel nozzles in oil and gas, refining and boiler work. As a long weld neck flange supplier based in Cangzhou, China, we produce LWN flanges in carbon steel ASTM A105 to ASME B16.5, with neck lengths to standard or to your drawing, and export them to the UAE, Oman and Saudi Arabia.
Description
Our long weld neck flanges are forged from ASTM A105 / ASME SA105 carbon steel, supplied in Class 3000 and 6000 with raised face or plain ends, and in standard long patterns (100/150/200 mm) or any neck length per drawing. Every flange is heat-number stamped and ships with an EN 10204 3.1 material test certificate. Our factory holds ISO 9001 and API certificates, and third-party inspection before dispatch is welcome.
Specifications
| Material | ASTM A105 / ASME SA105 forged carbon steel |
| Dimensions | ASME B16.5, Class 3000 / 6000 |
| Types | LWN, LWN with back-up lap joint (LB), equal or reducing bore |
| Neck length | Standard long pattern or per buyer drawing |
| End / facing | Plain, bevelled for welding, or raised face |
| Documentation | EN 10204 3.1 MTC, heat number traceability |
Typical Applications
- Pressure vessel and drum nozzles
- Boiler and heat exchanger shell connections
- Pump and equipment inlet/outlet nozzles
- Instrument and level-gauge connections on vessels
Buyer FAQ
What is a long weld neck flange?
A long weld neck flange (LWN) is a weld neck flange whose neck is extended — typically to lengths like 100, 150, 200 mm or to the length the buyer specifies — so the flange itself acts as the nozzle. It is widely used on pressure vessels, drums and equipment nozzles where a separate nozzle neck is not wanted.
What is the difference between LWN and standard weld neck flange?
A standard weld neck (WN) flange has a short tapered neck designed to butt-weld to pipe. A long weld neck has an extended neck so it can be welded directly into a vessel shell, replacing a separate nozzle. LWN is common on ASME B16.5 Class 3000/6000 threaded-and-welding ends and vessel nozzles.
Which standards cover long weld neck flanges?
Dimensions follow ASME B16.5; long pattern and elongated neck lengths are commonly produced to buyer drawings. Material is normally ASTM A105 / ASME SA105 for carbon steel service.
Can you produce LWN flanges to our drawing?
Yes. Neck length, bore and drilling can be produced to your drawing. Send the drawing or a sketch with neck length, class and facing, and we quote within 24 hours.
Related products
- Standard weld neck flanges — ASME B16.5, Class 150 to 2500
- ASTM A105 flanges — full type range
- Custom flanges — non-standard neck lengths produced to drawing
Need a price? Send your drawing or neck-length list to WhatsApp +86 15832712953 or email janie@mingyangpiping.com — we usually quote within 24 hours.