A long weld neck flange is a weld neck whose barrel is extended so it can act as the nozzle itself. The neck is bored to suit the vessel wall and welded straight into the shell, which takes one weld out of the assembly. We forge them to your drawing at our own plant in Shanxi, China, and sell direct: a single nozzle is a valid order.
Unlike a standard weld neck, the controlling dimensions are overall length, neck outside diameter and the bore transition, not just NPS and class. Ratings follow ASME B16.5 Class 150 to 2500 by drawing, with ASME B16.47 used where a large custom diameter needs review. Grades are ASTM A105, A350 LF2, stainless 304, 316, 321 and 347, duplex, and project alloys checked against the drawing.
Most of this work is vessel nozzles, heat exchangers, separators and reactors, so the part is usually quoted from a pressure-vessel drawing and often supplied as a forged blank with machining allowance. Wall transition, facing, bolt pattern, weld bevel and allowance are confirmed before cutting. Documents run to a dimensional report, UT or MT, the heat-treatment record, MTC 3.1 and third-party witness on high-pressure projects.
Product family: Flanges
BLD Forge Direct reviews long weld neck flange RFQs based on standard, drawing, pressure class, material grade, overall length, neck OD, bore, facing, inspection requirements and destination country before quotation.
| Scope and rating | |
|---|---|
| High-hub geometry | Overall length, neck OD, bore transition and weld-end geometry are the first quotation checks, not only NPS and Class. |
| Supplied variants |
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| Standards and materials | |
| Standards / drawings |
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| Material grades |
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| Geometry, tolerance and inspection | |
| Size and rating review | Commonly ASME B16.5 Class 150 to 2500 by drawing; custom high-hub and vessel-nozzle lengths are reviewed case by case. |
| Critical dimensions | Overall length, hub/neck OD, bore, wall transition, facing, bolt pattern, weld bevel and machining allowance. |
| Inspection depth | Dimensional report, UT/MT, MTC 3.1, heat-treatment record and third-party inspection for high-pressure projects. |
| Reviewed before quotation |
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| Buying logic | |
| Best-fit RFQ | Best for vessel nozzles, high hub designs and pressure connections requiring extended neck geometry. |
| Buyer application | Pressure vessels, heat exchangers, separators, reactors and high-pressure process equipment. |
Your standard, drawing revision and project specification govern.
Also known as
We confirm each step against your drawing or standard before we quote.
Material grade, heat number, certificate basis and substitution limits are checked against the Long Weld Neck Flanges drawing or standard before procurement is released.
The forging route is selected around flange type, section thickness, bore allowance, hub or neck geometry and pressure-service requirements.
Heat treatment is planned with the required record package, mechanical testing basis and impact-test condition where low-temperature or alloy service applies.
Rough machining opens reference faces, bore, hub, neck or sealing-face stock needed to control allowance before final flange machining.
Final machining controls facing, bore, bolt pattern, groove, sealing surface and flange-table or drawing tolerances before dimensional inspection is issued.
Inspection covers dimensional report, MTC 3.1, PMI and required UT, MT or PT records before the release documents are matched to the purchase order.
Marking, packing and export documents are prepared by PO line item so the Long Weld Neck Flanges shipment can clear customs and be identified at site receiving.
List document requirements in the first RFQ; they affect price and schedule.
Direct from us: send the nozzle or vessel drawing and we quote the long weld neck from our own forge in Dingxiang, Shanxi, China. One piece is a valid order, every RFQ gets a reply within 8 hours, and the lead time is 9 to 30 days after drawing approval. Shipment is FOB the Chinese port you designate, with CFR or CIF on request, and every order ships with an EN 10204 3.1 MTC.
Yes. Its barrel is extended so it can act as the nozzle itself: the neck is bored to suit the vessel wall and welded straight into the shell, which takes one weld out of the assembly.
Often, yes. Most of this work is quoted from a pressure-vessel drawing and supplied as a forged blank with machining allowance; wall transition, facing, bolt pattern, weld bevel and allowance are confirmed before cutting.
When the drawing calls for a large custom diameter. Otherwise ratings follow ASME B16.5 Class 150 to 2500 by drawing, and custom high-hub and vessel-nozzle lengths are reviewed case by case.
For high-pressure LWN flanges, provide the drawing, pressure class, bore, wall transition, facing, material, heat treatment, NDT requirements and any third-party inspection requirement.
Email quote@bldforgedirect.com with standard, drawing, material, quantity and inspection requirements.