ANSI B16.5 Weld Neck Flange

QS Flange: Wuxi Ansi B16.5 Wn Flange

ANSI B16.5 weld neck flange with a tapered hub butt welded to the pipe, dimensioned to the standard bolt pattern for process and cyclic duty.

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One-Minute Overview

Weld neck flange with a long tapered hub that butt welds to the pipe.
The taper spreads stress away from the weld and into the flange body.
Dimensioned to ANSI B16.5, so it matches standard flanges and gaskets.
Bore, class and facing are matched to your pipe at inquiry.

An ANSI B16.5 weld neck flange joins the pipe with a butt weld at the end of a long tapered hub. The hub is the point of the design: it carries the pipe wall thickness out to the flange ring gradually, so the weld does not sit at an abrupt change of section.

That taper matters wherever the joint is worked hard. Under pressure the flange ring tries to rotate, and a weld neck hub resists that rotation while spreading the resulting bending stress along the taper instead of concentrating it at the weld toe. The result is a joint that tolerates pressure cycling and thermal movement better than a slip on or socket weld connection, which is why the type is standard on process lines, high pressure headers and services that see repeated shutdown.

A butt weld also gives a full penetration joint with no crevice behind it, so the bore stays smooth and cleanable. The price is fit-up: the pipe end must be cut square and bevelled, the bore has to match the pipe wall thickness, and the weld is made from the outside with the two parts held concentric. Wall thickness, bore, pressure class and facing are confirmed at inquiry so hub and bore match the pipe you actually use, and the dimensional standard keeps the bolting interchangeable with the rest of the line.

Detailed specifications, bore and hub drawings for this weld neck flange can be provided on request.

FAQ

Q1. What does the tapered hub actually do?

It carries the pipe wall thickness out to the flange ring in a gradual change of section, so bending stress from the flange spreads along the taper instead of piling up at the weld toe. That is what lets the joint take pressure cycling and thermal movement without the weld becoming the weak point.

Q2. Why is a weld neck used instead of a slip on here?

A butt weld gives full penetration with no crevice behind the pipe wall, so the bore stays smooth and can be cleaned or inspected. The weld neck also resists flange rotation better under pressure. The trade-off is fit-up: the pipe must be cut square and bevelled, and the bore has to match the wall.

Q3. How do I get the bore right for my pipe?

Tell us the pipe outside diameter and wall thickness, or the schedule, with your inquiry. The bore is machined to suit, so a mismatch at the weld root is avoided. We confirm bore, hub dimensions, pressure class and facing together before the order is released, and the flange stays interchangeable with ANSI B16.5 flanges on the line.

Q4. How long will production take?

Standard sizes are typically ready within 30 days, and in-stock items ship immediately. Larger or custom orders get a confirmed date per order, because the schedule depends on quantity, material, the bolt pattern you specify, and how busy production is at the moment you order.

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