Stainless Steel Weld Neck Flange

QS Flange: Steel Pipe Flange

Forged stainless steel weld neck flange to ASME B16.5, 1/2 to 24 inch and 150LB to 2500LB, RF face, with a tapered hub that carries stress smoothly into the pipe.

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One-Minute Overview

Forged stainless steel weld neck flange to ASME B16.5 with an RF face, 1/2 to 24 inch.
Pressure classes run from 150LB to 2500LB under one dimensioning standard.
The hub tapers at 15 to 30 degrees, so stress moves smoothly into the pipe.
Full penetration welds to ASME BPVC Section IX suit cyclic and hot service.

The weld neck flange is the shape you choose when a joint has to survive pressure cycles, not merely hold pressure. A long tapered hub takes the flange ring thickness down to the pipe wall over a 15 to 30 degree cone, so the change in stiffness is gradual and the weld is not asked to absorb a step change in stress. This series is forged in stainless steel to ASME B16.5, from 1/2 to 24 inch, in classes 150LB to 2500LB.

Name: Stainless Steel Weld Neck Flange
Type: WN
Size: 1/2"-24"
Pressure: 150LB-2500LB
Flange Face: RF
Material: Stainless Steel
Process Method: Forged
Standard: ASME B16.5

Because the taper keeps the section change gentle, the hub reaches a fatigue life comparable with seamless pipe of the same wall, which is why WN flanges turn up on boiler and pressure vessel work, in petroleum and chemical plants, on shipboard piping, and in pharmaceutical, metallurgy, machinery and food service where the line is cleaned or cycled. The butt weld is a full penetration joint: groove angle, root gap and 100% penetration follow ASME BPVC Section IX, so weld strength is brought up to the base metal instead of being left as the weak link.

Fitting matters as much as the flange. Align the bore with the pipe, tack in four places, and check the face square to the line before the root pass; a weld neck welded off-square loads the gasket unevenly, and no amount of bolt torque will correct it. Stainless wants its own consumables and low heat input, and the bore should be purged for the root. The raised face takes the usual spiral wound gasket, and the stainless body covers wet, cleaned and mildly corrosive duty where carbon steel would not last.

FAQ

Q1. What makes a weld neck different from a slip on at the joint?

The hub. On a weld neck the wall thickness falls away from the flange ring in a 15 to 30 degree taper and meets the pipe at a butt weld, so pressure and bending stress pass into the pipe gradually. A slip on sits over the pipe with two fillet welds, which is faster and cheaper but leaves a sharper change of section and a crevice at the bore.

Q2. How good is the fatigue life, honestly?

Comparable with seamless pipe of the same wall, and that is the claim the shape is built around. The tapered hub keeps the stiffness change gentle and the full penetration butt weld removes the notch a fillet weld would leave. That is why weld necks are the default on cyclic, hot or high pressure lines rather than a premium extra.

Q3. Do I have to purge the bore when I weld stainless?

Unless you enjoy sugar. Without purge gas the root oxidises into a rough black scale that traps product and starts corrosion from the inside, and no amount of pickling paste reaches it. Purge, weld the root, then finish. The flange will not complain. The inspector will.

Q4. What are your production lead times?

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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