ASME B16.5 A182 Gr.F316L Weld Neck Flanges Custom-Bored for Russian Project

A few days ago, we wrapped up a small but very specific job for a client in Russia—16-inch weld neck flanges, made from ASTM A182 F316L stainless steel, with some non-standard requirements that needed a bit more attention than usual.

The client is working on a pipeline section that uses 406.4 mm OD pipe with 9.53 mm wall thickness, which brings the pipe ID to around 387.4 mm. Instead of adapting their weld procedure to a stock flange, they asked us to machine the flange bore to precisely match the internal diameter of their pipe. This was the critical part of the job.

Finished ASME B16.5 A182 Gr.F316L Weld Neck Flange

What They Ordered

Type: Weld Neck Flange (WN)

Standard: ASME B16.5

Size: 16″

Class: 150

Facing: Raised Face (RF)

Material: A182 Gr.F316L

Pipe OD: 406.4 mm

Wall Thickness: 9.53 mm

Required Bore: 387.4 mm

What We Actually Did

We started by pulling forged F316L blanks from stock and programmed our CNC machines to bore out each neck to exactly 387.4 mm, with a tolerance window of ±0.3 mm. Our operators double-checked the bore during and after machining using ID gauges and manual verification. Not all stock flanges can be reworked this way without compromising the hub, but we had the right raw material size for the job.

The bevel angle and raised face surface were finished according to ASME B16.5 specs, but everything behind the flange face had to match the client’s pipe geometry, down to the last decimal.

Measuring diameter on ASME B16.5 A182 Gr.F316L Weld Neck Flange

Inspection Notes

After machining, we went through our usual QC steps:

Visual check for any surface defects

Measurement log for bore, OD, thickness, bolt circle

PMI (Positive Material Identification) for stainless grade confirmation

We also applied a light protective oil coating—nothing special, just something to prevent surface discoloration during transit.

Each flange was marked with heat number, bore size, and material spec, all engraved for traceability.

Packing & Logistics

We packed the flanges in a custom-sized plywood crate with foam layers separating each unit. The client requested English-Russian bilingual labeling, which we’ve done before. Everything was labeled clearly with flange spec, material, and machining info to avoid customs delays. The shipment left our facility on a flatbed the next morning and is currently on its way to the Baltic port for final delivery.

There’s nothing revolutionary about machining a custom bore into a weld neck flange—but doing it right, first time, without holding up the client’s welding schedule? That’s where experience matters. We’ve seen enough pipeline specs to know that “just close” doesn’t always cut it.

So if you need ASME B16.5 weld neck flanges, especially with non-standard bores or matching specific pipe IDs, we can help. No minimum quantity, no drama—just clean machining and on-time delivery.