PN40 Weld Neck Forged Steel Flanges for Heat Exchanger Service

PN40 weld neck forged steel flanges for heat exchanger service are the standard connection component on exchanger channels, shells, nozzles and tube side covers across the process industry. A heat exchanger flange is bolted and unbolted repeatedly during maintenance, so it must maintain its sealing geometry, face finish and dimensional accuracy over many years of service.

The weld neck design of these PN40 forged steel flanges transfers the load smoothly into the shell or pipe, avoiding the stress concentration that causes fatigue failures in cyclic thermal service. Every PN40 weld neck forged steel flange is machined from a forged and heat treated blank, with the bore and hub prepared for full penetration butt welding.

We check the raised face finish, bolt circle and facing dimensions against the EN 1092-1 and ASME B16.5 tables before each flange is hydrostatically tested. Heat exchanger service often involves rapid temperature changes, so we confirm the material grade and impact properties with the customer before production and document the results with EN 10204 3.1 certificates.

• Weld neck hub provides smooth load transfer and full penetration welds for repeated thermal cycling
• PN40 rating matches common heat exchanger design pressures in European and Asian projects
• Dimensionally verified to EN 1092-1 tables for trouble-free assembly with exchanger nozzles
• Impact tested material options for low ambient temperature installations
• Raised face machined to controlled finish for reliable gasket seating after every maintenance break
• 100% hydrostatic tested with EN 10204 3.1 documentation for exchanger manufacturers

PN40 weld neck forged steel flanges for heat exchanger service are controlled from forging to final dimensional inspection. The heat treatment parameters, mechanical test results and hydrostatic test data are recorded for each batch, and the raised face finish is verified before the flange is released.

Exchanger manufacturers who fit our PN40 weld neck forged steel flanges receive EN 10204 3.1 documentation that satisfies their own quality systems, and we can coordinate third-party inspection when the exchanger contract requires it.

Weld neck forged steel flanges have a tapered hub that is butt welded to the shell or pipe, which distributes bending loads smoothly and reduces fatigue risk. Heat exchangers experience thermal cycles and vibration, so this connection geometry is the reliable choice.

PN40 is the nominal pressure rating in bar, defined by EN 1092-1. PN40 corresponds approximately to ASME Class 300, so the two flanges are commonly used in similar pressure ranges.

Yes. We regularly machine PN40 weld neck forged steel flanges to customer drawings for exchanger channels and shells, including special hub lengths, facing details and bolt patterns.

For chloride service we supply F316L or duplex grades, and for sour service we can supply material qualified to NACE MR0175 requirements. Share your service conditions and we will confirm the correct grade.