Northern Manufacturing fabricates high-temperature alloy equipment in stabilized austenitic stainless (321, 347) and nickel alloys (Inconel 625, Hastelloy C-22, Hastelloy C-276): furnace retorts and muffles, burner components, hot-side ductwork, and incineration system internals. Welding procedures are qualified per ASME BPVC Section IX across seven P-number groups, including P43 nickel alloys, with GTAW run at controlled low heat input so the alloy keeps the properties it was specified for.
60+ AWS-certified welders across 78 welding stations. ISO 9001:2015 certified (AVU Registrations). Stainless and nickel-alloy work runs with dedicated tooling in our 40,000 sq ft stainless-only production space in Oak Harbor, Ohio, where no carbon steel runs and no shared abrasives contaminate sensitive material.
The Failure Mechanisms You Are Specifying Against
Components in high-temperature service are under attack from three directions at once, and all three are sensitive to how the part was fabricated.
- Creep and stress rupture. Sustained stress at temperature, even below yield, slowly deforms the material until it ruptures. Weld zones with the wrong microstructure creep first.
- Thermal and creep-fatigue. Start-up and shutdown cycles drive internal stresses that initiate cracks, and at temperature, creep damage and fatigue damage accelerate each other.
- Oxidation and sulfidation. Hot gas chemistry consumes unprotected metal. The alloy is chosen to resist it, which is exactly why fabrication must not degrade the alloy.
You specified the grade to survive these mechanisms. Our job is to hand the material back to you with that capability intact.
What We Build for High-Temperature Service
- Industrial furnace components. Retorts, muffles, and burner components built in grades selected for the furnace atmosphere.
- Hot-side ductwork and expansion sections. High-temperature duct, transitions, and housings for incineration, waste-to-energy, and pollution control systems.
- Combustion-path and exhaust-side components. Casings, housings, and internals for power generation equipment running on the hot side of the process.
- Chemical and petrochemical process equipment. Tanks, housings, and equipment internals where elevated temperature combines with aggressive chemistry.
Choosing the Grade for the Temperature
| Grade | When to specify it |
|---|---|
| 321 | Titanium-stabilized austenitic for high-heat service like ovens and furnace components |
| 347 | Columbium-stabilized austenitic that resists sensitization after welding in elevated-temperature service |
| Inconel 625 | Nickel alloy holding strength and oxidation resistance where austenitic stainless fades |
| Hastelloy C-22 / C-276 | Nickel alloys for the acid-condensate end of thermal systems: quench zones and scrubber service |
The stabilized grades exist because plain austenitics sensitize: welding holds the material in the temperature range where chromium carbides form at grain boundaries, stealing the chromium that provides corrosion resistance. 321 and 347 tie up carbon with titanium and columbium instead, which is why they hold up in cyclic high-heat service where 304 fails along its welds.
Welding That Respects the Metallurgy
The performance of a high-temperature alloy hinges on the fabrication. Every degradation mechanism above concentrates in the weld zone, so that is where our process control concentrates too.
Welders work to ASME BPVC Section IX qualified procedures: P8 for the stabilized austenitics, P43 for Inconel 625 and the Hastelloy grades, plus qualified dissimilar-metal combinations, so a stainless structure can carry a nickel-alloy hot section under a qualified joint. GTAW with controlled low heat input and stringer bead technique prevents the hot cracking and distortion these alloys develop under careless heat. Preheat is deliberately avoided, because slow cooling is the enemy on this material, not the friend it is on carbon steel.
Weld integrity is verified to your drawing: visual, dye penetrant, radiographic, and ultrasonic examination under a Certified Welding Inspector and ASNT SNT-TC-1A Level III oversight. Where the spec requires it, post-weld pickling and passivation per ASTM A380/A967 restores the surface chemistry across the whole assembly in our 55-foot spray booth.
Contamination Control on Expensive Material
A nickel-alloy fabrication contaminated by carbon steel grinding dust is scrap you pay specialty-alloy prices for. High-temperature alloy work at Northern runs in our 40,000 sq ft stainless-only production space with dedicated tooling, abrasives, clamps, and work surfaces. PMI (positive material identification) verification by handheld XRF is available to confirm alloy composition from receiving through final assembly, so the material in the weld is provably the material on the MTR.
Quality Documentation
High-temperature equipment usually carries an engineering review behind it, and the turnover package is built to survive one:
- Material Test Reports (MTRs) traced by heat number from mill cert to final assembly
- Weld maps with WPS references for every joint, plus welder qualification records (WPS/PQR)
- NDE reports (VT, PT, RT, UT as specified on your drawing)
- PMI records confirming alloy composition where specified
- Dimensional inspection reports to your drawing tolerances
- Certificate of Conformance (CoC) to your purchase order requirements
