Our Specialty Alloy Fabrication Capabilities
When standard stainless steels are not sufficient for extreme environments — concentrated acids, chloride-rich solutions, high-temperature chemical processing — engineers specify high-nickel alloys like Hastelloy and super-austenitic grades like AL-6XN. These materials deliver exceptional corrosion resistance, but they demand fabrication procedures matched to their metallurgy.
Northern Manufacturing fabricates specialty alloys with ASME BPVC Section IX qualified procedures, PMI verification at every stage, and in-house alloy-specific pickling to restore the passive layer after welding.
Materials Handled
We have proven experience and qualified procedures for a range of specialty alloys:
- Hastelloy C-276 (UNS N10276) — the most versatile nickel-molybdenum-chromium alloy, resistant to a wide range of chemical environments including oxidizing and reducing acids
- Hastelloy C-22 (UNS N06022) — improved resistance to localized corrosion and oxidizing media compared to C-276, widely used in chemical processing and flue gas desulfurization
- AL-6XN (UNS N08367) — a super-austenitic stainless steel that bridges the gap between standard stainless and nickel alloys, offering excellent chloride pitting resistance at lower cost than full nickel alloys
Welding and Fabrication
Welding specialty alloys is the most critical step in fabrication. Hot cracking, sensitization, and loss of corrosion resistance are real risks when procedures are not matched to the specific alloy chemistry.
Strict heat input control. Excessive heat input in Hastelloy alloys promotes hot cracking and precipitation of deleterious phases in the weld metal and heat-affected zone. Our procedures specify narrow heat input ranges for each alloy.
Interpass temperature management. AL-6XN and Hastelloy alloys have strict interpass temperature limits — typically lower than standard stainless grades. We monitor and enforce these limits on every pass.
Alloy-matched filler metals. Each alloy requires a specific filler metal to maintain corrosion resistance across the weld joint. We stock and qualify filler metals for every specialty alloy we run, with full lot traceability.
Forming, Rolling, and Finishing
Heavy forming and bending. Specialty alloys have higher work hardening rates than austenitic stainless. Our forming operations account for the increased forces and springback these materials exhibit.
Cylinder and shell rolling. Rolling Hastelloy and AL-6XN plate into vessels and shells for severe-service applications. Forming parameters are grade-specific, with particular attention to minimum bend radii to prevent cracking.
Alloy-specific post-weld treatment. We perform alloy-matched chemical cleaning per ASTM A380 and ASTM A967 to restore the passive layer after welding. Pickling chemistry is formulated for each alloy — the standard stainless pickling solution is not appropriate for nickel alloys.
Why Choose a Specialty Alloy Fabrication Expert
Choosing a fabricator for high-nickel alloys is a critical extension of the engineering process. A non-specialist can introduce hot cracking by running too much heat into Hastelloy, or cause sensitization in AL-6XN by exceeding interpass temperature limits. These failures destroy the corrosion resistance your engineer specified the alloy for in the first place.
We mitigate manufacturability risk. Our deep experience prevents the costly failures that occur when fabricators lack qualified procedures for specialty alloys. Every procedure is developed and tested for the specific alloy grade.
We guarantee metallurgical integrity. Rigid controls over thermal operations, shielding gas coverage, and interpass temperatures preserve the properties that make these materials worth their cost.
We deliver verifiable quality. As an ISO 9001:2015 certified and ASME-compliant fabricator, we provide the documentation and traceability your critical quality audits require.
Quality Assurance
Our quality system incorporates alloy-specific inspection points:
- ASME code compliance — welding procedures qualified to ASME BPVC Section IX for each specific alloy grade
- Alloy-matched post-weld treatment — chemical cleaning and passivation formulated for each alloy per ASTM A380 and ASTM A967
- Positive Material Identification (PMI) — 100% PMI verification on all incoming raw materials and completed weldments
- Comprehensive documentation — full packages including MTRs, PMI certificates, weld maps, and dimensional inspection reports
Common Applications
- Chemical processing reactors and vessels
- Pharmaceutical manufacturing equipment
- Flue gas desulfurization systems
- Severe-service heat exchangers
- Chloride-rich environments (seawater, brine)
- High-temperature industrial furnace components