Northern Manufacturing fabricates chemical processing equipment in the alloys aggressive chemistry demands: 316L, duplex 2205 and 2507, Hastelloy C-276 and C-22, and AL-6XN. We have built corrosion-resistant alloy fabrications in Oak Harbor, Ohio since 1951, supplying process vessels, heat exchangers, pipe spools, storage tanks, mixing vessels, and scrubbers to chemical plants, specialty chemical producers, and the EPC firms managing their capital projects. Every project starts with the same question: what does this equipment contact, at what temperature, and for how long?
60+ AWS-certified welders. ISO 9001:2015 certified (AVU Registrations). Welding procedures qualified per ASME BPVC Section IX across P8 austenitic stainless, P10H duplex, P43 nickel alloys (Hastelloy C-276 and C-22), and P45 (AL-6XN). Certified Welding Inspector (CWI) on staff and ASNT SNT-TC-1A Level III NDE capability. In-house pickling and passivation per ASTM A380/A967 in a 55-foot spray booth.
Equipment We Fabricate for Chemical Processing
- Reactor and process vessels. Shell courses, nozzle reinforcements, and internal baffles fabricated with welding procedures qualified per ASME BPVC Section IX. Weld integrity is non-negotiable when the contents are corrosive.
- Heat exchangers. Tube-to-tubesheet welds in corrosion-resistant alloys, where joint geometry and heat input control decide whether the unit lasts two years or twenty.
- Pipe spools and piping systems. Prefabricated pipe spools with full weld documentation, NDE, and fit-up verification before they ship to the job site.
- Storage and batch tanks. Built to the corrosion allowances and surface finish requirements the application demands.
- Scrubbers and gas-contact equipment. Surfaces that face some of the most aggressive condensing chemistry in any plant, where material selection separates equipment that performs from equipment that gets replaced. Related work: pollution control fabrication.
- Mixing vessels and agitator tanks. Internal surface finish, baffle welding, and nozzle placement all affect process performance. We work from your engineering drawings or collaborate on design-assist projects.
Material Selection Drives Everything in Chemical Service
The wrong alloy in a chemical environment is not a maintenance problem. It is a safety problem, a production problem, and an insurance problem. Three failure modes account for most chemical equipment corrosion issues:
Chloride stress corrosion cracking (SCC) is the most common reason standard 304 and 316 stainless fails in chemical plants. Even trace chloride levels at elevated temperature can initiate cracking in austenitic grades. Duplex 2205 carries roughly twice the yield strength of 316L with far superior chloride SCC resistance, making it the standard choice for chloride-bearing chemical streams. The higher strength often allows thinner wall sections, which cuts weight and material cost.
Acid attack destroys the passive layer that gives stainless steel its corrosion resistance. Concentrated sulfuric, hydrochloric, and phosphoric acids require alloys engineered for those environments. Hastelloy C-276 handles reducing acids and chloride-contaminated acid mixtures that would destroy conventional stainless grades. For mixed-acid environments where both oxidizing and reducing conditions exist, Hastelloy C-22 provides broader resistance across a wider pH range.
Pitting and crevice corrosion targets weld zones, gasket surfaces, and any geometry that traps stagnant fluid. AL-6XN, a super-austenitic 6% molybdenum alloy, resists pitting in warm chloride solutions where 316L fails, and it welds with conventional GTAW technique.
Grade Selection Starting Points
Material selection always depends on the specific chemistry, concentration, and temperature your equipment will see. These are the starting points decades of corrosion-resistant fabrication have established:
| Grade | When to specify it |
|---|---|
| 316L | Mild chemical environments, food-grade chemical processing, moderate temperatures |
| Duplex 2205 | Chloride-bearing streams, caustic solutions, process water with elevated chlorides |
| Super Duplex 2507 | Severe chloride environments and high-demand lines where 2205 is marginal |
| Hastelloy C-276 | Concentrated reducing acids (sulfuric, hydrochloric, phosphoric), chloride-contaminated acid streams |
| Hastelloy C-22 | Mixed-acid environments and oxidizing-reducing transitions |
| AL-6XN | Warm chloride pitting conditions and brackish utility water where 316L pits |
We stock 316/316L plate from 20-gauge through 1 inch with 2-day availability from our distributor network; heavy plate through 2 inches arrives within 5 days. Duplex, Hastelloy, and AL-6XN are sourced per project in sheet, plate, pipe, and tube, typically within three to four weeks.
Weld Integrity in Corrosive Service
Every weld in a chemical vessel is a potential failure point. The heat-affected zone has different metallurgy than the base metal, and in corrosive service that difference matters: a weld that passes hydro test can still corrode preferentially and fail months into operation.
Our welding team runs procedures qualified per ASME BPVC Section IX for each alloy family we fabricate, with matching filler selection built into the WPS (ER2209 on duplex 2205, for example) and qualified dissimilar-metal combinations for transitions such as stainless to Hastelloy and stainless to AL-6XN. A Certified Welding Inspector oversees weld quality, and nondestructive examination is performed under ASNT SNT-TC-1A Level III supervision to the code and standard your project requires.
PMI and Material Traceability
When your spec calls for C-276 and a 316 nozzle gets welded in by mistake, the consequences in acid service are catastrophic. We verify alloy identity with PMI (positive material identification) on incoming material and completed assemblies, so the material certs match what is actually in your equipment. Material Test Reports are traced by heat number from mill cert to final assembly, and the traceability records ship in the documentation package.
Contamination Control by Separation
A single carbon steel particle embedded in a stainless surface will rust and initiate crevice corrosion. In chemical service, that small defect becomes a leak path.
Northern operates a 40,000 sq ft stainless-only production space. Tooling, grinding wheels, clamps, and work tables in that room are dedicated to stainless, and no carbon steel work runs there. Your chemical processing equipment is fabricated, ground, and finished without exposure to carbon contamination, and free-iron verification per ASTM A380 is performed on critical-service assemblies before passivation.
Surface Finish, Pickling, and Passivation
Many chemical applications specify interior surface finishes, measured in Ra, that affect cleanability, product purity, and corrosion resistance. We control surface finish through mechanical polishing and bead blasting with stainless media, then restore the passive layer chemically.
Pickling and passivation per ASTM A380 and ASTM A967 runs in-house in our 55-foot spray booth. Pickling strips weld heat tint and the chromium-depleted layer beneath it; passivation rebuilds the chromium-oxide layer that gives stainless its corrosion resistance. Oversized assemblies that other shops send out are treated whole, in one pass, under one quality system.
Quality Documentation
Every chemical processing project ships with a documentation package built for your quality audit:
- Material Test Reports (MTRs) traced by heat number from mill cert to final assembly
- PMI verification records confirming alloy identity where the spec requires them
- Weld maps with WPS references for every joint, plus welder continuity logs
- NDE reports to the examination method and acceptance criteria your project specifies
- Pickling and passivation certification per ASTM A380/A967
- Dimensional inspection reports to your drawing tolerances
- Certificate of Conformance (CoC) to your purchase order requirements
When an auditor asks which heat of C-276 went into a nozzle, or which welder made the closing seam, the answer is already in the binder.