Description
Quick answer
Hastelloy C276 stud bolts use UNS N10276, a low-carbon nickel-molybdenum-chromium-tungsten alloy selected for severe chemical-processing environments. The alloy offers broad resistance, but a bolted flange contains crevices and stressed threads; process chemistry and joint design still govern suitability.
Product specifications
| Material designation | Nickel-molybdenum-chromium-tungsten Alloy C-276; UNS N10276; W.Nr. 2.4819 |
|---|---|
| Material / bar reference | ASTM B574 rod and bar in the specified solution-treated condition |
| Finished fastener reference | ASTM F468 where alloy and requirements are applicable, or a project-specific severe-corrosion fastener specification |
| Stud configuration | Fully threaded stud bolts; custom double-end details by approved drawing |
| Inch threads | UNC, UNF and 8UN to ASME B1.1 as specified |
| Metric threads | Coarse or fine metric threads to ASME B1.13M / ISO requirements as specified |
| Dimensions | Diameter and length to flange bolting schedule, ASME B18.31.2 reference or approved drawing |
| Matching nuts | Compatible heavy hex or project-design nuts supplied after material and property review |
| Documentation | EN 10204 3.1 MTC, heat traceability and dimensional report; PMI/NDT/testing optional |
Why specify Hastelloy C276 stud bolts?
C-276 is evaluated for mixed acids, wet chlorine-related equipment, scrubbers and chemical waste service where less highly alloyed materials may be inadequate. Its premium cost makes accurate service definition, material verification and documented traceability especially important.
Corrosion resistance and material limits
The alloy is recognized for resistance across many reducing and oxidizing media and for resistance to localized corrosion. It is not immune to every hot oxidizing acid, molten salt or contaminated environment. Published corrosion tables should be screened against actual concentration and temperature.
Engineering note: Material selection must be based on the complete process environment and governing design code. Product-page information is not a design allowable or a guarantee of service life.
Temperature and mechanical-property control
C-276 can be used across a broad temperature range when design allowables and environment permit, but it is not selected solely by a headline maximum temperature. Confirm code stress values, oxidation conditions and thermal cycling.
Typical applications
- Chemical reactors, columns and transfer piping
- Flue-gas desulfurization and scrubber systems
- Acid production, recovery and waste treatment
- Pulp and paper bleaching equipment
- Pharmaceutical and specialty chemical plants
Standards, threads and flange fit-up
The material specification controls alloy chemistry, product form, heat treatment and mechanical tests. The finished-fastener specification controls stud manufacture and acceptance. The flange standard or bolting schedule controls diameter, thread and length. These documents perform different jobs and should all be identified at order review.
Cut threads and rolled threads can produce different dimensional, surface and residual-stress characteristics. State the required manufacturing method when it is a design requirement. Thread fit, end chamfers, nut engagement and exposed thread allowance must match the assembly procedure.
Matching nuts, lubrication and galling control
High-alloy studs should be purchased as part of an engineered bolting system. Nut material and proof strength must support the specified stud properties without creating an unacceptable corrosion couple. Clean threads, controlled surface finish and an approved lubricant reduce galling and torque scatter.
Torque values are not universal. Friction coefficient, coating or lubricant, nut condition, tightening sequence and reuse policy all affect achieved preload. Use a project-approved torque-tension or hydraulic-tensioning procedure.
Manufacturing, inspection and documentation
Production can include material verification, sawing, end preparation, thread machining or rolling, cleaning, dimensional inspection and permanent identification. Heat numbers remain traceable through manufacturing. Additional controls can include PMI, hardness, tensile tests, impact tests, microstructure examination, corrosion testing, ultrasonic testing or dye penetrant testing when specified.
Inspection documents should identify the ordered UNS grade, material specification and condition—not only a trade name. Third-party inspection, EN 10204 3.2 certification and customer hold points can be incorporated before production when agreed.
What to include in your RFQ
Specify ASTM B574 condition, finished-fastener requirements, exact process media, thread/nut system, PMI, corrosion testing if required, NDT, cleanliness, marking and EN 10204 3.1 or 3.2 documentation.
- Exact UNS designation and governing material specification/edition
- Finished-fastener and dimensional standard
- Diameter, thread series, pitch and overall length
- Required material condition and mechanical properties
- Nut and washer material, dimensions and quantity
- Design temperature, process environment and special service standard
- Testing, inspection, traceability and certificate type
- Lubrication, coating, marking, packing and delivery requirements
Authoritative material reference
Review Haynes International HASTELLOY C-276 alloy data together with the contractually required ASTM/ASME/ISO editions. Manufacturer literature supports material screening; the purchase order and governing code control supply.
Related stud bolt materials
Frequently asked questions
Is C276 suitable for every acid?
No alloy is universal. Acid species, concentration, temperature, impurities, aeration, velocity and crevices must be evaluated for the actual process.
What material specification is used for C276 bar?
ASTM B574 is a common rod and bar reference for UNS N10276. The purchase order must also define condition and finished-fastener requirements.
Can C276 nuts be supplied with the studs?
Yes, subject to material availability and confirmation of nut dimensions, properties, heat treatment, lubrication and inspection requirements.
Is 100-percent PMI available?
Yes when specified. Define the method, alloy acceptance, coverage of studs and nuts, reporting and identification requirements.
Trade names are used for material identification. INCONEL®, INCOLOY® and MONEL® are trademarks of Special Metals Corporation; HASTELLOY® is a trademark of Haynes International, Inc. SASA FLANGE supplies products to the specifications stated on the accepted order.
