ASTM A194
Grade 16
High-Temperature Alloy Steel Nuts
Why Vanadium Matters Here
Grade 16 takes the same chromium-molybdenum base that makes our Grade 7 nuts reliable and adds a controlled vanadium addition — a small amount of a genuinely effective element for improving high-temperature creep strength. Vanadium forms fine, stable carbides within the steel’s microstructure that resist coarsening at sustained elevated temperature, directly slowing the gradual, permanent deformation (creep) that limits how long a bolted joint can hold its clamping load under continuous heat and stress.
That makes Grade 16 the correct upgrade specifically when service temperature and duration genuinely push past what Grade 7 comfortably handles — sustained high-temperature steam and process service is where creep resistance becomes the limiting design factor, not just peak strength at any single moment. For joints operating at lower or intermittent temperatures, Grade 7’s simpler chromium-molybdenum composition remains the more economical, equally reliable default.
Grade 16 is the standard nut counterpart to ASTM A193 Grade B16 stud bolts, a well-established pairing in power generation, refinery, and high-temperature process piping — wherever elevated temperature is a sustained operating condition rather than an occasional excursion.
Akbar Fasteners Pvt. Ltd. exports to over 50 countries, and our Grade 16 nut range is manufactured and verified by chemical composition and mechanical testing under our ISO 9001:2015 quality system.
Where This Grade Genuinely Applies
Genuine Creep Strength Improvement
Vanadium carbide formation resists high-temperature microstructural coarsening over sustained service.
Correct Default Pairing With B16 Studs
The standard, widely-used nut match for one of the industry’s key high-temperature stud grades.
Long-Term Joint Load Retention
Reduces the gradual clamping-force loss that creep causes in sustained high-temperature bolted joints.
Verified Mechanical Properties
Batch testing confirms genuine vanadium content and mechanical properties for every lot.
Choosing Between Related High-Temperature Grades
Grade 7
The simpler, more economical chromium-molybdenum base, without the added vanadium creep-strength benefit.
View Grade 7 →Grade 16 (This Page)
Grade 7’s base plus vanadium — genuinely improved creep strength for sustained high-temperature service.
You Are HereGrade 7L / 7ML
The same chromium-molybdenum base impact-tested for cryogenic service, at the opposite temperature extreme.
View Grade 7L / 7ML →Grade 7 vs Grade 16 — Quick Reference
Confirming whether the joint’s operating temperature and duration genuinely require creep resistance before specifying the higher grade. This table is the quick reference we use with buyers before quoting.
| Aspect | Grade 7 | Grade 16 |
|---|---|---|
| Base Material | Chromium-molybdenum | Chromium-molybdenum-vanadium |
| Creep Strength | Standard | Genuinely improved via vanadium carbides |
| Matching Bolt | ASTM A193 Grade B7 | ASTM A193 Grade B16 |
| Best Suited For | Ambient to moderately elevated temperature | Sustained high-temperature service |
Grade 16 Specification Details
Nominal Composition
- Chromium Present, Alloy Grade
- Molybdenum Present, Alloy Grade
- Vanadium Controlled Addition
- Base Type Low-Alloy Steel
Typical Mechanical Range
- Proof Load Per ASTM A194 Grade 16
- Condition Quenched and Tempered
- Creep Strength Improved vs Grade 7
- Matching Bolt Grade ASTM A193 Grade B16
Fastener Types We Manufacture
- Hex Nuts Standard & Heavy Hex
- Jam Nuts Thin Profile
- Matching Studs ASTM A193 Grade B16
- Custom Sizes On Request
Application Areas
Wherever sustained high-temperature service genuinely pushes past what standard chromium-molybdenum Grade 7 comfortably handles.
Power Plant High-Temperature Steam Piping
steam service bolting
Refinery High-Temperature Process Units
refinery process piping
Turbine & Boiler Flange Bolting
connections, long-duration service
Petrochemical High-Temperature Reactors
vessel bolted joints
Standard Export Documentation
Prepared as standard practice for every Grade 16 nut shipment.
Mill Test Certificate (MTC)
Heat number, chemical composition, and mechanical property verification for every lot.
Chemical Composition Report
Confirms actual vanadium content falls within the specified Grade 16 composition range.
Certificate of Conformance
Confirms the shipment matches the purchase order grade/size specification in full.
Certificate of Origin (COO)
Confirms India as country of manufacture for destination customs purposes.
NABL Accredited Test Reports
Independent mechanical and dimensional testing available on request.
Commercial Invoice & Packing List
Itemized value, Incoterm, and detailed carton/weight breakdown for customs clearance.
Internationally Recognised Standards Coverage
Related Fastener Grades & Materials
ASTM A194 Grade 7
Our standard chromium-molybdenum grade, the simpler base that Grade 16 builds upon.
View Grade 7 →ASTM A194 Grade 7L / 7ML
Our low-temperature, impact-tested variant of the same chromium-molybdenum base material.
View Grade 7L / 7ML →ASTM A194 Grade 7M
Our restricted-hardness variant of the same base, for NACE sour service applications.
View Grade 7M →Stainless Steel Fasteners Manufacturer India
Our broader fastener manufacturing capability across all major carbon, alloy, and stainless grades.
View SS Manufacturer Guide →Sustained High-Temperature
Service Piping?
Tell us your operating temperature and duration — we’ll confirm whether Grade 16’s creep-strength benefit genuinely applies, matched with our B16 studs, and quote with full documentation. Akbar Fasteners Pvt. Ltd. responds within 24 hours.
Sales: +91 724 0000 733 · Support: +91 800 9315 333 · sales@akbarfasteners.in