INVAR-36 Rings manufactured at TorqBolt are corrosion resistant,high temperature resistant with ultimate tensile strength.
Dimensional standards as per DIN 471,DIN 472,DIN 5417,DIN 983,AS 568,BS 1806,ISO 3601,DIN 3771 are provided.
The raw material of these fasteners is further classified as Super Nickel Alloys. Being a PED certified Fasteners Manufacturer by TUV Rheinland,our fasteners are accompanied with EN 10204 3.1/3.2 certification. INVAR-36 Rings are available in hot forged,cold forged and bar stock machined conditions depending upon the order quantity.
Invar-36 Is A Nickel Based Alloy Providing Low Expansion .with 36% Nickel Content Alloy 36 Retains Good Strength And Toughness At Cryogenic Temperatures.
Invar 36 rings are seamless rolled or open-die forged components used as pressure-vessel flanges, valve bodies, hub-mount blanks, and shaft-end retention rings. TorqBolt supplies Invar 36 rings per ASTM A182 (forged flange standard), ASTM A266/A668 (carbon ring), and EN 10222 (pressure-purpose forging), in OD sizes from 50 mm up to 3000 mm.
Forging Process
Rings are produced via either seamless ring rolling (radial-axial mill, for OD > 200 mm) or open-die hammer forging (for short-run / oversize parts). Reduction ratio ≥ 4:1 from billet to final ring is enforced for grain-flow continuity. Heat treatment is per the alloy spec — solution-anneal + quench + age for precipitation-hardening alloys; quench & temper for low-alloy steels.
Dimensional Tolerance
Invar 36 rings are supplied to ASTM A788 dimensional tolerances by default: OD ±1.5 mm or ±1% (whichever is larger), ID ±1.5 mm, height ±0.8 mm. Tighter tolerances (machined finish, ±0.1 mm) available for direct-mount applications. Out-of-roundness controlled to 1.5 mm; concentricity 0.2 mm/100 mm.
Mechanical Testing
Each ring lot ships with full mechanical certification: tensile (ASTM E8), Charpy impact (ASTM E23) at the application's MDMT, hardness traverse, and grain size per ASTM E112. For Invar 36 ring stock destined for hydrogen / sour service, additional HIC testing (NACE TM0284) and SSC testing (NACE TM0177) per the customer's spec.
Surface & Inspection
Invar 36 rings ship rough-machined or finish-machined per drawing. Standard NDT: 100 % UT (ASTM A388 reference) and surface MT/PT to ASTM E709 / E165. Radiography on request. Each ring is hard-stamped with heat number, lot, and certification reference for traceability through the dispatch chain.
Specialty Fastener Alloys
TorqBolt manufactures specialty fasteners across the full range of corrosion-resistant alloys (CRAs), high-temperature superalloys, and engineered metallurgies required by the process industries. Beyond the high-volume Inconel, Hastelloy, Duplex, and stainless grades, our supply chain covers a long tail of specification-driven alloys for unique service envelopes — sour wells, extreme cryogenics, pharmaceutical-grade purity, oxidizing acids, chlorinated solvents, and high-temperature cyclic-load fasteners.
Each specialty alloy is sourced from approved mills with full melt traceability through a closed forging route. Heat-treat condition, mechanical properties, and corrosion testing are controlled to the customer's drawing or governing specification — whether ASTM, ASME, AMS, MIL, NORSOK, NACE, or proprietary end-user codes. EN 10204 3.1 (mill cert) or 3.2 (third-party witnessed) material test certificates are issued with every lot, listing chemistry, mechanicals at relevant test temperatures, hardness, dimensional inspection, and any corrosion or NDT test results required.
Third-party inspection by TUV, Lloyd's, BV, DNV, SGS, and Intertek is arrangeable. NACE MR0175 / ISO 15156 sour-service qualification, NORSOK M-650 mill qualification, API 6A wellhead bolting, API 20E subsea bolting, and PED 2014/68/EU pressure-equipment compliance available across the alloy range as the application demands.
