ALLOY 20 Nuts manufactured at TorqBolt are corrosion resistant,high temperature resistant with ultimate tensile strength.
Dimensional standards as per ANSI B18.2.2 in imperial and ANSI B18.2.4.6M in metric are provided.
The raw material of these fasteners is renowned as registered trademarks like Carpenter® 20, 20CB-3®. Being a PED certified Fasteners Manufacturer by TUV Rheinland,our fasteners are accompanied with EN 10204 3.1/3.2 certification. ALLOY 20 Nuts are available in hot forged,cold forged and bar stock machined conditions depending upon the order quantity.
Alloy 20 Is A Nickel Chromium Alloy With Maximum Resistance To Sulphuric Acid. Alloy 20 Has Good Resistance To Corrosion ,pitting’s And Crevice Cracking. Addition Of Niobium Stabilizes Sensitive Intergranular Corrosion. This Alloy Is Provided In Both Solution Annealed And Stress Relieved Condition.
Alloy 20 nuts are internally threaded fasteners that mate with bolts and studs to form clamped joints. TorqBolt manufactures Alloy 20 nuts per ASME B18.2.2, ISO 4032/4033/4034, DIN 934/EN 24032, and DIN 6915 (heavy hex), in sizes M6–M100 and 1/4"–4".
Nut Height Categories
Standard / regular hex nut — ~0.875×D height, ASME B18.2.2 Type 1
Heavy hex nut — ~D height, full strength matched to bolt grade (A194 2H pattern)
Jam / thin nut — 0.5×D height, used as locknut against a primary nut
Coupling nut — long-form for joining two threaded rods
Cap / acorn nut — closed-end, decorative + thread protection
Locking Variants
For vibration-loaded joints, Alloy 20 nuts are available as nyloc (polymer insert), all-metal prevailing-torque (DIN 980, distorted-thread style), flange-serrated (DIN 6923, integral washer face with anti-back-off teeth), and castle / slotted (DIN 935, cotter-pin retention). Each locking style trades reusability against prevailing-torque retention.
Thread & Mechanical
Alloy 20 nut threads are gauged per ASME B1.1 / ISO 965 to Class 2B / 6H by default; high-strength variants use 3B / 4H6H. Proof-load testing per ASTM F606 verifies the nut can develop the bolt's full strength without thread strip; hardness range is controlled to prevent stress-corrosion susceptibility (HV 250–353 typical for high-grade nuts). Each lot is EN 10204 3.1 / 3.2 certified.
Special Patterns
TorqBolt also produces Alloy 20 nuts in weld-nut, T-nut, square-nut, knurled thumb-nut, and rivet-nut patterns. NACE MR0175 / ISO 15156 sour-service certification available; NORSOK M-650 qualified mills supplying high-temperature service grades.
Super-austenitic stainless steels are high-molybdenum (Mo ≥ 6%), high-nitrogen austenitic alloys positioned above the 316L envelope but below nickel-alloy cost. They deliver chloride-pitting resistance approaching duplex grades while retaining the formability and weldability of austenitic structure — ideal for seawater + flue-gas-desulfurization service.
254 SMO (UNS S31254) is the benchmark with PREN ~43, formulated for the most aggressive chloride + sulfuric acid service. 904L (N08904) is the original 4.5% Mo super-austenitic, widely specified for sulfuric-acid plants. Alloy 20 (N08020) is a Cu-bearing variant optimized specifically for hot sulfuric acid (50-80%) where standard austenitics fail rapidly. AL-6XN (N08367) and 654 SMO (S32654) extend service to higher pitting resistance with 6.5%+ Mo.
Super-austenitic fasteners are supplied per ASTM A276 / A479 with EN 10204 3.1 / 3.2 certification including pitting-resistance testing per ASTM G48 Method A at the temperature appropriate for the alloy. Welding requires Ni-base filler (alloy 625 / C-276) to avoid molybdenum segregation in the weld pool that would create preferential corrosion sites. NACE MR0175 sour-service certification is standard.
