Alloy 20 Nuts

Alloy 20 Nuts — Specifications & Dimensions

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

Locking Variants

For vibration-loaded joints, Alloy 20 nuts are available as nyloc, all-metal prevailing-torque (DIN 980), flange-serrated (DIN 6923), and castle / slotted (DIN 935, cotter-pin retention).

Mechanical & Certification

Alloy 20 nut threads are gauged per ASME B1.1 / ISO 965 to Class 2B / 6H. Proof-load testing per ASTM F606 verifies the nut develops the bolt's full strength without thread strip. Each lot ships with EN 10204 3.1 / 3.2 certificates. NACE MR0175 / ISO 15156 sour-service certification available.

High-Mo Super-Austenitic Stainless (254 SMO, 904L, Alloy 20)

Super-austenitic stainless steels are high-Mo (≥6%), high-N austenitic alloys with chloride-pitting resistance approaching duplex grades while retaining austenitic formability.

254 SMO (S31254) is the benchmark with PREN ~43. 904L (N08904) is the original 4.5% Mo super-austenitic for sulfuric-acid plants. Alloy 20 (N08020) is Cu-bearing for hot sulfuric acid. AL-6XN (N08367) extends pitting resistance with 6.5%+ Mo.

Super-austenitic fasteners ship per ASTM A276 / A479 with ASTM G48 Method A pitting testing. Welding requires Ni-base filler (alloy 625 / C-276) to avoid Mo segregation.

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