What material grade does S31803 Acorn Nuts use?

S31803 Acorn Nuts are manufactured per the applicable ASTM, ASME, DIN, or ISO specification for the material grade. TorqBolt provides material test certificates (MTC) per EN 10204 3.1 or 3.2 with every supply.

What sizes are available for S31803 Acorn Nuts?

TorqBolt manufactures S31803 Acorn Nuts in metric sizes M6 to M100 and imperial sizes 1/4" to 4" diameter, with custom lengths from 10mm to 3000mm. Non-standard sizes are available on request.

Are S31803 Acorn Nuts NACE MR0175 / ISO 15156 certified?

Yes, S31803 Acorn Nuts can be supplied with NACE MR0175 / ISO 15156-2/3 sour service certification when specified at order. Material certificates and test reports are provided.

What is the typical delivery time for S31803 Acorn Nuts?

Standard stock items ship in 1-2 weeks. Custom manufactured S31803 Acorn Nuts typically ship in 4-6 weeks depending on quantity, material availability, and certification requirements.

Do you provide third-party inspection for S31803 Acorn Nuts?

Yes, third-party inspection by TUV, Lloyd's Register, BV, DNV, SGS, and Intertek is available upon request for S31803 Acorn Nuts. Witness testing and stage inspections can be arranged.

S31803 Acorn Nuts Manufacturer & Supplier

S31803 Acorn Nuts Specification

The raw material of these fasteners is classified as Duplex Stainless Steel. Being a PED certified Fasteners Manufacturer by TUV Rheinland,our fasteners are accompanied with EN 10204 3.1/3.2 certification. S31803 Acorn Nuts are available in hot forged,cold forged and bar stock machined conditions depending upon the order quantity.

S31803 Acorn Nuts Equivalent Designation

UNS Designation	British STD	Werkstoff No.	European STD	Swedish STD	Japanese STD	Forging
S31803	318S13	1.4470	X2CrNiMoN22-5-3	2377	SUS 329J3L	Sa 182 F51

Surface Treatments & Coatings

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S31803 Acorn Nuts — Specifications & Dimensions

S31803 Acorn nuts are internally threaded fasteners that mate with bolts and studs to form clamped joints. TorqBolt manufactures S31803 Acorn 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, S31803 Acorn 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

S31803 Acorn 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 S31803 Acorn 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.

Duplex & Super Duplex Stainless Steels

Duplex stainless steels have a roughly 50/50 ferrite-austenite microstructure, doubling the yield strength of austenitic 304/316 grades while improving chloride pitting + stress-corrosion resistance. Duplex is the modern default for offshore platform fasteners, desalination plants, and sour-gas piping where austenitics fail to chloride SCC and martensitics fail to hydrogen embrittlement.

Duplex 2205 (UNS S32205 / S31803) is the standard grade with PREN ~35, suitable for chloride-bearing service to ~250°C. Super Duplex 2507 (S32750) and Zeron 100 (S32760) push PREN to 41-42 with higher Cr+Mo+N, qualifying for the most aggressive seawater + sour-well environments. SA-182 F51 / F53 / F55 / F60 are the ASME forged-flange equivalents.

Phase balance is critical: ferrite content must stay within 35-65% in weld + HAZ to maintain corrosion + impact properties (ASTM A923 testing). Solution anneal at 1040-1100°C followed by water quench locks the duplex microstructure. Fasteners ship per ASTM A276 / A479 with EN 10204 3.1 / 3.2 certs including ferrite count and Charpy impact at -46°C. NACE MR0175 / ISO 15156 sour-service certification is standard.

S31803 Acorn Nuts