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SS 321 Nuts Manufacturer & Exporter in India

Explore SS 321 Nuts Manufacturer & Exporter in India manufactured for demanding industrial applications with reliable strength, corrosion resistance and compliance with international standards.
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-196

Min Temp

870

Max Temp

🌡

870

Suitable for continuous service up to approximately 870°C under typical operating conditions.

⚡

620

Typical tensile strength around 620 MPa depending on product form and heat treatment.

🛡

Very Good

Very Good corrosion resistance in a wide range of industrial environments.

⚖

8

Typical density is approximately 8.0 g/cm³.

Product Overview

What are SS 321 Nuts?

SS 321 nuts are austenitic stainless steel fasteners manufactured from UNS S32100 bar stock, conforming to ASTM A276 and ASTM A194 Grade 8T. Alloy 321 is stabilized with titanium, which prevents intergranular corrosion during welding and high-temperature service. These nuts are widely specified for bolted joints exposed to temperatures up to 870°C, where standard 304/316 stainless steel would suffer from carbide precipitation and loss of corrosion resistance.

SS 321 nuts are the preferred choice for petrochemical, power generation, and exhaust system applications requiring resistance to oxidation, scaling, and polythionic acid stress corrosion cracking. All nuts are supplied with full traceability and EN 10204 3.1 certification.

Quick Specifications

MaterialStainless Steel 321
UNS NumberS32100
DIN Number1.4541
Material StandardASTM A276 / ASTM A194 8T
Nut Standard (Metric)DIN 934 / ISO 4032
Nut Standard (Inch)ASME B18.2.2
Thread FormISO Metric / UNC / UNF
Size RangeM6-M64 / ¼"-2½"
Tensile Strength515 MPa (75 ksi) min
Yield Strength205 MPa (30 ksi) min
HardnessMax 95 HRB
? All material certified by NABL-accredited laboratory. PMI and IGC test available on request.

Complete the Fastener Set

Other SS 321 Fastener Products Available from RealBolt

RealBolt also manufactures the complete SS 321 fastener range from certified stainless steel bar stock, including SS 321 Bolts, SS 321 Screws, SS 321 Washers, SS 321 Studs, and SS 321 Threaded Rods. All SS 321 fastener types are produced to ASTM with full EN 10204 MTC 3.1/3.2 documentation.
SS 321 Bolts
SS 321 Screws
SS 321 Washers
SS 321 Studs
SS 321 Threaded Rods

Technical Data

SS 321 Nuts Dimensions, Sizes & Thread Standards

SS 321 Nuts are available in metric M6–M100 and inch ¼″–4″ as standard. Per DIN 934 (hex nut) / ISO 4032. Custom thread pitches and special nut forms available. Inch sizes per ASME B18.2.2. All SS 321 nuts dimensions are verified against applicable DIN, ISO, and ASME B18 standards before

Hex Nut Dimensions - Metric (DIN 934 / ISO 4032)

Size (M)Pitch (mm)A/F (mm)Height (mm)
M61.0105.0
M81.25136.5
M101.5178.0
M121.751910.0
M162.02413.0
M202.53016.0
M243.03619.0
M303.54624.0
M364.05529.0
M424.56534.0
M485.07538.0
M565.58545.0
M646.09551.0

Dimensional & Material Standards

StandardCoversThread
DIN 934Hex nutsMetric
ISO 4032Hex nutsMetric
ASME B18.2.2Hex & heavy hex nutsUNC/UNF
ISO 7040Prevailing torque nutsMetric
DIN 985Lock nutsMetric
Material StandardRequirement
ASTM A276Bar/rod - UNS S32100
ASTM A194 8TNut mechanical
EN 10204 3.1Mill test certificate
EN 10204 3.2TPI-witnessed MTC

Material Chemistry

SS 321 Chemical Composition

SS 321 Nuts are manufactured from an iron-chromium-nickel alloy with chromium (16–26%), nickel (8–28%), and grade-specific molybdenum additions per ASTM and ASTM A193/A194. Chromium content governs the self-healing passive oxide film; molybdenum (2–6%) enhances chloride pitting resistance; and carbon content determines sensitization risk in welded assemblies.

Chemical Composition per ASTM A276 / A194 8T

ElementComposition (%)
Chromium (Cr)17.0-19.0
Nickel (Ni)9.0-12.0
Carbon (C)0.08 max
Manganese (Mn)2.0 max
Silicon (Si)0.75 max
Phosphorus (P)0.045 max
Sulfur (S)0.030 max
Titanium (Ti)5xC min, 0.70 max
Iron (Fe)Balance
? All heats verified by NABL-accredited spectrometry. PMI and IGC test available on request.

Why SS 321 Alloy Composition Matters for Nuts

Titanium Stabilization
Titanium in SS 321 binds carbon, preventing chromium carbide precipitation at grain boundaries. This ensures nuts retain corrosion resistance after welding or high-temperature exposure, unlike standard 304/316 nuts.
High-Temperature Oxidation Resistance
The 17–19% chromium and 9–12% nickel content provides excellent resistance to oxidation and scaling up to 870°C, making SS 321 nuts ideal for exhaust manifolds and furnace assemblies.
No Sensitization in Service
SS 321 nuts are immune to intergranular attack in the 425–850°C range, ensuring long-term joint integrity in thermal cycling and polythionic acid environments.

Fastener Performance

SS 321 Nuts Mechanical Properties & Torque Reference

The table below lists mechanical properties and torque reference for SS 321 Nuts per ASTM. SS 321 nuts achieve 620 MPa tensile strength, with hardness, yield, and elongation values verified by NABL-accredited testing and reported in the EN 10204 MTC.

Nut SizeRecommended Torque (Nm)Clamp Load (kN)
M127032
M1617065
M20340110
M24590160
M301200260
M362100380
M423200510
M484700670
?? Anti-galling: Use molybdenum-based or PTFE anti-seize. Lubricated values assume K=0.16. Avoid dry assembly for austenitic stainless nuts.

Industry Applications

SS 321 Nuts Applications — Industries & End Uses

SS 321 Nuts from RealBolt are specified across food and dairy, pharmaceutical, marine, chemical processing, and oil and gas where very good corrosion resistance and 620 MPa tensile strength are required for reliable fastener performance. Click each industry below for detailed application examples.
SS 321 nuts are widely used for bolted joints in heat exchangers, reactors, and piping systems handling hot hydrocarbons, steam, and polythionic acid. Their titanium stabilization prevents intergranular corrosion during shutdowns and thermal cycling.
Hex nuts and lock nuts for automotive, marine, and industrial exhaust manifolds, turbochargers, and furnace assemblies. SS 321 nuts maintain mechanical integrity and resist scaling at elevated temperatures.
Used in heat recovery steam generator (HRSG) ductwork, boiler flanges, and turbine casings where resistance to oxidation and stress corrosion cracking is critical for long-term reliability.
SS 321 nuts are specified for process piping and pressure vessels in food and pharma plants where frequent steam cleaning and high-temperature sterilization cycles occur.

SS 321 Nuts Standards & International Certifications

SS 321 Nuts from RealBolt Engineering Industries are manufactured to internationally recognised fastener dimensional standards covering thread form, tolerances, strength grades, and quality requirements. Every batch ships with EN 10204 MTC 3.1/3.2, IS 12427 compliance, ISO 3506 material certification, NACE MR0175, and PMI (XRF) reports — available on request for all orders.
Standards
DIN 934 DIN 980 DIN 982 DIN 985 DIN 439 DIN 315 DIN 1587 DIN 6923 ISO 4032 ISO 7040 ISO 4161 ASME B18.2.2 EN ISO 4032 BS EN ISO 4032 IS 1363 IS 1364 IS 6623 IS 12427 SAE J995 UNI 5588 UNI 6593 CSN 021123 PN 82144
Certifications
ISO 9001:2015PED 2014/68/EUNABL LabMTC 3.1 / 3.2

Buy SS 321 Nuts from India's Leading Manufacturer — Get a Competitive Quote Today

Partner with RealBolt — India’s leading manufacturer of certified SS 321 Nuts — for competitive pricing, EN 10204 MTC 3.1/3.2 documentation, and fast Mumbai dispatch. Standard sizes are ex-stock; custom dimensions accepted with 2–3 week lead time. Request your quote today.
022-6743-7972
+91 90226 36025
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Answers for Buyers

SS 321 Nuts — Frequently Asked Questions

Browse expert answers to common questions about SS 321 Nuts from RealBolt — covering ASTM A193/A194 grades, chloride resistance, temperature limits, sensitization, sizes, and MTC documentation. Contact our technical team directly for project-specific guidance on SS 321 nuts selection and pricing.
SS 321 hex nuts are available to DIN 934 (metric), ISO 4032, and ASME B18.2.2 (inch hex and heavy hex). Lock nuts (DIN 985), prevailing torque nuts (ISO 7040), and custom forms are also available. Special threads (BSW, BSF, BSPP) can be supplied on request.
Molybdenum-based or PTFE anti-seize is recommended for SS 321 nuts to prevent galling and seizing during assembly. Avoid copper-based anti-seize in chloride or high-temperature environments. Always apply lubricant to both threads and nut bearing surfaces for consistent preload.
Yes – SS 321 nuts are specifically designed for high-temperature service up to 870°C. Their titanium stabilization prevents loss of corrosion resistance and ensures mechanical integrity in exhaust manifolds, turbochargers, and furnace assemblies.
No MOQ for standard sizes (M8-M36) held in stock – single-piece orders are accepted for urgent maintenance. Custom sizes or special nut types may require a 10 kg minimum. Bulk price breaks at 50, 200, and 500 pieces.

Industrial Cities We Serve:

  • Ahmedabad
  • Aurangabad
  • Bengaluru
  • Chennai
  • Coimbatore
  • Faridabad
  • Gandhidham
  • Greater Noida
  • Gurugram
  • Hazira
  • Hosur
  • Hyderabad
  • Jamnagar
  • Jamshedpur
  • Ludhiana
  • Mumbai
  • Mundra
  • Mysuru
  • Nagpur
  • Nashik
  • Navi Mumbai
  • Noida
  • Pune
  • Rajkot
  • Sanand
  • Surat
  • Thane
  • Tiruppur
  • Vadodara
  • Visakhapatnam

Countries We Export To:

  • US
  • Canada
  • Mexico
  • Germany
  • UK
  • France
  • Italy
  • Spain
  • Netherlands
  • Belgium
  • Poland
  • Sweden
  • Norway
  • Denmark
  • Turkey
  • UAE
  • Saudi Arabia
  • Qatar
  • Oman
  • Kuwait
  • Bahrain
  • South Africa
  • Egypt
  • Nigeria
  • Australia
  • New Zealand
  • Singapore
  • Malaysia
  • Indonesia
  • Thailand
  • Vietnam
  • South Korea
  • Japan
  • Brazil