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SS 310 / 310S Nuts Manufacturer & Exporter in India

Explore SS 310 / 310S 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 310 / 310S Nuts?

SS 310 / 310S nuts are austenitic stainless steel fasteners manufactured from UNS S31000 and UNS S31008 bar stock conforming to ASTM A276 and ASTM A479. The alloy’s high chromium content (24-26%) and elevated nickel (19-22%) deliver exceptional oxidation resistance up to 1150°C, making these nuts the standard choice for high-temperature bolted assemblies where standard 304 or 316 stainless steel fails within months.

SS 310S is the low-carbon variant (0.08% C max) that resists sensitisation during prolonged high-temperature service, preventing intergranular corrosion in the heat-affected zone of welded assemblies. SS 310 / 310S nuts are widely specified for furnace hardware, kiln linings, heat treatment equipment, and petrochemical reformer flanges where continuous or cyclic thermal exposure is the primary design challenge.

Quick Specifications

MaterialSS 310 / 310S
UNS NumberS31000 / S31008
DIN Number1.4841 / 1.4845
Material StandardASTM A276 / ASTM A479
Nut Standard (Metric)DIN 934 / DIN 6915 / ISO 4032
Nut Standard (Inch)ASME B18.2.2
Thread FormISO Metric / UNC / UNF
Size RangeM6-M100 / ¼"-4"
Tensile Strength515 MPa (75 ksi) min
Yield Strength205 MPa (30 ksi) min
HardnessMax 95 HRB / 217 HB
? All material certified by NABL-accredited laboratory. PMI available on request.

Complete the Fastener Set

Other SS 310 / 310S Fastener Products Available from RealBolt

RealBolt also manufactures the complete SS 310 / 310S fastener range — SS 310 / 310S Bolts, SS 310 / 310S Screws, SS 310 / 310S Washers, SS 310 / 310S Studs, SS 310 / 310S Threaded Rods — from certified bar stock per ASTM with full EN 10204 MTC 3.1/3.2 documentation and fast Mumbai dispatch.
SS 310 / 310S Bolts
SS 310 / 310S Screws
SS 310 / 310S Washers
SS 310 / 310S Studs
SS 310 / 310S Threaded Rods

Technical Data

SS 310 / 310S Nuts Dimensions, Sizes & Thread Standards

SS 310 / 310S Nuts are available in metric M6–M100 and inch ¼″–4″ as standard. Per DIN 934 (hex nuts) / DIN 6915 (heavy hex nuts) / ISO 4032. Custom sizes available. Inch dimensions per ASME B18.2.2. All SS 310 / 310S nuts dimensions are verified against applicable DIN, ISO,

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

Size (M)Pitch (mm)A/F (mm)Nut Height (mm)A/C (mm)
M61.0105.011.05
M81.25136.514.38
M101.5178.018.90
M121.751910.020.03
M162.02413.026.75
M202.53016.032.95
M243.03619.039.55
M303.54624.050.85
M364.05529.060.79
M424.56534.071.30
M485.07538.082.60
M565.58545.093.56
M646.09551.0104.86
M726.010558.0116.16
M806.011564.0127.46
M1006.014580.0160.00

Dimensional & Material Standards

StandardCoversThread
DIN 934Hex nuts, standard heightMetric
DIN 6915Heavy hex nuts, high-strengthMetric
ISO 4032Hex nuts, style 1Metric
ISO 4033Hex nuts, style 2 (tall)Metric
ASME B18.2.2Hex & heavy hex nutsUNC/UNF
ASME B16.5Heavy hex nuts for flangesUNC
MSS SP-75Heavy hex nuts, high-pressureUNC
Material StandardRequirement
ASTM A276Bar/rod - UNS S31000 / S31008
ASTM A479Bar for pressure vessels
ASTM A194 Gr. 8Nut mechanical properties
EN 10204 3.1Mill test certificate
EN 10204 3.2TPI-witnessed MTC

Material Chemistry

SS 310 / 310S Chemical Composition

SS 310 / 310S 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 / EN 10088-3

ElementSS 310 (%)SS 310S (%)
Carbon (C)0.25% max0.08% max
Chromium (Cr)24.0-26.0%24.0-26.0%
Nickel (Ni)19.0-22.0%19.0-22.0%
Manganese (Mn)2.0% max2.0% max
Silicon (Si)1.5% max1.5% max
Phosphorus (P)0.045% max0.045% max
Sulphur (S)0.030% max0.030% max
Iron (Fe)BalanceBalance
? All heats verified by NABL-accredited spectrometry. PMI available on request.

Why SS 310 / 310S Alloy Composition Matters for Nuts

Cr (24–26%) — High-Temperature Oxidation Resistance
The elevated chromium content forms a dense, adherent Cr2O3 oxide scale that remains stable up to 1150°C in continuous service. This prevents scaling and thread degradation in furnace door bolting, kiln hardware, and heat treatment basket assemblies where nuts are repeatedly cycled through high temperatures.
Ni (19–22%) — Structural Stability at Elevated Temperature
High nickel content stabilises the austenitic structure at elevated temperatures, preventing sigma phase embrittlement during long-term thermal exposure. SS 310 / 310S nuts retain adequate ductility and thread integrity even after thousands of hours above 800°C.
Low Carbon in 310S — Sensitisation Prevention
The 310S variant limits carbon to 0.08% max, suppressing chromium carbide precipitation at grain boundaries during slow cooling or prolonged service in the 425–870°C sensitisation range. This makes 310S nuts the preferred choice for welded assemblies and cyclic thermal applications where intergranular corrosion is a risk.

Fastener Performance

SS 310 / 310S Nuts Mechanical Properties & Torque Reference

The table below lists mechanical properties and torque reference for SS 310 / 310S Nuts per ASTM. SS 310 / 310S nuts achieve 620 MPa tensile strength, with hardness, yield, and elongation values verified by NABL-accredited testing and reported in the EN 10204 MTC.

Tightening Torque Reference - SS 310 / 310S Hex Nuts

Nut SizeDry (Nm)Lubricated (Nm)Clamp Load (kN)
M12554420
M1613510849
M2026521278
M24460368113
M30920736180
M3616001280261
M4225502040360
M4838003040473
?? Anti-galling: SS 310 / 310S nuts are prone to galling against stainless steel bolts at elevated temperatures. Use high-temperature anti-seize (Molykote 1000 or Jet-Lube SS-30) on all threads. Lubricated values assume K=0.17. Inspect threads for cold welding after each thermal cycle.

Industry Applications

SS 310 / 310S Nuts Applications — Industries & End Uses

SS 310 / 310S 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 310 / 310S hex nuts and heavy hex nuts are the standard fastener for furnace door frames, muffle furnace shell assemblies, heat treatment basket hardware, and annealing bell furnace flanges. Continuous service temperatures up to 1150°C are handled without scaling or thread seizure that would occur with 304 or 316 stainless steel nuts.
Heavy hex nuts for reformer tube hanger connections, fired heater tube support brackets, and radiant section flange assemblies in hydrogen reforming and steam cracking units. The high chromium-nickel content resists carburisation and oxidising flue gas atmospheres at tube skin temperatures exceeding 900°C.
SS 310 / 310S nuts are used on kiln shell bolting, riding ring attachment hardware, and tyre retaining plate connections where continuous exposure to 800-1100°C process temperatures and abrasive dust environments demands superior oxidation resistance and dimensional stability over long maintenance intervals.
Flange nut sets for waste-to-energy incinerator grate assemblies, superheater header connections, and boiler casing expansion joint hardware. The alloy’s resistance to sulphidation and chlorine-bearing combustion gases at elevated temperatures makes it the preferred choice over lower-alloy stainless grades in these environments.

SS 310 / 310S Nuts Standards & International Certifications

SS 310 / 310S 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, hardness test certificate, ISO 3506 material certification, and NABL-accredited lab reports — available on request for all orders.
Standards
DIN 934 ISO 4032 ASME B18.2.2 EN ISO 4032 IS 1364 IS 1367
Certifications
ISO 9001:2015PED 2014/68/EUNABL LabMTC 3.1 / 3.2RoHS Compliant

Buy SS 310 / 310S Nuts from India's Leading Manufacturer — Get a Competitive Quote Today

Partner with RealBolt — India’s leading manufacturer of certified SS 310 / 310S 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.
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Answers for Buyers

SS 310 / 310S Nuts — Frequently Asked Questions

Browse expert answers to common questions about SS 310 / 310S 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 310 / 310S nuts selection and pricing.
The primary difference is carbon content. SS 310 nuts allow up to 0.25% carbon, while SS 310S limits carbon to 0.08% maximum. In practice, 310S is preferred for most high-temperature applications because the lower carbon content prevents chromium carbide precipitation at grain boundaries during prolonged exposure in the 425-870°C sensitisation range. This eliminates the risk of intergranular corrosion in service. Both grades share identical chromium (24-26%) and nickel (19-22%) content and are interchangeable dimensionally. Specify 310S for welded assemblies or cyclic thermal service; 310 is acceptable for short-term or non-welded high-temperature applications.
SS 310 / 310S nuts are available to DIN 934 (standard hex nuts, metric), DIN 6915 (heavy hex nuts), ISO 4032 (style 1) and ISO 4033 (style 2 tall), and ASME B18.2.2 for inch heavy hex nuts used in ASME B16.5 flange assemblies. Coupling nuts, dome nuts, and flange nuts are also available in SS 310 / 310S on request. Custom thread forms including BSW, BSF, and BSPP are available with a 15 working day lead time.
Austenitic stainless steel grades including SS 310 and 310S are susceptible to galling – a form of adhesive wear that cold-welds mating threads under high contact pressure. This risk increases significantly at elevated temperatures. To prevent galling, always apply a high-temperature anti-seize compound such as Molykote 1000, Jet-Lube SS-30, or Bostik Never-Seez High-Temperature to all threads and bearing faces before assembly. Reduce torque values by approximately 20% when using anti-seize. After thermal cycling, inspect threads before re-torquing, as partial cold welding can occur even with lubrication.
SS 310 / 310S nuts are rated for continuous service up to 1150°C and intermittent service up to 1040°C. Above 1040°C in intermittent cycling, sigma phase formation can occur over extended periods, reducing ductility. For applications above 1100°C or involving rapid thermal cycling, consider specifying solution-annealed material with a post-fabrication anneal, or consult our engineering team regarding alternative alloys such as Alloy 330 or Inconel 601 for extreme conditions.

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