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SS 310 / 310S Washers Manufacturer & Exporter in India

Explore SS 310 / 310S Washers 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 Washers?

SS 310 / 310S washers are austenitic stainless steel fasteners manufactured from UNS S31000 and UNS S31008 plate or bar stock conforming to ASTM A240 and ASTM A276. The alloy’s high chromium (24-26%) and nickel (19-22%) content delivers exceptional oxidation resistance up to 1150°C in continuous service, making these washers the standard choice for high-temperature bolted assemblies.

The combination of chromium and nickel in SS 310 / 310S creates a stable austenitic structure that resists scaling, carburisation, and thermal fatigue under cyclic heating conditions. These washers are widely specified for furnace construction, heat treatment equipment, and petrochemical fired heater flanges where standard 304 or 316 stainless steel washers fail prematurely due to oxidation and creep.

Quick Specifications

MaterialSS 310 / 310S
UNS NumberS31000 / S31008
DIN Number1.4841 / 1.4845
Material StandardASTM A240 / ASTM A276
Washer Standard (Metric)DIN 125 / DIN 9021 / ISO 7089
Washer Standard (Inch)ASME B18.22.1 / ANSI B18.22M
TypePlain / Spring / Flat / Fender
Diameter RangeM3-M100 / #4-4"
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 Nuts, SS 310 / 310S Screws, 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 Nuts
SS 310 / 310S Screws
SS 310 / 310S Studs
SS 310 / 310S Threaded Rods

Technical Data

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

SS 310 / 310S Washers are available in metric M6–M100 and inch ¼″–4″ as standard. Per DIN 125 (flat washers) / DIN 9021 (large OD washers) / ISO 7089. Custom OD and thickness available. Inch dimensions per ASME B18.22.1. All SS 310 / 310S washers dimensions conform to applicable DIN, ISO, and ASME B18 standards.

Flat Washer Dimensions - Metric (DIN 125 / ISO 7089)

Bolt Size (M)ID (mm)OD (mm)Thickness (mm)Large OD DIN 9021 (mm)
M33.270.59
M44.390.812
M55.3101.015
M66.4121.618
M88.4161.624
M1010.5202.030
M1213.0242.537
M1617.0303.050
M2021.0373.060
M2425.0444.072
M3031.0564.092
M3637.0665.0110
M4243.0787.0125
M4850.0928.0145
M5658.01059.0168
M6466.01159.0185

Dimensional & Material Standards

StandardCoversSystem
DIN 125Plain flat washers, normal seriesMetric
DIN 9021Large OD flat washersMetric
ISO 7089Plain washers, normal series, 200 HVMetric
ISO 7090Plain washers with chamferMetric
ASME B18.22.1Plain washers, inch seriesInch
ANSI B18.22MMetric plain washersMetric
DIN 6796Conical spring washers for bolted connectionsMetric
Material StandardRequirement
ASTM A240Plate/sheet - UNS S31000 / S31008
ASTM A276Bar/rod - UNS S31000 / S31008
ASTM A480General requirements for flat-rolled stainless
EN 10204 3.1Mill test certificate
EN 10204 3.2TPI-witnessed MTC

Material Chemistry

SS 310 / 310S Chemical Composition

SS 310 / 310S Washers 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 A240 / ASTM A276

ElementSS 310 (S31000)SS 310S (S31008)
Chromium (Cr)24.0-26.0%24.0-26.0%
Nickel (Ni)19.0-22.0%19.0-22.0%
Carbon (C)0.25% max0.08% max
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 Washers

Cr (24–26%) — High-Temperature Oxidation Resistance
The elevated chromium content forms a dense, adherent Cr2O3 oxide scale that protects the washer surface from oxidation and scaling at continuous service temperatures up to 1150°C — far beyond the capability of 304 or 316 stainless steel washers.
Ni (19–22%) — Austenitic Stability & Thermal Fatigue Resistance
High nickel content stabilises the fully austenitic microstructure across the entire service temperature range, preventing sigma phase embrittlement and maintaining ductility under repeated thermal cycling — critical for washers in furnace door and kiln car assemblies.
310S vs 310 — Lower Carbon for Weld-Adjacent Applications
SS 310S limits carbon to 0.08% max versus 0.25% in SS 310, significantly reducing the risk of sensitisation and intergranular corrosion in the heat-affected zone when washers are used in welded assemblies or exposed to temperatures in the 425–870°C sensitisation range.

Fastener Performance

SS 310 / 310S Washers Mechanical Properties & Torque & Proof Load Reference

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

Washer Bearing Load Reference - Metric Flat Washers (DIN 125)

Washer SizeID (mm)OD (mm)Thickness (mm)Max Bearing Load (kN)
M88.4161.612
M1010.5202.020
M1213.0242.530
M1617.0303.055
M2021.0373.085
M2425.0444.0125
M3031.0564.0195
M3637.0665.0285
?? Note: Bearing load values are indicative at room temperature. At elevated service temperatures above 600°C, apply a derating factor per ASME VIII Div.1 Appendix 2 allowable stress tables. Use anti-galling compound on mating surfaces in high-temperature assemblies.

Industry Applications

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

SS 310 / 310S Washers 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 washers are the standard specification for bolted connections on industrial furnace shells, muffle furnace doors, annealing bell covers, and heat treatment basket assemblies. Continuous service to 1150°C without scaling or distortion makes these washers the preferred choice over 304 or 321 stainless steel in thermal processing plants.
Flat and large-OD washers for fired heater tube support hangers, radiant section flange connections, and refractory anchor bolt assemblies in crude distillation units and catalytic reformers. SS 310 / 310S resists the combined effects of sulphidation, oxidation, and carburisation present in refinery fired heater environments.
Washer sets for superheater tube support clamps, boiler casing flange connections, and steam header insulation cladding fixings in coal-fired and biomass power stations. The alloy’s resistance to steam oxidation and thermal cycling fatigue at temperatures above 900°C makes it suitable where 347H stainless steel is not available.
SS 310 / 310S washers are used in rotary kiln shell bolted connections, kiln hood flange assemblies, and preheater cyclone casing fixings where process gas temperatures exceed 1000°C and sulphur-bearing atmospheres accelerate corrosion of lower-alloy stainless steel fasteners.

SS 310 / 310S Washers Standards & International Certifications

SS 310 / 310S Washers 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 125A DIN 126 DIN 127 DIN 128 ISO 7089 ISO 7090 ASME B18.21.1 EN ISO 7089 IS 5372 IS 1367
Certifications
ISO 9001:2015NABL LabPED 2014/68/EUMTC 3.1 / 3.2RoHS Compliant

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

Partner with RealBolt — India’s leading manufacturer of certified SS 310 / 310S Washers — 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 Washers — Frequently Asked Questions

Browse expert answers to common questions about SS 310 / 310S Washers 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 washers selection and pricing.
The primary difference is carbon content. SS 310 (UNS S31000) allows up to 0.25% carbon, while SS 310S (UNS S31008) limits carbon to 0.08% maximum. Both grades share the same chromium (24-26%) and nickel (19-22%) content and offer identical oxidation resistance to 1150°C. SS 310S is preferred for applications involving welded assemblies or exposure to the sensitisation temperature range of 425-870°C, where the lower carbon content prevents intergranular corrosion. For purely high-temperature non-welded applications, SS 310 is acceptable and typically more cost-effective.
SS 310 / 310S washers are rated for continuous service up to 1150°C and intermittent service up to 1040°C in oxidising atmospheres. In sulphidising or carburising atmospheres, the effective maximum temperature is lower – typically 900-1000°C – due to accelerated attack on the chromium oxide scale. For cyclic thermal applications such as furnace door assemblies, the intermittent rating of 1040°C applies. Always consult the ASME VIII Div.1 allowable stress tables for the specific service temperature when calculating bolted joint integrity at elevated temperatures.
SS 310 / 310S flat washers are manufactured to DIN 125 (normal series), DIN 9021 (large OD series), and ISO 7089 for metric sizes. Inch-series washers are produced per ASME B18.22.1 (narrow, regular, and wide series). Spring washers are per DIN 127 (split lock) and DIN 6796 (conical disc). Custom OD and thickness combinations outside standard series are available with a 10-15 working day lead time. All dimensional standards are met with material conforming to ASTM A240 or ASTM A276 as applicable.
Yes – SS 310 / 310S washers are fully compatible with A4-70 and A4-80 (316 / 316L) stainless steel bolts and nuts. There is no significant galvanic potential difference between austenitic stainless steel grades in the same family, so galvanic corrosion is not a concern. However, in high-temperature applications above 800°C, the bolt material should also be SS 310 or a higher-temperature alloy – using SS 310 / 310S washers with 316 stainless bolts at temperatures above 800°C is not recommended as the bolt will fail before the washer.

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