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SS 347 / 347H Washers Manufacturer & Exporter in India

Explore SS 347 / 347H 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 347 / 347H Washers?

SS 347 / 347H washers are austenitic stainless steel flat, spring, and lock washers manufactured from stabilized grades UNS S34700 and UNS S34709. These grades are alloyed with columbium (niobium) to prevent intergranular corrosion after welding and at elevated temperatures. SS 347H contains higher carbon (0.04-0.10%) for improved high-temperature creep strength, making these washers ideal for bolted joints exposed to thermal cycling and aggressive process media.

SS 347 / 347H washers are specified for use in petrochemical, power generation, and refinery applications where resistance to polythionic acid stress corrosion cracking and scaling up to 870°C is required. All washers are produced to ASTM A240/A276 and supplied with EN 10204 3.1 certification.

Quick Specifications

MaterialStainless Steel 347 / 347H
UNS NumberS34700 / S34709
DIN Number1.4550 / 1.4961
Material StandardASTM A240 / ASTM A276
Washer Standard (Metric)DIN 125 / DIN 127 / DIN 9021
Washer Standard (Inch)ASME B18.22.1
TypeFlat, Spring, Lock, Tab, Belleville
Size RangeM3-M100 / 1/8"-4"
Tensile Strength515 MPa (75 ksi) min
Yield Strength205 MPa (30 ksi) min
HardnessMax 217 HB
? All washers supplied with full traceability and PMI. Custom sizes available on request.

Complete the Fastener Set

Other SS 347 / 347H Fastener Products Available from RealBolt

RealBolt also manufactures the complete SS 347 / 347H fastener range — SS 347 / 347H Bolts, SS 347 / 347H Nuts, SS 347 / 347H Screws, SS 347 / 347H Studs, SS 347 / 347H Threaded Rods — from certified bar stock per ASTM with full EN 10204 MTC 3.1/3.2 documentation and fast Mumbai dispatch.
SS 347 / 347H Bolts
SS 347 / 347H Nuts
SS 347 / 347H Screws
SS 347 / 347H Studs
SS 347 / 347H Threaded Rods

Technical Data

SS 347 / 347H Washers Dimensions, Sizes & Thread Standards

SS 347 / 347H Washers are available in metric M6–M100 and inch ¼″–4″ as standard. Per DIN 125 (flat), DIN 127 (spring), DIN 9021 (large OD), and ASME B18.22.1. Custom thicknesses and outside diameters available. Metric and inch sizes supplied as standard.

Flat Washer Dimensions - Metric (DIN 125)

Size (M)ID (mm)OD (mm)Thickness (mm)
M66.4121.6
M88.4161.6
M1010.5202.0
M1213.0242.5
M1617.0303.0
M2021.0373.0
M2425.0444.0
M3031.0564.0
M3637.0665.0
M4243.0786.0
M4849.0926.0
M5657.01058.0
M6465.01158.0
M7273.013010.0
M8081.014010.0
M100101.018012.0

Dimensional & Material Standards

StandardCoversType
DIN 125Flat washersMetric
DIN 127Spring lock washersMetric
DIN 9021Large OD washersMetric
ASME B18.22.1Plain & lock washersInch
ISO 7089Flat washersMetric
ISO 7090Chamfered washersMetric
Material StandardRequirement
ASTM A240Plate/sheet - SS 347/347H
ASTM A276Bar/rod - SS 347/347H
EN 10088-2Stainless steel flat products
EN 10204 3.1Mill test certificate
EN 10204 3.2TPI-witnessed MTC

Material Chemistry

SS 347 / 347H Chemical Composition

SS 347 / 347H 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 / A276

ElementSS 347 (%)SS 347H (%)
Chromium (Cr)17.0-19.017.0-19.0
Nickel (Ni)9.0-13.09.0-13.0
Carbon (C)0.08 max0.04-0.10
Manganese (Mn)2.00 max2.00 max
Silicon (Si)1.00 max1.00 max
Phosphorus (P)0.045 max0.045 max
Sulfur (S)0.030 max0.030 max
Niobium (Nb)10xC-1.010xC-1.0
Iron (Fe)BalanceBalance
? All heats spectro-tested and certified. PMI and full traceability available.

Why SS 347 / 347H Alloy Composition Matters for Washers

Nb Stabilization — Intergranular Corrosion Resistance
Niobium (columbium) additions prevent chromium carbide precipitation at grain boundaries, ensuring SS 347 / 347H washers resist intergranular attack after welding or high-temperature exposure.
High Carbon (347H) — Creep Strength
The higher carbon content in SS 347H improves creep resistance and mechanical stability at temperatures above 500°C, making these washers suitable for bolted joints in heat exchangers and reactors.
Austenitic Structure — Ductility & Formability
The austenitic matrix provides excellent ductility, allowing washers to be formed into various shapes (flat, spring, tab) without cracking, and ensures reliable sealing under dynamic loads.

Fastener Performance

SS 347 / 347H Washers Mechanical Properties & Torque Reference

The table below lists mechanical properties and torque reference for SS 347 / 347H Washers per ASTM. SS 347 / 347H washers achieve 620 MPa tensile strength, with hardness, yield, and elongation values verified by NABL-accredited testing and reported in the EN 10204 MTC.

Bolt SizeRecommended Washer OD (mm)Recommended Thickness (mm)
M12242.5
M16303.0
M20373.0
M24444.0
M30564.0
M36665.0
M42786.0
M48926.0
?? Washer selection: Use matching SS 347/347H washers with SS 347/347H bolts/nuts for optimal corrosion resistance and thermal expansion compatibility. Custom sizes available for non-standard assemblies.

Industry Applications

SS 347 / 347H Washers Applications — Industries & End Uses

SS 347 / 347H 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 347 / 347H washers are widely used in heat exchanger tube sheets, reactor vessel closures, and process piping flanges in refineries and petrochemical plants. Their resistance to polythionic acid and high-temperature scaling ensures reliable sealing in sulfur-rich and oxidizing environments.
Flat and spring washers for steam drum manways, superheater header flanges, and HRSG ductwork connections. SS 347H is preferred for bolted joints exposed to thermal cycling and creep conditions above 500°C.
Washer sets for acid reactor closures, agitator assemblies, and pressure vessel nozzles in nitric acid, organic acid, and mixed chemical environments where standard 304/316 washers fail due to sensitization or intergranular attack.
SS 347 / 347H washers are specified for use in aircraft engine exhaust systems, thermal shields, and high-temperature mounting brackets where oxidation resistance and mechanical stability are critical.

SS 347 / 347H Washers Standards & International Certifications

SS 347 / 347H 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, IS 12427 compliance, ISO 3506 material certification, NACE MR0175, and PMI (XRF) reports — available on request for all orders.
Standards
DIN 125A DIN 126 DIN 127 DIN 128 DIN 433 DIN 434 DIN 436 DIN 6796 DIN 6797 DIN 9021 ISO 7089 ISO 7090 ISO 7091 ISO 7092 ISO 7093 ISO 7094 ASME B18.21.1 EN ISO 7089 BS 4320 IS 5372 IS 1367 IS 12427
Certifications
ISO 9001:2015PED 2014/68/EUNABL LabMTC 3.1 / 3.2

Buy SS 347 / 347H Washers from India's Leading Manufacturer — Get a Competitive Quote Today

Partner with RealBolt — India’s leading manufacturer of certified SS 347 / 347H 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.
022-6743-7972
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Answers for Buyers

SS 347 / 347H Washers — Frequently Asked Questions

Browse expert answers to common questions about SS 347 / 347H 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 347 / 347H washers selection and pricing.
SS 347 / 347H washers are available to DIN 125 (flat), DIN 127 (spring), DIN 9021 (large OD), ISO 7089/7090, and ASME B18.22.1 (inch). Custom profiles such as tab, Belleville, and square washers can be manufactured to drawing. All washers are produced from ASTM A240/A276 certified material with full traceability.
Yes – SS 347 / 347H washers are designed for continuous service up to 870°C. The niobium stabilization prevents intergranular corrosion after welding or thermal cycling, and the higher carbon in 347H improves creep strength for bolted joints in boilers, reactors, and exhaust systems.
Absolutely. The niobium-stabilized structure of SS 347 / 347H provides excellent resistance to polythionic acid stress corrosion cracking, making these washers ideal for refinery, petrochemical, and sulfur-rich process environments where sensitization is a risk.
No MOQ for standard sizes (M6-M36) held in stock – we supply from single pieces for urgent maintenance. Custom sizes or special profiles have a minimum order of 10 kg. Price breaks are available at 100 pcs, 500 pcs, and 1000 pcs.

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