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SS 347 / 347H Nuts Manufacturer & Exporter in India

Explore SS 347 / 347H 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 347 / 347H Nuts?

SS 347 / 347H nuts are high-temperature austenitic stainless steel fasteners manufactured from stabilized grades UNS S34700 and UNS S34709. These nuts are alloyed with columbium (niobium) to prevent intergranular corrosion and carbide precipitation during welding and prolonged exposure to elevated temperatures. SS 347H contains a higher carbon content than SS 347, enhancing its creep resistance and mechanical strength above 500°C.

SS 347 / 347H nuts are widely specified for bolted joints in heat exchangers, pressure vessels, and piping systems operating in the 400-900°C range, where standard 304/316 stainless steel nuts would fail due to sensitization or loss of strength. They are compliant with ASTM A194 Grade 8 and 8H, and are suitable for both oxidizing and moderately reducing environments in the chemical, petrochemical, and power generation industries.

Quick Specifications

MaterialStainless Steel 347 / 347H
UNS NumberS34700 / S34709
DIN Number1.4550 / 1.4961
Material StandardASTM A276 / ASTM A193 / ASTM A194
Nut Standard (Metric)DIN 934 / ISO 4032
Nut Standard (Inch)ASME B18.2.2
Thread FormISO Metric / UNC / UNF
Diameter RangeM6-M64 / ¼"-2½"
Tensile Strength515 MPa (75 ksi) min
Yield Strength205 MPa (30 ksi) min
HardnessMax 223 HB (Brinell)
? All material certified by NABL-accredited laboratory. PMI and IGC test reports 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 Screws, SS 347 / 347H Washers, 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 Screws
SS 347 / 347H Washers
SS 347 / 347H Studs
SS 347 / 347H Threaded Rods

Technical Data

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

SS 347 / 347H 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 347 / 347H nuts dimensions are verified against applicable DIN, ISO, and

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
DIN 439Thin nutsMetric
ISO 4035Thin hex nutsMetric
Material StandardRequirement
ASTM A194Heavy hex nuts - UNS S34700/S34709
ASTM A276Bar/rod - SS 347/347H
ASTM A193Bolt/nut mechanical
EN 10204 3.1Mill test certificate
EN 10204 3.2TPI-witnessed MTC

Material Chemistry

SS 347 / 347H Chemical Composition

SS 347 / 347H 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

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
Columbium (Nb)10xC-1.010xC-1.0
Iron (Fe)BalanceBalance
? All heats verified by NABL-accredited spectrometry. IGC and PMI reports available on request.

Why SS 347 / 347H Alloy Composition Matters for Nuts

Columbium (Nb) Stabilization
Columbium (niobium) additions prevent chromium carbide precipitation at grain boundaries, ensuring SS 347 / 347H nuts resist intergranular corrosion after welding or long-term service at 425–900°C.
High Carbon for Creep Strength
SS 347H’s higher carbon content (0.04–0.10%) increases creep resistance and mechanical strength at elevated temperatures, making it ideal for nuts in high-pressure, high-temperature bolted joints.
Austenitic Structure
The austenitic matrix provides excellent ductility and toughness, even at cryogenic temperatures, ensuring reliable nut performance in thermal cycling and vibration-prone environments.

Fastener Performance

SS 347 / 347H Nuts Mechanical Properties & Torque Reference

The table below lists mechanical properties and torque reference for SS 347 / 347H Nuts per ASTM. SS 347 / 347H 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)
M126530
M1616060
M2032095
M24550140
M301100225
M361900325
M423000480
M484500650
?? Anti-galling: Use molybdenum-based or PTFE anti-seize. Lubricated values assume K=0.16. Avoid over-torquing to prevent thread galling in austenitic stainless nuts.

Industry Applications

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

SS 347 / 347H 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 347 / 347H nuts are used for bolting in reactors, reformers, and process piping where resistance to polythionic acid stress corrosion and high-temperature service is critical. Suitable for flange joints, valve bonnets, and heat exchanger covers.
Heavy hex nuts for steam drum manways, superheater header connections, and turbine casing joints, where creep resistance and oxidation stability at 600-870°C are required.
Nuts for pressure vessel closures, agitator assemblies, and acid handling systems exposed to organic acids, nitric acid, and mixed chemical environments where standard 304/316 nuts are prone to sensitization.
SS 347 / 347H nuts are specified for jet engine exhaust assemblies, afterburner flanges, and furnace hardware due to their ability to retain strength and resist scaling at elevated temperatures.

SS 347 / 347H Nuts Standards & International Certifications

SS 347 / 347H 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 LabEN 10204 3.1 / 3.2

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

Partner with RealBolt — India’s leading manufacturer of certified SS 347 / 347H 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
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Answers for Buyers

SS 347 / 347H Nuts — Frequently Asked Questions

Browse expert answers to common questions about SS 347 / 347H 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 347 / 347H nuts selection and pricing.
SS 347 / 347H nuts are available to DIN 934 (metric hex), ISO 4032, ASME B18.2.2 (inch hex and heavy hex), and ASTM A194 Grade 8/8H. Thin nuts per DIN 439 and ISO 4035 are also available. Custom thread forms (UNC, UNF, BSW) can be supplied on request.
Molybdenum-based or PTFE anti-seize is recommended for SS 347 / 347H nuts to prevent galling and seizing during assembly. Avoid copper-based anti-seize in chloride or high-temperature environments. Always apply to both threads and nut face for optimal performance.
Yes – SS 347 / 347H nuts are specifically designed for high-temperature service up to 870°C. The niobium stabilization and, in 347H, higher carbon content, provide excellent creep resistance and prevent intergranular corrosion during prolonged exposure to heat.
No MOQ for standard sizes (M8-M36) available ex-stock. Custom sizes or special coatings may require a minimum order of 10 kg. Bulk price breaks are available at 50, 200, and 500 pieces. Sample orders for urgent maintenance are accepted.

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