SS 347/347H Flanges

SS 347 and SS 347H flanges are stabilized austenitic stainless steel components designed to deliver reliable performance in high-temperature and corrosive environments. These flanges are stabilized with niobium also known as columbium, which significantly improves their resistance to intergranular corrosion, especially following prolonged exposure to high temperatures within the chromium carbide precipitation range of 427°C to 816°C. While SS 347 offers excellent mechanical strength and oxidation resistance, SS 347H is the high-carbon variant engineered for improved creep resistance and high-temperature strength. These attributes make them ideal for critical applications where thermal cycling and long-term durability are primary concerns.

Manufactured in a variety of types including weld neck, slip-on, blind, socket weld, and lap joint configurations, SS 347/347H flanges ensure robust connectivity in piping systems. Their superior weldability, formability, and resistance to sensitization after welding make them a preferred choice in operations involving frequent thermal variations. Compliance with international standards like ASTM A182 and ASME B16.5 ensures that these flanges meet global quality benchmarks. Every flange is subjected to thorough quality checks and precision inspections to ensure accurate dimensions, structural integrity under pressure, and optimal metallurgical performance.

Technical Overview

Constructed mainly from chromium 17 to 20% and nickel 9 to 13%, SS 347/347H flanges are enhanced with niobium or columbium, which acts as a stabilizing element to prevent carbide precipitation during high-temperature exposure. This makes them particularly suitable for services where exposure to heat and corrosive media is constant. With a carbon content ranging between 0.04% and 0.10%, 347H stainless steel flanges offers greater creep resistance at temperatures exceeding 600°C, outperforming standard SS 347 in high-temperature applications. These flanges exhibit excellent resistance to oxidizing environments, nitric acid, and many organic and inorganic chemicals.

The material’s austenitic structure ensures low magnetic permeability, excellent toughness, and strength across cryogenic to elevated temperature ranges. The flanges are also highly resistant to stress corrosion cracking, pitting, and crevice corrosion in chloride-rich environments. With superior mechanical properties and thermal stability, these flanges are frequently used in systems requiring flange-to-flange or flange-to-equipment connections where sealing integrity under fluctuating pressure and temperature is critical. Surface finish, dimensional precision, and material traceability are maintained throughout the production and post-production phases, ensuring operational safety and compliance.

Applications & Industry Use

SS 347/347H flanges are widely used across industries that operate in high-temperature and aggressive environments. Their robust performance makes them ideal for use in chemical processing plants, petroleum refineries, power generation facilities, and thermal fluid piping systems. In the aerospace and marine sectors, these flanges are employed in exhaust manifolds, heat exchangers, and engine components where superior corrosion and thermal resistance are essential. Their sanitary characteristics and low maintenance requirements make them a preferred choice in pharmaceutical production and food processing environments.

These flanges are critical to applications involving superheated steam, high-pressure lines, and corrosive media transport. They are regularly utilized in process equipment such as pressure vessels, reactors, distillation columns, and catalytic converters. Our major supply network spans across India, the United Arab Emirates (UAE), the Kingdom of Saudi Arabia (KSA), Kuwait, Qatar, the Sultanate of Oman, Iran, and Iraq, ensuring timely delivery and compliance with regional engineering standards. Their proven reliability and versatility across multiple industries have cemented their role as a trusted solution for mission-critical piping systems.

Our SS 347/347H Flanges are used in a wide range of applications and various industries. Below are a few of them: