SS 321/321H Buttweld Fittings

SS 321 and SS 321H buttweld fittings are engineered stainless steel components designed for high-temperature, corrosive, and pressure-intensive environments. These fittings are widely used in pipelines and process systems to enable smooth directional flow, efficient branch connections, and secure end closures. SS 321 is stabilized with titanium to prevent intergranular corrosion in the heat-affected zone, while SS 321H is a high-carbon version, offering superior strength and creep resistance at elevated temperatures.

From elbows and tees to reducers and end caps, the fittings are produced in multiple types, each adhering to strict global quality norms for reliable use and dimensional integrity. Whether it's for complex installations or basic transitions, SS 321/321H buttweld fittings are favored for their formability, weldability, and resistance to oxidation and scaling. Available in welded and seamless options, they are selected based on the technical needs of the project.

Technical Overview

SS 321 is an austenitic stainless steel alloy containing chromium 17–19% and nickel 9–12% with the addition of titanium where minimum 5x carbon content to enhance stabilization against carbide precipitation during welding. Engineered for high-heat applications, it maintains mechanical strength and corrosion resistance even at elevated temperatures up to 870°C or 1600°F. On the other hand, SS 321H includes higher carbon content 0.04–0.10%, enhancing creep strength and structural integrity under high thermal stress environments beyond 500°C.

These buttweld fittings exhibit excellent mechanical properties, including tensile strength exceeding 515 MPa and good impact resistance across a wide temperature range. Their weldability is excellent using standard welding techniques, and post-weld annealing is typically not required unless severe forming or corrosive exposure is expected. In addition, these fittings offer strong resistance against chloride stress corrosion cracking, oxidizing chemicals, and mild organic acids.

Due to their robust metallurgical structure and enhanced temperature tolerance, SS 321/321H fittings conform to standards such as ASTM A403 for wrought austenitic stainless steel buttweld fittings and ASME B16.9 for dimensional specifications. They are ideal for systems requiring long-term stability and low maintenance in thermally dynamic environments.

Applications & Industry Use

SS 321/321H buttweld fittings are extensively used across industries where thermal endurance and corrosion resistance are critical. In petrochemical and refinery applications, these fittings maintain structural integrity during high-temperature catalytic processes and pipeline transfers. They are equally vital in power plants, where high-pressure steam lines and superheater systems demand materials with high creep strength and resistance to oxidation.

In the aerospace sector, SS 321's stabilization properties make it ideal for exhaust manifolds, jet engine components, and other parts subjected to thermal cycling. The chemical processing industry benefits from their resistance to organic acids and oxidizing environments, particularly in acid production and handling systems. Food processing, pharmaceutical plants, and water treatment facilities also utilize these fittings due to their sanitary finish, ease of cleaning, and resistance to scaling and corrosion.

Given their high-performance characteristics, SS 321/321H buttweld fittings are a critical component in projects throughout India, the UAE, KSA, Kuwait, Qatar, Oman, Iran, and Iraq, where industrial infrastructure demands materials that perform reliably under extreme conditions.

Our SS 321/321H Buttweld Fittings are used in a wide range of applications and various industries. Below are a few of them: