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Stainless Steel Plate

Alloy 321 Stainless Steel Petroleum Refining: Polythionic Acid Service

Petroleum refining processes involve converting crude oil into useful products using semi-corrosive catalysts and high temperatures and pressures. In refineries, hydrogen sulfide is a compound frequently found in gaseous form. Compounds known as polythionic acids involve mixtures of hydrogen sulfide, metallic sulfide scales, water, air, and oxygen. It is believed that sulfides in these compounds contribute to intergranular stress corrosion and cracking of refining materials. Due to the corrosive properties of polythionic acids, refinery equipment must be constructed of a durable material that can resist these harsh conditions. Type 321 stainless steel is an ideal choice for this equipment because of its exceptional heat and corrosion resistance.

Alloy 321 Stainless Steel Properties

Alloy 321 is a durable stainless steel plate stabilized with titanium, which helps it withstand the threat of stress cracking caused by sulfides found in polythionic acid services. This alloy is known for both its durability to fight intergranular corrosion and its structural integrity that can withstand harsh conditions of the refining processes. Additional type 321 stainless steel properties include its ability to be used in most dilute organic acids at room temperature, as well as pure phosphoric acid at lower temperatures. Furthermore, petroleum refining processes include crude oil treatment, distillation, hydrotreating, and hydrocracking. These processes sometimes require chemical reactions that create extreme heat and use compounds that encourage corrosion and cracking. Type 321 stainless steel is a great alloy to use when operating under these conditions because of its ability to resist temperatures and oxidation up to 1500°F. Type 321 stainless steel also welds, forms, and machines easily. It cannot be hardened by heat treatment. Using this titanium-stabilized plate for polythionic acid services, can decrease plant maintenance and heighten operation efficiency.

Sandmeyer Steel: The Alloy 321 Stainless Steel Supplier

A lead supplier of type 321 stainless steel plate, bar, pipe, tubing, and sheets, Sandmeyer Steel Company stocks Alloy 321 in thicknesses from 3/16" to 4". If you are in the petroleum refining industry and are looking for an excellent material for your polythionic acid services, call (1-800-523-3663) or email( to obtain information on pricing and shipping.

NOTE: The information and data in this product data sheet are accurate to the best of our knowledge and belief, but are intended for informational purposes only, and may be revised at any time without notice. Applications suggested for the materials are described only to help readers make their own evaluations and decisions, and are neither guarantees nor to be construed as express or implied warranties of suitability for these or other applications.