Low Alloy Steel

Low Alloy steels A/SA335 P11/P22/P5/P9/P91/P92

For over 20 years, Stainalloy has supplied A/SA335 Low Alloy pipes, A/SA 234 fittings and A/SA 182 flanges for applications in the petrochemical and power industries. ASTM A335 (ASME S/A335, Chrome-Moly) is a seamless ferritic Alloy-Steel for high temperature service. Material ordered to this specification is suitable for bending, flanging and similar forming operations, and for fusion welding.

Low alloy piping materials are often called chrome moly materials because of the chemical makeup of Molybdenum (Mo) and Chromium (Cr). Chromium increases the hardness and strength and only minimally reduces elasticity. Molybdenum improves tensile strength and especially heat resistance. Furthermore, it has a favorable influence on the welding properties. Moly is the most effective single additive that increases high temperature creep strength. It also enhances the corrosion resistance of steel, and inhibits pitting. The composition chrome-moly alloy steel makes it ideal for use in power plants, refineries, petrochemical plants, and oil field services where fluids and gases are transported at extremely high temperatures and pressures.

Low alloy materials are in accordance with the ASTM standards known as P-grades. The most frequently used P-grades are: P5, P9, P11, P22, and P91. With regards to the power industry and the petrochemical industry, P11 UNS K11597, P22 UNS K21590 and P91 UNS K91560 are most frequently used, as these alloys ensure longer mechanical life time, do not deteriorate and provide improved creep resistance properties. P5 UNS K41545 and P9 UNS K90941 are commonly used in refineries.

Stainalloy stocks ½” up to and including 48” seamless ASTM A335, mainly P9 and P91, manufactured by only the most reputable mills. The pipes are manufactured in accordance with ASTM A335/ASME SA335, seamless & welded fittings in accordance with ASTM A234, and flanges & forgings in accordance with ASTM A182 alloy steel.

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Vincent van Beest
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