ASTM B668 UNS N08028 Seamless Incoloy Pipe
ASTM B668 is the standard specification for seamless pipe and tube made from UNS N08028 (also known as Incoloy Alloy 028 or Sanicro 28), an iron-nickel-chromium-molybdenum alloy designed for superior resistance to corrosive environments, particularly sulfuric acid and phosphoric acid services. This material is commonly used in chemical processing, oil and gas, and marine applications due to its high strength, pitting resistance, and stress corrosion cracking resistance. The specification covers both cold-finished and hot-finished seamless products, which must be supplied in a solution-annealed condition (typically heat-treated at 1,900–2,050°F or 1,040–1,120°C, followed by rapid quenching).The "seamless" designation refers to pipes and tubes produced without welds, ensuring uniformity and enhanced corrosion resistance. UNS N08028 is not a true stainless steel but a nickel-based superalloy, often marketed under the Incoloy brand by Special Metals Corporation.
