Nipoflanges are available in different materials, such as carbon steel ASTM A105 (high-temperature service), ASTM A350 (low-temperature carbon steel), ASTM A182 (stainless steel grades, including duplex and super duplex) and nickel alloys (Inconel, Incoloy, Hastelloy, etc).
Nipoflanges are also manufactured in the reinforced variant, which has additional mechanical strength compared to a standard Nipoflange.