The KTN 581 is our class 800 check valve and NPT thread. Made of A316 stainless steel. The range is from 1/2 ″ to 2 ″ (inches). Maximum working pressure: 140 Bar. The working temperature range covers -29ºC to + 425ºC. The valve features a stellite-hardened stainless seat. Indicated to conduct and retain the passage of aqueous media, oil and gas.