Cast triple offset butterfly valve in CN7M material. We ask the foundry to take an addition testing sample stickers with the casting body together, because this special material need to do chemical test. The testing sample is used to check the chemical composition whether it is qualified, then issue the report. CN7M is the casting of the Alloy 20, the operating temperature is -196℃~460℃, mainly applied to sulfuric acid and phosphoric acid.