TTF forged steel check valve has three types of bonnet. One is bolted bonnet, which the body is connected with bonnet by bolts and sealed by spiral gasket (316SS filled flexible graphite), and available to follow metal sealing ring for special requirements by the client; one is welded bonnet, which the body is fully welded; another is pressure-in bonnet, which the body is screwed into the bonnet and sealed by inner pressure-in ring. There are three different design of check valve: Lifting Check Valve, Ball Type Check Valve and Swing Check Valve. Design Structure and Features: A. TTF check valve's design and manufacturing in conformity with MSSP-118 and ASME B16.34. B. Inspection and Test as per API 598. C. Markings as per MSS-SP-25