This DN80 (3") Class 1500 swing check valve has a pressure seal cover (PSC). It meets API 6D and BS 1868. The body is cast steel A216 WCB. The trim is 13% Cr+HF stainless steel. End connections are butt-welding per ASME B16.25. The PSC design gives reliable sealing at high pressure. Sealing gets tighter as pressure goes up. The valve works automatically to stop flow reversal. The swing disc gives reliable sealing. The stainless trim resists wear and corrosion well. It is used in high-pressure industrial pipelines that need strong backflow prevention.