Check valve is designed and produced entirely according to the requirements of API 6A 《Equipment Specifications for Wellhead and Christmas Tree》, able to be used interchangeably with corollary equipment at home and abroad that is inline with API 6A Standard. The core adopt sulfide-resistance steel and able to be used in H2S condition, valve body made by alloy steel forging with good performance. Two types of Check valves are offered by landrill: Swing type and Lift type.