It developed quickly and science progressed steadily，the requirements for industrial valve transferred to higher level，the upgrade valve came out into the open as the point of an awl sticking out through a bag.
    API 6D 370D-4、API 6D 310 &370CT Series Steel Ball Valve and tailpiece. with many types，higher grade and wide application range，have passed through ISO 9000 Quality Assurance System Certification been acclaimed by users for It’s exquisite material，fine workmanship，good interchangeability and reliable quality after having sold to Europe，USA and Middle East these years.