Yulong fo Tianjin, INC. Is an integrated manufacturer and wholesale Supplier of oilfield equipment including api 6a and api 6d certified gate valves, ball valves, check valves, needle valves, chokes, ellheads, wellhead components and other specialty products. Yulong of Tianjin, INC. All equipment is inspected, tested and certified through yulong's extensive api and ISO quality programs. And we also deal with machining parts, casting, machining casting etc... We have many type machines for the work.