Headquartered in Shanghai with a nationwide branch network, Shanghai Changyun Ocean Engineering Co., Ltd. is a specialist underwater contractor serving the merchant shipping, offshore wind, port and bridge sectors. The Changyun group maintains ten branches in Dalian, Qinhuangdao, Tianjin, Yantai, Rizhao, Qingdao, Xiamen, Shenzhen, Guangzhou and Zhanjiang, together with cooperative arrangements that share commercial diving certification, personnel and equipment across the principal Chinese ports. Commercial diving services cover non-docking in-water hull inspections in lieu of drydocking, ultrasonic thickness measurement of hull plating and submerged structures, hatch cover ultrasonic tightness testing, and watertight integrity verification of doors and penetrations. Divers also perform underwater installation work, wet welding and cutting, hull and propeller marine growth cleaning, propeller polishing and underwater CCTV survey of vessels, offshore facilities, wind power foundations, jetties and wharfs. The team supports tankers, bulk carriers, container ships and offshore units, providing report packages suitable for intermediate, special and bottom-survey purposes, with response times typically measured in hours rather than days at the firm's branch ports. Underwater non-destructive testing capability includes magnetic particle inspection on mooring chains and submerged welds, alongside underwater photographic survey of propellers, rudders, sea chests and stern frames. Shanghai Changyun maintains recognition with the principal IACS classification societies including ABS, Bureau Veritas, DNV, the Indian Register of Shipping, Korean Register, Lloyd's Register and CCS, so reports issued by its IMCA-trained divers and NDT technicians are accepted for statutory and class verifications on a wide range of merchant tonnage operating along the Chinese coast and across the wider Asia-Pacific region.