Shanghai Rongjun Marine Engineering is based in Shanghai and supports merchant vessels calling at Shanghai, Waigaoqiao, Yangshan and adjacent ports with hull thickness gauging, underwater inspection and non-destructive testing services. Hull ultrasonic thickness gauging documents the remaining steel of plating, frames, longitudinals and tank boundaries, providing data used by owners and class surveyors to evaluate diminution and plan steel renewals during intermediate and special surveys. Underwater inspection is delivered by trained diver teams supporting in-water surveys covering hull plating, rudder, propeller, sea-chests, anodes and similar appendages, with video documentation prepared for attending class surveyors so afloat examinations can be accepted in lieu of dry-docking when condition and visibility allow. NDT and remote inspection complements the gauging and underwater work with techniques used to evaluate welds, plating, machinery components and structural details where cracks, corrosion thinning and weld defects need quantifiable evaluation during periodical, intermediate and special surveys. Service approvals from ABS, DNV, LR and RINA evidence that procedures, equipment and qualified personnel meet the criteria these classification societies apply to thickness gauging, in-water survey and NDT contractors. The technical team coordinates attendance around tight port stays and anchorages in the Yangtze estuary, with reports prepared in formats acceptable to attending surveyors and to owner, manager and crewing offices. The combined scope supports consolidated attendance during single port stays for international operators of bulk carriers, tankers, container ships and general cargo tonnage. Working with both Chinese-flag and foreign-flag merchant tonnage, Shanghai Rongjing coordinates equipment logistics, qualified personnel and class liaison so attending teams deliver consolidated gauging, underwater and NDT scopes within available port time, aligning documentation with the vessel's survey programme and continuous hull and machinery records used by managers and superintendents during periodical, intermediate and special class survey cycles in eastern Chinese waters.