The 3 sets of 29 MW gas-fired hot water boilers serving for Jin-an Thermal Power in Tianjin were installed in 2015. The boiler is a common type for central heating which adopts the full membrane wall structure and a D-type layout. It has the characteristics of micro-positive pressure combustion, no air leakage, low heat loss caused by exhaust gas and high thermal efficiency. During the boiler manufacturing process, ZOZEN Boiler emphasizes that the welding of each baffle must be tight, and the height of welding leg should meet the requirements specified on the design drawing to ensure the leakproofness of the boiler. In addition, ZOZEN Boiler also sets strict welding standards for detailed parts including the door opening and kiln eye to prevent the high-temperature flue gas from leaking.