This document specifies the terms and definitions, types and parameters, basic requirements, technical requirements, inspection and testing methods, inspection rules, marking, packaging, transportation and storage and quality commitments of condensing gas steam boilers. This document applies to condensing gas steam boilers using natural gas as fuel, with a rated evaporation capacity of not less than 1 t/h, and a rated steam pressure of not less than 0.1 MPa and not greater than 3.8 MPa.