GB/T 18619.1-2002 is used for the determination of water content in natural gas, using Coulometry in Karl Fischer method. The standard describes its determination principle, using chemical reactions to quantitatively analyze water in natural gas. Clarify the required instrumentation and equipment, including the technical requirements of key devices such as Coulometry Moisture Analyzer. Detail the process from natural gas sampling, Sample Handling to operating the determination on the instrument, as well as data processing and result calculation methods. The standard provides reliable specifications for the accurate determination of natural gas water content, which is essential to ensure the quality of natural gas and prevent problems such as pipeline corrosion caused by water.