GB/T 23711.7-2019 "Test Methods for Plastic-Lined Pressure Vessels—Part 7: Leak Test" applies to the leak detection of steel pressure vessels with various plastic linings. It specifies the test principles, equipment, methods, result evaluation, and reporting requirements. The test can be conducted using either a gas tightness test or an ammonia leak test. Key instruments include an ammonia mass spectrometer leak detector with a minimum detectable leakage rate meeting the specified requirements, as well as pressure gauges with adequate accuracy and suitable measurement ranges. During the test, the vessel is filled with dry air, nitrogen, or other media, and the pressure is gradually increased to the specified level and maintained for no less than 30 minutes. Leakage at connections, seals, and other parts of the vessel is determined through pressure observation and leak detector detection to ensure the sealing reliability of the equipment.