GB/T 23711.6-2019 "Test Methods for Plastic Lined Pressure Vessels - Part 6: Pressure Resistance Test" applies to the pressure resistance inspection of steel pressure vessels lined with plastics such as PVC-U and PVDF. It specifies the test equipment, samples, methods, result evaluation, and reporting requirements. The test requires the use of electric or manual pressure test pumps suitable for the specified pressure range, along with two calibrated pressure gauges with an accuracy not lower than class 1.6. Hydraulic, pneumatic, or combined hydraulic-pneumatic pressure test methods may be selected. The test site must be equipped with reliable safety protection facilities. By following the prescribed steps for pressure increase, pressure holding, and observing pressure changes, it can be determined whether the vessel meets the pressure resistance requirements, ensuring the safe operation of the equipment under pressure.