First purging of the new device

There are many things to consider when purging; it’s best to carry out blasting on newly installed equipment, otherwise too much rust or other impurities will remain inside. Precautions for purging: 1. When purging one section of a heat exchange unit, the other section must be kept at atmospheric pressure or both sections should be purged simultaneously to prevent pressure buildup in the other section. 2. Steam should be supplied slowly to avoid water hammer. 3. The connections to the heat exchanger should be purged for a short period of time. 4. When purging towers, steam should be supplied slowly to prevent the trays from being displaced; steam supply can be increased only after steam is observed coming out of the tower’s vent. 5. Pumps cannot be purged for long periods; they should only be used for a short time during the purging process. 6. Pay attention to the purging pressure – low-pressure equipment must not experience excessive pressure. 7. Before purging water coolers, ensure that the circulating water has been stopped, drained completely, and the vent has been opened. 8. When purging low-temperature areas, the thermometer should be removed first

Chapter 4: Pressure Testing for Airtightness and Purging Procedures I. Objectives, Requirements, and Precautions for Pressure Testing for Airtightness (1) Objectives: 1. To assess the airtightness of the process pipelines and stationary equipment (furnaces, towers, heat exchangers, containers, valves, flanges, etc.) that have been replaced or repaired during maintenance, under normal operating conditions. 2. Operators conduct technical training on-site. (II) Requirements: (1) Two pressure gauges with the same range and that have passed calibration must be installed at designated locations prior to pressure testing. (2) Before pressure testing, carefully inspect the process and ensure proper isolation. (3) Prepare the pressure testing procedure diagram; during the pressure testing process, a dedicated person should be assigned to carry out inspections, and records must be kept. (4) The passing criteria for steam pressure testing are as follows: there is no abnormal deformation or noise in any pipelines or equipment, no steam leakage is detected upon inspection, and the pressure remains stable without dropping within 30 minutes of holding the pressure. (5) Coordinate with units such as dispatching, instrumentation, maintenance, and power to ensure proper cooperation. (6) During the pressure testing period, take appropriate measures to prevent freezing based on the temperature conditions. Once the pressure testing is complete, it is necessary to promptly open the high and low point vent valves of the equipment and pipelines to remove any remaining water vapor inside ； For the various steam and water lines that are not in use during startup, their root valves should be closed promptly, and their low-point vents should be opened. (III) Methods and precautions: (1) For pressure testing one side of the heat exchanger, the other side must be opened for venting to prevent damage to the equipment; in the case of water cooling, the inlet and outlet valves should be closed and a vent should be opened. Steam must be introduced into the heat exchange equipment slowly, with a preheating process in place, to prevent sudden temperature increases from causing uneven thermal expansion of the heat exchanger and resulting in leaks. (2) During pressure testing, the pressure should first be increased slowly to 10% of the specified test pressure, and held at that level for 5–10 minutes; meanwhile, a preliminary inspection of all welds and joints should be carried out. If no leaks are detected, the pressure can then be increased to 50% of the specified test pressure. If there are no abnormal phenomena, the pressure is then increased step by step to 10% of the specified test pressure, until reaching the test pressure, after which it is held at that level for 30 minutes. (3) Contact the instrument maintenance team; the instrument lead wires can be pressure-tested together after being thoroughly purged. (4) All control valves, flow orifice plates, flow-limiting orifice plates, level gauges, steam traps, control valves as well as on-site thermometers and pressure gauges have been installed for the pressure testing; safety valves are also included in this pressure testing. (5) The gauge is connected via a bypass line; the upstream and downstream valves are opened only during pressure testing. In the final stage of testing the system’s airtightness, the pump is then tested for airtightness as well. (6) After the steam pressure test is completed, the vents at the lowest and highest points of the system should be opened to prevent steam from condensing, which could create negative pressure in the system and damage the equipment.

I’ve learned it, thanks to the moderator! ! ! ! ! ! !

The first purge should be different from a normal purge; it should fall within the scope of the \"three inspections and four determinations\" for initial commissioning!

I think there’s also 1. short-distance purging; there are many debris in the pipelines when starting operation for the first time. 2. Avoid dead corners