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I. Precautions for purging 1. The pressure before the purge valve should generally be maintained at 0.5–1.0 MPa. 2. Detailed records must be kept throughout the purging process. The content should include: 2.1 Flush pipeline number and date. 2.2 Purge type, purge medium, pressure, and location of the purge outlet. 2.3 Pipe reset confirmation form after purging. 3. When disassembling or resetting, be sure to confirm that the valve on the upstream pipeline is closed and there is no pressure in the pipeline. 4. A dedicated person must inspect and sign off on the purging of each pipeline section. 5. After the blowing and cleaning process is completed, any equipment that can be cleaned manually must be cleaned manually again. 6. After the purging process is completed, manholes on some equipment need to be opened for cleaning. II. Technical requirements to be met for purging: 1. The steam pipeline system should be purged with steam of the same grade; the water pipeline system should be flushed as much as possible using the pumps available in that system. For the gas pipeline system and other pipelines that cannot be flushed using pumps, low-pressure nitrogen or compressed air should be used for purging. 2. The purging sequence should follow the order of main pipes, large-diameter pipes, branch pipes, drain pipes, and instrument pressure guide pipes, from near to far; each system’s branch pipes should be purged separately. 3. Purging of the control valve assembly: First, disconnect and purge (wash) the connections in front of the manual valve of the inlet valve assembly as well as in front of the bypass valve. Then, replace the control valve with a short section in order to carry out purging (washing); the bypass and drain lines should also be purged (washed). 4. Purging of individual pump units: Disconnect the front flange of the pump or the front section of the pump body, flush the inlet pipeline, and then install a temporary filter on the inlet pipeline (or use the filter that is already present in the pipeline). Remove the flow control orifice plate from the return pipeline as well as disconnect the front flange before the equipment, and then start the pump to flush the return pipeline. 5. When the purging medium is to pass through the equipment, the upstream pipeline connected to the equipment must first be purged thoroughly to prevent debris from entering the downstream pipelines and equipment. If it is difficult to leave a purge port before entering the stationary equipment, depending on the convenience of cleaning, the purge medium can be introduced into the equipment, and the equipment must be cleaned. 6. It is used to purge (flush) utility piping systems using the fluid it transports as a cleaning medium. 7. The blind flanges added during the purging process should be identifiable from the outside, and tags should be attached along with proper records kept. 8. When the water pipeline passes through flanged globe valves or gate valves, the supply should be cut off in front of the valve, and a baffle should be installed in the downstream pipeline for flushing. The ball valve can remain open as a passage. 9. After purging the pipeline, it should be restored immediately to prevent yarns, debris, and other substances from entering the pipelines, control valves, and flow meters ； At the same time, to create conditions for the next purge. 10. Criteria for completing the purging: Water flushing is considered successful when the color and transparency of the water at the outlet are visually consistent with those of the water at the inlet ； For air purging, a white cloth or gauze should be placed at the exhaust outlet for target inspection, and the process should continue until no dirt is detected on the cloth or gauze.

5 Principles and requirements for cleaning: 5.1 Mechanical cleaning and inspection: Use brushes or other methods to remove as much debris and dirt as possible from within the equipment, especially removing any nails, wooden pieces, tools, wires, welding slag, and other residues left over from the installation process. Use safety lights to inspect each device and each pipeline one by one; after cleaning, make proper records. 5.2 The air purging pressure for process pipelines is generally required to be between 0.5 and 0.7 Mpa; for low-pressure pipelines, the pressure after the valve is used for control, with the air purging pressure set at 0.15–0.20 Mpa. The purging pressure must not exceed the design pressure of the equipment and pipelines. 5.3 When purging the process gas pipelines, sufficient gas volume must be ensured so that the flow rate of the purge gas is higher than that during normal operation; it should be at least 20 m/s, or the flow rate should be above 150,000 m3/h. 5.4 During system purging, purge each piece of equipment and each pipeline in sequence according to the process; it is not allowed to bypass equipment (except for pipelines that are connected to equipment by socket welding), pipelines, valves, or the connection pipelines between different processes. Purging should be carried out multiple times, and a white cloth should be used at the discharge outlet to check whether there is any dirt adhering to it. If the inspection with the white cloth is successful, a target testing is required, and the target plate must pass the inspection by both the company and the workshop before it is acceptable. While purging the main pipeline, analyze and sample the lines as well as the instrument pipes. The principle of working from upstream to downstream, from main pipes to branch pipes, and from pipelines to equipment should be followed. 5.5 During system purging, be sure not to use instrument control valves as purging control valves; instead, use isolation valves or temporarily installed manual valves for control. 5.6 Appropriate protective measures should be taken for control valves; purging should be routed around the instrument control valve, and a temporary short pipe should be installed in place of the control valve. Otherwise, it is necessary to wait until the pre-valve purging is successful before proceeding. 5.7 During purging, the safety valve and its root valve should be disconnected from the pipeline connection flanges, and blind plates or shunts should be installed to prevent debris from damaging the safety valve’s sealing surface. (When the pipeline in front of the safety valve is short, there is no need to remove the safety valve; if the pipeline is long, purging must be carried out separately before the valve.) 5.8 Before purging, baffles must be installed in front of the entrances to equipment such as heat exchangers and towers, using these baffles as purge ports. Purging can proceed inside the equipment only after the inlet pipelines have been properly purged. 5.9 The purging of all vent flare lines and drain lines shall be carried out after the purging of the main pipelines to which they are connected; the drains on the equipment housings, valves, and all instrument pressure lead pipes shall all be opened for purging. 5.10 In the lowest areas or dead corners of the equipment, manual cleaning should be carried out if necessary to ensure that no residues remain. 5.11 During purging, use a hammer (a wooden or rubber mallet for stainless steel) to tap; pay special attention to tapping areas such as weld corners and the bottom of the pipes, but be careful not to damage the pipes. 5.12 After the flushing and purging process is completed, any system must be carefully inspected to ensure that the normal circuitry has been restored, that temporary pipelines have been removed, and that any components that were temporarily removed have been reinstalled ； In particular, the added blind flanges must be numbered and used accordingly; a work order for random inspections of these blind flanges should be prepared, and label tags should be attached to them. After purging is complete, the blind flanges should be removed one by one in order to ensure that none are left inside the system. 5.13 To ensure the safe operation of the compressor, pipeline air purging should combine intermittent (or burst) purging with continuous purging, and each pipeline should be purged with discharge at the lowest point. 5.14 Pipeline purging is carried out in groups according to different pressure levels. The purging sequence should follow the main pipe, branch pipes, and drain pipes in order. Equipment and pipelines that do not participate in the system purging should be isolated from the purging system. 5.15 After the purging is completed, all containers such as towers, tanks, and vessels should be manually cleaned again; they must be restored to their original state promptly, their internal components replaced, and sealed in accordance with the procedures for sealing concealed works. Additionally, a record of the pipeline system purging process must be prepared. 5.16 For pipes with a nominal diameter of ≥600 mm, if the purging flow rate or purging efficiency is insufficient, manual cleaning of the pipe is required. 6 Precautions for Purging 6.1 At the start of purging, air should be introduced into the pipeline slowly; only once it is confirmed that air is being discharged from the outlet can the flow rate be increased gradually to the required level. This is to prevent overpressure in the system or accidents caused by improper handling of valves, blind flanges, etc. 6.2 When encountering a manual valve, first remove the front flange of the valve for purging; once purging is complete, reinstall the flange. 6.3 For purging, use a wooden hammer to strike the pipes continuously; special attention should be paid to welding areas and dead corners, but the pipes must not be damaged until purging is successful. 6.4 Before purging, the demister screens inside the equipment, orifice plates on the pipelines, control valves, flow meters, and other components that are prone to clogging or damage must be removed and replaced with short pipes; they should be reinstalled after the purging process is complete. 6.5 After the pipeline has been thoroughly purged, open the valves on the outlet pipelines on both sides of the flow orifice plate, as well as the analysis sampling point and the valve at the base of the pressure gauge, in order to carry out further purging. 6.6 No one shall stand at the blowing outlet to prevent injury from the blown materials; a dedicated person must be assigned to all blowing tasks, and records must be kept.