Precautions for the overall piping of the compressor circulating oil system

When pipes are connected using joints or flanges, the piping is pre-installed first, then removed for pickling before being installed permanently. After the piping installation is complete, online cyclic pickling is carried out. Attention should also be paid to the following three points: ① Determine the most suitable piping method based on the project timeline and workload； ②Examine the working environment to determine what anti-rust and anti-contamination measures should be taken for the pipes ； ③During piping, try to avoid any artificial contamination, such as failing to clean out debris from within the pipes after cutting them, not using an adequate amount of shielding gas during welding, or failing to seal off the exposed pipe ends. It is also important to note the following: 1. During cyclic acid cleaning, one acid pump is used to transport several different fluids; special care must be taken during operation to avoid mixing these fluids together (including water). In severe cases, this can lead to a decrease in the concentration of the fluids, or even render them unusable. After each processing step, the area must be cleaned with water and the water drained thoroughly. 2. When discharging liquid, an exhaust point should be installed at the highest point of the circuit pipeline, and a drain point at the lowest point ； The dead point in the circuit should be in a horizontal position; if it is tilted downward, the connection at the dead point should be loosened during the alternating stages of the pickling process, in order to drain out the liquid remaining from the previous stage within the dead point. In the final step, it is essential to ensure that all liquid in the pipeline is drained and dried with dry gas; otherwise, any remaining liquid will cause emulsification of the oil during flushing. In the case of oil emulsification, an oil-water separator can be used to dehydrate the flushing oil in the tank while rinsing, until no water remains. 3. The length of the loop piping for cyclic pickling should be determined based on the size of the pipes, and it generally should not exceed 300 m. The circuit should be designed so that the inner wall of each pipe is in full contact with the acid. 4. Different testing methods are used for pickling with various formulations. After pickling with HCl, HNO3, and H2SO4, the inner wall of the pipe appears grayish-white ； The inner wall of the pipe after pickling with H3PO4 is grayish-black; 5. The inclination of the inlet and outlet pipes, etc.

The stainless steel pipes we used weren’t subjected to any further processing aside from blasting and pressure testing for leaks; the manager said it was to save money. But after 5 years of use, they’re still in good condition: lol

The stainless steel pipes we used weren’t subjected to any further processing beyond blasting and pressure testing for leaks; the manager said it was to save money. But after 5 years of use, they’re still in good condition... The manager said it was to save money!:P

When installing the circulating oil pipelines, each joint must first be welded with TIG welding as a base layer, followed by welding with MIG welding; in my experience, it is necessary to have someone supervise the entire process. If it’s TIG welding with a backing oil, it will be ready in a few days; if it’s shielded metal arc welding, it will take one or two months. The reason is that the weld bead inside the tube forms a bulged layer, and the impurities within the tube are located behind the coating; since the flow velocity is lowest at the tube wall, it is very difficult for the oil to flow properly.

Using argon arc welding for backing is now quite common; this is the requirement for our circulating water pipes. It doesn’t cost much. As for pickling, I personally think it’s unnecessary – reciprocating pipes aren’t that fragile; just cleaning them with air is sufficient

For the oil circulation circuit of a reciprocating compressor: 1. When welding, it is necessary to use TIG welding for the root pass first, followed by MIG welding； 2. Install a blind flange at the flange area before welding, and remove the blind flange after welding; ensure that all weld slag is cleaned away when removing it ； 3. After welding is complete, the pipeline can be rinsed with water first; once rinsing is finished, it should be dried with air before the flanges are connected ； 4. Clean the fuel tank thoroughly and then add flushing oil ； 5. Remove the inlet flanges at each lubrication point of the compressor (to prevent lubricant from reaching those points); connect them to the equipment’s lubrication points only after the lubricant inlet pipelines have been thoroughly flushed ； 6. When flushing the pipes, magnets should be installed at the fuel tank inlet to remove rust from the pipes as well as any metal left over from equipment installation ； 7. The fuel tank filter should be switched over in a timely manner and its filter element cleaned ； 8. If the facility is equipped with a lubricant filter, it is advisable to use online filtering in order to reduce the time required for lubricant filtration.

If it is a centrifugal compressor pipeline, it must be pickled and passivated before installation.