1. Aging or damage of sealing components
Wear of piston rings: In piston compressors, piston rings play a crucial role in sealing the gap between the cylinder and the piston. With the extension of usage time and the reciprocating motion of the piston, the piston ring will continuously rub against the cylinder wall, leading to wear. Once the wear exceeds a certain limit, the piston ring cannot effectively prevent nitrogen gas from leaking from the gap between the piston and the cylinder wall. For example, when the opening clearance of the piston ring increases, nitrogen gas will leak from this opening to the crankcase or other parts.
Packing box sealing failure: For some compressors, the piston rod part is sealed through a packing box. If the sealing components (such as packing rings) inside the stuffing box are worn, aged, or installed improperly, leakage may occur. Especially in the presence of high temperature, high pressure, or corrosive media, the sealing of the stuffing box is more prone to failure. For example, in compressors used in the chemical industry, if nitrogen contains a small amount of corrosive gas, it will accelerate the corrosion of the packing ring, leading to a decrease in sealing performance.
Valve sealing surface damage: The sealing surfaces of the intake and exhaust valves of the compressor are crucial in preventing gas leakage. If the sealing surface of the valve is scratched, worn, or damaged by impurities, it will cause the valve to not close tightly, resulting in nitrogen leakage at the valve. For example, when the compressor sucks in nitrogen gas containing solid particles, these particles may get trapped between the sealing surfaces when the valve is closed, causing damage to the sealing surfaces.
2. Loose or damaged connection parts
Loose pipeline connection: The connection between the compressor and the pipeline is usually achieved through flanges, threads, or welding. If these connecting parts are not tightened or become loose under long-term vibration, gas leakage will occur. For example, gaskets for flange connections may age and deform after long-term use, leading to poor sealing; The threaded connection may loosen due to vibration, causing nitrogen gas to leak from the thread gap.
Poor sealing of cylinder head or end cap: The sealing between the cylinder head and end cap and the cylinder block is also crucial for preventing nitrogen leakage. If the sealing gasket is damaged or installed improperly, leakage may occur. For example, during the maintenance process of the compressor, if the sealing gasket of the cylinder head is not installed correctly or if a gasket that does not meet the requirements is used, it is easy to cause nitrogen leakage.
3. Damage or deformation of equipment components
Cylinder wear or rupture: Long term high load operation, corrosion, or accidental impact may cause cylinder wall wear or rupture. Once the cylinder wall wears out, the gap between it and the piston will increase, leading to nitrogen gas leakage. If the cylinder ruptures, the leakage will be even more severe. For example, when the compressor is suddenly hit by water or other external forces, cracks may appear in the cylinder wall, and nitrogen gas will leak out from the cracks.
Pipeline rupture or perforation: During long-term use, pipelines may rupture or perforation due to corrosion, fatigue, or external factors such as being squeezed or impacted by heavy objects. Especially in some harsh environments, such as corrosive gas environments in chemical enterprises or harsh outdoor weather conditions, pipelines are more prone to damage. Once the pipeline ruptures, a large amount of nitrogen will leak.
4. Overpressure operation or excessive pressure fluctuations
Overpressure caused by safety valve failure: If the safety valve of the compressor fails and cannot be opened to release pressure in a timely manner when the pressure is too high, it will cause the pressure in the system to exceed the limit that the equipment can withstand. This overpressure situation can cause excessive pressure on the sealing components of the equipment, leading to seal failure and nitrogen leakage. For example, if the valve core of a safety valve is stuck by impurities or the spring fails, it may prevent the safety valve from working properly.
Pressure fluctuations cause seal failure: During the operation of the compressor, frequent fluctuations in intake or exhaust pressure can cause periodic impacts on the sealing components. This impact may cause the seal to loosen or be damaged, leading to nitrogen leakage. For example, when the resistance of the exhaust pipe suddenly changes, it will cause fluctuations in exhaust pressure, which will affect the sealing of the exhaust valve.
Solution to leakage
1. Solutions for sealing component issues
Replacement and maintenance of piston rings
When it is found that the wear of the piston ring causes leakage, the piston ring should be replaced in a timely manner. When selecting piston rings, ensure that their material and size match the model of the compressor. For example, for high-pressure compressors, it may be necessary to use piston ring materials with higher strength and wear resistance.
At the same time, when installing piston rings, attention should be paid to the correct installation method, ensuring that the opening positions of the piston rings are staggered and the opening clearance meets the technical requirements of the equipment. After installation, the piston ring can also be run in to better fit the cylinder wall.
Sealing repair and replacement of stuffing box
If the sealing of the stuffing box fails, the first step is to check the wear of the sealing components (such as the packing ring). For slightly worn packing rings, grinding repair can be attempted to restore the sealing surface to a smooth state.
If there is severe wear or corrosion damage, the packing ring needs to be replaced. When replacing, it is important to choose the appropriate packing ring material. For environments with corrosive gases, packing rings made of materials such as polytetrafluoroethylene with anti-corrosion properties can be used. And it should be installed in the correct order and according to the installation requirements, and the tightness of the packing box should be adjusted appropriately after installation.
Valve sealing repair
For leakage caused by damage to the valve sealing surface, if the damage is minor, the sealing surface can be repaired by grinding. Suitable grinding tools and grinding paste should be used during grinding to ensure the flatness and smoothness of the sealing surface.
If the sealing surface is severely damaged, such as deep scratches or deformation, the valve needs to be replaced. When installing a new valve, attention should be paid to the correct installation direction of the valve, and a sealing test should be conducted to ensure that the valve can effectively prevent gas leakage when closed.
2. Solutions for connection issues
Pipeline connection fastening and sealing inspection
If the pipeline connection is loose, for flange connected pipelines, check whether the gasket is damaged first. If the gasket is damaged, a new gasket should be replaced, and during installation, it should be ensured that the gasket is placed correctly. The flange bolts should be tightened evenly and tightened according to the specified torque value.
For pipelines with threaded connections, it is necessary to check whether the threads are damaged. If the thread is damaged, methods such as repairing the thread or replacing the connector can be used. When reconnecting, use sealing tape or sealant for sealing, and tighten the connectors to prevent loosening.
Sealing treatment of cylinder head and end cover
When the cylinder head or end cover seal is poor, the first thing to check is whether the sealing gasket is intact. If the gasket ages, deforms, or is damaged, a new gasket should be replaced. When installing a new gasket, it is necessary to clean the sealing surface to ensure that there are no impurities, oil stains, or other factors that may affect the sealing.
For some parts sealed with sealant, it is necessary to check whether the sealant has failed. If the sealant fails, it is necessary to clean the old sealant, reapply an appropriate amount of sealant that meets the equipment requirements, and then install the cylinder head or end cover, and tighten the bolts in the prescribed order and torque.
3. Solutions for damage or deformation of equipment components
Cylinder repair or replacement
If there is slight wear on the cylinder wall, repair methods such as boring the cylinder can be used to machine the inner diameter of the cylinder wall to the appropriate size, and then match it with enlarged pistons and piston rings. But this repair method requires professional equipment and technicians to operate.
For cases of cylinder rupture, it is generally necessary to replace the cylinder with a new one. When replacing the cylinder, attention should be paid to the installation accuracy of the cylinder, ensuring that the clearance between the piston and the cylinder wall meets the requirements, and conducting a pressure test on the new cylinder to check for leaks.
Pipeline repair or replacement
For cases of pipeline rupture or perforation, if the damaged area is small, welding, leak repair, and other methods can be used for repair. For example, for some small perforations, repair fixtures or welding patches can be used to fix them.
But if the pipeline is severely damaged, such as extensive rupture or severe corrosion, a new pipeline needs to be replaced. When replacing pipelines, it is important to ensure that the material, specifications, and installation method of the pipeline are consistent with the original pipeline, and pressure testing should be conducted to ensure good sealing of the new pipeline.
4. Solutions for overpressure operation or pressure fluctuations
Inspection and maintenance of safety valves
Regularly inspect and maintain safety valves to ensure their proper functioning. Check whether the valve core of the safety valve is flexible, whether the spring is ineffective, and whether the sealing surface is intact. You can manually open the safety valve to check if its action is normal.
If a malfunction is found in the safety valve, it should be repaired or replaced in a timely manner. After repairing or replacing the safety valve, pressure adjustment and calibration should be carried out to ensure that the opening pressure and reseating pressure of the safety valve meet the safety requirements of the equipment.
Pressure fluctuation control
For seal failure caused by pressure fluctuations, pressure stabilization devices can be installed to reduce pressure fluctuations. For example, buffer tanks can be installed separately on the intake and exhaust pipes, which can store and release a certain amount of gas to smooth pressure fluctuations.
At the same time, it is necessary to check and optimize the control system of the compressor to ensure stable control of the intake and exhaust volumes. For example, checking whether the intake and exhaust control valves are working properly, adjusting the parameters of the control system to make the operation of the compressor more stable, and reducing the impact of pressure fluctuations on the equipment.
