Maintenance of Long-Distance Natural Gas Pipeline Valves

Abstract: Natural gas is one of the main energy sources in China and is widely used worldwide. One of the primary methods of transporting natural gas is through pipelines. Pipeline transport is not only convenient and fast but also highly safe. It is currently one of the most commonly used methods for energy transport. However, pipeline transport still faces issues such as significant energy waste and leakage during transmission. As a key device for controlling the inflow and outflow of natural gas, the primary function of the valve is to regulate or block the flow of natural gas and control its direction through manual operation. Therefore, maintaining and caring for valves is particularly important. Proper valve maintenance can significantly reduce the likelihood of incidents and ensure valves function effectively while maintaining the safety of energy transport. This article discusses and analyzes in depth the maintenance measures for natural gas pipeline valves, providing feasible references for industry professionals.
 

In pipeline design, relevant personnel should first select the optimal transportation method based on the pipeline’s load value, timely optimize and adjust the pipeline’s peak capacity, and conduct necessary tasks such as pressurization. These tasks need to be thoroughly planned in advance and can only be implemented once construction safety is ensured. Secondly, during severe climate changes, residential gas consumption will increase accordingly. Therefore, when designing the gas distribution system, personnel should analyze seasonal variations in gas consumption, fully understand user behavior, and allocate natural gas distribution according to specific time periods. Finally, different design schemes and installation methods for long-distance pipelines will impact the overall costs of natural gas engineering projects. To optimize input and output, personnel must conduct thorough preliminary research and site surveys to ensure the rationality and scientific basis of the design scheme.
 

To ensure the stable and safe operation of natural gas pipelines, personnel must regularly and thoroughly inspect and repair various components of long-distance pipelines. For example, if the valve’s seal is found to be substandard during inspection, it should be repaired or replaced immediately based on the situation. When checking the valve opening, debris around the valve operational should be cleared promptly. When inspecting the connection points of pipeline equipment, they should be thoroughly checked for leaks. If a leak occurs, the cause should be identified promptly, and the appropriate solution should be applied. Typically, natural gas station equipment undergoes daily minor inspections and monthly major inspections, with maintenance scheduled every six months. Additionally, winter maintenance frequency should be increased based on actual conditions.
 
 

After selecting the appropriate valve material, the valve must be installed. Once installed, the valve will continue to be rotated and used. Pipeline operators will need to operate the valve multiple times. Rotating the valve inevitably causes some wear and tear. Therefore, maintaining the valve’s rotation is particularly important (as shown in Figure 1). Personnel can apply lubricating oil to maintain the valve’s rotating parts. Lubricating oil dissipates over time, and the internal temperature of the natural gas pipeline accelerates this process. When the lubrication of the valve’s rotating parts is insufficient, wear increases. Therefore, regularly applying lubricating oil to the valve’s rotating parts is crucial. Timely lubrication and maintenance can effectively reduce wear and minimize the impact of valve performance issues on pipeline safety.


Figure 1 Maintaining the valve’s rotation
 

Personnel may easily overlook the issue of grease injection during valve maintenance. After the operator fills the tool with grease, it is injected into the valve and the grease injection connection. This operation can lead to the following two issues:
(1) Insufficient grease injection makes basic valve operations difficult, leading to significant valve wear.
(2) Excessive grease injection leads to wasted resources.
To avoid these issues, the amount of grease should be accurately calculated based on the valve’s actual needs before greasing, and then applied. Additionally, factors such as pressure should be fully considered. The amount of grease injection will vary with pressure changes, ensuring efficient grease usage, preventing waste, and reducing valve wear.
 

Special attention must be paid to unexpected situations during valve packing. The valve is prone to leakage during its opening and closing. If the packing is not installed properly, the pipeline valve may lose its function. Therefore, personnel should enhance maintenance efforts to extend the packing's service life. Manufacturers typically test the valve's packing elasticity before it leaves the factory to ensure it meets relevant standards. During valve installation, personnel must tighten the valve nut, but not excessively, to prevent the packing from losing elasticity. For packing maintenance, personnel should lubricate it periodically after installation. If the material is found to be insufficient, it should be replenished promptly to maintain the packing's seal, ensuring the valve's safety.
 

Enhancing the internal and external surface coating of long-distance pipelines can effectively improve their corrosion resistance. Epoxy powder is commonly used in natural gas pipelines for anti-corrosion purposes. It has strong adhesion and can effectively improve the wear resistance of both the interior and exterior of the pipeline. Epoxy powder typically uses a three-layer PE process (as shown in Figure 2), a widely used pipeline anti-corrosion technique that enhances the pipeline's resistance to corrosion. Epoxy coating not only improves the pipeline's anti-corrosion ability but also reduces the impact of ultraviolet rays on the coating. This allows the coating to maintain a close fit with the pipeline, even under light exposure, maximizing its anti-corrosion effect.
 
It should be noted that before the anti-corrosion coating is applied, the pipeline surface must first be phosphated, degreased, and derusted. The thickness of the anti-corrosion coating must be controlled between 150 and 200mm during application. Additionally, anti-corrosion work at the pipeline's welding points is a major focus. The anti-corrosion treatment of the welding patch is crucial to the pipeline's overall anti-corrosion quality. The most widely used welding patch anti-corrosion material today is "two-component solvent-free liquid epoxy coating," a new type of patch material.

Before applying the anti-corrosion coating to the weld patch, the patch surface must be prepared to ensure the weld height is no more than 2.55mm. The weld connection of the pipeline must be smoothed to prevent excessive thickness or cracking. Weld bumps, slag, corners, burrs, and other imperfections generated during welding or pipeline cutting should be cleaned and smoothed promptly. During the anti-corrosion coating process, a layer of primer should be applied to thinner areas before applying the anti-corrosion coating.
 

During natural gas transportation, buried pipelines are concealed, making it extremely difficult to discover and address problems. Therefore, an automated control system is employed to monitor both pipeline gas transmission and corrosion. Once corrosion is detected in the pipeline, the system can respond quickly and address the issue promptly, which significantly enhances the safety and efficiency of natural gas pipeline transportation and extends the service life of long-distance pipelines. The natural gas transportation management department must establish robust rules and regulations, apply modern management methods and technologies to ensure the safety of long-distance pipelines, and use the SCADA system to enhance electronic inspection. Regular inspections of natural gas transmission pipelines are necessary to promptly identify safety hazards and prevent leaks.
 

As discussed above, the natural gas transportation industry continues to advance alongside societal progress and development. To facilitate the use of natural gas, pipeline valves are widely employed in both daily production and daily life. Moreover, valves are crucial components for effectively ensuring the safety of natural gas pipeline transportation. They serve a protective role in natural gas pipelines. Therefore, maintaining pipeline valves is crucial, and relevant personnel must pay close attention to ensure the safety of natural gas transportation and use, benefiting society as a whole.