Industrial Pipeline Maintenance: Ensuring the Smooth Flow of the Industrial “Blood Vessels”

In the complex system of modern industrial production, industrial pipelines are like intertwined blood vessels, continuously transporting various fluid media and serving as the key infrastructure for maintaining the normal operation of the entire industrial production process. Once industrial pipelines malfunction, it will not only lead to production stoppages and declines in product quality but also may trigger serious safety accidents, bringing huge economic losses and reputational damage to enterprises. Therefore, having an in-depth understanding of the knowledge and key points of industrial pipeline maintenance, formulating a scientific and reasonable maintenance plan and strictly implementing it are of great significance for ensuring the safe and stable operation of industrial production.

I. Classification and Characteristics of Industrial Pipelines
Industrial pipelines can be classified into various types according to the different media they transport, such as pipelines for conveying water, steam, petroleum, natural gas, and chemical raw materials. Different types of pipelines have their own unique physical and chemical properties and requirements for working conditions. For example, pipelines for transporting high-temperature and high-pressure steam need to have good high-temperature and high-pressure resistance and thermal stability; pipelines for transporting corrosive chemical raw materials must have excellent corrosion resistance and are usually made of special alloy materials or steel pipes lined with corrosion-resistant coatings. In addition, there are also significant differences in the diameter, wall thickness, connection methods, and laying environments of industrial pipelines. These factors determine that targeted measures need to be taken when carrying out maintenance.
II. Daily Inspection and Monitoring

1. Visual Inspection
Regular visual inspections of industrial pipelines are an important means to detect potential problems in a timely manner. Inspectors should carefully examine the surface conditions of the pipelines along the pipeline routes, focusing on whether there are signs of leakage, deformation, corrosion, wear, and peeling of the surface coating on the pipelines. For above-ground pipelines, direct observation can be carried out; for buried pipelines, some detection equipment, such as underground pipeline detectors, needs to be used to first determine the location of the pipelines, and then conduct local excavation inspections or use non-destructive testing techniques for detection. During the inspection process, once slight corrosion is found on the pipeline surface, its location and the degree of corrosion should be recorded in a timely manner, and the causes of corrosion should be analyzed, such as whether it is caused by factors such as high humidity in the surrounding environment, leakage of corrosive gases or liquids. For deformed or worn parts, the impact on the strength and sealing performance of the pipelines should be evaluated to determine whether immediate repair or temporary protection measures are required.

2. Pressure and Temperature Monitoring
During the operation of industrial pipelines, pressure and temperature are two key parameters that must be monitored in real-time. The pressure sensors and temperature sensors installed on the pipelines should be calibrated regularly to ensure the accuracy of the measured data. Through the analysis of pressure data, it can be judged whether the flow state of the fluid in the pipelines is normal and whether there are problems such as blockage, leakage, or pump and valve failures. For example, if the pressure suddenly increases, it may be that there are foreign objects blocking the pipelines; if the pressure continues to drop, it may be that the pipelines have leaks. Temperature monitoring is particularly important for pipelines transporting high-temperature or low-temperature media. Abnormal changes in temperature may indicate that the insulation layer of the pipeline is damaged, the flow rate of the medium is unstable, or a chemical reaction has occurred. For example, if the temperature of a pipeline transporting high-temperature steam suddenly drops, it may be due to steam leakage leading to heat loss or damage to the insulation layer. This will not only affect the transportation efficiency of the steam but also may cause thermal stress on the pipeline due to a sudden local temperature drop, resulting in pipeline rupture.

III. Pipeline Cleaning and Maintenance
1. Physical Cleaning Methods
(1) Pigging Cleaning

Pigging is a commonly used physical cleaning tool for pipelines. It can move forward in the pipeline relying on fluid pressure or external power to remove dirt, deposits, rust and other impurities on the pipe wall. There are many types of pigs, and different types of pigs, such as cup pigs, straight plate pigs, and foam pigs, can be selected according to the diameter, shape and cleaning requirements of the pipeline. Before pigging operations, a detailed assessment of the pipeline route, valve settings and the passing ability of the pig needs to be carried out to ensure that the pig can run smoothly in the pipeline and complete the cleaning task. At the same time, a pig receiving device should be set up at an appropriate position of the pipeline so that the pig can be taken out after the pigging operation is completed and the dirt carried by the pig can be inspected to judge the cleaning effect of the pipeline.
(2) High-Pressure Water Jet Cleaning
High-pressure water jet cleaning uses the high-pressure water jet generated by a high-pressure water pump to flush the inner wall of the pipeline. This method has the advantages of good cleaning effect, high efficiency and little damage to the pipeline, and is suitable for cleaning pipelines of various diameters and shapes. The pressure and flow rate of the high-pressure water jet can be adjusted according to the degree of dirt on the pipeline and the material of the pipeline. Generally, the pressure range is between 100 – 2000 bar. During the cleaning process, the high-pressure water jet nozzle needs to be sent into the pipeline through special pipeline cleaning equipment, and the rotation and forward speed of the nozzle should be controlled to ensure comprehensive and uniform cleaning of the inner wall of the pipeline. Meanwhile, attention should be paid to collecting and disposing of the sewage and dirt generated during the cleaning process to avoid polluting the environment.
2. Chemical Cleaning Methods
When the dirt in the pipeline is relatively stubborn, such as scale, oil stains or chemical deposits, chemical cleaning methods are often adopted. Chemical cleaning uses chemical cleaning agents to react chemically with the dirt, dissolve, peel off or convert the dirt into soluble substances, and then discharge them out of the pipeline through water flushing. The selection of chemical cleaning agents should be carefully considered according to the material of the pipeline, the transported medium and the composition of the dirt to avoid corrosion or other damage to the pipeline caused by the cleaning agents. For example, acidic cleaning agents can be used for rust dirt, and alkaline cleaning agents or organic solvents can be used for oil stains. Before chemical cleaning, a local test on the pipeline should be carried out first to determine the process parameters such as the concentration, temperature and cleaning time of the cleaning agent, and a detailed cleaning plan should be formulated. During the chemical cleaning process, the injection amount and flow rate of the cleaning agent should be strictly controlled to ensure that the cleaning agent circulates fully in the pipeline and reacts fully with the dirt. After the cleaning is completed, the pipeline must be thoroughly flushed with a large amount of clean water until the discharged water meets the specified water quality standards. At the same time, the pipeline should also be neutralized to remove the residual acidic or alkaline substances to prevent pipeline corrosion.

IV. Anti-corrosion Measures for Pipelines
1. Coating Anti-corrosion
Applying anti-corrosion coatings on the surface of industrial pipelines is a widely used and cost-effective anti-corrosion method. Anti-corrosion coatings can isolate the pipelines from the external corrosive environment, preventing corrosive substances such as oxygen, moisture, acids, alkalis and salts from contacting the metal surface of the pipelines, thereby slowing down the corrosion rate of the pipelines. Commonly used anti-corrosion coating materials include epoxy resin, polyurethane, polyethylene, inorganic zinc-rich paint, 等. The coating construction process includes surface pretreatment, primer coating, intermediate coating and topcoat coating. Surface pretreatment is a key step in coating construction. Methods such as sandblasting and shot blasting are usually used to remove rust, oxide scale, oil stains and other impurities on the pipeline surface to make the pipeline surface reach a certain roughness and enhance the adhesion of the coating to the pipeline surface. The primer is used to provide good anti-rust performance and adhesion to the pipeline surface. The intermediate coating is mainly used to increase the thickness and shielding performance of the coating, and the topcoat is used to resist the erosion of the external environment and play a decorative role. During the coating construction process, the thickness, uniformity and coating interval time of the coating should be strictly controlled to ensure that the coating quality meets the relevant standard requirements.
2. Cathodic Protection
For industrial pipelines in strong corrosive environments such as buried or underwater ones, cathodic protection is an indispensable anti-corrosion means. Cathodic protection suppresses the anodic dissolution reaction of metal by applying cathodic current to the pipeline to make the metal surface of the pipeline become the cathode, thereby achieving the purpose of anti-corrosion. Cathodic protection mainly includes the sacrificial anode method and the impressed current cathodic protection method. The sacrificial anode method uses a metal with a more negative potential (such as magnesium alloy, zinc alloy, 等。) as the sacrificial anode and connects it to the protected pipeline. The sacrificial anode dissolves to provide cathodic protection current for the pipeline. This method has the advantages of simple construction and no need for an external power supply, but its protection range is relatively small and it is suitable for anti-corrosion protection of short-distance pipelines or local areas. The impressed current cathodic protection method uses an external DC power supply, connects the pipeline to the negative pole of the power supply, and sets auxiliary anodes around the pipeline. The power supply provides continuous cathodic protection current for the pipeline. The impressed current cathodic protection method has a large protection range and adjustable current, but it requires the installation of special power supply equipment and a monitoring system, with relatively high investment and maintenance costs. During the implementation of cathodic protection, the protection potential of the pipeline needs to be monitored and adjusted regularly to ensure that the protection effect is always in the best state.

V. Pipeline Repair and Renovation
1. Leak Repair
Pipeline leakage is one of the more common failures in industrial pipelines. Once pipeline leakage is found, measures should be taken immediately to repair it to reduce the impact of the leakage on production and the environment. For smaller leakage points, such as weld pores and small holes caused by corrosion, temporary repair methods such as welding, using pipe clamps, and winding sealing tapes can be adopted. However, for larger leaks or pipeline ruptures, it is necessary to first stop the operation of the pipeline, empty the medium in the pipeline, and then formulate a detailed repair plan according to the material, diameter and damage degree of the pipeline. Repair methods may include replacing the damaged pipe section, repairing by welding, and using pipeline repair clamps. During welding repair, it should be ensured that the welding process meets the relevant standard requirements, the welders have corresponding qualification certificates, and non-destructive testing should be carried out on the welds after welding to ensure the welding quality.
2. Pipeline Renovation
With the development of industrial production and the progress of technology, it is sometimes necessary to renovate industrial pipelines to meet the requirements of new production processes or improve the transportation capacity of the pipelines. Pipeline renovation involves changes in pipeline routes, enlargement or reduction of pipeline diameters, changes in connection methods and other aspects. Before pipeline renovation, detailed engineering design and feasibility studies need to be carried out, fully considering the impact of the renovation on the existing production system, such as whether production needs to be stopped, how to switch and empty the media. During the renovation process, construction should be carried out strictly in accordance with the design requirements to ensure the compatibility and safety of the newly installed pipelines with the original pipeline system. Meanwhile, comprehensive tests and acceptance inspections, including pressure tests, sealing tests and flow tests, should be carried out on the renovated pipelines to ensure that the pipeline renovation achieves the expected goals.

VI. Maintenance Plan and Personnel Training
1. Formulating a Maintenance Plan
In order to ensure that the maintenance work of industrial pipelines is carried out in an orderly manner, enterprises should formulate a scientific and reasonable pipeline maintenance plan based on factors such as the types of pipelines, operation status, service life and relevant laws and standards. The maintenance plan should include the time interval of daily inspections, inspection contents and standards, the cycle and methods of cleaning and maintenance, the implementation plan of anti-corrosion measures, the pre-plan for repair and renovation, and the arrangements for personnel training. After the plan is formulated, it should be strictly implemented, and the implementation of the plan should be regularly checked and evaluated. The plan should be adjusted and improved in a timely manner according to the actual situation.
2. Personnel Training and Qualification Management
The maintenance work of industrial pipelines requires professional technicians to complete. Therefore, enterprises should strengthen the training and qualification management of relevant personnel. The training content should include basic knowledge of pipelines, maintenance techniques, safety operation procedures, the use of detection equipment and emergency treatment measures. The training methods can be a combination of internal training, external training, online learning and practical operations. Meanwhile, enterprises should ensure that the personnel engaged in pipeline maintenance work have corresponding qualification certificates, such as welder certificates, non-destructive testing personnel certificates, and pipeline repair qualification certificates, and regularly review and update the qualifications of personnel to ensure that their professional skills and qualities can meet the work requirements.

Industrial pipeline maintenance is a long-term and complex systematic project. Enterprises need to start from multiple aspects, establish and improve a sound maintenance management system, strengthen daily inspections and monitoring, adopt scientific and reasonable cleaning, anti-corrosion, repair and renovation measures, and pay attention to personnel training and qualification management. Only in this way can it be ensured that industrial pipelines are always in good operating condition, providing a solid and reliable guarantee for the safe, stable and efficient operation of industrial production and helping enterprises remain invincible in the fierce market competition