Equipment lined with PE (polyethylene) is widely used in chemical, storage, and transportation industries. Its corrosion resistance and wear resistance depend on the tight bond between the lining layer and the substrate. However, blistering of the lining layer is a common defect, mainly caused by construction techniques, material compatibility, and environmental factors, requiring systematic control.
Proper operating procedures during construction are the primary step in preventing blistering. When winding the lining layer, a spiral winding method should be used, with each winding overlapping the previous one by at least 50% to avoid gaps. Moderate tension should be maintained during winding to prevent excessive tape length, which could lead to wrinkles or air bubbles. For example, in the construction of steel pipe linings, winding should be done evenly from one end to the other, while using a special tool to smooth out wrinkles to ensure complete adhesion between the lining layer and the substrate. Furthermore, the humidity of the construction environment must be strictly controlled. If moisture or humid vapor is present on the substrate surface, it is prone to expansion and bubble formation upon heating. Therefore, the substrate must be thoroughly dried before construction and fully sun-dried.
Material compatibility directly affects the adhesion of the lining layer. Chemical reaction between the primer and the polyethylene adhesive layer is a common cause of blistering. If the two are incompatible, the solvent may separate from the bottom and blister. Therefore, a matching anti-corrosion primer must be selected, and substandard primers or those containing chemical impurities should be avoided. For example, in storage equipment containing highly corrosive media, a special primer resistant to chemical corrosion should be selected, and its compatibility with the polyethylene adhesive layer should be verified through small-area tests. Simultaneously, the tension of the tape itself must be uniform to avoid air trapping due to localized slack. Tension control equipment should be used during construction to ensure stable tension in each section of tape.
Environmental factors have a significant impact on the quality of the lining layer. Low temperatures reduce the fluidity of the hot melt adhesive, leading to loose adhesion and air residue. During winter construction, the equipment must be preheated to a suitable temperature, and the construction speed must be controlled to ensure the hot melt adhesive melts completely. For example, in northern regions, the steel pipe should be heated to 30-40℃ before construction, and the winding speed adjusted to prevent the adhesive layer from becoming brittle due to excessively low temperatures. Furthermore, direct sunlight can cause excessively high local temperatures, leading to shrinkage or blistering of the adhesive layer. Therefore, construction should be avoided during high-temperature periods, or shading measures should be implemented.
Ventilation design is a crucial aspect of preventing blistering in the lining layer. Sufficient venting channels must be included in the equipment design to ensure smooth air escape during the winding process. For example, in the lining construction of large storage tanks, vent holes can be installed at the top of the tank, and the venting effect should be checked periodically during the winding process. For complex structures, a segmented winding process should be adopted, with each segment inspected and air bubbles removed before proceeding to the next step. Additionally, the uniformity of pressure from the pressure rollers directly affects the density of the lining layer. Pressure calibration equipment must be used to ensure consistent pressure at both ends of the pressure rollers to avoid localized blistering due to uneven pressure.
Post-construction quality inspection and maintenance are equally important. After the lining layer is completed, a comprehensive inspection is necessary, focusing on checking for air bubbles or voids at the edges, joints, and bends. Non-destructive testing can be performed using tapping or ultrasonic testing. Any air bubbles found must be repaired promptly. During repair, the air bubble area must be thoroughly removed, the primer reapplied, and tape wrapped around it to ensure a tight bond between the repaired area and the original lining layer. During equipment use, the condition of the lining layer should be checked regularly to prevent air bubble expansion due to media corrosion or mechanical damage.
Long-term prevention requires establishing standardized construction procedures. Companies should develop detailed construction specifications, clearly defining material selection, construction parameters, and testing standards, and provide professional training to construction personnel. For example, construction record archives can be established to track the construction parameters and subsequent usage of each piece of equipment, and process optimization can be achieved through data analysis. Simultaneously, long-term cooperation with material suppliers should be established to ensure the stability of primers and tapes, avoiding quality problems caused by batch differences in materials.
For equipment lined with PE (PE) equipment, anti-bubbling control needs to be integrated throughout the entire process of design, construction, testing, and maintenance. By optimizing construction processes, strictly matching materials, controlling environmental factors, improving venting design, and establishing standardized procedures, the risk of blistering in the lining layer can be significantly reduced, extending the equipment's service life and ensuring its stable anti-corrosion performance.
