The sealing basis of pvc-u large diameter spiral wrapping pipe connection lies in scientific structural design. Socket-type connection is a common method. One end of the pvc-u large diameter spiral wrapping pipe is designed as a flared socket and the other end is a spigot. When installing, the spigot is inserted into the socket to form a nested structure. This structure provides sufficient attachment space for the sealing material by increasing the contact area between the pipes. At the same time, it can also disperse the fluid pressure inside the pipeline to avoid local excessive force causing sealing failure. In addition, there is also an electric hot melt tape connection. By wrapping the electric hot melt tape at the connection part, the pipe and the melt tape are fused after power is turned on to form an integrated connection structure, which fundamentally eliminates the gap and ensures the reliability of the seal.
The selection of sealing materials is crucial to ensure sealing performance. The rubber sealing ring is the core sealing component of the socket-type connection, usually made of ethylene propylene diene monomer rubber (EPDM) or nitrile rubber (NBR). EPDM rubber has excellent weather resistance, aging resistance and chemical stability. It can maintain good elasticity under different temperatures and media environments. It is not easy to deform or corrode even if it is immersed in sewage for a long time. Nitrile rubber has strong tolerance to oil pollution and is suitable for oil-containing medium transportation scenarios. The cross-sectional shape of the sealing ring has also been carefully designed. The common O-type and lip-type sealing rings can fit tightly against the pipe wall after the pipe is connected, forming an effective sealing barrier to prevent fluid leakage.
In the electric hot melt tape connection method, the performance of the hot melt material determines the sealing of the connection. The electric hot melt tape is usually composed of a polyethylene (PE) substrate and an electric heating wire. The PE material has good compatibility with PVC-U pipes and can be fully fused at high temperatures. The electric heating wire is evenly distributed in the melting tape. The heat generated after power is turned on causes the melting tape and the pipe surface to melt at the same time, and a firm connection layer is formed after cooling. In order to ensure the quality of welding, the thickness of the welding belt, the spacing of the electric heating wire and other parameters are strictly calculated and tested to ensure that the heat is evenly conducted during the heating process, so that the pipe connection parts are completely fused and zero-gap sealing is achieved.
Standard operation of the construction process is the key link to ensure the sealing performance. When constructing a socket-and-spigot connection, the socket and the spigot of the pipe must first be cleaned to remove impurities such as oil and dust on the surface to avoid affecting the sealing effect of the sealing ring; then lubricant is evenly applied to the spigot end to facilitate the smooth insertion of the pipe into the socket, while preventing the sealing ring from twisting or breaking during the insertion process. After insertion, a special tool is required to measure the insertion depth to ensure that the design requirements are met and to avoid poor sealing due to shallow insertion. For electric hot-melt connection, check whether the welding belt and the electric heating wire are intact before construction. When connecting, the specified voltage, current and heating time must be strictly followed to ensure sufficient welding.
Quality inspection methods provide double protection for sealing performance. After the construction is completed, a closed water test or a closed air test is usually used to test the sealing of the pipeline. The water-tightness test is to inject water into the pipe to the specified water level and observe the water level drop within a certain period of time. If the water level does not drop significantly, it means that the seal is good; the air-tightness test is to fill the pipe with compressed air and determine whether there is a leak by detecting the change in air pressure. In addition, non-destructive testing technologies such as ultrasonic testing and infrared thermal imaging can be used to inspect the internal structure of the connection parts to timely discover potential sealing defects and ensure the quality of the project.
In order to cope with complex engineering environments, some projects will also adopt a combined sealing method. For example, on the basis of the socket connection, additional sealant is used to seal the interface for a second time. The sealant has good filling and adhesion properties, and can penetrate into the tiny gap between the pipe and the sealing ring to further enhance the sealing effect. This combination is particularly suitable for projects such as drinking water transportation and underground drainage that have extremely high requirements for sealing. Through multiple protective measures, the risk of leakage can be effectively reduced.
With the continuous advancement of technology, the connection and sealing technology of PVC-U large diameter spiral wrapping pipe is also continuously innovating. The new intelligent sealing monitoring system installs sensors at the sealing part to monitor the pressure and temperature changes of the sealing ring in real time. Once an abnormality occurs, an alarm will be immediately issued to achieve dynamic monitoring of the sealing performance. At the same time, the research and development of degradable sealing materials also provides new options for environmental protection projects. These innovative technologies will further improve the sealing performance and reliability of PVC-U pipe connections and promote the development of related engineering fields.
