The hydraulic expansion tube is a new expansion joint technology. It applies plastic pressure to the inner surface of the tube to plastically deform the tube and expand to the inner surface of the plate hole. The hydraulic expansion joint is a section of the core rod having a diameter slightly smaller than the inner diameter of the tube. The outer surface of the core rod has a plurality of sealing members on the outer circumference surface, and an oil inlet hole is arranged in the middle of the core rod, between the two sections of the sealing member. A high pressure is applied to the pipe section to cause plastic expansion and deformation of the pipe to achieve expansion.

The use of hydraulic expansion tube in high-altitude manufacturing has obvious advantages over the use of mechanical expansion tube, especially for the expansion joint of the product as long as the sealing property is required to be expanded, which not only effectively improves the work efficiency, but also the quality of the expansion joint is obviously Improve, avoid or reduce pipe end leakage during power plant operation, reduce the economic loss caused by high-altitude shutdown to power plants, and its social benefits are significant.

The new technology of rubber expansion is developed on the basis of the deformation of the rubber. It is the expansion of the tube to the tube sheet by the radial pressure generated by the axial compression of the rubber elastomer. When the pulling rod applies a pulling force, the expanding rubber is axially compressed and simultaneously has a radial expansion which is sufficient to deform the tube material to achieve the connection between the tube and the tube sheet.

The expansion tube rubber is made of a material with high elasticity and high strength. In order to prevent the axial movement of the rubber under high pressure, a special hard rubber sealing ring is installed at both ends of the expansion head. The rubber tube expansion rod is made of high strength steel. It is loaded on the tie rod by pressure water or oil of about 20 MPa. Since the tension is balanced against the pressure ring, an internal force system is formed without other support or restraint.

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