Introduction To Metal Expansion Joints

U-shaped Expansion Joints: These joints bend the pipe into a U-shape or other form, also known as an expansion bend. They utilize the elastic deformation of the shape to compensate for deformation. Their advantages include high strength, long service life, and the ability to be fabricated on-site. Disadvantages include large space requirements, high steel consumption, and high frictional resistance. These expansion joints are widely used in various steam pipelines and long pipelines.

Belled Expansion Joints: These expansion joints are made of metal bellows. They can expand and contract along the axial direction and also allow for slight bending. A common type is the axial bellows expansion joint, used for axial length compensation in pipelines.

To prevent exceeding the allowable compensation amount, protective tie rods or rings are installed at both ends of the bellows, and guide supports are installed on the pipes connected to it at both ends.

There are also angle and lateral expansion joints, which can be used to compensate for angular and lateral deformation of pipelines. The advantages of these expansion joints are space saving, material saving, and ease of standardization and mass production. The disadvantage is a shorter service life.

Belled expansion joints are generally used in pipelines with relatively low temperatures and pressures and shorter lengths. With the improvement of bellows manufacturing technology, the application range of this type of expansion joint is expanding.

Sleeve Expansion Joint: A sleeve expansion joint consists of inner and outer sleeves capable of axial relative movement.

A stuffing box seal is used between the inner and outer sleeves. During use, the two ends of the pipe move along a single axis. Guide supports are installed at both ends of the expansion joint.

Its advantages are low frictional resistance to fluid flow and a compact structure. Its disadvantages are poor sealing performance and a relatively large thrust on the fixed supports. Sleeve expansion joints are mainly used in water pipelines and low-pressure steam pipelines.