Pipe joints connect pipes and fittings into an integrated pipeline.
Joints can be divided into two main types: tension resistant and non-tension resistant. Joints may also be divided by application as follows:
Used primarily in tension-resistant pressure lines such as oil, natural gas and district heating pipelines. Used in water pipelines, especially when the diameter is ≥DN 600 and the joint can be repaired from the inside after welding.
Used in water lines to facilitate installation and to allow 1.5–3.0 degree bends at joints. Since the joint is welded from the inside to make it tension resistant, it is suitable for diameters ≥DN 600 and pressures up to 20 bar.
The DIN joint is made with a rubber ring partially embedded in the concrete (type DIN/G), which eliminates the need to complete the internal concrete lining after welding. Used in pipelines where easy installation of the tension-resistant joint and the possibility of making less than 1.0 degree bends are a must. Welded from the outside. Suits pipe diameters DN 400–1000.
Flange joints are widely used in industry. In the case of underground pipes flange joints are used mainly to connect large bends.