Pipe Joints: Class, App, & Standards

The structure of pipe joints generally consists of three parts: the joint body, the connecting sleeve or connecting nut, and the sealing element. As a component that provides group sealing, it serves to connect pipes, change direction, and branch out pipes. Pipe joints are leak-proof components used to connect pipelines to pipelines or other components. The joint body in the pipe joint is the main connecting part of the joint, and the joint body may be the entire joint or a part of it. The sealing elements in the pipe joint are mainly made of two types of materials: metal and non-metal. The former is commonly referred to as a metal sealing joint, while the latter is commonly referred to as an elastomer sealing joint.
Pipe joints are mostly standardized both domestically and internationally. Regarding the existing pipe joint standards in China at present, they can be broadly categorized into two types. One type is the hydraulic pipe joint, which is suitable for pipeline systems carrying liquid and gas media. The other type is the pipe joint suitable for pipelines carrying various media.
Hydraulic pipe joints, as a sealing component for small-diameter pipeline connections, are widely used in various machines with hydraulic transmissions. Their suitable working temperature range is usually -20 to 100℃; the nominal pressure PN≤40 MPa; their specifications are generally not large, and the outer diameter of the pipe DO is usually 4 to 34 mm.
Pipe joints used for transporting seawater, fresh water, hot and cold water, drinking water, domestic sewage, crude oil, fuel oil, lubricating oil, finished oil, air, coal gas, and various media such as steam not exceeding 170℃ and particulate powders are mostly used in pipeline systems and pipeline installations in urban water supply systems, ships, and the petrochemical industry. Their size range is relatively wide, suitable for pipeline nominal diameters DN of 10 to 3000 mm.
Hydraulic pipe joints mainly include welded joints, flared joints, clamp joints, and flexible hose joints for welding, cutting, and related process equipment. Pipe joints for various media pipelines mainly include clamp-type flexible pipe joints, pipeline compensation joints, corrugated metal hose pipe joints (including joints made of alloy steel and stainless steel), and stainless steel threaded joints for the food and water supply industry.