The difference between casing nipple and casing coupling

The difference between casing nipple and casing coupling

Casing pipe is an insulating device that introduces live conductors into electrical equipment or passes through walls. The former is called an electrical casing, and the latter is called a wall casing. The casing structure generally consists of three parts: a conductor (guide rod), an insulator, and a metal flange. The conductor passes through the axis of the cylindrical insulator, and the metal annular flange is installed outside the insulator and used for grounding. The casing is an insulating structure with a strong vertical electric field component. The electric field intensity at the metal flange is very large, which is prone to corona discharge and flash discharge along the surface of the medium. The radial electric field intensity between the flange and the guide rod is also very high, which is prone to breakdown of the insulating medium. In addition to the use of a single solid insulating material for casings of 35kV and below, multiple insulating materials are often used or electric field uniformity measures are taken to make the axial and tangential electric field distribution tend to be uniform.

Casing nipple

A casing nipple is a pipe joint that is put on the casing pipe and is used to connect the two ends of the casing pipe . This joint usually consists of two joints plus a sealing gasket. The installation of the casing nipple can be disassembled and installed as needed, which is very convenient when the pipeline needs to be repaired or replaced. The production process of the casing nipple is mainly to thread the surface of the steel pipe, then make a hole in the casing pipe , put the casing  pipe on the steel pipe, and finally fix it with a joint. The Casing nipple is mainly used for pipeline connections in the fields of petroleum, chemical industry, natural gas and construction.

Casing coupling

A coupling is a part used for pipeline connection, mainly used to connect the outside of the pipeline. Like the Casing nipple, the coupling can also be disassembled and installed as needed. casing couplings are usually used to connect pipelines, pumps, valves and other equipment to facilitate the installation and maintenance of pipelines. The production process of the coupling is to first fold a piece of steel plate, then weld the steel plates together, and then process them into a semicircle, and finally fix the two semicircular parts to the outside of the pipeline with bolts. 

The difference between Casing nipples and couplings

1. Different structures: The Casing nipple is installed on the casing pipe , while the coupling is installed on the outside of the pipe. The structure of the casing coupling mainly consists of two parts, namely the casing of the pipe and the connecting pipe. The casing pipe is generally cylindrical, with a larger inner diameter and a smaller outer diameter, which is convenient for casing s on pipes with smaller outer diameters; the connecting pipe is generally a flat ring, which is used to connect the casing pipe and the pipe with a larger outer diameter.

2. Different manufacturing processes: The casing nipple needs to be threaded on the casing pipe , then a hole is opened on the casing pipe, and finally fixed with a joint. The coupling needs to fold a piece of steel plate, then weld the steel plates together, and then process it into a semicircle, and finally fix it on the outside of the pipe with bolts.

3. Different application scenarios: The casing nipple is mainly used for pipeline connections in the fields of petroleum, chemical industry, natural gas and construction, while the casing coupling is mainly used for pipeline connections in general industries.

4. Type: The types of casing joints include plug-type casing heads, inner cone-type casing heads, outer cone-type casing heads, and cone-hole casing heads; there are many types of casing couplings, mainly including cast iron casing joints, steel casing joints, and stainless steel casing joints. According to the different connecting pipes, casing couplings are also divided into bayonet casing joints and flange casing joints.

The above is the difference between casing joints and couplings. Whether it is a casing joint or a coupling, it needs to be selected and installed according to the actual situation when in use to ensure the normal operation and safe production of the pipeline.