What Is A Flanged Pup Joint?

The flanged pup joint is a type of steel butt-welded pipe fitting, usually a section inside a loose flange. The flanged pup joints are mainly used in situations where the medium temperature and pressure are not high, but the medium is highly corrosive. In this case, the part of the flange that contacts the medium (the flanged pup joint) is usually made of corrosion-resistant high-grade materials such as stainless steel, while the outside is clamped with a flange ring made of low-grade materials such as carbon steel to achieve sealing. The flanged pup joint is connected to the flange by bolts, which is easy to disassemble and maintain. Its structure is compact and can adapt to different pipe diameters and pressure requirements.

Dimensions

Nominal size DN: Ranging from 15 to 692, the specific dimensions include outer diameter, pipe length, fillet radius, etc. ‌ These standards ensure the manufacturing quality and performance of the flanged pup joint, which is suitable for the connection needs of various industrial piping systems.

‌Standards for flanged pup joints

Mainly include GB/T12459, GB/T9124.1 and ASME B16.5:

‌GB/T12459‌: This is a standard for steel butt-welded seamless pipe fittings, applicable to the manufacture and inspection of flanged pup joints‌.

‌GB/T9124.1‌: This is a standard for flanges, which specifies the dimensions and tolerances of flanged pup joints‌.

‌ASME B16.5‌: This is an American standard, applicable to the manufacture and inspection of flanged pup joints‌.

Main features

‌1. Excellent sealing performance‌: The flanged pup joints form a smooth and flat sealing surface through precise processing technology, which effectively improves the sealing performance of the connection. Compared with traditional welded flanges, flanges avoid defects that may occur during welding and significantly reduce the risk of leakage‌.

‌2. Strong corrosion resistance‌: The flanged pup joints are usually made of high-grade materials such as stainless steel and have excellent corrosion resistance. This enables the flanged pup joint to be used for a long time in a highly corrosive medium environment, is not susceptible to corrosion damage, and extends the overall service life of the pipeline system.

‌3. Flexible installation and disassembly: The flanged pup joint is compactly designed and can be connected to the flange by bolts, making the installation and disassembly process simple and quick. This design makes it more convenient to maintain or replace the pipeline, greatly improving the construction efficiency.

‌4. Adapt to a variety of working conditions: The flanged pup joint can be customized according to different pipeline sizes and pressure levels, and is suitable for a variety of working conditions such as high temperature, high pressure, low temperature, and low pressure, maintaining stable performance and meeting various engineering needs.

‌5. Improve system reliability: The high strength and durability of the flanged pup joint improve the reliability of the loose flange connection. Even in an environment with large vibration or impact, the flanged pup joint can still maintain a stable connection state to ensure the safe operation of the pipeline system.

Application and material requirements

The flanged pup joint is usually used to connect pipeline systems, and its materials include carbon steel, stainless steel, and alloy steel.

The flanged pup joint is often used in conjunction with the flange, which is fixed to the end of the steel pipe by welding, so that the flange can be movable and easy to install and disassemble. In addition, in the connection of oil pipes, the flanged pup joint is used as a short section of oil pipe, with a length ranging from 0.25 meters to 1.5 meters, and is often used to assemble the downhole pipe string.

Summary

In summary, the flanged pup joint has become an ideal choice for pipeline connection with its excellent sealing performance, corrosion resistance, installation flexibility, adaptability to working conditions, economic and environmental protection, and high reliability. It is widely used in the fields of petroleum, chemical, gas, medicine, etc.