The forming technologies of large-size seamless pipe fittings mainly include: hot spinning, hot extrusion, hot piercing and rolling, and hot pushing and expanding. details as follows:

1.hot spinning method

It is to fix the flat blank or pre-formed blank to the rotating mandrel, apply pressure to the blank with the rotating wheel, and the rotating wheel is fed axially at the same time. After one or more processing, various thin-walled hollow rotating systems are obtained. The process method of the product. Its advantages are high product precision, good mechanical performance and wide size range. The tool mold is simple, easy to replace, and the production cost is lower than other methods. The main disadvantages are the long production hours and low output. The processed pipe fittings are limited by the length of the equipment and the size is short.

2.hot extrusion method
The billet needs to be pre-processed by machining before extrusion. When extruding pipes with a diameter of less than 100mm, the equipment investment is small, the material waste is small, and the technology is relatively mature. However, once the diameter of the pipe is enlarged, the hot extrusion method requires equipment with large tonnage and high power, and the corresponding control system must be upgraded.

3.hot piercing and rolling method
Hot piercing rolling is mainly based on longitudinal rolling and cross rolling. Longitudinal rolling and extension rolling are mainly limited-moving mandrel continuous tube rolling, small-stand limited mandrel continuous rolling tube rolling, three-roll restricted mandrel continuous rolling tube rolling and floating mandrel continuous tube rolling. These methods have high production efficiency, low metal consumption, good product quality, advanced control systems, and increasingly widespread applications. The skew extension rolling method has also been widely used because of its low investment, short process, suitable for small batches, multiple varieties, multiple specifications and high-precision production of medium-thick wall seamless pipes.

4.thermal expansion method
The diameter expansion equipment is simple, low cost, convenient maintenance, economical and durable, and flexible product specification change. If you need to prepare large diameter elbows and other similar products, you only need to add some accessories. It is suitable for the production of medium and thin-walled and large-diameter seamless steel pipes, as well as thick-walled pipes that do not exceed the equipment capacity.