About ASME B16.9 Bend

The ASME B16.9 bend is an essential pipe fitting that enables the redirection of pipelines within a pipeline system.

The Classification Of ASME B16.9 Bend

With commonly used angles of 45°, 90°, and 180°, as well as options for non-standard angles like 60°, these bends offer versatility to suit various project needs. They are fabricated from diverse materials, including cast iron, stainless steel, alloy steel, wrought iron, carbon steel, non-ferrous metals, and even plastics. Additionally, they offer various connection methods such as direct welding, flange connection, hot melt connection, electric fusion connection, threaded connection, and socket connection, providing adaptability to different systems. The production process also offers options such as welded, stamped, pushed, or cast bends, ensuring a suitable solution for any project requirement. These bends are also recognized by alternative names such as 90-degree and right-angle elbow.

The Meaning Of ASME B16.9 Bend Symbols

Schxx is the wall thickness grade of the elbow, 90e(s) indicates a short radius 90-degree elbow; 90e(l) indicates a long radius 90-degree elbow; 45e(l) indicates a long radius 45-degree elbow; 45e(s) indicates a short radius 45-degree elbow; 180e(s) indicates a short radius 180-degree elbow; 180e(l) indicates a long radius 180-degree elbow; r(c) indicates a concentric reducer; r(e) indicates an eccentric reducer; t(s) indicates an equal tee; t(r) indicates a reducing tee; cr(s) indicates an equal cross; cr(r) indicates a reducing cross; c indicates a pipe cap.

Advantages Of ASME B16.9 Bend

ASME B16.9 bend changes the direction, elevation, or diameter, closing the pipe end, and leading the branch pipe from the main pipe in the pipeline system. Due to the different shapes and complexity of the pipe system, there are many types of pipe fittings. ASME B16.9 bends are made from pipes as raw materials through deep processing. They have the dual characteristics of pipes and mechanical parts and combine the two.

There are many ways to ASME B16.9 bend, which are generally divided into manual and mechanical bending.

Method For Producing ASME B16.9 Bend

There are many mechanical bending methods, such as press bending, rolling bending, return bending, and extrusion bending.

Regardless of the bending method, the main contradiction in the entire bending process is how to overcome the problem of local deformation.

The most widely used in engineering are manual bending and return bending. The return bending method involves bending the pipe on a rotary pipe bending machine, which can be divided into mold bending and moldless bending.

Manual pipe bending does not require special equipment or complex process equipment. It can bend pipes of various radii, angles, and spatial directions. However, this pipe-bending method is labor-intensive, low in productivity, and unstable in quality.

Manually bent steel pipes are mostly hot-bent, while cold-bending suits stainless steel and non-ferrous metals.

Before bending, fill the pipe with fillers. The fillers for steel pipes are generally pure, dry, fine sand. The fillers for stainless steel and non-ferrous metals are preferably low-melting-point materials such as rosin and lead to prevent wrinkles and reduce ovality.

All die-bending machines use die-bending. The main dies are disc-shaped groove wheels and horn core heads.

When bending a tube with a disc-shaped groove wheel, the bending die is on the outside of the tube, half of the bent tube lies in the groove, and the other half of the tube in the bending area is pressed by a small roller with grooves (also called a clamping roller).

The end of the tube is fixed to the disc-shaped bending die by a chuck. If the clamping roller does not move, the disc-shaped bending die actively rotates to complete the bending, which is called a pull bending type;

If the tube is subjected to a thrust that causes the disc-shaped bending die to rotate passively to complete the bending, it is called a push bending type;

If the disc-shaped bending die does not move, the clamping roller presses the tube to rotate around the disc-shaped bending die to complete the bending, which is called a press bending type.

When bending a tube with a horn core head, the bending die is on the inside of the tube. The horn core head is shaped like a horn, with an axis length of 1/4 of a circle, a bending radius the same as that of the bent tube, and a maximum bending angle of 180°.

The thin end of the horn core head is slightly thinner than the inner diameter of the tube blank. The tube blank is inserted from the thin end. The thick end is the outlet, slightly thicker than the inner diameter of the tube blank. When bending the tube, the tube blank is first heated and then inserted into the mold. Under the action of thrust, the tube undergoes two processes: bending and expansion. When it slides out of the end of the core head, it is bent and formed.

The pipe bending machine used in the dieless pipe bending method does not need to determine the bending die of a certain bending radius.

It can be divided into two types: pull bending and push bending. The pipe-bending machine has a rotating arm whose length can be extended and retracted. When bending the pipe, the pipe is fixed on the rotating arm, and the distance from the pipe’s central axis to the rotating arm’s rotation center is the bending radius.

During operation, the pipe is covered with a copper induction coil, and the induction coil is passed through the medium frequency (for thicker pipes) or high frequency (for thin pipes) electricity to locally heat the pipe to 900~950℃, then bend the pipe.

If the rotating arm actively rotates to bend the pipe back to form, it is called pull bending; if the end of the pipe is subjected to thrust, the pipe pushes the rotating arm to rotate, thereby realizing the pipe back bending forming, called push bending.

Then, water is sprayed from a circle of small holes on the inner side of the induction coil to the bent pipe section to cool it quickly. Spraying water limits the heating section and deformation zone to a very small range, thereby preventing the pipe from wrinkling and flattening.