Although stainless pipe is an intensely hard material, stainless steel is ductile and malleable and can be formed using various mechanical means into a wide variety of shapes.
Bending stainless tube is a process that can be utilized to shape stainless tubing into many useful configurations.
Bending Basics of Steel
Steel can be bent into a number of shapes but the process takes an enormous amount of direct pressure applied by specialized equipment.
The difficulty of bending a section of tubing depends upon the thickness of the tubing. While thick-walled tubing requires more force to bend, it is less likely to fail during the bending process than thinner walled material.
Different sizes and shapes of pipe each require their own sets of bending tools. Companies that specialize in bending stainless tubes must maintain dozens or even hundreds of sets of bending implements in order to bend different tubing configurations.
How to bend stainless steel pipe
Stainless steel tubing may be shaped into gentle curves by rolling.
This process uses rollers to force a section of tubing over or around a die, a specially formed tool designed to change the shape of a piece of metal.
When making a sharp bend in stainless steel tubing a metal piece called a mandrel is inserted inside to prevent the tube from losing its shape during bending. The tubing is then placed near a die and mechanical pressure is applied to the tubing which forces it to bend around the die.
There are limitations to the degree of curvature that can be achieved with any pipe shaping process but bending generally produces much sharper curves than rolling.
Bending Seamed Stainless Steel Tubing
While any kind of steel tubing can be shaped by bending, tubing that is formed without seams generally responds better to the bending process than welded or seamed tubing.
Even moderate bending can weaken or rupture a seam although this problem can be diminished somewhat by bending the tubing in a manner that lessens the stresses placed directly on the seam.
In addition to weakening a seam, the process of bending can weaken the structure of the tubing itself.
When a tube is bent the steel along the outside of the curve is stretched while the material on the inside of the curve is compressed.
If the tubing is bent too sharply the exterior of the curve may become significantly thinner than the rest of the tubing, making that area more prone to failure.
Another important consideration with stainless steel tubing is the preservation of the pipe’s internal diameter and structure. Even when a mandrel is used the tubing may deform slightly during bending.
Any deformation in the internal diameter of a tube or pipe that carries a liquid can disrupt the flow pattern of the fluid inside. This in turn can lead to scouring of the inside of the tube which could lead to thinning and eventual failure. When tubing is bent for structural or decorative purposes deformation of the internal dimension of the pipe is less important.