What is a Backing Ring?
A backing ring is a small piece of material welded between two pipes. They are usually round to fit most pipes, but there are also square-shaped rings. It is also called a back-up ring or anti-extrusion ring. A typical backing ring is made of rubber or metal such as aluminum, chrome, or carbon steel. Pipe backing rings allow proper alignment between two joined pipes, hold the pipe joints together, and prevent leaks.
There are many types of backing rings, including plain rings, machine-welded rings, and gasket rings. Other, more advanced ones include grove, flat, and ridge types. The exact choice of ring depends on the application it is intended to be used for. They are used to hold pipes and fittings together in industries like automotive, construction, and aerospace.
The backing ring is placed in between the ends of two pipes to secure a joint. It is then welded so that the material is melted and fused with pipes. When used properly, it prevents the solder from penetrating through the pipes. This transforms the two pipes and the ring into one single pipe.
The quality, type, and skill of the welder are crucial factors for backing rings to be effective. The objective is to create a seamless and smooth look for the pipes. More importantly, no cracks or crevices should be left to ensure the integrity of the pipe. No welded material can be allowed to spatter and attach itself to the insides of the pipe to ensure the smooth flow of water, gas, or other chemicals.
A backing ring is a good welding piece because the joint it creates is relatively stronger than that created by direct soldering. A pipe joint backing ring supports and aligns the two pipes to make it easier for the worker to weld and fit it correctly. It has the disadvantage of leaving very small cracks and crevices not seen by the naked eye. After some time, these crevices will trap bacteria and ions, such as chloride, that will cause corrosion. Rings that are not installed correctly will break because of thermal and mechanical stress.
I recently had my catalytic converter changed in my car. I bought an after-market part and had a friend install it. The reason I mention that it was after market is that the converter was slightly shorter than the size needed to fit the pipes on both ends.
So my friend used a backing ring to complete the joins and screw the converter tight. It seemed to stretch a little but it did fit, and it was certainly a lot better than trying to weld the catalytic converter into the pipes.
Welding the pipes is not at all recommended, because in the future if you need a new converter again, you basically have to burn through the pipes, which makes installing the new converter harder.
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