Knowing how to determine wall reduction is important; however it is equally important to know the characteristics of the popular tubing materials. A simple rule of thumb is the harder the material, the less wall reduction required to obtain a tube joint.
Getting the right tools for your application is critical in order to complete the job right the first time. One of the most overlooked factors when ordering tooling, is determining whether you have minimum wall or average wall tubing.
The American Society Of Mechanical Engineers (ASME) develops standards to provide consistency and ensure public safety and reliability. While these codes are not always required, they have been widely adopted and implemented across many industries. As a result, it is important to be knowledgeable and aware of these standards prior to beginning a job.
Tube Expanding is the art of reducing a tube wall by compressing the O.D. of the tube against a fixed container, such as rolling tubes into tube sheets, drums, ferrules or flanges. To assure a proper tube joint, the tube wall must be reduced by a predetermined percentage.
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For tube expanding it is desirable to roll the tube quickly as it prevents work hardening of the tube and less frictional heat is generated. The limiting factors in this balance of speed vs. power are voltage or pneumatic pressure. These either limit the speed or power being produced.
Tube rolling occurs when the tube rotates due to inadequate friction between the tube OD and the hole in the tube sheet. This can cause increased expansion times and decrease the efficiency of the operator. Increasing the friction between the tube and tube sheet and or collar the tube will not rotate within the tube sheet. Increasing the friction can be done using several different methods: