Published: 14 October, 2016
This article is based on guidance provided in the British Fluid Power Association’s training course titled ‘Small Bore Tubing Integrity Course – using twin ferrule compression fittings’. This month, we look at tube preparation.
Tubing that has been selected correctly, combined with correct assembly of twin ferrule compression fittings, will provide a reliable seal on a range of applications.
Maximum performance will be achieved by:
• Selecting high-quality tube.
• Compression fittings assembled in accordance with the manufacturer’s assembly procedures.
• Using tube clamps to limit the movement during normal service.
• Adhering to good tube installation practices.
Correct tube handling
Careful storage of the tubing must be implemented. Tubing will quickly become damaged if proper storage is not implemented.
Correct tube storage and handling practices will reduce scratches and indentations that could lead to potential leaks.
Never drag tubing across surfaces such as the workshop floor, workbenches, racking or the ground.
Tubing that has been damaged can cause the tube and to be out of round, which may mean it cannot be located and assembled correctly. Out-of-round tubing must not be forced into compression fittings.
Three common tools used
Three common tools are used in the preparation of tube ends.
There are several manufacturers of tube cutter. The concept is the same; they do not remove material, but drive the material downwards and apart.
A dull or blunt wheel will increase the burr at the end of the tube, also causing the tube to collapse at the cut tube end.
Ensure that the blade remains sharp at all times and replace the blades frequently for best results.
Using a hacksaw can create unwanted problems. Points to consider are that the tube requires to be cut as straight and as square as possible. The tube vice similar to the one pictured will assist in cutting the tube at an angle of 90° to its length.
Another important point to consider is the hacksaw blade. The correct blade should have a minimum of 32 teeth per inch, which will prevent producing a rough cut tube end. At least two teeth should be in contact with the tube wall thickness during the cutting process.
The above information has been edited from course booklet for the British Fluid Power Association’s new training course titled ‘Small Bore Tubing Integrity Course – using twin ferrule compression fittings’. For more information about the new course and how you or your staff can enrol, please contact the Association at: firstname.lastname@example.org. For general enquiries, please contact: email@example.com, or Tel: 01608 647900.