In industrial applications where high pressures (over 6,000 psi) are used, safety is of paramount importance. Even well below these pressures, precautions are needed to ensure a safe working environment. Tubing from different manufacturers may look the same on first glance – and, indeed, it may be certified to meet minimum requirements, but is it going to perform correctly, do the job and ultimately, not risk the safety of plant and personnel?
Because of the risks with connection leaks, there is a real need to make sure it is has undergone all necessary tests, is specified alongside appropriate fittings and will, therefore, optimise safety and performance.
To reassure customers that our tubing is certified over and above current requirements, we introduced our own AES 222 (Autoclave Engineers Specification). This covers an extensive range of additional requirements for which the tubing is tested, including bore finishes, milled sections, and non-destructive testing. The bore examination that we carry out, for example, involves the tubing being cut and then sectioned to allow microscopic examination of the bore finish.
Another important consideration with tubing is its ovality and wall thickness. If this is not rigorously tested, then uncertified, untested tubing will have different dimensions. This could lead to leakage and unnecessary safety risks.
It is therefore important to ensure that outside dimensions are specified, to ensure a correct fit of tubing. If the manufacturer operates to tight tolerances on tubing wall thickness and run-out it will ensure a more uniform wall thickness. This provides an even wall at the sealing point and leads to higher calculated design pressures.
These rigorous tests ensure that when the tubing is installed for the first time, risks are much reduced. Leakage is the biggest worry with any tubing system and our tests ensure that risks are kept to a minimum
What is sometimes overlooked is the fact that warranties for fittings are often not valid if the associated tubing is not specified from the same manufacturer. The reason for this is that another manufacturer’s tubing may compromise the safety of the fitting, as Parker Autoclave Engineers’ tubing and fittings are designed to work as a complete system. Our AES specifies and controls both material and critical dimensions and tolerances to meet the conditions for which they are designed.
So it can clearly be seen why safety should be a major concern when specifying tubing for industrial, high-pressure applications. By selecting tubing that has been rigorously tested, there is much less risk of tube leakage or failure, which compromises the safety of the whole system.
Franck Grignola is product manager, Autoclave Engineers, Parker Hannifin manufacturing, Instrumentation Products Division Europe.