Clearly There are Benefits
Clearly there are benefits of leak testing. These benefits can be appreciated by a diversity of groups within an organization: Quality Control, Production, Finance, Sales, Marketing and Development. Some of these benefits include:
- Increased Sales: Obviously, products which are intended for holding or conducting fluids, including gases are required to be leak-tight as part of their specification. Their leak-tight nature then becomes a selling feature or benefit. Since there is no such thing as a leak-proof product it follows that leak-tightness by degrees becomes a differentiating factor. It is therefore clear that a regular check needs to be made to ensure that certain standards of leak-tightness are being satisfied during the production and quality control stages.
Those products which leak less will be more attractive than their competition.
- Improved Reputation: If customer rejects are the norm, then the company which makes products which experience less rejection than similar products will benefit from a better reputation within its market.
- Reduced Costs: Manufacturing reject products is not a profit maximizing business! Every product has a manufacturing cost: – materials, labor, overheads etc. Unless it is possible to recycle rejected production everything is lost when a product fails in Quality Control or, worse, fails in service. Tighter control over production processes permits adjustment to specifications and an improvement in reject rates which will result in lower overall costs.
Modern leak Testing methods are non-destructive. Tested product which passes the test is returned to production.
- Repeatable Leak Testing: Automatic leak testing is not operator subjective. Each test is highly repeatable and accurate.
- Improved Working Environment: Air, vacuum, flow measurement, and trace gas leak Testing is clean and dry. There are no messy dyes or water to spill on floors or equipment. Wet floors are a safety hazard and should be avoided.
- Fast Throughput: Air leak testing takes a matter of seconds. Unlike underwater testing where operators are waiting for bubbles to appear (this can take as much as 30 minutes or more), air pressure leak Testing can give a clear pass or fail result in a fraction of the time. The method is dry (see above) which means that there is no drying period required.
Leak Testing Benefits Case Study
The manufacture of car radiators is a complicated process. Companies are generally specialists and are subject to huge pressure by their customers in the automotive industry. High quality and competitive prices are essential. The loss of one customer due to quality or price issues can be catastrophic.
The radiators were subject to two tests. The first was the Core Test which was carried out prior to the header tanks being fitted to either end of the core (radiator). The reason for performing two tests and the core test first was that the core could be repaired if a tube to header leak has occurred.
Testing the cores under water was carried out at a positive pressure and was very time consuming, subjective, and relied upon the operator to watch the whole of the test with extreme care.
Good cores were then passed on to the next stage where the header tanks were fitted. The radiator assembly was then subjected to another under water test with similar problems. The floor in the test areas were covered in water and oil, and water filled the gloves of the test operatives.
Radiator assemblies which passed this ‘test’ were next placed in an oven to dry. Operation of the oven added more expense to the manufacturing process and was time consuming.
The relationship between the air leakage rates to water leakage rate has been determined empirically. Several radiators were prepared with holes of varying sizes and pressure tested with air and the results noted. Each radiator was then filled with a water/glycol mix and conditioned to normal operating temperature and pressure. Each radiator was inspected for liquid leakage; the smallest hole that allowed water to appear on the surface was a hole that leaked air at 22 cc/min. A specification of 4 cc/min of air was chosen to provide a comfortable safety factor.