Inboard, Outboard, Internal Leaks... and Tips on How to Stop Them
by Katie Reid, on Thu, Sep 06, 2018 @ 15:09 PM
Any energy management program should include efforts to prevent and repair leaks
In any fluid system, there could be one or more kinds of leaks:
- Inboard leakage, where something is flowing into the system from outside
- Outboard leakage, where something is flowing out of containment into the environment, or
- Internal leakage, where something is flowing across internal seals within containment, such as a leaky valve seat
There can even be virtual leaks, where nothing is breaching the containment, but internally trapped fluid gets released into the system due to material out-gassing, absorbed or adsorbed fluids, entrapment in cracks or dead-legs, etc.
Leakage can take many forms, like:
- Compressed air leaking out of a pneumatic system
- Steam escaping from a processing line
- Hydraulic fluid seeping out of machinery
Bad installation techniques are frequent causes of leaks. Common mistakes include failing to fully insert tubing into the tube fitting body, under-tightening, over-tightening, putting bends in the tubing too close to the end of the tube, and poorly preparing the tube. Surface defects such as dents and scratches can lead to leaks too.
Another cause of leakage is using components outside their rated temperature and pressure ratings or with incompatible materials. Also, low quality fluid system components also contribute to leaks. Proper selection of high quality fluid system components are an integral part of creating leak tight fluid systems.
(Recommended: Get local help with product selection.)
Isn't some leakage normal?
It's true that whether it's an inboard, outboard, or virtual leak, no man-made system will always be leak-free. But consider the following:
A group of 1,304 different process installations leak checked more than 600,000 fittings for a five-year period ending in September 2013, and reported the results to Swagelok Company. Almost 10% of the fittings that had been interchanged or intermixed with another manufacturer's components were found leaking, and pipe fittings had a leak rate of about 7 percent. In contrast, Swagelok tube fittings had a leak rate of about 1%. (This data is not offered as test results that are scientifically valid or statistically significant.)
While the 1% leak rate for Swagelok fittings is 7-10 times better than pipe fittings and intermixed/interchanged fittings, we believe that one leak is one too many. So, we strive to get to the root cause of every leak. We find that many Swagelok tube fittings are not installed according to our installation instructions. Poor installation practices, low quality tubing, improper tubing or fitting selection - all these contribute to leak rates. We have found that customer leak rates can approach zero when Swagelok tube fittings are used in concert with high quality tubing, a robust Swagelok safety and installation training program, and energy management services.
Isn't tracking down and stopping all the leaks expensive?
Possibly -- but not stopping them is likely to be expensive too.
The leak data noted above correlates well with a study performed by Dr. Arthur Sterling of the Chemical The-Hidden-Costs-of-Leakage.png Engineering Department at Louisiana State University in 1999. Dr. Sterling surveyed eleven industrial plants in the Louisiana area and determined that leaks were present in many areas of the plant. The average instrument air leak was 494 milliliters per minute. Using a cost of $0.40 per 1000 cubic feet of instrument air, the average fitting leak costs $0.31 per month.
Leaks can damage equipment, hurt production, cause product contamination, and create unsafe working conditions and other health hazards. All it takes is a small puddle of hydraulic fluid or a jet of steam to put someone in the hospital.
If that is not motivation enough to engage in proactive leak detection and prevention programs, fluid loss is also expensive. According to a study conducted by the Energy Department's Office of Industrial Technologies, even something as simple as a ¼” diameter leak of compressed air can cost as much as $8,382 a year using a rate of five cents per kWh and assuming constant operation and an efficient compressor.
How to find leaks
We have a few ways to spot leaks. One is to put the suspect parts under water in a chamber made of transparent polycarbonate and look for bubbles. Another is to apply one of our Snoop® liquid leak detectors. When the parts are pressurized, the leak will produce bubbles. Leaks are usually expressed as a flow — a volume per unit of time. Anyone using Snoop will get the basic idea instantly: the bigger the bubbles, the worse the leak.
Leaks can also be detected by measuring losses in pressure, and of course by simply looking to see if any fluid is escaping. Technology has added to the arsenal of tools. The list now includes thermal imaging cameras and ultrasonic (acoustic) leak detectors.
Leak detection + leak prevention = better safety and lower costs
Any good energy management program should include efforts to prevent and repair leaks. If you don't have such a program, start one. If you already are making the effort, make sure you document any resulting energy savings. You may be surprised at how fast leak prevention and repair can pay for itself. You'll have lower maintenance costs, less downtime, higher production, and safer workers. Lower overall system costs add up to more profitability.
Get in touch
Talk with our team about finding, assessing, and addressing leaks at your facility: