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The Effects of Overtightening Compression Tube Fittings

Properly sealed tube fitting connections are crucial in a tubing network of any size. We’ve compiled a brief overview of avoidable problems to help steer clear of potential pitfalls.

Have you ever thought about the importance of proper tightening when connecting stainless steel tubing, tube fittings, and tubing valves?

Many installers don’t follow the proper tightening techniques, leaving room for error. Then, there’s another group of installers who believe that tighter is better and they end up over-tightening. Others believe they can feel when a fitting is tight enough. This is also incorrect because fitting torque can vary widely based on tubing wall thickness, fitting manufacturer, or factors like tubing side-load. That’s not even mentioning the countless number of installers who don’t know what a gap gauge is, let alone how to use one.

Properly sealed tube fitting connections are crucial in a tubing network of any size.

The reason for this is, these systems often route high pressure, high temperature, or even caustic chemicals that could be hazardous if spilled. Undoubtedly, allowing any gasses to leak could mean a huge risk to personnel, property, and the environment.

Below, we’ve compiled a brief overview of avoidable problems to help steer clear of potential pitfalls.

How to Diagnose and Fix Over-Tightening Issues

Correct installation of tube fittings and valves is essential to a well-maintained system.

Most would assume under-tightening to be the usual suspect for leaks in a system. The truth is, workers will more commonly over-tighten because they’re worried about under-tightening. They would rather over-tighten to make sure the connection holds instead of failing to apply enough force.

Here are four ways you can identify an over-tightened compression fitting or valve.

1 - If You Can’t Disassemble the Fitting

During maintenance, it’s common for workers to disassemble compression connections. After loosening the nut, the tubing should come away easily. Once disassembled, if the tubing is yet married to the fitting, inspect that union for signs of over-tightening.

The tubing will bulge and stick inside of the fitting if the ferrules are overly secure.

If you can’t disassemble the valve or fitting, it’s a good indicator that the connection is much too tight.

The only thing to do in this instance is to remove and replace the fitting in question. Additionally, you’ll need to replace any tubing run that you can’t remove from the fitting.

2 - The Fittings or Tubing are Becoming Deformed

If proper tightening procedures aren’t followed, it’s possible for tubing or fittings to become deformed. To identify this on fittings, look at the wrench flats of the fitting. If the corners are starting to round over, the fitting has most likely been strained.

On tubing, it’s harder to see this deformation without disassembling the fitting. Inside the fitting, the ferrules will begin to crush the tubing. This, in turn, will constrict flow and thin the wall of the tubing. Subsequently, this increase of local pressure and weakening of the tubing will cause compression fittings to catastrophically release the tubing.

3 - What if the Valve Breaks

Look for cracks near valve connection points, this could be a sign of over-tightening. Though valve breakage is a rare occurrence, never underestimate a poorly trained installer with a big wrench.

This is a threaded needle valve that was severely over-tightened.

Unfortunately, if a compression valve or fitting has sustained this kind of damage from over-tightening, you should replace it.

4 - You Start Having Leaks

This one may seem self-explanatory, but if you’re experiencing leaks, now is the perfect time to check for over-tightened connections. First, inspect the fitting gap with a gap gauge to rule out under-tightening. If your gauge does not fit, it’s time to start looking for the other signs of over-tightening.

The Number One Avoidance Technique

All of the above-mentioned problems are human error related. Accordingly, the best way to solve these issues is to remove human error from the equation. Superlok i-Fitting eliminates human error by including a gap gauge on every fitting. Gone are the days of leaky over tightened fittings. Just tighten until the red ring snaps away for a perfect leak-free seal every time. Additionally, Superlok fittings change to a blue color once tightened meaning that you can see from a distance if a fitting is secure. (More info).

Alternatively, if you must use a traditional tube fitting, read up on their manufacturer’s installation procedure. Use your gap gauge on every fitting and mark fittings as you complete them. Limiting the chance for mistakes makes for a safer working environment for installers and future system users alike.

The Author

Ethan McNeese
Marketing Specialist
Ethan is our resident content marketer, blog author, YouTube host, and general knower of things. When he's not at his keyboard working on new web pages and videos, he's usually out in the shop wrenching on valve assemblies, developing diagrams for projects, or praying for rain.

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