Sooner or later every tech has to break a tube fitting loose: to swap out a gauge, reroute a line, or get a valve out for service. The good news is that a properly made-up compression fitting can usually be taken apart and remade many times. The bad news is that most remake leaks come from rushing the job. Here is how I've done it for years, step by step.
Start With Safety: Prove the Line Is Dead
Never loosen a nut on a line you think is depressurized. Isolate it, lock and tag it out per your site's procedure, bleed it down through a vent or drain valve, and verify zero pressure on a gauge before you put a wrench on anything. Trapped pressure between two closed valves is a common way people get hurt. If the line held a hazardous fluid, follow your plant's draining and purging requirements first.
If your crew could use a refresher on this, A-Best Industrial Inc. Fittings, Valves, and Tubing offers a free Safety training course for new and existing customers.
Mark the Nut Before You Break It
Before you loosen anything, put a marker line across the nut and the fitting body. That mark is your reference point for the remake. Then back off the nut, holding the body with a second wrench so you don't twist the tube or stress the connection on the other end.
Inspect Before You Reassemble
Once the tube is out, take a minute and look closely:
- The ferrules should stay seated on the tube. Don't try to pry them off and reuse them on new tubing.
- Check the tube for scratches, gouges or flat spots near the ferrules. Damaged tube will leak no matter how well you tighten it.
- Look at the threads and the seat inside the body. Wipe out any dirt, grit or old debris.
If anything looks wrong, cut back to clean tube and make up a fresh connection instead of gambling on a remake.
Remake It the Right Way
Push the tube with its pre-swaged ferrules back into the body until the front ferrule seats. Run the nut down finger-tight. Then, holding the body steady, snug the nut with a wrench until you feel resistance pick up sharply, which usually lines up close to your original mark. From there, a small additional turn is typically all it needs. Always follow the fitting manufacturer's remake instructions for your brand and size; don't just crank on it. For most brands it’s typically 1/4 turn from finger-tight to remake a fitting.
Holding small fittings still while you do this is half the battle, especially on a bench. Our Fitting Tool holds stainless steel tube fittings from 1/16" to 1/2" steady while you work on them, so your wrench does the work instead of your fingers.
A Word About Gap Gauges
A gap inspection gauge is a great check on a brand-new, first-time makeup. On a remake, though, the nut sits further along than it did originally, so the gauge isn't meant to be used for that check. Rely on your mark, the feel of the nut and the manufacturer's instructions instead. Then leak-test the connection before you put the system back in service.
When to Replace Instead of Remake
If a fitting has been remade many times, keeps weeping, or the nut bottoms out, stop remaking it. Cut back, prep new tube, and install fresh components. You can find the tools to do that right, including the Fitting Tool, gap inspection gauges, deburring tools and RIDGID tube cutters, in our tools collection, along with replacement compression tube fittings.
Need a Hand?
Call A-Best Industrial Inc. Fittings, Valves, and Tubing at 310-833-3353 or email sales@abesttube.com. We'll help you get the right parts and get your line back in service safely.