When a hose assembly fails early, the hose usually gets the blame. In my 20 years in the instrumentation valve and fitting business, though, most of the early failures I've looked at came down to how the hose was installed: a twist, a bend too close to the fitting, or a run that rubbed on a bracket every time the machine moved. A good hose installed poorly won't last. Here's how to install one so it gets its full service life.
Make It Safe Before You Start
Follow your site's lockout/tagout procedure, isolate the line, bleed it down, and verify zero before you loosen the old hose. Hydraulic systems can hold pressure in accumulators and trapped sections long after the pump is off. Never loosen or tighten a connection under pressure.
Get the Length Right
A hose pulled tight between two ports has nowhere to go. Many hoses change length a little when pressurized, and equipment moves and vibrates. Leave some slack so the hose isn't straining the end fittings. Too much slack is a problem too, because a long loop can snag or rub. If the old hose was the wrong length, don't copy it. Measure the run and have the new one built to fit.
Don't Twist It
Twisting a hose during installation is one of the fastest ways to shorten its life. A twisted hose is stressed at the reinforcement and can loosen its own connections. Most hoses have a printed layline along the cover. After you tighten both ends, that line should still run straight. Hold the hose fitting hex with a backup wrench while you tighten the swivel nut so the hose doesn't wind up with it.
Respect the Bend Radius
Every hose has a minimum bend radius from the manufacturer. Bend it tighter and you crush the reinforcement and restrict flow. Also give the hose a straight section coming out of the fitting before it starts to bend. A sharp bend right at the crimp is where I see hoses crack and blow. If the routing forces a tight bend, use an elbow or angled adapter at the port instead of making the hose do the work.
Route It Away From Wear and Heat
Look at the whole run, not just the ends. Keep the hose clear of sharp edges, moving parts and hot surfaces like exhaust or steam lines. Where hoses cross or touch a frame, use clamps or sleeving so they don't rub through. Abrasion is slow and quiet until the day the cover wears through to the wire.
Seal the Connection the Right Way
Know what type of end you have. Flare and O-ring face seal ends seal on the flare or the O-ring, so no tape or paste goes on them. NPT ends seal on the threads and need a sealant suited to the material. Putting tape on a flare fitting can keep it from seating and send shreds into the system. If you're unsure, see our page on Anti-Seize Technology compounds and sealants or give us a call.
Leak Test Every Joint You Touched
Once the line is pressurized per your site procedure, apply Gator Leak Detector all the way around each connection you made and watch for bubbles or foam. If a hose end threads into an adapter, check the adapter's pipe-thread joint as well as the hose nut, since that side is often skipped. If something leaks, isolate and depressurize before putting a wrench on it. Never tighten a fitting under pressure.
Where your site requires them, install whip restraints, and keep people out of line with the end connections while the system comes up to pressure.
Built While You Wait
A-Best Industrial Inc. Fittings, Valves, and Tubing builds hose assemblies while you wait, and CNG hoses are built off-site at our CNG certified facility. Bring the old hose or your measurements and we'll match the ends and length. Learn more on our hose assemblies page.
We're Here to Help
Need a hose built or a second opinion on a routing problem? Call A-Best Industrial Inc. Fittings, Valves, and Tubing at 310-833-3353 or email sales@abesttube.com. We're open Monday–Friday, 8:00 AM–5:00 PM Pacific, with after-hours emergency service.