PEX Crimping: Definition & Maintenance Guide
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PEX crimping is a pipe joining method that uses a copper or stainless steel crimp ring and a specialized crimping tool to compress the ring around a PEX tube where it sits over a barbed brass fitting, creating a permanent, watertight mechanical connection. PEX crimping is one of the most widely used connection methods in residential plumbing due to its speed, reliability, and lower material cost compared to expansion or press-fit alternatives.
Crimp Ring Compression, Go/No-Go Gauge & Barbed Fitting Mechanics
The crimp connection process involves three components: the PEX tubing, a barbed insert fitting (typically made of brass or polymer), and a crimp ring. The plumber slides the crimp ring onto the PEX tube, inserts the barbed fitting into the tube end, positions the crimp ring over the area where the tube overlaps the fitting barbs, and compresses the ring using a calibrated crimping tool. The compressed ring squeezes the PEX tubing tightly against the barbs, creating a seal that resists pullout forces and internal water pressure.
Proper crimp ring compression is critical. An under-crimped ring allows the tube to slide off the fitting under pressure. An over-crimped ring can cut into the PEX material, weakening it and creating a future failure point. Professional plumbers verify every crimp with a go/no-go gauge — a calibrated tool that checks whether the compressed ring falls within the acceptable dimensional range specified by ASTM F1807.
Crimp connections are rated for the full pressure and temperature range of the PEX tubing itself, typically 100 PSI at 180 degrees Fahrenheit for potable water applications. The connections are permanent and are not designed to be disassembled — if a crimp joint needs to be remade, the plumber cuts out the section and installs a new fitting.
Copper Rings, Stainless Clamps & Brass Insert Fitting Types
Copper crimp rings are the most common type, made from annealed copper that deforms permanently when compressed. They are compatible with PEX-A, PEX-B, and PEX-C tubing in sizes from 3/8 inch to 1 inch.
Stainless steel clamp rings (cinch clamps) use a ratcheting clamp tool instead of a compression crimper. The stainless ring has an ear tab that the tool compresses to tighten the ring. Cinch clamps are popular because the ratchet tool works on all pipe sizes without changing the tool head.
Brass insert fittings are the standard fitting material for crimp connections. They are available in every common configuration: couplings, elbows, tees, stub-outs, and transition fittings to copper, CPVC, and threaded connections.
Polymer insert fittings are an alternative to brass, eliminating lead concerns and reducing dezincification risk in aggressive water chemistries. Polymer fittings have a slightly larger barb profile to compensate for the lower stiffness of plastic.
Repiping, Bathroom & Kitchen Fixture Applications
PEX crimping is a core skill in residential plumbing installation and repiping projects. Bonded Plumbworks’ technicians use crimp connections in repiping projects, new construction plumbing, and fixture replacement work. The method is particularly efficient for whole-house repipes because PEX tubing routes through wall cavities more easily than rigid copper, and crimp connections can be made quickly without torches or solvents.
For bathroom plumbing and kitchen plumbing renovations, crimp connections provide reliable joints at stub-outs where supply lines transition from in-wall PEX to fixture shutoff valves.
ASTM F1807, F2159 & NSF/ANSI 61 Certification Standards
ASTM F1807 governs metal insert fittings used with crimp ring connections for PEX tubing. ASTM F2159 covers the plastic insert fittings alternative. The applicable state building codes permits PEX crimp connections for potable water distribution and requires that all fittings and rings be listed and labeled by a recognized testing laboratory (NSF, CSA, or IAPMO). Crimp tools must be calibrated per manufacturer specifications, and go/no-go gauges must be used to verify every connection.
Viega, Apollo & SharkBite Crimp Ring Systems
Viega produces brass crimp fittings under the PureFlow line. Apollo (Elkhart Products) manufactures the APXCR series of copper crimp rings and brass fittings. SharkBite offers crimp rings and insert fittings alongside their push-fit product line. Watts manufactures brass PEX crimp fittings in standard and lead-free configurations. Additional manufacturers in this category include iCrimp, iCrimp ICP-BJ03, and Watts Water Technologies.