PEX Crimp Tool Calibration/Inspection Guide

Step-by-step calibration and go/no-go gauge inspection procedures to ensure leak-free PEX crimp connections every time.

Why Calibration Matters

Critical for Code Compliance: Improperly crimped PEX connections can fail inspection and leak

Water Damage Prevention: Under-crimped rings can leak; over-crimped can damage pipe

Tool Wear: Crimp tools wear over time and need regular calibration checking

Liability: Failed connections can cause significant water damage

Go/No-Go Gauge Measurements
PEX SizeGo Gauge (Min-Max)No-Go GaugeResult
1/2"0.520" - 0.540"≤ 0.516"Go fits, No-Go doesn't = PASS
5/8"0.645" - 0.665"≤ 0.641"Go fits, No-Go doesn't = PASS
3/4"0.765" - 0.785"≤ 0.761"Go fits, No-Go doesn't = PASS
1"1.010" - 1.030"≤ 1.006"Go fits, No-Go doesn't = PASS

✓ PASS: "Go" gauge fits over crimped ring, "No-Go" does NOT fit

✗ FAIL: Either Go doesn't fit (over-crimped) OR No-Go fits (under-crimped)

How to Use Go/No-Go Gauge
  1. Make test crimp: Crimp a ring on scrap PEX with fitting inserted
  2. Test with "Go" gauge: Place larger opening of gauge over crimped ring
    • Should slide over ring smoothly
    • If it doesn't fit: Tool over-crimped (too tight) - adjust tool
  3. Test with "No-Go" gauge: Try smaller opening of gauge over same ring
    • Should NOT slide over ring
    • If it fits: Tool under-crimped (too loose) - adjust tool or replace
  4. Pass/Fail:
    • PASS = Go fits, No-Go doesn't
    • FAIL = Either Go doesn't fit OR No-Go fits
  5. Test all sizes: If tool crimps multiple sizes, test each size
Calibration Frequency

Check calibration:

  • Before starting each major plumbing project
  • After every 200-300 crimps (professional use)
  • If tool is dropped or damaged
  • Annually for occasional DIY use
  • Any time connections fail inspection

New tools: Even brand new tools should be tested before first use

Rental tools: ALWAYS test before using - unknown maintenance history

Tool Adjustment Procedures

If Tool Over-Crimps (Go gauge doesn't fit):

  • Check for adjustment screw/mechanism (tool-specific)
  • Loosen adjustment slightly (1/8 turn at a time)
  • Test again on fresh crimp
  • Repeat until Go gauge fits properly

If Tool Under-Crimps (No-Go gauge fits):

  • Tighten adjustment if available
  • Check for worn jaws - may need replacement
  • If adjustment doesn't help, tool may need service or replacement
  • Under-crimped connections are not code-compliant

Tool-Specific Instructions:

  • Consult manufacturer's manual for adjustment procedure
  • Some tools have adjustment screws, others require jaw replacement
  • Professional tools often have calibration marks
Visual Inspection Criteria

Good Crimp Should Show:

  • Even compression around entire ring
  • No gaps between ring and pipe
  • Ring ears pulled together (nearly touching but not overlapping)
  • Crimp marks visible on ring from tool jaws
  • Ring positioned 1/8" to 1/4" from end of fitting
  • No pipe deformation or splitting

Bad Crimp Indicators:

  • Uneven compression (oval shape)
  • Ring ears overlapping (over-crimped)
  • Gap between ring ears (under-crimped)
  • Pipe crushed or split
  • Ring positioned incorrectly on fitting
  • Incomplete crimp marks on ring
Common Crimp Failures & Causes

Under-Crimped (leaks immediately or later):

  • Tool worn or out of calibration
  • Wrong size ring for pipe
  • Fitting not fully inserted into pipe
  • Debris between pipe and fitting

Over-Crimped (immediate failure or stress cracks):

  • Tool adjusted too tight
  • Crimped multiple times
  • Wrong tool for ring type

Misaligned Crimp:

  • Tool not perpendicular to pipe
  • Ring slipped during crimping
  • Fitting moved before crimp completed
Crimp Ring vs Clamp Systems

Copper Crimp Rings (Most Common)

  • Require crimp tool and Go/No-Go gauge
  • One-time use (cannot be removed/reused)
  • Most economical per connection
  • This calibration guide applies to crimp rings

Stainless Steel Cinch Clamps

  • Require clamp (cinch) tool
  • Visual inspection: ears should be flat
  • No Go/No-Go gauge needed
  • Slightly more expensive per connection

PEX-A Expansion System

  • Different system - expands pipe, no rings
  • Doesn't use crimp tools or gauges
  • Most expensive initially (special tool)
  • Most forgiving installation method
Code & Inspection Requirements

Most plumbing codes require:

  • Use of properly calibrated crimp tools
  • Go/No-Go gauge verification for crimp rings
  • Documentation of tool calibration for professional work
  • Accessible connections (behind access panels, not sealed in walls permanently)

Inspection Process:

  • Inspector may test random connections with gauge
  • Visual inspection of accessible crimps
  • Pressure test of entire system
  • Failed inspection requires re-doing connections

Keep gauge with tool for inspection day!

Purchasing & Tool Selection

Buy complete kit: Tool + Go/No-Go gauge for all sizes you'll use

Tool quality matters:

  • Professional-grade tools maintain calibration longer
  • Budget tools may need frequent adjustment
  • Consider rental for one-time projects

Gauge availability:

  • Often included with tool purchase
  • Can be purchased separately (~$10-20)
  • Digital gauges available but more expensive
  • Keep gauge accessible - you'll use it frequently
Best Practices Summary
  • Test tool calibration before every project
  • Use Go/No-Go gauge on test crimps, not final connections
  • Make practice crimps on scrap material when starting
  • Visually inspect every crimp in addition to gauge testing
  • Document tool calibration for inspections
  • Replace worn tools rather than constantly adjusting
  • Keep gauge with tool in storage
  • When in doubt, cut off connection and re-do it

Additional Information

About This PEX Crimp Calibration Guide

This comprehensive PEX crimp tool calibration and inspection guide helps plumbers and DIYers verify their crimp connections meet industry standards for leak-free performance. Proper crimp ring compression is critical for preventing leaks - both under-crimped and over-crimped connections can fail, causing water damage and costly repairs.

Go/No-Go gauges provide a simple, reliable method to verify crimp quality. This guide covers the correct gauge dimensions for each PEX pipe size, visual inspection criteria, troubleshooting common crimp problems, and best practices for tool maintenance and calibration. Regular testing ensures consistent, code-compliant connections throughout your plumbing system.

Whether you're a professional plumber or a homeowner tackling a PEX installation, understanding crimp calibration helps you work confidently and avoid failed inspections or future leaks.

Why Use This PEX Crimp Calibration Guide?

Properly calibrated crimp tools and verified connections prevent leaks and ensure your plumbing work passes inspection. This guide helps you maintain quality standards.

  • Understand Go/No-Go gauge dimensions for each PEX pipe size
  • Identify under-crimped and over-crimped connections visually
  • Troubleshoot common crimp tool problems and solutions
  • Follow proper calibration procedures before each project
  • Document tool testing for building inspections
  • Know when to adjust, service, or replace your crimp tool
Frequently Asked Questions

Free PEX Crimp Tool Calibration Guide - Simple Go/No-Go Check | DIYProject.ai