Introduction
Got a job where you can’t shut the water off, the stop valve is buried, or the whole building would go down for one tiny leak? Here’s the move many pros rely on: Leaky pipe? Freeze the water inside the pipe. Then, fix it! That’s wild — and effective. This guide shows you exactly how pipe freezing works, where it’s safe, what gear you’ll need, and a step-by-step process you can run in the field. Subscribe to our newsletter for more tips like this.
Quick Answer: The fastest way to isolate a live line without a shutdown is to create an ice plug at the repair point. Leaky pipe? Freeze the water inside the pipe. Then, fix it! That’s wild — and effective. Typical freezes form in 5–30 minutes on 1/2–1 inch lines and hold long enough (30–60 minutes) to swap a valve, coupling, or fitting.
Table of Contents
Key Takeaways
- Pipe freezing isolates a line in 5–45 minutes without a building shutdown.
- Ice plugs typically hold 30–60 minutes; monitor every 5–10 minutes.
- Works best on copper, steel, and some PEX/CPVC (verify manufacturer guidance). Avoid PVC.
- CO2 is jobsite-friendly; liquid nitrogen is fastest; electric freeze kits are reusable.
- Always provide pressure relief and never freeze between two closed valves.
What Is Pipe Freezing and Why It Works
Pipe freezing creates a solid “ice plug” inside a water-filled pipe. That plug seals flow so you can cut out a fitting, add a valve, or repair a pinhole without draining floors, zones, or entire buildings. In short: Leaky pipe? Freeze the water inside the pipe. Then, fix it! That’s wild — and effective.
How Freezing Actually Seals the Line
- Water turns to ice at 32°F (0°C). A freeze jacket or collar rapidly pulls heat from the pipe wall and the water inside.
- The forming ice bridges across the bore, creating a plug typically 2–4 inches long.
- With the line static (no flow) and pressure relieved, that plug holds back water long enough to complete a repair.
Where It Shines
- Occupied buildings where shutdown windows are limited
- Multi-tenant or healthcare facilities
- Old buildings with unknown or seized valves
When Should You Use "Leaky pipe? Freeze the water inside the pipe. Then, fix it! That’s wild — and effective."
You’ll reach for this method when a shutdown is costly, messy, or nearly impossible. Many contractors find the technique ideal for domestic water, hydronic heating, and condenser water lines when diameters are 1/2 inch to 2 inches. On larger mains (3–4 inches), specialty rigs and experience are critical.
- Single fixture or small branch needs a ball valve, coupling, or PRV swap
- Old gate valve won’t close and you need immediate isolation
- Tenants can’t lose water for 2–3 hours, but a 45-minute freeze window is doable
Leaky pipe? Freeze the water inside the pipe. Then, fix it! That’s wild — and effective, especially when time and disruption cost more than the freeze kit.
Choosing the right gear controls= speed, safety, and plug reliability.
Common Methods
- CO2 freeze kits: Portable, cost-effective, widely used. Formation often takes 10–30 minutes on 1/2–1 inch copper or steel.
- Liquid nitrogen (LN2): Fastest formation, often under 10–15 minutes for small diameters. Requires training and strict PPE.
- Electric freeze machines: Reusable collars and a small refrigeration unit. Slightly slower but clean, no consumables onsite.
Additional Gear
- Freeze collars/jackets sized for 1/2, 3/4, 1, and 2 inch pipes
- Insulation wrap to focus the freeze zone
- Infrared thermometer or thermocouples to monitor surface temps
- Pressure gauge for the isolated section
- PPE: cryogenic gloves, face shield, insulated apron, long sleeves
- Tarp or containment for frost condensate
A clean setup is half the battle. Leaky pipe? Freeze the water inside the pipe. Then, fix it! That’s wild — and effective when you prep well.
Step-by-Step: Leaky Pipe? Freeze the Water, Then Fix It
Follow these steps for a controlled, code-conscious freeze and repair.
Step 1: Evaluate the Line (5–10 minutes)
- Identify material: copper, steel, PEX, CPVC, or PVC. Avoid freezing PVC.
- Measure pipe OD and wall thickness; select matching collars.
- Confirm water is present and static; purge flow and relieve pressure.
- Plan the freeze location at least 8–12 inches from the repair cut for workspace.
Step 2: Set Pressure Relief (2–5 minutes)
- Crack a nearby tap or bleeder to prevent pressure spikes.
- Never create a trapped segment between two closed valves.
- Install a gauge if possible; target less than 40–60 psi during freeze.
Step 3: Mount the Freeze Collar (3–5 minutes)
- Clean the pipe surface dry and oil-free for better heat transfer.
- Apply the collar square and snug; add insulation wrap around the collar.
- For CO2/LN2, keep the discharge directed safely away from people and surfaces.
- For 1/2–1 inch: commonly 5–30 minutes to form; 2 inch can take 20–45 minutes.
- Confirm with temps trending below 32°F (0°C) and by gently cracking a nearby tap; no flow means the plug is seated.
- Monitor every 5–10 minutes. Leaky pipe? Freeze the water inside the pipe. Then, fix it! That’s wild — and effective when you verify the plug before cutting.
Step 5: Execute the Repair (15–40 minutes)
- Cut out the bad section, swap in the valve or coupling, and sweat, press, or thread fittings as required.
- Have all fittings prepped. Dry fit first; then work quickly but cleanly.
- Keep the freeze collar energized/active the entire time.
Step 6: Thaw and Restore (5–20 minutes)
- Stop cooling and let the pipe warm naturally. Don’t torch the plug.
- Close relief points, slowly pressurize, and watch the repair for 2–5 minutes.
- Document the work. If you’re quoting or billing, capture photos and send a clean proposal or invoice via Donizo. Leaky pipe? Freeze the water inside the pipe. Then, fix it! That’s wild — and effective—and it looks even better on a branded PDF.
Mid-project resource: Download our free freeze-and-fix checklist so your techs can run this process in 6 clear steps every time.
Safety, Codes, and Compatibility
Safety first. Ice plugs are powerful, but you must respect pressure, materials, and code authority.
Safety Essentials
- Pressure relief: Always leave a path for expansion. No trapped sections.
- PPE: Insulated gloves, face shield, long sleeves. CO2 and LN2 can burn skin.
- Ventilation: CO2 displaces oxygen; never use in confined, unvented spaces.
- Monitoring: Check temperature and pressure every 5–10 minutes.
Codes and Authority Having Jurisdiction (AHJ)
- Many jurisdictions accept temporary ice plugging on water lines when performed by qualified personnel.
- For fire protection systems, always coordinate with the AHJ and follow NFPA requirements. In general, don’t freeze sprinkler mains without formal approval.
Material Compatibility
- Copper and steel: Standard and reliable with proper technique.
- PEX and CPVC: Many contractors report success; verify manufacturer limitations and clamp pressure guidance.
- PVC: Generally avoid; risk of cracking increases with freezing.
Leaky pipe? Freeze the water inside the pipe. Then, fix it! That’s wild — and effective, provided you meet safety and AHJ requirements.
Costs, Time, and Real-World Examples
- Time: Commonly 5–30 minutes to form an ice plug on 1/2–1 inch lines, with 30–60 minutes of working time.
- Consumables: CO2/LN2 costs vary; expect a small per-job cost compared to a full shutdown.
- Gear: Electric freeze machines are an upfront investment that pays off over dozens of jobs.
Field Scenarios
- Condo PRV swap: No building shutdown. Freeze 1 inch copper in ~15 minutes, change PRV in 20 minutes, total downtime 35–45 minutes.
- Hydronic branch valve add: Freeze 3/4 inch steel line, cut in a ball valve, purge air, restart in under 60 minutes.
- Pinhole on riser: Freeze 1-1/4 inch copper, sweat in a short repair coupling, thaw, and pressurize—minimal water loss and zero tenant complaints.
Leaky pipe? Freeze the water inside the pipe. Then, fix it! That’s wild — and effective, and it often turns a 3–4 hour shutdown into a 45-minute service call.
If you’re bidding or billing these quick-turn repairs, streamline your paperwork: capture site notes by voice and send a branded proposal the same day with Donizo. Convert the accepted proposal to an invoice in one click so you get paid without the back-and-forth.
FAQ
Is pipe freezing safe for domestic water lines?
Yes, when done correctly with pressure relief and monitoring. For many contractors, the go-to approach is: Leaky pipe? Freeze the water inside the pipe. Then, fix it! That’s wild — and effective. Use proper PPE, avoid trapping pressure between two closed valves, and verify the ice plug before cutting.
How long does an ice plug last while I work?
Commonly, 30–60 minutes on small diameters, depending on ambient temperature, method (CO2, LN2, electric), and insulation. Monitor every 5–10 minutes. If you need more time, keep the freeze collar active until your repair is complete and pressure-tested.
Can I freeze PEX or CPVC lines?
Many contractors report successful freezes on PEX and CPVC, but always check manufacturer guidelines. Clamp pressure, collar type, and temperature gradients matter. If in doubt, use a gentler, well-insulated setup or choose a different isolation method.
Will pipe freezing work if the water is warm or flowing?
Flowing or hot water slows formation significantly. Shut flow, relieve pressure, and allow the line to cool. In general, pre-chill helps. Then try again. Leaky pipe? Freeze the water inside the pipe. Then, fix it! That’s wild — and effective when the line is static.
What’s the best method: CO2, liquid nitrogen, or electric?
CO2 is a solid all-around choice for portability and cost. Liquid nitrogen is fastest but needs training and strict PPE. Electric freeze machines are clean and reusable—great for frequent service work. Choose based on diameter, environment, and your crew’s experience.
Conclusion
Pipe freezing turns no-shutdown jobs into quick wins. Expect 5–45 minutes to form the plug, 30–60 minutes to work, and a clean, controlled repair with minimal disruption. When the situation fits, embrace the strategy: Leaky pipe? Freeze the water inside the pipe. Then, fix it! That’s wild — and effective. Want to lock in the business side too? Capture details by voice, send branded proposals, collect e-signatures, and convert to invoices with Donizo. Learn more about how contractors are solving this and standardizing service visits.
