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Cut and Remove Old Cast Iron Pipe — Gaining Access to Pipes

Intermediate40 hours

Part of project

How to Replace Grey Polybutylene Pipe with PEX · Step 3 of 9

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In this video

The plumber begins the demolition by using a reciprocating saw to cut the PVC pipe that connects the bathroom lavatory to the old drain. To protect the nearby gas line from sparks, he covers it with a wet towel. He then uses an angle grinder with a metal cutting wheel to carefully cut through the heavy cast iron stack, making one cut above and one cut below the faulty sanitary tee. Once the section is free, he carefully wiggles and pries the heavy cast iron piece out of the wall.

Goal: Plumbing Pipes Repair

  • Cutting cast iron with an angle grinder produces intense sparks and is a fire hazard. Ensure no flammable materials are nearby and use appropriate protection like a wet towel over gas lines.
  • The cast iron stack is heavy and not well-supported. It can drop unexpectedly once cut, posing a significant safety risk. Be prepared to support its weight.

Used in this video

  • Reciprocating Saw (brand: DeWalt, Tool Type: Power Tools, Power Source: Battery)Cutting the PVC drain pipe.
  • Angle Grinder (Tool Type: Power Tools, Power Source: Electric)Cutting through the thick cast iron stack pipe.
  • Work Gloves (Material: Fabric)Protecting hands from heat, sparks, and sharp metal.
  • Safety Glasses (brand: DeWalt)Protecting eyes from flying debris and sparks.
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FAQs

Is replacing polybutylene with PEX a suitable DIY project for someone with limited plumbing experience?

This project is rated 'intermediate' and is quite involved, requiring significant time (40 hours) and attention to detail. While achievable for a determined DIYer, it demands careful planning, systematic execution, and a willingness to learn new skills like PEX connection. If you're unsure about tackling major plumbing, consider hiring a licensed plumber for the main connections or at least consulting one for advice.

What are the most important safety precautions to take when undertaking this major plumbing replacement?

Always ensure the main water supply to your home is completely shut off and lines are drained before starting any work. Exercise extreme caution when cutting into walls to avoid electrical wires, gas lines, or other hidden utilities. Wear appropriate personal protective equipment (PPE), including safety glasses and gloves, throughout the project, especially when using power tools or handling sharp objects.

Do I need specialized tools to make secure PEX connections, or can I use basic plumbing tools?

Yes, specialized tools are essential for secure PEX connections. You will need a PEX cinch tool (or crimp tool) to properly fasten the cinch rings onto the fittings, ensuring a leak-proof seal. While not listed, a dedicated PEX pipe cutter is also highly recommended for making clean, straight cuts that are vital for good connections. Do not attempt to use generic pliers or cutters, as this will compromise the connection integrity.

What are the most common mistakes DIYers make when installing PEX, and how can I avoid leaks?

The most common mistakes are improper seating of the PEX pipe onto the fitting, and incorrect crimping or cinching of the ring. To avoid leaks, ensure the PEX pipe is fully pushed onto the fitting's barb and that your cinch tool is properly calibrated. After crimping, visually inspect each connection and give it a firm tug to confirm it is secure before moving on.