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This is the most critical and labor-intensive step. Use a hammer and a cold chisel to carefully break up the old lead seal inside the hub. Place the chisel against the lead and strike it firmly to fracture it. Work your way around the pipe circumference. An alternative is to drill a series of small, closely spaced holes into the lead using a drill and a metal bit, which will weaken it for easier removal. Once the lead ring is broken and removed, use a pair of pliers or a large screwdriver to pry and pull out the old, packed oakum (a tarred, fibrous rope) from underneath the lead.

You're viewing a step from: How to Connect PVC Drain Pipe to a Cast Iron Hub

Beginner

30 minutes

2/4 Inventory

This guide details the process of creating a durable, watertight connection between a modern PVC drain pipe and an existing old-style cast iron hub, typically found in older plumbing systems. The primary method described uses a rubber compression gasket, often referred to as a 'donut', to create a seal inside the hub.

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Frequently Asked Questions

Why is a cold chisel listed as a required tool, and how is it used in this project?

A cold chisel, specifically the Dasco Pro 3/4 in. x 12 in. Cold Chisel G410, is essential for carefully excavating the old lead and oakum seal from inside the cast iron hub. It allows you to break apart and remove the old, brittle material without damaging the cast iron itself. Use it with a hammer, chipping away small pieces at a time to ensure a clean interior for the new seal.

What are the most critical safety precautions I should take when connecting PVC to old cast iron pipes?

Always wear safety glasses (like the listed Safety Glasses) to protect your eyes from flying debris, especially when chiseling old material or dealing with rust. Use heavy-duty work gloves (e.g., Husky Large Premium Grain Cowhide Leather Heavy Duty Impact Work Glove) to protect your hands from sharp edges, rust, and potential contaminants. Ensure good ventilation, as old drain pipes can contain unpleasant odors and bacteria.

How long does this project typically take for a beginner, and what's the approximate cost?

For a beginner, this project generally takes 2-4 hours, depending on the condition of the old seal and your comfort level with the tools. The primary cost will be the PVC pipe and fittings, the rubber compression gasket (donut), and a few specialized tools like the cold chisel, totaling roughly $30-$70 if you don't own the tools already. These costs can vary based on local prices and specific product brands.

What's the most common mistake DIYers make when installing the rubber compression gasket, and how can I avoid leaks?

The most common mistake is not thoroughly cleaning the inside of the cast iron hub, which prevents a proper, watertight seal. Ensure the hub is free of all old debris, rust, and scale using a wire brush. Additionally, apply a generous amount of plumber's grease (Oatey 1 oz. Plumber's Grease 30620) to both the gasket and the PVC pipe end to help it slide in smoothly and create a tight seal.