Connecting a PVC waste pipe to a PVC soil pipe is a common task in plumbing, and using a boss adaptor makes it straightforward. The boss adaptor comes in two main types: rubber and solvent weld. Here's a guide on how to use each type and tips for different applications.
Understanding the Boss Adaptor and Boss Shoulders
Boss Adaptor Types:
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Rubber Boss Adaptor: Features lugs on the inside and outside to grip the boss shoulder and the waste pipe tightly.
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Solvent Weld Boss Adaptor: Requires solvent weld cement for a permanent and watertight seal.
Boss Shoulder Types:
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Boss Shoulder on Existing Fittings: Found on standard fittings like branches.
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Boss Pipe: A specialized pipe with built-in boss shoulders (short or long versions).
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Strap Boss Shoulder: A retrofitting option with a strap that secures around the soil pipe.
Step-by-Step Guide to Connecting a Waste Pipe to a Main Soil Stack
Using a Boss Shoulder on Existing Fittings:
- Locate the boss shoulder on the existing fitting (e.g., a branch).
- Drill through the plastic in the boss opening.
- Insert the boss adaptor (rubber or solvent weld) into the boss shoulder.
- For the rubber boss adaptor, push it firmly into the shoulder, ensuring a tight grip.
- For the solvent weld boss adaptor, apply solvent weld cement to the inside of the shoulder and the outside of the adaptor. Twist the adaptor into place and let it cure for about 10 minutes.
- Push the waste pipe into the boss adaptor until it sits about 1 cm inside the soil pipe, avoiding blockages.
Using a Boss Pipe:
- Choose a short boss pipe (solvent weld) or a long boss pipe (ring seal). The short boss pipe is more commonly used.
- Fit the boss pipe onto the soil pipe, ensuring it’s secure.
- Drill out additional boss openings if needed (short pipes usually come with one open boss and two closed ones).
- Insert the boss adaptor (rubber or solvent weld) into the side boss opening and connect the waste pipe.
Using a Strap Boss Shoulder (Retrofit):
- Mark and drill a 54 mm hole in the soil pipe.
- Apply solvent weld cement around the hole and the lug on the inside of the strap boss.
- Push the strap boss tightly around the soil pipe and secure it.
- Insert the boss adaptor into the boss shoulder, then connect the waste pipe.
Tips for Success
- Check Alignment: Ensure the waste pipe is properly aligned and doesn’t protrude too far into the soil pipe.
- Solvent Weld Curing: Allow at least 10 minutes for the solvent weld cement to set before testing.
- Debris-Free Installation: Clean the inside of the soil pipe and boss opening to prevent leaks or blockages.
- Use the Right Tools: A hole saw is ideal for drilling clean, accurate holes.
By understanding the types of boss adaptors and shoulders and following the correct method for your installation, you can achieve a secure, leak-free connection between your PVC waste and soil pipes.
