Can you transition from PVC to ABS?

Quick Answer

Yes, it is possible to transition from PVC to ABS plastic piping systems, but it requires using proper transitional fittings and following some important steps. The key considerations when transitioning between PVC and ABS are the differences in materials, solvent cements, handling requirements, and transition fittings needed. With the right connectors and cement, a secure transition can be made between the two plastic piping systems.

What is PVC?

PVC (polyvinyl chloride) is a popular plastic piping material used in plumbing and drainage applications. Key properties of PVC include:

• Made from vinyl polymers and chlorine.
• Can be rigid or flexible.
• Rigid PVC is typically white or gray in color.
• Withstands corrosion, abrasion, and chemicals.
• Used for cold water supply, drainage, venting, sewage, and industrial liquid handling.
• Available in multiple schedules/pressure ratings.
• Joined by solvent welding/cementing.

PVC is an inexpensive, durable piping material. However, it can become brittle over time when exposed to sunlight and temperature extremes. PVC also releases toxic fumes when burned. Still, its resistance to chemicals and corrosion makes it well-suited for waste drainage applications.

What is ABS?

ABS (acrylonitrile butadiene styrene) is another common thermoplastic piping material:

• Made from acrylonitrile, butadiene, and styrene polymers.
• Rigid opaque piping, typically black or gray.
• Withstands impact and shock better than PVC.
• Used for residential and commercial drain, waste, and vent (DWV) systems.
• Available in Schedule 40 and 80.
• Joined by solvent welding.

ABS offers more strength and impact resistance but is more expensive than PVC. It also withstands a wider temperature range. Like PVC, ABS resists corrosion and many chemicals. Its fire performance is also better, producing less smoke and toxic fumes when burned. This makes ABS well-suited for drainage systems.

Key Differences Between PVC and ABS

While both are popular plastic piping materials, there are some notable differences between PVC and ABS:

PVC	ABS
Less expensive	More expensive
Lower strength and impact resistance	Higher strength and impact resistance
More brittle, less ductile	Less brittle, more ductile
Withstands lower temperatures	Withstands higher temperatures
Creates more toxic fumes when burned	Lower smoke generation and less toxic fumes

These differences mean that ABS is better suited to exposed or high-impact applications, while PVC works well for underground drainage and venting. The piping materials also require different solvent cements.

PVC and ABS Solvent Cements

Joining and cementing is a key aspect when working with plastic pipes. Solvent cements are used to fuse joints between pipes and fittings. This creates strong, permanent connections.

PVC and ABS piping use different solvent cement formulations:

• PVC cement – Contains PVC resins dissolved in solvents like tetrahydrofuran, acetone, or methyl ethyl ketone.
• ABS cement – Uses ABS resins dissolved in acetone, along with cyclohexanone and/or MEK.

Using the wrong cement can result in weak joints prone to leaking and failure. So it’s crucial to use the proper cement for each plastic material. PVC cement won’t bond well with ABS, and vice versa. The cement literally dissolves and fuses the pipe surface, forming a continuous bond.

Transitioning Between PVC and ABS

When combining PVC and ABS piping, proper transitional fittings must be used:

• PVC male adapters can connect to ABS female sockets.
• ABS male adapters can connect to PVC female sockets.
• Couplings are also available for joining ABS and PVC pipes.
• For best results, use transitional fittings listed for PVC-ABS connections.

The joining process when transitioning between materials is:

1. Cut pipes squarely and deburr the ends.
2. Dry fit connections before cementing to check fitup.
3. Use a PVC-to-ABS transition cement.
4. Apply a thick layer of cement to both joining surfaces.
5. Quickly join parts together with a slight twisting motion.
6. Hold joint together firmly for 30 seconds to prevent pipe push out.
7. Allow cement to fully cure based on specs before pressure testing.

Following this process helps create a reliable joint between the ABS and PVC components.

Applications for Transitioning PVC to ABS

Some common situations where a transition between PVC and ABS may be useful include:

• Connecting a PVC solid waste system to an ABS vent stack.
• Tying ABS sink drains or tub drains into PVC waste piping.
• Joining an ABS toilet drain arm to a PVC stack.
• Connecting ABS piping to PVC underground drainage.
• Transitioning from an ABS drain inside to a PVC drain extending outside.
• Making repairs to existing piping systems.

PVC-to-ABS transitions allow combining the benefits of both materials where appropriate. PVC can be used for its chemical resistance underground, while ABS provides better strength and impact resistance for interior drainage lines.

Pros and Cons of Transitioning PVC to ABS

Some key advantages and disadvantages of transitioning between PVC and ABS include:

Pros:

• Allows using PVC and ABS where each material suits the application.
• Appropriate transitions prevent having to replace entire existing systems.
• Makes repairs simpler with fewer parts to replace.
• Saves costs compared to replacing all PVC or ABS piping.
• Pre-made transition fittings ensure proper connections.
• Produces durable joints when cemented correctly.

Cons:

• Transition joints can potentially leak if not properly cemented.
• Requires having proper solvent cement and transition fittings on hand.
• More potential failure points in the system.
• Transition fittings add some initial costs versus using all one material.
• Absorb some time and labor for installing transition connections.

So in most cases, the pros of targeted PVC to ABS transitions outweigh the cons. But proper installation is essential.

Conclusion

Transitioning from PVC to ABS piping is possible using the appropriate adapters and following the proper cementing technique. This allows combining these two common plastic piping materials in drainage, waste, and vent systems. By using suitable PVC-to-ABS transition fittings and cement, durable and reliable joints can be produced. With some planning and careful work, installers can make effective transitions between PVC and ABS piping where needed.