Understanding the Burst Resistance of CPVC Pipe

When designing a new plastic piping system, it is crucial to keep in mind that the success of that system depends on a number of key factors: the quality of the parts manufactured ; the stresses imposed from operating conditions and installation issues; and the chemical substances in contact with both the outside and inside of the system. Every one of these aspects can affect the performance of the system during its service life.

Whether a piping system is metallic or plastic, typically the most vulnerable point – the one where most failures will occur – is the joint. But that statement couldn’t be further from the truth when it comes to CPVC and the chemical bonding process unique to CPVC installations. 

In fact, over its nearly 60-year history in the field, CPVC piping joints have proven to be the strongest, least vulnerable part of the system – stronger than either the pipe or the fitting alone. The reason is simple and yet complex: the marvel that is solvent cement welding. Not a glue, solvent cement works by softening the topmost layers of the pipe and fitting socket, curing as the CPVC molecules harden and the solvent flashes off. In a properly assembled system, 80% of the joint strength comes from this ‘fusion area’.

CPVC Piping Joints Offer Burst Resistance

This point is illustrated well in this video of a solvent-welded joint burst test conducted on FlowGuard^® CPVC pipe to determine burst pressure for CPVC schedule-sized pipe per ASTM F441 requirement. During the short-term hydraulic pressure test shown (conducted according to ASTM D1599, the test method for short-term hydraulic failure pressure), the welded joint maintains pressure resistance up to 1895 psi, limited only by the capabilities of the test fixture, which burst during the test.

Of course, the ability to stand up to intense internal pressure goes hand in hand with proper installation of the solvent-cemented joint. That is why knowing the ropes of solvent cement application is the other part of the equation. Whether you are new to CPVC or just want to brush up on the basics, you can download the FlowGuard Pipe and Fittings Installation Guide now to review the simple steps.