In some buildings, CPVC piping is regularly found in fire protection systems. This common practice includes its share of challenges, which Technorm has witnessed in several investigations when a part was broken after installation.
Piping and fittings are made from a CPVC (chlorinated polyvinyl chloride) resin. These pipes were introduced in 1984, but have gained popularity with fire protection contractors since the 2000s. There are two main brands of pipe in Quebec: Blazemaster (distributed by IPEX in Quebec) and Spears (FlameGuard) made from different resins.
REGULATION
The installation of CPVC piping and accessories is conditionally accepted by the Quebec Construction Code (Chapter I) which has adopted since January 2022 the NBC 2015 am. QC. The NBC has been referring to NFPA 13, a standard that specifically addresses CPVC piping since the late 1990s.
Sentence 3.2.5.19.2) a and 3.2.5.13.1) of NBC 2015 am. QC permits, under certain conditions, the installation of combustible piping for sprinkler systems for underwater systems in residential and other light hazard installations for which incombustible construction is required.
FEATURES: ADVANTAGES AND DRAWBACKS
The popularity of using CPVC piping and fittings is due to several factors including the following:
- Its purchase cost is lower than steel for diameters less than DN 50.
- Its installation cost is lower than to steel (faster).
- It does not require a pipe threading machine.
- The pipe is easily cut.
- A DN20 diameter (¾ in.) can be used, although few contractors do (less inventory for contractors).
- It has a better hydraulic quality (C-factor of 150 vs. 120 for steel), which represents 20% less friction.
- It is insensitive to microbiological corrosion (MIC).
However, plastic piping comes with its share of limitations and precautions to consider (non-exhaustive list):
- The maximum ambient temperature must be 65°C (the piping must not be located near heat-generating equipment).
- It requires more pipe supports for horizontal runs.
- Its chemical compatibility must be verified.
- The use of a caulking products in walls and floors must be approved by the manufacturer.
- Edible oils should not be used as a gasket lubricant.
- It must be ensured that there are no traces of oil in the water in the steel piping system when connecting to an existing or new steel system.
- Its curing time is much longer when the ambient temperature is below 16°C. For example, for DN 32 pipe, the hardening time is 3 h if the ambient temperature is above 16°C and 32 h at a temperature from 4.4°C to 16°C.
- It must not be stored outside without protection.
- Sprinkler heads must be installed after the piping and fittings.
- Accidental nail or screw perforation is possible after installation and/or reception of installations.
CHEMICAL INCOMPATIBILITIES WITH CPVC
The presence of a chemical agent that is incompatible with plastic can lead to Environmental Stress Cracking (ESC). This phenomenon causes the plastic to crack prematurely. The ESC agent penetrates the chemical structure of the plastic, reducing the energy required to induce cracking. Thus, under normal and expected stresses on a plastic, a part that has been in contact with an ESC agent could crack after only a few months. Examples of ESC agents are esters, ketones and aromatic solvents.
RECORDS CONFIRMING CHEMICAL INCOMPATIBILITY
In one of our projects, we observed this phenomenon at several locations in the CPVC piping network as traces of cutting oils in the existing network migrated into the CPVC piping network. Figures 1 and 2 show longitudinal cracks created by an ESC phenomenon.
Source: Technorm
Another example of a chemical incompatibility phenomenon was observed following the installation of telecommunication cables in contact with CPVC piping. In this case, the ESC phenomenon happens because of the presence of plasticizers in the sheath of the electrical conducts. Figure 3 shows a discoloration of the electrical conduct sheath and figure 4 shows a crack in the CPVC pipe at the contact location. This situation can occur in any building if attention is not paid to the specifics of CPVC.
Source: Technorm
INFORMATION TO BE KEPT ON SITE
CPVC piping installation is widely used for fire protection networks. It is important that the design and installation of this piping be done according to the manufacturer’s recommendations. This is also true throughout the life of the piping in the building. It is important to leave a sign on the construction site and to warn the owner of the presence of CPVC so that he can take the required measures and precautions. The CPVC resin in the piping and accessories has characteristics that can degrade if the environment in which the resin is found is chemically incompatible.
