Chlorinated Polyvinyl Chloride (CPVC) Pipes

Chemical Resistance of Astral Corzan^® HP CPVC

One of the key advantage of ASTRAL CORZAN° HP CPVC is its execellent resistance to a broad range of corrosive environments. By replacing traditional materials with ASTRAL CORZAN® HP CPVC, engineers can extend equipment service life and reduce maintennace, while minimizing process life-cycle costs. This technical report is intended to provide engineers and end-users with guidance as to the suitability of ASTRAL CORZAN® HP CPVC industrial piping systems in corrosive applications.

Specific use conditions must also be considered since these will determine the chemical resistance of any thermoplastic piping system.Variables that can affect chemical resistance include chemical concentration, temperature, pressure, external stress, and final product quality. Since the number of possible use conditions is so large, the final decision regarding material suitability often must be based on in- service testing.

The information contained in this report was developed to include conditions that are most often encountered in industry. CPVC samples were immersed in the particular reagent for at least 90 days at 73°F(23°C) and 180°F(82°C). Changes in weight and tensile strength for each sample were reviewed in conjunction with field experience and information gathered from various sources to develop recommendations shown. Note that these recommendations are based on specific use conditions and may not apply to all situations. For this reason,the final decision regarding material suitability must rest with the end- user.

The notes following the chemical resistance chart list specific areas where caution must be used when considering ASTRAL CORZAN® HP CPVC. Additional chemical resistance data will become available as testing of ASTRAL CORZAN® HP CPVC continues. Consult with your product supplier or for the latest ASTRAL CORZAN® HP CPVC chemical resistance information.'

Table 2.1

CPVC is not recommended for use with most polar organic materials including various solvents i.e., chlorinated or aromatic hydrocarbons, esters, or ketones. Resistance of CPVC to certain other fluid mixtures such as fuel oils with moderate aromatic content cannot be determined on basis of immersion testing alone. Actual use data must be obtained. There are a number of similarities in chemical resistance between PVC and CPVC materials. However, one must exercise caution when comparing the chemical resistance properties of CPVC to those of PVC, which are not always the same.

Table 2.2

CPVC test samples exposed while under stress to surfactants, certain oils, or grease have shown signs of environmental stress cracking. Environmental stress cracking is a situation in which the manufactured pipe or fittings are weakened by contact with certain chemicals and propagated by external stresses. External stresses include not only the known pressure stress on a system but also stresses from sources such as expansion and installation.When CPVC is intended for use in handling such chemicals, special consideration should be taken during design and installation to avoid unusual stresses in the piping system,or advance testing of the chemical in simulated use conditions is strongly suggested. Certain organic solvents which are soluble with water, such as alcohols, may safely be handled below a certain concentration. Many of these limiting concentrations are noted in the chemical resistance table. Solvents which are insoluble in water, such as aromatics, will be absorbed by the piping over time, even when they are present at very low levels in the water. This will lead to a decreased service life expectancy for the system.

Table 2.3

The full hydrostatic pressure rating of the pipe may not apply to the entire range of temperature and concentration designated as "recommended."

Table 2.4

Thermal Expansion & Thermal Stress

Thermal Expansion

It is important to considerthermal expansion when designing a system with ASTRAL CORZAN® HP CPVC pipe. Most therm° stics have a coefficient of thermal expansion which is significar higher than those of metals. However, ASTRAL CORZAN® HP CP has the lowest thermal expansion of any commonly used thermoplastic.The thermal expansion of a piping system subjecl a temperature changecan therefore be significant, and may ne compen- sation in the system design

Thermal Stress

Thermal Stresses If thermal expansion is not accommodated, it is absorbed in the pipe as an internal compression. This creates a com-pressive stress in the pipe. The stress induced in a pipe which is restrained from expanding.