CPVC VS PVC | The Definitive Guide

Hello people, Today I’m going to share a very interesting post on PVC vs CPVC. It is a timeless debate among pipe professionals, but things will be made clear today.

CPVC VS PVC | Difference Between PVC and CPVC 

The most significant difference between PVC and CPVC is the range of temperatures each can resist. CPVC can withstand temperatures up to 200° Fahrenheit (39°C), while PVC peaks at 140° Fahrenheit (60°C). Above those temperatures, both CPVC and PVC will start showing effects and softening, increasing the risk of pipes and joints failing and, after that, failing the plumbing system.

CPVC (Chlorinated Polyvinyl Chloride) is in the same thermoplastics family as PVC (Polyvinyl Chloride) and shows superior heat and pressure resistance, which is why it is the preferred material for high-end industrial applications among the two.

Because of the various chemical compositions, the bonding agents, primers, and solvent cement differ for CPVC and PVC. For instance, CPVC solvent cement must cater to ASTM F493 specifications, and PVC must cater to ASTM D2564 specifications. Because of this, CPVC and PVC pipes and fittings, along with their solvents and bonding agents, should not be used reciprocally.

Apart from meeting ASTM standards, different solvent cement is needed depending on the pipe’s size and applications. To do that perfectly, always check the product containers to ensure you’re the ideal agent for an ideal application.

PVC is only available in nominal sizes. On the other hand, CPVC is available in nominal pipe sizes and copper tube pipe sizes. CPVC is more flexible than PVC and requires support at a three-foot distance to maintain its position.

Molecular Composition of CPVC and PVC 

CPVC is a PVC that goes through a chlorination reaction. Generally, PVC and chlorine react with each other utilizing a free radical mechanism which can be commenced using thermal and UV energy.

CPVC is different from PVC as approximately 40% of its backbone structure is filled with chlorine atoms. On the contrary, PVC contains only 25 chlorine in its backbone, filling the remaining sites with hydrogen. The chlorine atoms surrounding the carbon backbone of CPVC are large and bulky enough to cushion its carbon chain from the environment, which often weakens other thermoplastics.

Interesting Read – HDPE Pipe Sizes and Dimensions | A Complete Analysis

General Properties: CPVC VS PVC 

Property Schedule 40 PVC Schedule 80 PVC Schedule 40 CPVC Schedule 80 CPVC
Colour white, dark grey white, dark grey light grey, off-white, yellow light grey, off-white, yellow
End Shape plain, bell plain, bell plain plain
Max. Working Pressure 450 PSI 630 PSI 450 PSI 630 PSI
Max. Temp 140°F 140°F 200°F 200°F
Min. Temp 33°F 33°F 33°F 33°F
Sizing NPS NPS NPS NPS
Standard Length 10′, 20′ 10′, 20′ 10′ 10′
Tensile Strength 7500 PSI 7500 PSI 8200 PSI 8200 PSI

Chemical Resistance

Thermoplastics’ exceptional chemical properties make them increasingly popular amongst traditional metal enthusiasts. CPVC and PVC are inert to most acids, salts, bases, and aliphatic hydrocarbons. That ability extends their service life by years and sometimes even decades. Chemical resistance, without a doubt, is a distinct advantage for both PVC and CPVC.

However, subtle differences are made between CPVC and PVC because of the former’s chlorine content; each has a niche advantage. One great example is the great concentration of sulphuric acids. In a general scenario, CPVC is superior to PVC.

Paradoxically, CPVC’s high chlorine makes it vulnerable to ammonia and other amines, whereas PVC excels because of its non-existent chlorine content.


Source - corzan.com

However, before choosing CPVC or PVC for your desired application, consulting the material supplier and referring to a chemical compatibility chart will be wise.

Temperature Resistance

As the chlorine content in CPVC increases, it also gives rise to its Glass Transition Temperature (Tg). The Tg is when a polymer transforms from hard, glassy material to a soft, rubbery substance losing its structural solidarity.

As said earlier, CPVC’s higher chemical resistance is shown in the ASTM standards for each material as the max. Service temp. for PVC is up to 140°F (60°C), and for CPVC, it is up to 200°F (93.3°C). Please note that one should always consult your material supplier about material individual operational capabilities before making any major procuring decision.

Pressure Resistance

CPVC and PVC piping test results with the pressure ratings at 73°F (22.8°C) are the same, but as the temperature increases, CPVC maintains its pressure ratings much better than PVC.

For instance, let’s determine the pressure rating of 10 in. Schedule 80 piping at 130°F (54.4°C) for both PVC and CPVC. Each material is pressure rated at 230 psi at 73°F (22.8°C).

  1. PVC has a derating factor of 0.31 at 130°F (54.4°C), making it pressure-rated up to 71.3 psi at that temperature (230 psi x 0.31 = 71.3 psi).
  2. CPVC has a derating factor of 0.57 at 130°F (54.4°C), making it pressure-rated up to 131.1 psi at that temperature (230 psi x 0.57 = 131.1 psi).

While PVC can still be utilized for applications at 130°F (54.4°C); however, the material can resist significantly less pressure at higher temperatures (above 73°F or 22.8°C) than CPVC.

Engaging Read – Top 5 Heat Resistant Plastic Materials | A List of High Temp Plastic Materials

PVC VS CPVC: Comparision of Derating Factor 

Temperature (F°) CPVC PVC
73 1 1
80 1 0.88
90 0.91 0.75
100 0.82 0.62
110 0.72 0.51
120 0.65 0.40
130 0.57 0.31
140 0.51 0.22
150 0.42
160 0.40
170 0.29
180 0.25
190 0.20
200 0.20

Fire Resistance

Mainstream thermoplastic such as polyethylene and polypropylene has given all thermoplastics a bad reputation for being flammable. However, vulnerability to melting and burning is not true for all thermoplastics.

Industrial PVC is engineered to be less prone to flammability and smoke production; specific ASTM tests are designed to determine a material’s fire resistance capabilities.

Flash Ignition Temperature

A tiny outward flame can ignite sufficient combustible gas at the lowest temperature. For CPVC for this to happen, the temperature is about 900°F (482°C), and rigid PCVC should be somewhere around 750°F (399°C).

Material
PVC 399 750
CPVC 482 900
Paper 232 450
White Pine 204 400
Chart by Visualizer

Limiting Oxygen Index (LOI): The percentage of oxygen needed in the near atmosphere to maintain a flame. For example, CPVC’s LOI is 60, and PVC’s is 45.

Material LOI
CPVC 60
PVC, Rigid 45
Chart by Visualizer

Common CPVC and PVC Products 

PVC and CPVC resin are generally found in powder or pellet form with additives already mixed in. The resin is then molded into residential, industrial, and commercial products.

The two flagship manufacturing techniques for PVC and CPVC are Injection Molding and Extrusion.

Injection Molding: This technique is advisable for large-volume production. A ram or screw-type plunger forces molten plastic into a mold cavity. Then the resin is again fed into a heated barrel through a mold tool and cooled to harden.

Extrusion: This technique can also be utilized for bulk production. Extrusion starts when the resin is forced through the top of the machine. The raw material will gradually melt by the force of the spinning screw and heater, along with the barrels. It is then formed into a continuous profile and hardened.

Pipes & Fittings

According to a 2016 study by Zion Market Research, pipes and fittings contribute about 62% of global PVC revenue. Easy installation, corrosion, and weather resistance are a few features that make PVC stand out from alternative materials. CPVC is the ideal choice for pipes and fittings where heat, chemical, and pressure resistance is the main requirement.

Sheets and Linings

The outstanding corrosion resistance and fire performance of CPVC are huge leverage for industrial applications and are often overwrapped with Fiber Reinforced Plastic (FRP). However, when sheets and liners require less pressure and temperature demands, then PVC should be used.

Ducting

With air pollution on the rise and governments worldwide looking for measures to curb it, the need for reliable fume handling systems, especially in corrosive environments, is witnessing healthy growth. Depending on the applications and temperature, both PVC and CPVC can be utilized.

Fascinating Read – How is Plastic made? A Simple and Detailed Explanation.

PVC VS CPVC: Applications 

Both PVC and CPVC, thanks to their salient properties like versatility, ease of installation, and low-cost corrosion resistance.

PVC Applications

PVC’s most significant advantages are its low cost and easy installation. It can be installed without any hassle and without using any skilled welders. According to an estimate globally, more than 50% of PVC manufactured is utilized in the construction sector.

Water Solutions: The corrosion resistance feature and relatively low cost make PVC the go-to plastic material for plumbing applications.

  • Drinking water
  • Sanitary Sewers
  • Drainage
  • Storm Sewers

Housing: PVC sheets can be fabricated to replace other materials like wood as a lightweight and robust alternative. The material is often painted or furbished to imitate other materials.

  • Window frames
  • Window sills
  • Cabinet finishes
  • flooring

Signage: As PVC is inexpensive, durable, and easy to paint, its sheets are commonly used for signage.

Electrical cable insulation: With the blending of certain plasticizers, PVC can become softer and more flexible for use as cable insulation. In addition, it’s also fire-resistant and inexpensive.

CPVC Applications

Since CPVC has all the strengths and benefits and PVC, it can be utilized for many applications. However, it is a bit more expensive, which can pose a challenge in replacing it with PVC.

However, in situations where there is a need for chemical resistance and to endure more pressure and heat, CPVC is the ideal option.

Industrial Applications: CPVC is a reliable, long-lasting solution for the most rugged industrial environments and is often referred to for the more demanding industries.

Chemical Processing – Safely transport aggressive chemicals at elevated temperatures, under pressure, without corrosion-related problems.

Mineral Processing –  Resist the harsh environments and demands of special and raw material processing operations.

Power Generation – Resists high pressure and corrosive chemicals for a long time, very common in power plants.

Semiconductor – Great flame and smoke resistance improves efficiency and safety and averts contamination in cleanrooms.

Wastewater management – Restricts corrosion completely, even when transporting the harshest disinfection chemicals.

Residential and Commercial Plumbing

For plumbing applications that require more pressure and temperature compatibility, CPVC provides a sufficient and flexible mechanism resisting pitting, scaling, and bacteria build-up – it doesn’t matter whatever the chlorine and Ph levels are.

Retail Small and mid-sized office buildings and shopping malls.

Hospitality Restaurants and low-sized office buildings.

High-Rise Hotels, condos, and apartments span over seven stories or more.

Education – K-12 schools, colleges, and universities.

Healthcare – Hospitals, medical complexes, and medical clinics.

Multi-family – Buildings spanning six stories or less – apartments, condos, hotels, and motels.

Interesting Read – What is Warpage? | Causes of Warpage | Warpage Variations

Which One To Choose? 

The answer to what you should choose completely depends on your application. I have shared the difference between CPVC and PVC.

It would be best if you went with CPVC for its superior resistance and performance. Most suitable for chemical handling, hot water distribution, and commercial applications.

And it would help if you went for PVC because it is budget-friendly. Most suitable for cold water distribution, recreational applications, residential construction, and DIY projects.

FAQs

Below are the frequently asked questions on the CPVC pipe vs PVC. Let’s dig deep to know more.

Can PVC and CPVC be glued together?

Yes. However, CPVC solvent cement technical will work very well with PVC. But, I recommend that a suitable weld-on primer and PVC solvent cement for the particular application be utilized. Always keep in mind that PVC solvent cement, because of its temperature limitations, is not advisable for CPVC piping.

Which PVC pipe is suitable for outdoor use?

Regarding manufacturers’ recommendations, gray-colored Schedule 80 PVC pipe is a good option for outdoor use as it is a heavy-duty material that can withstand outdoor surroundings.

Are PVC and CPVC Pipes UV resistant?

UV light radiation can cause the outer part of the PVC and PVC pipes to degrade moderately but not significantly. Over time, pipes exposed to sunlight will have a visible color change called “UV Discoloration.

Long-term exposure to sunlight can decrease the CPVC and PVC’s impact strength and resistance; however, it doesn’t seem to significantly impact the pipes’ pressure, malleability, and rigidity. Interestingly, furniture-grade PVC pipes are impact and UV-resistant. They will not change color in sunlight.

What is the life expectancy of PVC and CPVC Pipes?

Both PVC and CPV pipes have a life expectancy of 75 to 100 years.

How Does CPVC reliability compare to other materials?

The chlorination of CPVC gives it a clear advantage over other materials in dealing with common water treatment chemicals. The chlorine molecules in the CPVC pipe block the chlorine and chloramine from attacking the pipe, making it immune to chlorine destruction and extending its lifespan.

Copper enthusiasts should know that copper plumbing is susceptible to chlorine-related issues. Neither copper nor any other material has such an effective chlorine barrier. Permeation and leaching are other problems that can contaminate water running through the pipe.

Suggested Read 

The Conclusion 

That is all I want to say about CPVC VS PVC. Both of them have their pros and cons but are overall extremely useful in several applications. Before making any major decisions related to procuring that material, consult your material supplier and understand your requirements, upon which you can make a final decision.

Thanks for reading. Share your thoughts and questions in the comment section.

Have a lovely day.

Leave a Comment