CHEMICAL RESISTANT CHART

 

 

A CHEMICAL RESISTANT GUIDELINE FOR

PP / PTFE / PFA / PVDF

 

The following Chemical Resistance Chart is provided as a guide to help select chemical protective materials used in Valves, piping and Fittings best suited for aggressive chemicals and gases. This Chart is also used as guide for evaluating the resistance of fluoropolymer materials to a wide range of chemicals used in Chemical, mining, industrial, Pharmaceutical, laboratory and medical applications.  

It is advisable to refer to these charts when selecting the ideal product such as piping, valves or fittings that will be used in a chemical, acidic or aggressive gas area or medium to  ensure that all wetted parts are chemically compatible with, and resistant to, the pumped media as well as avoiding line failure. 

 

Since the resistance of metals, plastics, and elastomers can be affected by concentration, temperature, presence of other chemicals, and other factors, this information should be considered as a general guide rather than an unqualified guarantee. Ultimately, the customer must determine the suitability of the materials used in various environments.

All recommendations and ratings for these materials are based on the chemical resistance only. Added consideration must be given to material selection when the chemical is abrasive, viscous in nature, or has a Specific Gravity greater than 1.1. 

HIGH PERFORMANCE CHEMICAL

RESISTANT PLASTICS

 

A high-performance chemically resistant plastic is typically more expensive than standard performance plastics. It has superior chemical resistance to a wide range of aggressive chemicals. Here are some of the commonly used high-performance plastics.

 

PVDF (polyvinylidene fluoride) – PVDF is highly resistant to temperature changes and has a high melting point, making it suitable for use in high-temperature applications. It is a high-performance plastic material that has excellent chemical resistance to acids, alkalis, and organic solvents. 

 

Some of the chemicals that PVDF is highly resistant to include hydrochloric acid, sulfuric acid, nitric acid, sodium hydroxide, and many organic solvents such as acetone, benzene, and toluene. PVDF is also highly resistant to UV radiation, ozone, and weathering, making it ideal for outdoor applications.

 

PTFE or Teflon (polytetrafluoroethylene) – PTFE is a well-known high-performance plastic material that has excellent chemical resistance to acids, alkalis, and organic solvents. PTFE is commonly used in chemical processing equipment, laboratory equipment, and medical applications.

 

Some of the chemicals that PTFE is highly resistant to include hydrochloric acid, sulfuric acid, nitric acid, sodium hydroxide, and many organic solvents such as acetone, benzene, and toluene. PTFE is also highly resistant to UV radiation, and weathering, and is non-reactive to most chemicals.

 

As shown in the chemical resistance chart for plastics, PVDF and PTFE offer the highest chemical resistance. At the same time, PVC and HDPE are suitable for low concentration chemical exposure. PP offers good chemical resistance across various chemicals, making it a versatile choice for many chemical-resistant applications.

ELEMENTS TO CONSIDER WHEN MAKING A CHOICE

Determining the chemical resistance of plastic material requires careful consideration of several factors, such as exposure time and chemical concentration. Considering these factors, the appropriate plastic material can be selected to ensure reliable and safe performance in the intended application.

TEMPERATURE

It’s vital to match the container’s material to the chemical’s temperature range to ensure it can withstand the conditions. One way to do this is to consult material datasheets or ask plastic manufacturers for advice. By taking these steps, you can avoid a “meltdown” and keep your chemicals safely contained.

For example, polypropylene (PP) can withstand temperatures up to 100°C, polyvinylidene fluoride (PVDF) can withstand temperatures up to 150°C. On the other hand, polytetrafluoroethylene (PTFE or Teflon) can withstand temperatures as high as 260°C.

EXPOSURE TIME

 

How long plastics are left exposed to chemicals can determine to a large extent, the effect of the chemical on the plastic. Short-term exposure to a chemical may not significantly impact the plastic material, while long-term exposure may cause degradation, swelling, or chemical attack.

For example, high-density polyethylene (HDPE) can withstand short-term exposure to concentrated acids, while PVDF and PTFE are suitable for long-term exposure to aggressive chemicals.

CHEMICAL CONCENTRATION

 

The concentration of the chemical is another crucial factor to consider when selecting a chemical resistant plastic. Some plastics may perform well in low chemical concentrations but may degrade or fail in higher concentrations. Therefore, it is essential to determine the concentration of the chemical and its compatibility with the plastic material. 

 

 

For example, PVC, PP and HDPE can withstand low concentrations of acids and alkalis, while PVDF and PTFE are suitable for high concentrations of aggressive chemicals. 

 

EXPOSURE AREA

 

The exposure area of the plastic material to the chemical is also an important factor to consider. Different plastics have different resistance to chemical exposure depending on the type and location of exposure. For example, PVC is resistant to acid exposure in piping systems but may not perform well in exposure to concentrated acids in a storage tank. 

 

 

CHEMICAL COMPATIBILITY

 

Finally, it is essential to consider the compatibility of the plastic material with the specific chemical. Different plastics have different ways they react to chemicals. Some plastics may create a chemical bond with plastics. Some plastics may be incompatible with certain chemicals, leading to degradation or failure. 

 

For example, polycarbonate (PC) may not be suitable for exposure to chlorinated solvents, while PTFE is highly resistant to a wide range of aggressive chemicals.