Title: High Temp Geomembranes

Although all geomembranes have excellent chemical resistance, elevated temperatures can cause dramatic changes in performance. There are three applications where a geomembrane will be exposed to high temperatures: primary and secondary containment of chemicals stored at elevated temperatures, or high service temperatures. We normally consider a service temperature over 40ºC as an elevated temperature.

Primary Containment of Hot Water/ Brine Solution

High temperatures accelerate chemical attack on plastics and a geomembrane can show dramatically different performance when the temperature goes up. Most chemical resistance tests that we have available for reference are done at room temperature (20ºC) and for a short period of time (usually 7 days). To contain a hot chemical will almost always require a long-term chemical immersion test.

When faced with an elevated service temperature we always recommend a chemical immersion test. For primary containment an immersion test of 30 days is the minimum recommended. Additional long term testing should also be considered if time permits.

There are a few common uses for primary containment of hot chemicals. One use is a solar gradient pond, which absorbs and stores heat from the sun. In this application the geomembrane contains saturated brine solution at temperatures in the range of 90ºC. These ponds have been successfully lined with XR-5 and many have been in service for many years. Another common use is for the lining of metal plating and pickling tanks. PVC liners have been used for many years to line tanks for plating operations. Often the solution used in these tanks is heated.

Secondary Containment of Hot Materials

In the secondary containment application we are normally only containing the hot chemical until it can be cleaned up. In many cases the spilled material will begin to cool as soon as the spill occurs so the required time for high temperature containment is quite brief.

As part of our on going research, we exposed samples of geomembranes to Naptha, Light Gas Oil, and Heavy Gas Oil at 105ºC for 6 days in a sealed container. At the end of this test we opened the container and only found 4 of the six materials that we had started with; the other two had dissolved! The HDPE and LLDPE materials had completely dissolved under these test conditions while a PP sample had swelled to over twice its original size. Our specialized Hazgard 100, High Temp 2000, and 5000 materials all survived this test with weight losses/gains under 20%. This kind of result emphasizes that you may not always be able to predict the chemical reaction at high temperatures. It also showed us that our High Temp materials were much better than polyolefin materials for the containment of hot hydrocarbons. A standard 7-day immersion test (at the target temperature) will normally give us a good level of confidence that the geomembrane will contain any spills. Another important consideration is to backfill the geomembrane. Backfill can cushion the thermal shock on the geomembrane and reduce the temperature of the material before it contacts the liner. Backfill also helps confine the geomembrane while it is in a softened state preventing movement that could lead to a discontinuity.

As with the primary containment it is good practice to perform a chemical test on every elevated temperature project. Elevated temperature test results are very rare in the chemical literature so it is always important to check.

There are a number of typical applications for the secondary containment of hot materials. A tricky application is the secondary containment of transformer oil in a power transformer. Some transformers can have operating temperature ranges that are near the melting point of some geomembranes (over 200ºC). We have had good success with using a backfilled geomembrane and filling the contained area with a temperature absorber such as a rock or a granulite material. In the event of a significant spill the large surface area of rock cools the oil quickly to prevent liner damage. A more typical application is the secondary containment of process liquids in a manufacturing plant. In this case a chemical immersion test is recommended with the chemicals, or mixtures of chemicals to be contained in the tanks at the anticipated process temperatures.

High Service Temperatures

Recent developments in the heavy oil, and tar sands extraction industries have seen the proliferation of large tanks that are continuously heated. These tanks, often over 30 m in diameter are placed in a tank farm with a secondary containment liner underneath. The issue in this instance is that the heat from the tank will eventually heat the ground beneath the tank so that the ground temperature under the tank pad will eventually be nearly equal to the temperature in the tank. Although it may take a few years for the ground under the tank to heat up, eventually the temperature in the soil 1 to 3 m below the tank is approximately equal to the tank temperature. A geomembrane placed at this position needs to be able to withstand these temperatures for the lifetime of the tank farm.

There are two aspects to this containment application. The first is the secondary containment of the hot materials in the main part of the tank farm. This falls under the secondary containment of hot materials section above. The second part of the problem is more difficult. This is the need to find a geomembrane that will withstand the high temperatures in the soil under the tank pad for a long period of time. Since high temperatures accelerate the degradation of most plastics, finding a geomembrane for service at high temperatures that will last 20 years is a challenge. Fortunately our High Temp line of geomembranes has been formulated for just this type of service.

To determine whether a geomembrane will perform at high temperatures for an extended period requires that we expose them to even higher temperatures for a short period and extrapolate the data. We performed two tests of high temperature resistance.

One common measure of stability is the weight retained in a geomembrane sample after a period of exposure to high temperatures. Weight loss is caused by degradation products volatizing from the sample. In this type of test an exposure temperature that is well above the reasonable long-term service temperature of the geomembrane is used. By selecting a high test temperature meaningful weight loss data can be seen in a relatively short period, even in a very stable material. The weight loss in an effectively heat stabilized material under normal long-term service conditions would be imperceptible and higher temperatures are necessary to accelerate the test.

Layfield performed a series of tests on our High Temp materials and a competitive high temperature rated material. We ran two sets of tests. In the first test we exposed the samples to 135ºC for a 7-day period. After exposure the samples were tested for changes in tensile and elongation.


% Tensile Retained (135ºC for 7 Days)
Material % MD Tensile Retained % CD Tensile Retained
HZ 100 94 86
High Temp 2000 100 100
Competitive Product 101 83


% Elongation Retained (135ºC for 7 Days)
Material % MD Elongation Retained % CD Elongation Retained
HZ 100 103 94
High Temp 2000 137 125
Competitive Product 114 93

The results show that High Temp 2000 suffered no loss in tensile strength or elongation, demonstrating outstanding heat resistance at 135ºC. The polymer blend used to manufacture High Temp 2000 is the same one used for Layfield’s polyester reinforced High Temp 5000. Hazgard 100 showed a slight loss in tensile strength and elongation, similar to the performance of competitive material.

A second test was performed to measure weight loss after 28 days at 135 C. Our competitors had offered a 28 day test at 135ºC as proof that their material would be able to perform in extended service at temperatures above 100ºC. In comparative side-by-side testing our Hazgard 100 material was significantly more stable than the competitive product.


% Weight Retained (135ºC for 28 days)
Material % Weight Retained
HZ 100 87.43%
Competitive Product 81.45%

Additional laboratory testing and challenging field applications continue to demonstrate the stability of Layfield’s high temperature resistant geomembranes. Our laboratory testing compared the performance of our geomembrane products with that of other competitive high temperature resistant materials. Our High Temp series of geomembranes consistently demonstrated the highest levels of stability at elevated temperatures.


The stability of our High Temp materials has also been confirmed under field service conditions, supporting our laboratory conclusions. Hazgard 100 has been used for several years as a containment geomembrane for liquid molten sulfur. In this case the Hazgard 100 geomembrane is installed on the ground and the liquid sulfur poured on top. The Hazgard 100 geomembrane must withstand the 145ºC sulfur temperature for 1 or 2 days until the initial lift of sulfur can cool.

The careful design of heat resistant geomembrane materials has extended the use of geomembranes into temperature ranges that were unattainable in the past. Layfield’s line of High Temp Geomembranes provides proven performance over a wide range of service temperatures and chemical exposure. If you would like more information about the use of geomembranes in contact with high temperatures, or if you require more information about any of Layfield’s High Temp Geomembranes, please contact your Layfield Representative.