We are often asked the question: “How hot can my product be when going into a bulk bag?”
Bulk bag fabric is made by weaving polypropylene tapes together. So, when this question is posed, we refer to the SDS sheet for polypropylene to get the basics. Polypropylene’s melting point is between 230 and 275 degrees Fahrenheit. As a general rule of thumb the polypropylene will begin to soften once it reaches around 195 degrees Fahrenheit. So where you may not see a breakage at this range, you will start to see a change in the physical properties of the fabric, specifically elasticity. If the material does not stretch as it is designed, due to this change, you may be lowering the 5 to 1 safety ratio built into the Global-Pak bag construction. To err on the side of caution, Global-Pak recommends staying under the threshold of 165 degrees Fahrenheit when filling a bulk bag to avoid the softening of the material or semi-melting the fabric and ending up with brittle polypropylene or a compromised tensile strength that will not stretch properly when the bag is handled.
Specialty liners may help increase the filling temperature of the bag, but this should be specifically addressed with your Global-Pak sales representative. FIBCs with a surface temperature in excess of 120 degrees Fahrenheit may not stack as well and should be supported from the bottom when transporting.