Plastic process equipment used in chemical plants and steel mills, such as pickle tank covers, pickle and other end use tanks, duct work, fume hoods, etc., generally is fabricated from materials, such as polypropylene plastic, which have good resistance to chemical attack and which are relatively inexpensive. However, in many such applications, the relatively high combustibility of regular or non-flame retardant polypropylene is a significant drawback.
To reduce the chance of combustion, it is possible to fabricate plastic process equipment completely of flame retardant plastic materials, such as polypropylene materials. On the other hand, such flame retardant materials are far more expensive than regular or non-flame retardant plastic materials and, in addition, flame-retardant materials are far more difficult to weld than non-flame retardant materials.