Downhole seal stacks are generally a combination of metal, non-elastomeric seal (Thermoplastics) and elastomeric seal (Rubber). Most common designs are combination of V-ring (Chevron seal), O-ring, thermoplastic or metal as back-up or spacer ring. In some special cases, the entire seal stacks are made of thermoplastic and metal. Most thermoplastic used in oil field are virtually chemically immune and not subject to explosive decompression. These seal stacks are used in many applications downhole such as tie back sealing, PBR, sand control service sealing, sliding sleeve, safety valve, etc. Maxrub® customized seal stacks has been proven to be very effective in the field.