Resistoflex Thermalok steel pipe and PTFE liner act as an integral piece. Combining dissimilar material with very different coefficients of thermal expansion, the precision Thermalok Process locks the isostatically moulded PTFE liner into pipe housing, making it full vacuum rated from -20°F to 450°F. Resistoflex developed and patented the Thermalok process for lining steel & pipe in the 1950's and have been the world leader since. The Thermalok process positively locks the plastic liner in the metal pipe housing while effectively relieving stress that cause unwanted liner movement in the service. Incoming lots of resin are analysed in a Quality Assurance Laboratory for the conformance to established raw material specifications.
The Thermalok Process: The liner is processed under controlled conditions to size somewhat larger than the ID of the steel housing into which it will be installed. It is then thoroughly inspected for conformance to design specifications. Next the PTFE Liner is subject to a battery of quality tests designed to ensure liner integrity.
The liner is drawn through a sizing die at carefully controlled draw rates which results in calculated reduction in outside diameter. A programmed heating cycle relaxes the liner inside the steel housing, resulting in a snug liner fit. Design allowances are incorporated in this procedure to eliminate undesirable stress in the finished product. Both liner ends of the pipe spool are then hot flared. Temperature, time and pressure are careful monitored.
The finished pipe pipe is then tested in accordance with ASTM F1545 standards. This unique Thermalok process provides lined pipe with dimensional stability under vacuum, pressure & thermal cycling conditions, which prevent liner buckling and cracked flares within the operational limits.