Transport Ultrapure water

various thermoplastic pipes used in upw systems.



a upw installation using pvdf piping.

stainless steel remains piping material of choice pharmaceutical industry. due metallic contribution, steel removed microelectronics upw systems in 1980s , replaced high performance polymers of polyvinylidene fluoride (pvdf), perfluoroalkoxy (pfa), ethylene chlorotrifluoroethylene (ectfe) , polytetrafluoroethylene (ptfe) in , europe. in asia, polyvinyl chloride (pvc), chlorinated polyvinyl chloride (cpvc) , polypropylene (pp) popular, along high performance polymers.

methods of joining thermoplastics used upw transport

thermoplastics can joined different thermofusion techniques.

socket fusion (sf) process outside diameter of pipe uses “close fit” match inner diameter of fitting. both pipe , fitting heated on bushing (outer , inner, respectively) prescribed period of time. pipe pressed fitting. upon cooling welded parts removed clamp.
conventional butt fusion (cbf) process 2 components joined have same inner , outer diameters. ends heated pressing them against opposite sides of heater plate prescribed period of time. 2 components brought together. upon cooling welded parts removed clamp.
bead , crevice free (bcf), uses process of placing 2 thermoplastic components having same inner , outer diameters together. next inflatable bladder introduced in inner bore of components , placed equidistance within 2 components. heater head clamps components , bladder inflated. after prescribed period of time heater head begins cool , bladder deflates. once cooled bladder removed , joined components taken out of clamping station. benefit of bcf system there no weld bead, meaning surface of weld zone routinely smooth inner wall of pipe.
infrared fusion (ir) process similar cbf except component ends never touch heater head. instead, energy melt thermoplastic transferred radiant heat. ir comes in 2 variations; 1 uses overlap distance when bringing 2 components while other uses pressure. use of overlap in former reduces variation seen in bead size, meaning precise dimensional tolerances needed industrial installations can maintained better.




^ cite error: named reference astm d5127 invoked never defined (see page).
^ sixsmith t, wermelinger j, williamson c , burkhart m, advantages of infra-red welding of polyethylene pipes industrial applications”, presented @ plastic pipes conference xv, vancouver, canada, september 20–22, 2010