a process and system is provided for making a connection between two fluid - filled plastic tubes that ensures total containment of potentially dangerous fluids and maintaining sterility of the connection . the tubes are folded to remove all fluid from the weld site and positioned to cause the connection to take place in this fluid free zone . each folded section is first cauterized to create a bacteria free zone , the tubes are slit in the zone , and cauterized a second time to insure sterility and melt the tube ends . the tubes are urged together and as the thermoplastic resin cools , a totally contained , sterile weld is formed .