Threads sealing tape

FIGURE 4.11 Schematic of the process for producing thread seal tape. (Courtesy of DuPont.)... 

Fluoropolymers possess excellent thermal stability and are nearly completely inert to chemical attack. Polytetrafluoroethylene (FIFE), discovered in 1938 by Roy Plunkett at I.E. du Pont de Nemours and Company, is the world s most used fluoropolymer. PIPE accounts for 59% of the fluoropolymers market and its production amounted to some 79,000 metric tons in 2004 [1], Applications exploiting the extraordinary properties of the material are wide-ranging and include gaskets, thread-seal tape, pipe liners, bearings, gears, slide plates, filter bags, medical prosthetics, and architectural material [2,3]. 

Figure 4.19 Thread sealing tape made from PTFE film. DmitryKramar/ Shutterstock.com.

Tape may be made by a similar process. In this case the lubricant selected is a non-volatile oil. The preform is placed in the extruder and a rod extruded. The rod is then passed between a pair of calender rolls at about 60-80°C. The unsintered tape is often used for lapping wire and for making lapped tube. Sintering is carried out after fabrication. The current most important application of unsintered tape is in pipe-thread sealing. 

Initially, the as-received pump could not pass a 13.8-bar (200 psig) static pressure test at ambient temperature. Consequently, the pump was returned to the manufacturer for extensive seal modifications. Upon receiving the modified pump, the unit was placed into service for a hot shakedown test with C30 oil at 175 psig pressure under the present experimental setup. The modified seal continued to leak at a small but acceptable rate on the order of 1 g/min. However, leak problems were encountered in the threaded seal of the stator and the pump housing. The stator was resealed with a thick Teflon tape and a high-temperature pipe sealant that initially slowed the total system leaks to less than 50 g/h. 

First, test by screwing on the flanges to the pipe nipple to see generally how much travel you get. The screw-on flanges will not cover all the threads on the nipple. This test will indicate how much of the nipple to thread seal and tape. 

Thread seal and Teflon tape each end of the nipple, covering the surface indicated by the test. 

Apply thread seal and Teflon tape from the end of the insert to 3/i6M from end. Wrap the Teflon tape around the rod at east three times. The Teflon tape is an electrical insulator for the rod and keeps it from inadvertently touching the walls of the compression fitting at its exit point. 

Coat two 34" NPT x 3/a" Yor-Lok fittings on the 34" NPT side with thread seal, and tape with Teflon. Screw these into the positive electrode port holes and tighten. 

Apply thread seal and Teflon tape to the NPT ends of the straight 34" NPT x %" tubing Yor-Lok fittings, and screw and tighten them into the four holes in the top and bottom blind flanges. 

Thread seal Teflon tape, screw in and tighten the two elbows to the top disk. 

Our coalescer is simply screwed on to the 90° Yor-Lok elbow on top of the bubbler after the fitting is thread sealed and taped. 

Thread seal and Teflon tape the male end of the T pipe fitting, screw into tank and tighten. 

Thread seal and tape the male NPT end of the valve and screw into the T fitting and tighten. 

Thread seal and tape the Vk" x 34" hex nipple on both ends, screw into the tank s Vk" port and tighten... 

Thread seal and tape the 34" male end of the elbow and insert and screw in and tighten into the female filter inlet port. 

The Ya" NPT female end of this fitting is then attached to the flexible metal hose with swivel male fitting after you thread seal and tape. The hose part number is in the storage tank connections section on page 225. 

Thread seal and tape the Vs" hose x 34" pipe male end of 34" NPT male x 34" NPT female with attached barb and male pipe fitting. Screw this into the female 34" miniature chrome plated brass ball valve before screwing the ball valve into the case. 

Thread seal and Teflon tape the 34" male end, and screw and tighten gently onto the box. 

Major applications of unsintered polytetrafluoroethylene are as tape in thread sealing and wrapping electrical cables, and as rod and tape in packings. Important properties of PTFE like chemical resistance, broad service temperature, low friction, flexibility, high machine direction strength, and deformability in the cross direction make unsintered fine powder PTFE ideal for these applications. 

Another material used on pipe threads is sealant tape. This tape, which is made of Teflon, provides an effective means of sealing pipe connections and eliminates the necessity of torquing connections to excessively high values in order to prevent leaks. It also provides for ease of maintenance whenever it is necessary to disconnect pipe joints. The tape is applied over the male threads, leaving the first thread exposed. After the tape is pressed firmly against the threads, the joint is connected. 

A mixture of aluminium powder and PTFE has been evaluated as an underwater missile propellant [1], It is suggested that using PTFE tape to lubricate and seal aluminium screw threads is inadvisable [2],... 

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