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Joint Fabrication Procedures for Swaged Piping with Polytetrafluoroethylene (PTFE) Liners

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1. To arrive at the required finished length "X", select the proper cut-off length "D" from the cutting dimensions table for your liner material.

NOTE: Although PP is shown, the process in steps 1-6 are identical for PVDF.

2. Cut pipe to proper cut-off length "D" using a sharp angled tip cutter to assure an accurate cut. DO NOT USE hacksaw or wheel-type cutters. A hacksaw tends to "lead", which produces non-right-angle cuts. A wheel-type cutter produces a slightly beveled cut that leaves burrs and can cause severe stress risers in the plastic liner.

3. Determine the cut-back dimension "E" from the cutting dimensions table. Using the same angled cutter, cut through the metal just to the surface of the plastic liner at this distance "E" from the end of the steel shell. Once the tool begins to "break through" the steel, extra care should be taken in feeding the tool further to avoid cutting the plastic liner. A clear indication that the cutting tool is near the plastic is the appearance of "pick-marks" in the steel.

4. Remove the cut steel ring from the end of the pipe by inserting the proper size guide plug into the pipe and pulling with a modified gear puller.
NOTE: A guide plug has two diameters. Choose the end that fits snugly in the pipe bore.

5. Cut a standard tapered pipe thread on the end of the pipe with any conventional threader to accommodate a chamfered threaded flange. Use standard thread length and adjust thread depth to allow flange to be turned on hand tight until the last 1½ turns.

6. Place flange on pipe with chamfer facing outward. Tighten flange with wrench until turn-up dimension "F" between end of plastic stub and face of flange matches requirement shown in the cutting dimensions table. Also be sure that bolt holes on flanges at either end of pipe spool are aligned. Flanges must be tightened with a flange wrench and must be beyond hand tight.
Rotatable Flange Option. Place flange and stub assembly on pipe with chamfer facing outward. Tighten to turn-up dimension "F" measured from end of plastic face of stub assembly.
NOTE: Stub assembly must be beyond hand tight like the chamfered flange.

7. Clamp prepared pipe in horizontal or vertical position. File away any notches on end of exposed plastic stub. File or sand away any notches on end of exposed plastic stub. Using a clean rag and a non-flammable degreaser that is compatible with the liner, wipe away cutting oil, shavings and dirt from exposed plastic stub.

8. With spring compressed on proper forming tool (1" - 4" or 6" - 8" tool) attach molding die that matches pipe diameter. Fit the guide pins in the clamping block assembly to match the flange bolt holes. With the flaring die centered in the extended liner and the drive screw retracted, check the guide pins fit freely in the bolt holes with the clamping dogs behind the flange. If adjustment is needed, loosen the adjusting nuts, center the tool and retighten the nuts.
NOTE: No compression spring is used behind the flaring die.

9. Place the proper patented venting collar over the plastic stub and place tight against the flange face, with curved crimped edge inward, fitting into flange chamfer.
NOTE: For PTFE face, be sure to only use nickel-plated collar with small perforated holes. DO NOT USE stainless steel collar with large holes, which is designed for use with PVDF-lined pipe.

CAUTION: When field forming, use adequate ventilation (indoors, use exhaust fans). Avoid breathing of vapors resulting from overheating and possible degradation of the plastic. Do not consume food or beverages and do not smoke during fabrication process. Please refer to the Material Safety Data Sheet before heating the material. For more details of cautions for heating PTFE, see The Society of the Plastics Industry (SPI) booklet on "Guide to the Safe Handling of Fluoropolymer Resins", available from the E.I. Dupont de Nemours and Co., Inc. (1-800-292-0181, ext.5209). Also, to prevent electrical shock, do not use heat gun near water.

10. The plastic stub can now be heated with a heat gun - attach proper size of heat cup to the hot air gun, set the heater dials as shown here, and allow the gun to preheat for 15-20 minutes. When gun is ready, place gun with heat cup against the flange and heat until most of the plastic stub becomes translucent. Let the last ¼" at flange remain white. Heating time is 2-4 minutes. Frequently rotate heat gun to balance heat over plastic surface.

Heat Dial Settings
1" 10 5-6
1 1/2" 6-7
2" --- 7
3" 7-8
4" 8
6" 10
The 110V gun is only recommeded for doing pipe up through 1 1/2" dia.

11. Using gloved hand, gradually insert cone-shaped preformed tool into translucent plastic stub until it reaches the flange face. Allow plastic to cool until end lifts away from preformer before proceeding to next step (1" - 4" sizes only). On 6" - 8", use preformer to form plastic into trumpet shape. Allow PTFE to turn white before next step.

12. With the forming die centered in plastic stub, place forming tool guide pins into flange holes and lock clamping dogs in place. Crank the forming die snug to flange. Use cool air or water to speed cooling of plastic to room temperature. The remove tool.
NOTE: To assure properly flared face, it is extremely important to cool plastic and flange to room temperature. Also, be sure to achieve the minimum flare diameter listed here.

13. Visually inspect the finished sealing face for a flat, smooth surface and a smooth bend radius.

14. Spark test the finished face for defects the may not be readily visible. Adjust the sparker to arc about 1" to the flange. Insert probe into the pipe end and circle the inside near the liner. A defect is identified by apparent major arcing through the liner. DO NOT USE pipe with a defective liner.
15. To identify plastic liner, always be sure to attach a yellow color-coded plastic band to the spool.

16. A ½" thick plywood cover should be bolted to the flange to protect the plastic face and to prevent the face from "remembering" its preformed shape and pulling away from the flange.

17. Attach proper label to plywood cover.

Standard Thread Length (in.)
Pipe Size Thread Length
1 13/16
1 1/2 1
2 1 1/16
3 1 7/16
4 1 1/2
6 1 11/16
8 1 7/8
Cutting Dimensions for PTFE with venting collar††
1 X + 1 3/8 1 1/16 7/8 X + 11/16
1 1/2 X + 1 7/8 1 5/16 1 1/8 X + 15/16
2 X + 2 1 3/8 1 3/16 X + 1
3 X + 2 3/8 1 9/16 1 3/8 X + 1 3/16
4 X + 2 1/2 1 5/8 1 7/16 X + 1 1/4
6 X + 2 1/4 1 5/8 1 7/16 X + 1 1/8
8 X + 2 3/8 1 3/4 1 9/16 X + 1 3/16
†† PTFE venting collars are nickel plated with small perforated holes.

"This page is a machine translation of the source page, which is written in
English. This translation is intended to provide a general idea of the
page's content, and is not guaranteed for accuracy."