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Get Acrobat Reader You will need Acrobat Reader to view pdf Field Flaring of Thermalok PTFE Heavy Duty Lined Pipe with Swaged Tooling

Preparation of Lined Pipe

CAUTION: The Thermalok process custom fits each liner to its housing; therefore liners must not be removed from their original housings and indiscriminately used in other housings. If a liner must be removed from its housing, mark both the liner and the housing to assure the right liner goes back into the housing from which it came. Further, put the liner back in as soon as possible, otherwise it could relax slightly and make reinsertion difficult.

Using the driving plug, push the liner along the steel pipe at one end, until it projects out the other end a distance equal to dimension "A" in the table below. (If the liner is difficult to move, use ice, dry ice or some other cooling medium to contract the liner to facilitate its movement.)

Driving plug in lined pipe with liner pushed back.

Inches Millimeters
1" 2 1/8 54
1 1/2" 2 51
2" 2 51
3" 2 1/4 57
4" 2 1/2 64
6" 2 1/2 64
8" 2 7/8 73

Cut the lined steel pipe to length "L" minus dimension "B" (from table below) using an abrasive cut-off wheel, lathe parting tool or power hacksaw. Cut must be square with as little burr as possible. Do not use a pipe wheel or a tube cutter since these can deform the inside of the steel pipe.

Inches Millimeters
1" 13/16 21
1 1/2" 13/16 21
2" 13/16 21
3" 13/16 21
4" 7/8 22
6" 15/16 24
8" 1 1/16 27

Using the driving plug at the newly cut end, push the liner approximately 2" (50mm) farther along the steel pipe. Then take a reamer or grinder and make a small radius on the inside edge of the steel pipe to eliminate any sharp corners or burrs at the newly cut end.

Note: Each assembly must have at least two vent holes, one at each end approximately 3" to 4" from the end. This distance will allow flanging without obstructing the vent hole. To drill the holes, first push the liner far enough back inside the already cut-to-length housing to permit drilling the first hole safely. The hole diameter should be 3/23" (2.4mm) for pipe sizes through 4" and 5/32" (4mm) over 4". Be sure to deburr the hole inside the pipe and clean up any chips to prevent damage to the liner when repositioning it in the pipe. Repeat this operation at the opposite end.

Thread the end of the pipe with either a straight pipe thread (NPSM) or a tapered pipe thread (NPT). Keep the interior of the lined pipe free of oil. If a straight pipe thread is used, to prevent the flanges from rotating out of position, apply Loctite* thread sealant or equivalent to the pipe threads before putting on the flange. Part # R60451DI-XXX can be screwed wrench tight to within 1/16" (1.5mm) of the internal flange shoulder.

Note: No step or offset is permitted on pipe ID where pipe end and flange meet. Grind smooth if necessary. Insure all burrs and chips are removed. Corner radius should be 1/4" in 1"-2", 5/16" in 3", 3/8" in larger sizes.

Using the driving plug at the unflanged end, push the liner back along the pipe until the end of the liner is at least two inches inside the steel housing. Repeat the reaming, threading and flange installation procedures in steps 3 and 4. Make certain flange bolt holes are properly aligned. Flanges may be backed-off as much as 1/4 turn from the fully bottomed position.

* Trade name Loctite Corp.

Note: Backing-off of flange must be done before thread sealant has had time to set up.

Using the driving plug, push the liner along the flanged pipe until it projects an equal amount at each end (Dimension "C" in table below). Make certain that the cut ends of the liner are square and even. Failure to make a clean, square cut could result in a split of the liner during flaring. If necessary, use a sharp knife to trim, from the end of the liner, any loose edges which may have resulted from the sawing or cutting operation.

Inches Millimeters
1" 11/16 17
1 1/2" 5/8 16
2" 5/8 16
3" 3/4 19
4" 7/8 22
6" 7/8 22
8" 1 1/16 27

Next, use a coarse cut file to chamfer the outer edge of the liner to an angle of approximately 45° as shown in the diagram. This chamfer will smooth out any notch left in the edge of the liner after cutting, thereby preventing splits that cold occur during flaring.

Install the liner expander (see photo) far enough into liner to allow clearance for forming tools. Tighten capscrew on expander to prevent liner from slipping in the pipe during the forming operation.

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.

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.

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 1/4" at flange remain white. Heating time is displayed in chart below. Frequently rotate heat gun to balance heat over plastic surface.

Heating Times
Heat Gun
Heat Time
1 5-6 2 1/2
1.5 6 2 1/2
2 7 2 1/2
3 8 4 1/2
4 8 5 1/2
6 10 5 1/2
8 10 10

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.

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. Then 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.

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

Spark test the finished face for defects that 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.

To identify plastic liner, always be sure to attach a yellow color-coded plastic band to the spool.

A 1/2" 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.

Attach proper label to plywood cover.

"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
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