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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.
STEP 1
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. |
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Pipe Size |
A |
| 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 |
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STEP 2
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. |
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Pipe Size |
B |
| 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 |
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STEP 3
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. |
STEP 4
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. |
STEP 5
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. |
STEP 6
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.
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|
Pipe Size |
C |
| 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 |
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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. |
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STEP 7
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. |
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STEP 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.
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. |
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STEP 9
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 |
Size in. |
Heat Gun Setting |
Heat Time (minutes) |
| 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 |
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STEP 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. |
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STEP 11
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. |
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STEP 12
Visually inspect the finished sealing face for a flat, smooth surface
and a smooth bend radius. |
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STEP 13
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. |
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STEP 14
To identify plastic liner, always be sure to attach a yellow
color-coded plastic band to the spool.
STEP 15
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.
STEP 16
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
page's content, and is not guaranteed for accuracy."
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