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Joint Fabrication Procedures for Swaged Piping with Polypropylene (PP) 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.

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. 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 molding 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. Remove forming tool and set aside.

9. Attach proper size of heat cut to hot air gun, adjust guide pins to fit flange bolt hole spacing and set heater dials as shown in table. When forming 1" to 2½" pipe, use standard heat cup. When forming larger pipe, use special baffle heat cup. The heat gun settings are approximate and may be adjusted to compensate for ambient temperature conditions and the length of electrical extension cord used.

9. All hot air guns considered here use long-life, plug-in type elements, which will have extended life if the unit is allowed to cool for 5-10 minutes before shutoff. "Cool Air Only" position on Leister 110V and 220V hot air guns is at "0". Allow gun to preheat for 15-20 minutes. The hot air given off by gun during this time should be used to preheat the molding die to about 140°F just above "too hot to touch".

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. Also, to prevent electrical shock, do not use heat gun near water.

10. Place heat gun and cup against the flange and rotate cup position every 10 seconds to balance heat over surface of plastic stub. Heating time is 2-4 minutes. Heat until the plastic stub appears to be uniformly wet and glossy, checking softness with clean glove. If pipe is clamped in horizontal position and excessive plastic droop occurs, rotate pipe to control.

Heat Dial Settings
1" 6 3
1 1/2" 4
2" 6-7 4-5
2 1/2" 6-8 5
4" 8 6
6" --- 7

11. Plastic is ready when the PP resin feels like rubber and looks shiny. Heating time should be 2 minutes at least, to soften the liner on 1" - 4" size, at least 4 minutes for 6" - 8" size. Remove hot air gun, then fold end of sagging plastic stub out toward the outside diameter of the flange and form plastic back to face of flange with gloved hand. Quickly align molding tool and forming die assembly to plastic and crank the molding die tight to the flange.

12. Allow plastic to cool at least 2 minutes before removing forming tool. When finished for the day, allow hot air gun to cool for 5-10 minutes with cool air blowing through the dial position 0, or lowest point on rheostat on Leister 110V and 220V hot air guns.

13. Visually inspect the finished sealing face for a flat, smooth surface, having inner and outer edges that are sharp and fully formed from filling the die cavity.

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 an orange plastic band to polypropylene-lined pipe spool. 16. A ½" thick plywood cover should be bolted to the flange to protect the plastic face. 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
2 1/2 1 3/16
3 1 7/16
4 1 1/2
6 1 11/16
8 1 7/8
Cutting Dimensions for Polypropylene
1 X + 1 13/16 1 1/8 1 X + 15/16
1 1/2 X + 1 3/4 1 1/8 1 X + 7/8
2 X + 1 3/4 1 1/8 1 X + 7/8
2 1/2 X + 2 1 1/4 1 1/8 X + 1
3 X + 2 1/4 1 7/16 1 5/16 X + 1 1/8
4 X + 2 1/2 1 5/8 1 7/16 X + 1 1/4
6 X + 2 3/8 1 1/2 1 3/8 X + 1 3/16
8 X + 3 1 15/16 1 11/16 X + 1 1/2

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