Butt Fusion up to 114mm

Transcription

1 Butt Fusion up to 114mm Procedure Overview This standard describes the procedures for butt fusion of PE pipe up to mm outer diameter using the McElroy Pitt Bull No. 14 or similar machine. Topics covered include machine operations, heating cycles, and quality control inspections. Procedures may vary slightly depending on the fusion equipment used. References o CON Distribution System Tie-Ins o Form 1575 Fusion Procedures for Medium Density PE Equipment o 120 Volt AC power source o butt fusion machine, c/w facing unit o flat plate heating tool and storage box o clamping inserts for various pipe diameters o pipe cutter o stopwatch o pyrometer o clean dry cotton cloth o alcohol wipes o sawdust bags or pipe support stands o pipe rollers (if building sub-assemblies) Butt Fusion (Pipe to Pipe) 1. Check the equipment. Make sure all the necessary equipment is on site. Make every effort to protect the pipe, fittings, and heating tool from bad weather conditions. 2. Assemble the equipment. Install the correct size clamping inserts into the upper and lower portion of both the fixed and sliding jaws. Be sure the four insert bevels each face away from the space between the fixed and sliding jaws. 3. Preheat the heating tool. When the tool is hot enough, the gauge should read 221º C 232º C (430º F 450º F). A thermo-switch on the heating tool controls the temperature. If the switch requires adjustment:

2 Unplug the tool for safety. Use the thermostat adjustment screw. To increase the temperature, turn the screw counterclockwise. To lower the temperature, turn the screw clockwise. One complete turn will increase or decrease the temperature by 55 C (100 F). Check heating tool temperature. Use pyrometer at least once per shift. Check heater pipe contact surface with a pyrometer; temperature at all points on the face should be in the range of 221º C 232º C (430º F 450º F). 4. Prepare the pipe. Cut the pipe joint ends as squarely as possible using an approved wheel or guillotine cutter. Do not cut the pipe with a hacksaw, as shavings could impede the operation of downstream regulators. Clean the pipe ends with a clean, dry cotton cloth to remove ink, dirt, and moisture. Let the alcohol evaporate completely. CAUTION: If you are extending a main, after cutting the main, ensure that you have a 100% crimp off. 5. Load the PE pipe joint ends into the machine. Position one end in the sliding jaw and the other in the fixed jaw. No less than 19 mm and no more than 25 mm of each pipe end should extend beyond the jaw faces. Use rollers, wooden blocks, sawdust bags, or support stands to support the pipe lengths. This aligns the pipe ends properly in the machine and prevents bending or gapping at the pipe joint. 6. Align the components. Bring the two components as close together as possible, and align them. Secure both jaw clamps. 7. Mount and lock the facer unit on the guide rods. Mount and lock the power facer unit on the two guide rods between the fixed and sliding jaws. The facer must be installed so that the electric motor is located over the fixed jaw. In this position the power unit faces both pipe ends, so exactly 13 mm of each pipe end extends beyond the jaw faces. Installing the power facer incorrectly leaves one pipe end with only 6 mm extending, and the other about 19 mm. If this happens, the heating tool will not fit properly into the butt fusion machine.

3 Face the pipe ends. Start the facing process and apply steady, light pressure on the lever as the facer shaves the pipe ends. Stop the facing operation only when both sides of the bushing on the power facer unit bottom out against the fixed and sliding machine jaws. Stopping in mid-cut can produce a stepped edge on the PE ends, and an unacceptable fusion joint. 8. Remove the facer. Remove the power facer and clean any shavings from the pipe ends with a clean, dry cotton cloth. Do not touch the machined pipe ends. 9. Inspect the pipe ends. Check for: evenness and complete facing rough spots ridges or grooves loose shavings Bring the pipe ends together and check the circumference alignment (high low) and the end gap. The end gap must be zero, and the high low as close to zero as possible. Adjust alignment as necessary by tightening down the high side of the fixed or sliding jaws. If the alignment is unsatisfactory: Loosen both jaw clamps. Extend each pipe to 19 mm beyond the jaw faces. Repeat the facing procedure beginning with step Check that the temperature gauge on the heating tool reads 221º C 232ºC (430º F- 450º F). 11. Separate the pipe ends, and place the flat plate heater between, but clear of, each pipe end. Make sure the heater is properly supported in the fusion machine. This is important for separating the pipe ends from the heater when the heating cycle is over. 12. Heat the pipe ends. Bring the pipe ends together sharply. Back off, maintaining only enough pressure to ensure contact with the heater face. Do not force it: a lip could form during the heating cycle, and could create a cold lap or void within the fusion. Start clocking when the polyethylene pipe touching the heater begins to form a bead.

4 Maintain contact for the heating duration specified. See Table 1: Heating and Fusion Duration Table. Table 1: Heating and Cooling Duration Table Pipe Diameter (mm) Melt Bead Size Approximate Heating Duration After Bead Forms Cooling Holding Duration in Joiner Additional Cooling Duration Before Rough Work, Pulling, or Pressure Testing mm (1/32" 1/16") 30 sec. 2 min. 30 min mm (1/16") 45 sec. 2 min. 30 min mm (1/16") 60 sec. 3 min. 30 min mm (1/8" 3/16") 65 sec. 4 min. 30 min. 13. After the heating cycle, open the jaws by striking the handle up sharply. This pulls the hot pipe ends quickly away from the tool. The support bracket on the heating tool prevents it from falling to the ground. Remove the heater. 14. Butt fuse pipe to pipe. Bring the pipe ends together with steady pressure on the lever to form an even, double bead. Do not slam the hot pipe together, or force the lever. This could create an internal cold face, and an unacceptable fusion. Hold the fusion pressure for the holding duration shown in Table 1 to allow the fusion to set. Maintain pressure with the handle or use the cam locking mechanism.

5 15. Allow the joint to cool in the jaws for another 5 minutes. Disengage the cam locking mechanism. 16. Remove the fused pipe. Unlock the two jaw clamps and remove the fused pipe. Allow the joint to cool for another 30 minutes before rough handling, pulling, or pressure testing. 17. Inspect the butt joint visually. Make sure an even, fully rolled back, double bead forms around the entire joint. Fused components must be properly aligned at the joint. The joint must be free of gaps, voids, or foreign material. If the joint doesn t meet all of the above criteria: cut it out and redo it. 18. When installing a long run of stick pipe, prepare several sub-assembly stick sections ahead of time. Support these sub-assemblies on rollers, wooden blocks, or sawdust bags, and manually help them to move during the fusion process. Typical sub-assemblies are three lengths of 114 mm or four lengths of 88 mm pipe. 19. Clean the equipment. Use a clean and dry cotton cloth to clean the heating tool faces. Butt Fusion (Pipe to Fitting) The procedure for fusing a fitting onto pipe is the same as fusing pipe to pipe, but follow these instructions: 1. Check the butt fusion fitting for: correct size damage or irregularities mould flash misalignment dirt or oil 2. As with pipe, face all butt fusion fittings. Manufacturers usually make them long enough to face a maximum of about 25 mm off each end of the fitting. Insert a fitting into the butt fusion machine jaws so they remove only 6 mm during the facing operation. Inserting the fitting incorrectly may reduce its length so much that it prevents a second length adjustment. 3. Clamp the PE fittings and pipe into the butt fusion machine. If fusing a fitting to a tied-in string of pipe, clamp the fitting into the moveable jaw and the pipe in the fixed jaw.

6 4. If it is not possible to rotate a pipe, the position of the fitting is important. Valves must be in the upright position. Elbows and three-way tees must be positioned horizontally. 5. If a fitting clamped in the moveable jaw interferes with the machine mechanism, and a pipe is tied in, or a pipe string is too long for the moveable jaw: Fuse a PE pipe pup to the fitting. The pipe pup length must be at least six pipe diameters long. Mount the pipe pup and fitting in the moveable jaw. Mount the long pipe in the fixed jaw. Fuse the pup to the long pipe. NOTE: When faced with awkward or difficult situations, you may want to consider the possibility that using electrofusion equipment to complete the work would be more effective.