The purpose of this method statement is to establish a standard procedure for the proper cutting and jointing of copper pipe by using the right tools and procedure i.e. flaring or swaging joints. This will also serve as guideline for newly hired employee which will be dealing with Air-conditioning unit Maintenance activity or cutting of copper pipes to be used for refrigeration and air-conditioning piping system.
Responsibilities: It is the responsibility of the A/C technician to properly us the right tool in cutting soft-drawn and hard-drawn copper pipes. He should be competent enough to use this equipment to avoid any damage and to provide the proper result. The Supervisor and the Site Engineer should assure that this maintenance procedure will be followed.
Procedure Of Pipe Cutting Using Cutter
A pipe / tube cutter is best option to make a straight cut for copper pipes. It comes in single blade and an adjustable lever to provide the proper force while cutting.
- Prior to the work, wear safety shoes, gloves and goggles.
- Prepare copper tube, tube cutter, reamer, sand cloth, brush and hacksaw.
- Make measurements to the desired length of the pipe.
- Mark the pipe where cutting is to be done.
- Insert the copper pipe inside the cutting tool.
- Hold the pipe properly to produce a good result.
- Adjust the lever until the blade touches the pipe.
- Using a counter clockwise direction, move the pipe cutter by one whole turn until you feel that the blade is starting to cut the pipe. After that, reverse it by clockwise rotation.
- While on clockwise turning, adjust the lever from time to time until the pipe is completely cu
- By using a reamer, remove the burrs from the inside of the tube. The burrs must be removed because they restrict the flow of the gas.
- Clean the tube by sand cloth and by brush.
PIPE CUTTING USING A HACKSAW
- Prior to the work, make sure that all PPE’s are available and is being used. PPE’s like safety shoes and goggles should be used.
- Make measurements to the desired length of the pipe.
- Mark the pipe where cutting is to be done.
- Make the cut at a 90 Degree angle to the tubing.
- A fixture may be used to ensure an accurate cut.
- After cutting, ream the tubing and file the end.
- Remove all the chips and fillings, making sure that no debris or metal particles get into the tubing.
Flare Jointing Of Copper Pipes
One method of joining tubing and fittings is the flare joint. The joint uses a flare on the end of the tubing against an angle on a fitting and is secured with a flare nut behind the flare on the tubing. The flare on the tubing can be made with a screw-type flaring tool.
Jointing Procedure
- Prior to the work, wear safety shoes, gloves and goggles.
- Prepare flaring tool, tube cutter, reamer, sand cloth, brush, flare nut and fittings.
- Cut the tube to the specified length.
- By using the reamer, remove all the burrs and clean all residues from the tubing.
- Slip the flare nut or coupling nut over the tubing with the threaded end facing the end of the tubing.
- Clamp the tube in the flaring block. Adjust it so that the tube is slightly above the block (about one third of the total height of the flare).
- Place the yoke on the block with the tapered cone over the end of the tube. Use a drop or two of refrigerant oil to lubricate the inside of the flare while it is being made.
- Turn the screw down firmly. Continue to turn the screw until the flare is completed.
- Remove the tubing form the block. Inspect for defects. If you
- found any, cut-off the flare and start over.
- Assemble the joint.
Swage Joint: Swaging is the process of joining two pieces of copper tubing of the same diameter by expanding or stretching the end of one piece to fit over the other so that joint may be soldered or brazed. As a general rule, the length of the joint that fits over the other is equal to the approximate outer dia of the tubing. You can make a swaged joint by using a punch or a lever-type tool to expand the end of the tubing.
Procedure
- Prior to the work, wear safety shoes, gloves and goggles.
- Prepare tube cutter, reamer, sand cloth, brush, flaring block, swaging tool and hammer.
- Cut the tube to the specified length.
- By using the reamer, remove all the burrs and clean all residues from the tubing.
- Place the tubing in a flare block or an anvil block that has a hole equal to the size of the OD of the tubing. The tube should extend above the block by an amount equal to the OD of the tube plus approximately 1/8 inch.
- Place the correct swaging punch in the tube and strike it with a hammer until the proper shape and length of the joint has been obtained.
- A drop or two of refrigerant oil on the swaging tool will help but must be cleaned off before brazing.
- Assemble the joint. The tubing should fit together easily.
- Inspect the tubing after swaging to see if there is crack or other defects. If any defects/cracks are seen or suspected, cut-off the swage and start over.
More Details can be found on below references:
- Refrigeration and Air-conditioning Technology, 3rd Edition By: William C Whitman & William M. Johnson
- TESDA Refrigeration and Air-conditioning Manual