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INTRODDUCTION In our previous bulletins we presented information on copper pipelines, their properties and the advantages of using what has been considered the choice of professionals worldwide. Additionally, we presented forms of supply. All these factors assure many years of performance and reliability. However, we must have to consider also a correct installation since it guarantees optimum results throughout time. In this section, we will focus on preparing the tube and the procedures needed during this process. Firstly, we will show how to measure tubes according to specifications. Secondly, we will explain how to cut tubes with different tools and the reasons for eliminating interior and exterior flashes from the tubes by using files or reamers, which are tools specially designed for this purpose. Further on, we will explain the annealing of copper tube parts which should be expanded, reduced or bended to obtain the greater malleability from the metal. We will also describe the procedures for bending tubes. Finally, we will show the tools used in the expansion and flaring processes.
1.
LENGTH OF TUBES: MEASURING ACCORDING TO SPECIFICATIONS Measuring is simple but it is important to have it done properly. The tube should have the exact measure since the tube edges shall have to adjust completely to the accessories thus eliminating problems related to lack of resistance. If tube sections do not have the correct length, it will not be possible to obtain resistance. It is advisable to measure and mark the pipeline during the first morning hours since temperature differences may cause it to expand.
2.
CUTTING TUBES The pipe should be cut perpendicularly. There are two ways: using a special metal-cutting saw or a tube cutter. 2.1 Cutting tubes with metal-cutting saws Steps to cut tubes using the hacksaw frame: • Fasten the tube onto the bench screw. • Hold it correctly using both hands. • Only cut on the pitch travel. • Slightly pull the cutting sheet up into the backward travel since there should not be any pressure at this time in order to prevent cogs to break.
Cutting with a saw 2.2 Cutting tubes with tube cutters This is the most recommended procedure since it is not does not need a bench screw and allows to have a perpendicular cut to the axis. It eliminates the excess of flashes and provides a clean and square cut. According to the construction design, tube cutters may be classified as follows: a. Jointed cutters These cutters are formed by a series of links and steel sheels that adjust perfectly to the tube surface. They have a great capacity to adjust to surface irregularities in certain tubes. b. Cutters with fixed disk and mobile rollers.
c. Cutters with mobile wheel and fixed rollers
Wheel and roller tube cutters are manual. They are very useful due to their size and easy to use. 2.3. Procedure to cut tubes using tube cutters Steps to cut tubes:
• Place the tube into the tube cutter between the cylinders and the cutting wheel.
• Slightly press the tube with the tube cutter handle.
• Turn the cutter around the tube one complete turn.
It is advisable to press gradually the handle turning the tube cutter at the same time in order to obtain a good cut. • Repeat this operation until cutting the tube. 3.
FLASH ELIMINATION Flashes are produced when cutting tubes both with saw and tube cutter, which should be eliminated. When interior flashes are eliminated, it prevents: The reduction in the tube’s interior diameter which impedes water to pass through the tube and possibly causing a load loss unexpected for the designer. When interior flashes are eliminated, it prevents: The expansion of the tube’s exterior diameter which will impede the accessory’s appropriate adjustment.
3.1. Tools used in eliminating flashes
The following tools are used when flashes are eliminated: • Triangular steel blade of the tube cutter. • Tube reamers specifically built for flash elimination. • Round file, actually it is the tool mostly used.
4.
PIPELINE ANNEALING The procedure to obtain this condition is as follows: Use a gas welding torch to put the tube section in dark red. It will only be necessary to expose the tube for some time to temperatures above 300ºC.
It is important to point out that during heating, oxidation is always produced onto the interior and exterior surface of the tube. If the metal is let to cool down outdoors, oxidation will be shown as a more or less thick black layer. It may be loose as scales. Therefore, it is advisable that the sudden cooling be with water either by immersion or humidification with a wet cloth. This causes the separation of the oxide film. Additionally, the sudden cooling does not modify the metal’s characteristics in any way.
5.
PIPELINE
BENDING The most accepted procedure is by using bending machines or tools which are available for users.
Bending of tubes with small dimensions (16 x 1 mm ó 5/8") may be made by cooling without the need of using heat.
There are three procedures for bending tubes: 5.1 Machine bending
This procedure is performed with a manual tube bender or a bench bender.
Procedure 1. The tube to be bended is introduced into the pulley’s throat. 2. The guide is placed in contact with the tube with a gripping pad. 3. The guide is blocked with a fixation hook. 4. The lever is rotated. This process obliges the tube to rotate around the pulley.
Bench bending
The guide will distribute pressures onto a tube section thus preventing it to flatten or wrinkle.
In general, the bending operation of a copper tube should not be carried out with hot metals because the copper’s mechanical resistance taken to dark red falls very rapidly. Therefore, it will be necessary to let it cool down to start working on it.
5.2. Spring bending
This procedure is applicable to annealed tubes with common dimensions, i.e., 12 x 1mm to 22 x 1mm or its equivalent of 3/8" to 3/4".
This procedure is each time less used since it does not allow obtaining small radius.
Spring tube bender
5.3. Bending with filler
At first sight, bending with filler is a procedure apparently slow and little technology, but it is mostly used by installers. This procedure is recommended in the following situations: • Market shortage of elbows and diameters needed. • Series of complete elbows and very close to each other. • Lack of bending machine adequate for the diameter of the tube to be bended.
Procedure 1. Choose fine sand of the smallest degree. 2. Sieve to clean the sand. 3. Dry the sand with a gas welding torch in order to eliminate humidity..
4. Close an edge of the copper tube using a paper plug or wood piece.
5. Add the sand through the open edge of the tube.
6. Hit the copper tube filled so the sand is compressed and goes down, filling completely the tube.
7. Close the tube with a plug or wood piece, leaving its base in contact with the sand. 8. Mark with a pencil or chalk the length where it should be heated for bending.
6.
PIPELINE
EXTENSION These tools are excellent for uniform expansions. They allow perfect joints applying a minimum effort even though it involves big diameters. In the case of hard copper, the pipeline edge that will be extended should be previously annealed or heated.
Expander The Flarers are tools used to increase the diameter of a pipeline edge that will be used preferably in the joints with plug cocks.
Flared Tube
Procedure Follow these steps to make a joint compression using the pipeline flaring:
1. Cut the pipeline in right angle and eliminate flashes. 2. Flare the pipeline edge leaving a conic flange.
3. Introduce the pipeline into the joint nut up to the flange.
4. Press the flange against the conic edge of the part.
Most commonly used tools The most common tools used in sanitary installations are:
Welding Equipment
7.
PROCEDURES
TO MAKE A GOOD INSTALLATION • Cut the tube meticulously and perpendicular. • Eliminate flashes. • Anneal pipelines and eliminate the oxide film before installing the pipeline. • Bend the tube in case of not using accessories such as elbows. • Expand tube edges to assure perfect joints.
Sources
and References: • The Copper Pipe in Construction Installations [El Tubo de Cobre en las Instalaciones de la Edificación] - CEDIC – Spain • The Copper Tube Hand Book, Copper Development Association – USA • Chile Piles [Tubos de Chile], Procobre Chile. • Uses of Copper in Sanitary Installations [Usos del Cobre en las Instalaciones Sanitarias], Procobre Chile • Copper Pipes and Accessories [Tubos y Accesorios de Cobre] - CEDIC - Spain
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