CMYK / .ai CMYK / .ai CMYK / .ai acrjournal.uk 29 BRAZING Types of joint Three main types of configurations are used in the jointing of copper pipework for refrigeration systems. The pipework connections all form lap type joints and set out as follows: Expanded joint: This type of joint is made by using a forming tool such as a swager where the tube (pipe) is expanded to accept another length of tube of the same circumference. Care must be taken to ensure that tube is not expanded beyond the gap size specified. Sockets and fittings: There are several ranges of “Refrigeration” type capillary action fittings available from leading refrigeration wholesalers. These fittings are manufactured specifically for the refrigeration industry and are based on the “outside diameter” measurement of refrigeration grade copper tube. These fittings are not to be confused with the range of capillary fittings produced for the plumbing industry. HSCA fittings are specifically designed for HSCA (copper alloy tubing) and typically have a PS of 130 barg. Care should be taken to ensure the PS of the fittings is equal to or greater than the tubing they are being used to connect to. Accuracy in the fit-up components is essential for a good joint, and care must be exercised to ensure the clearance between the faces of components is not greater or less than specified. Bi-metal joints and flanges: Bi-metal sockets and flanges are usually used where there is a need for dismantling of the pipework system during maintenance and servicing operations, e.g. bolt-on flanges and bi-metal sockets to service valves of a compressor or evaporator.