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9 Repainprocedures Cutting repair couplings <br /> Cont.) On 2-inch couplings the center holes have been located near the middle of the <br /> coupling.Cut exactly between these two holes.The resulting half-couplings are <br /> ti <br /> 7 inches long.Two cuts are necessary when making 3-and 4-inch half-couplings. <br /> The resulting half-couplings are 51/2 inches long. <br /> D D <br /> 0 0 0 0 <br /> 0 0 0 <br /> 0 0 0 0 _ <br /> 0 0 o 0 <br /> Fig.9-6.Cut full-length couplings so Cut to make 2-inch <br /> that all bolt holes on half-couplings half-couplings , <br /> Cut to make 3- <br /> are equidistant from the ends. and 4-inch <br /> half-couplings' <br /> 10 Primary system Recommended practices <br /> testing Plan tests carefully and carry them out with all due precautions.Pressurizing <br /> equipment should be suited to the size of the system and the pressure required and <br /> should be operated by qualified and experienced personnel only. <br /> r-----------------------------� <br /> I The following recommendations are offered only as a guide.Ameron assumes no 1 <br /> responsibility or liability for the consequences of any testing practices. 1 <br /> L-----------------------------J <br /> • Pressure sources should be capable of approaching test pressure gradually. <br /> • Use gauges with a full-scale reading of no more than twice the test pressure:Do <br /> not use a 100 psi gauge for a 10 psi test.Use reliable gauges calibrated against <br /> a dead weight tester and zeroed for atmospheric pressure. <br /> • Isolate tanks from the piping when pressure testing. <br /> • The recommended hydrostatic pressure is 150%of expected operating <br /> pressure and should be maintained at least 10 minutes. <br /> • Do not exceed 150%of system rating.Check the pressure rating of all the <br /> components of the system—not just the pipe—because hoses and flexible <br /> connectors are almost always rated lower than the pipe. <br /> • Do not adjust fittings while system is under pressure.If threaded adapters or <br /> bushings leak,release the pressure before attempting to tighten. <br /> • Temperature changes can affect the pressure in the test line.Substantial <br /> pressure increases may occur in closed systems exposed to the sun. <br /> Conversely,overnight decreases in pressure due to cooling from afternoon to <br /> early morning are normal and do not necessarily indicate a leak. <br /> • After testing,maintain 5 to 10 psi(35 to 70 kPa)in the system during subsequent <br /> construction so that damage caused by stakes,excavation equipment,etc.can <br /> be detected and corrected before pavement is installed or product is pumped. <br /> r-----------------------------� <br /> Ameron recommends hydrostatic testing of primary systems as the effects of , 1 <br /> 1 sudden pressure loss when testing with liquids are far less severe than with gases. <br /> 1 If pneumatic testing is necessary,restrain the system adequately to prevent <br /> damage or injury in case of rapid pressure loss.Pneumatic testing can be <br /> 1 extremely dangerous and is not recommended. 1 <br /> L—-------------------------------� <br /> 15 <br />