BS ISO 7509:2015 pdf free
BS ISO 7509:2015 pdf free.Plastics piping systems一Glass-reinforced thermosetting plastics (GRP) pipes
The use of an electronic device to measure the electrical resistance between the test fluid and a conductive material wrapped around the circumference of the test specimen has been used for many years to assist in the detection of weeping or leaking failures, typically for filament wound pipes. This use of electronic detection was first recognized in ASTM D 2143 in determining the cyclic pressure strength of thin wall filament wound GRP pipes in the 1960s.
The conductive material wrapped around the test specimen is typically a metallic foil or mesh placed around the sample in the valid failure zone, i.e. away from the end closures. Measurement of the resistance between the test fluid and the conductive material can be indicative of failure or pending failure.
The resistance trigger for insipient failure will depend on the test fluid. Historically, for test fluids containing sodium chloride, a resistance in the range of 10 MA to 20 MI was considered as failure onset. For municipal water as the test fluid, failure is frequently taken as when the first drop of fluid has passed through the pipe wall.
In recent years, the testing of GRP-UP pipes has found a resistance of 3 MI to be indicative of pending failure by either weeping or leaking. Some testers use electronic monitoring to identify possible pending failure and the need for more frequent visual observation. The use of such detection methods is particularly useful for longer time periods of test where direct observation is frequently not practical.
When testing at elevated temperatures, the use of electronic detection can be particularly helpful as the almost simultaneous appearance of a water droplet on the pipe surface and the evaporation of the droplet makes visual detection difficult, if not impractical.BS ISO 7509 pdf download.
