Abstract
A laboratory investigation into erosion corrosion in copper water tubing has been carried out. For aerated water at pH 8 and continuous flow, the maximum flow velocity not causing erosion corrosion was 3 m/s at 65°c and 6 m/s at 30°c in small diameter (6/4 mm) tubes; at pH 6·5 the maximum velocity must be reduced. With intermittent flow (<25% of the time), or with water poor in oxygen (as in central heatingsystems) higher flow velocities are acceptable. Small diameter tubes admit higher flow velocity than larger ones.
No differences in erosion corrosion resistance between annealed and hard-drawn copper tubes have been observed. Flared joints are much more liable to cause erosion corrosion at high water flow velocities than are joints withcapillary fittings.
The limits quoted were obtained in well-defined laboratory conditions; in practice a proper safety margin should be allowed.
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