CORROSION ENGINEERS generally agree that, among other factors, the contraction stresses produced by the drying of certain clay-type soils must be taken into account when selecting the exterior coating material for piping to be buried in these soils. For the lining of the interior of water-bearing pipe, such factors as corrosiveness of water, water velocity, quantity of water-borne abrasives, and temperature are considered.
Normally it would not be expected to find an interior lining damaged by soil stress. Thus, it came as something of a surprise to discover the deep cracking and alligator pattern which typifies soil stress action on the interior coal-tar enamel lining of the 18-foot-diameter penstock at Alcova Powerplant near Casper, Wyoming.
The Alcova Powerplant was constructed in the years 1952 through 1954. Water stored in the reservoir is used for irrigation and development of power. The power penstock, which was lined with coal-tar enamel during the...
