| 摘要 |
<p>In a method for determining the level of protection provided by a cathodic protection system to a sub- sea structure, e.g. a pipeline, at an area of the structure which is buried beneath the sea-bed, in addition to measuring the potential of the sea adjacent the bed above the area relative to the (reference) potential of the sea remote from the protection system, measurements are made of the electrical field gradient of the sea- water at the test area, and of the electrical resistivities of the sea-water and mud at that area, whereby a more accurate calculation of the potential at the surface of the buried structure can be made. Shown is a probe suitable for such measurements and including two spaced identical silver/silver chloride electrodes 44, 46 in brine 48 and two stainless steel electrodes 40, 42 between which alternating current may be passed for resistivity measurements. Porous plug 52 between brine 48 and the seas carried in a flexible pressure balancing diaphragm enabling close rectifying of electrodes 44, 46 to be maintained. A separate silver/silver chloride brine reference Rolf cells similarly constructed. <IMAGE></p> |
