Monitoring Casing Wear Ditch Magnets
The metal worn away from the casing and tooljoint is carried by the mud to the shaker header box where it will be attracted to the ditch magnet. Not all the metal particles will be trapped and so the amount of metal cannot be used as an exact quantitative measurement of metal worn away.
Any metal removed by corrosion will not be collected by the magnet.
Regular recording of the weight of metal recovered should show changes in wear rate. There is no way of telling if the wear is . . .