Flowlines, shaker header boxes (possum bellies) etc., shall be inspected regularly and cleaned out as required, in order to prevent solids build-up. Ditch magnet to be inspected as required if installed.
Jet lines, if fitted, shall also be inspected regularly to ensure that they function properly.
Settling tanks shall never be by-passed.
Settling tanks shall be checked and dumped as and when required according to cuttings.
Settling tanks shall not be dumped whilst drilling or circulating as a dump valve malfunction could result in suspension of operations and, ultimately, the possibility of stuck pipe.
New volume of mud to be build up as settling tanks are dumped.
The operation of the dump valve shall be checked every time the settling tank is dumped and cleaned out.
Settling tanks shall never be dumped direct when using oil based mud, the contents shall be passed via the shakers.
Note: It is not always necessary to dump the complete contents of the tank, since this results in the immediate need for a large replacement volume within the circulating system. It may be easier to operate if smaller volumes of solids are dumped at more regular intervals.
Settling may be assisted by dilution with water, which should be added before the settling tank. However, this practice should never be used with a weighted mud system.