Function of Casing Inclinometer casing is a special purpose, grooved pipe that: Provides access for the inclinometer probe, allowing it to obtain subsurface  measurements; Controls the orientation of the inclinometer probe; Deforms with the adjacent ground or structure. Inclinometer casing is typically installed in boreholes, but may also be  embedded in fills, cast into concrete, or attached to structures. Casing Diameter Casing diameter affects the useful life of an inclinometer installation,  since deformation eventually causes closure of the casing. Larger diameter  casing offers longer life and is recommended for most applications. However,  borehole size often determines which size of casing can be installed, and  sometimes smaller diameter casing is the only choice. 85 mm (3.34 inch) casing is suitable for long term monitoring and narrow or  multiple shear zones and is required for horizontal installations. 70 mm (2.75 inch) casing is suitable for most construction projects where a  moderate degree of deformation is anticipated. 48 mm (1.9 inch) casing, designed for installation in small diameter  boreholes in rock, may also be cast into concrete or attached to structures  where expected deformations are small or distributed over a broad zone. Collapse Strength In borehole installations, the annular space around the casing is usually  backfilled with grout. The grouting process can generate pressures high enough  to cause the casing to collapse. To guard against this possibility, Slope  Indicator manufactures strong couplings and thick-walled casing. Also, the depth  of guide grooves is carefully controlled to prevent weakening of the casing  wall. Sealable Couplings It is important to seal casing joints, since grout entering the casing  can cause blockages, unreliable tracking, and damage to the wheels of the  inclinometer probe. For this reason, Slope Indicator has designed couplings that  are easily sealed. QC casing, shown at right, features an integral coupling with  an o-ring seal. Spiral Control Guide grooves control the orientation of the inclinometer probe. If grooves  are twisted during installation, the orientation of the probe will vary during  the survey, making it impossible to determine the direction of ground movement  unless a special spiral survey is obtained. Slope Indicator's inclinometer casing sets the industry standard for control  of spiral in the manufacturing process. Machine-broached guide grooves exhibit  less than 1/3 degree of spiral per casing section. Coupling-induced spiral is  eliminated by tight fitting keys that prevent misalignment of successive  sections of casing. Guide Groove Precision When the  inclinometer probe is drawn upwards through casing deformed by ground movement,  its wheels are forced against the sides of the guide grooves. Unless the grooves  are designed to facilitate tracking through curvatures of the casing, the wheels  may jump out of the groove. If this occurs, repeatable positioning of the probe  is nearly impossible and the reliability of the data suffers. Slope Indicator has optimized the width and shape of guide grooves to  minimize tracking errors and has developed manufacturing techniques that  consistently deliver straight, evenly spaced, precision-formed grooves. Casing Materials The high-impact ABS plastic used in Slope Indicator's casing is suitable for  long term contact with all types of soils, grouts, and ground water. ABS casing  can be formed with greater precision than aluminum casing and does not corrode.  It is also more flexible than aluminum casing and provides better conformance to  movement in soft ground. ABS casing retains its shape and flexibility over a  wider temperature range than does PVC casing and is easier to handle than  fiberglass casing, since it does not shatter, split, splinter or irritate the  skin. Assembly All styles of casing manufactured by Slope Indicator are self-aligning and  easy to assemble. QC casing is our latest and most convenient style. It features  self-sealing joints and snap-together convenience.