3. Restoring Force. Restoring Force is the Force exerted by Bow Spring of a Centralizer against the casing to keep away from Well bore wall. The test is performed with the inner pipe and outer pipe within 5 degree of the horizontal. External force is applied to the outer pipe, which is transferred to the Centralizer. Load is then applied and load deflections reading are recorded for three times. We repeat the process until each spring and each set of spring has been tested with load applied directly above them and then in between two springs. As shown in figure A & B. When the minimum restoring force has been obtained. Each spring has been tested and final load deflection curve is prepared using the arithmetic mean of the force reading at corresponding deflections. Restoring Force is determined from this curve at 67% Stand Off Ratio. Field experience shows that Stand Off values of 75-90% are adequate even in horizontal wells.

                                                                               

4. Compression Test. IN ADDITION TO API, testing SledgeHammer also performs the Compression test, under this test we put load on Standard Centralizer until both ends meet (as shown in Figure). Compression testing of the Centralizers ensures that the Centralizers can withstand very high forces when running casing. This test ensure that damaged Centralizer will still remain intact under severe conditions and it also ensure that even badly distorted Centralizer bows will not fracture and leave metal fragments in the well.

5. Load Deflection Curve. A good centralization consists of low Starting Force, Low Running & pulling Force. High Restoring Force and high Stand Off for proper annular clearance and centering. To maintain the proper balance between these requirements SledgeHammer manufactures Centralizers Bows in various sizes and height that exceeds the restoring force required as those specified in API 10D specifications. Load deflection curve is prepared to indicate the operators on the performance of the Centralizer in a given hole. This further helps the operators to determine Centralizer spacing required in deviated wells.