Breaking Capability Research Articles

Development of new drill geometry and its performance evaluation

A new type of drill, namely, the crankshaft multifacet drill, has been developed for crankshaft drilling. Thrust has been selected as a main index for the development of this drill geometry. The crankshaft multifacet drill can reduce the thrust by 25.2% under operating conditions identical to those of the conventional split point drill. This indicates that drill life could be increased. Under accelerated life test conditions, this new drill is capable of producing at least 25% more oilholes than would be produced by the conventional split point drill. Test results for radial force measurements, chip breaking capability, exit burr evaluation, and drill wear comparison have also been evaluated. This drill yields much better performance in all aspects than the drill currently used in industry. The crankshaft multifacet drill can not only enhance productivity but also improve hole quality as compared to the conventional split point drill.

The Relocation of the SSDC/MAT in 1987

The Canmar SSDC/MAT drilling unit was relocated in the U.S. Beaufort Sea in the fall of 1987. The relocation plan consisted of the initial breakout phase, the lift before the tow, the tow to the new drilling location, and the setdown on the new location. This paper discusses some of the experiences gained during the relocation. The main concerns for relocation of a bottom-founded drilling unit are the soil suction and adhesion effects, the time required for lifting free of the seabed, the stability during breakout, the control that can be exercised over the unit when it breaks free of the seabed, and the positioning and ballasting accuracy that can be achieved during setdown. This relocation has shown that lift-off in adverse or soft cohesive soil conditions is not limited by the suction breaking capability of the unit. The relocation also showed that high horizontal position accuracies were achieved during setdown. Comparisons are made between the target procedures developed in the planning stage and the actual procedures monitored during the relocation. A brief description is given of the equipment installed on board as used for the control and monitoring of the operation. The design operating requirements of the unit are highlighted.

Reactions of organosilicon compounds on metals: III. Selective poisoning by Et 3SiH of catalytic hydrogenation and dehydrogenation

The transformation of Et 3SiH occurring with CSi bond breaking was studied on CabOSilsupported Cu, Ni, Rh, Pd, and Pt catalysts by the pulse technique in H 2 and He at 473–673 K. A serious poisoning of the CSi bond breaking capability of the metals was observed. Cu proved to be much less sensitive to poisoning, and, contrary to the other metals, could be partially reactivated. The poisoning effect of the surface silicon residues was found to be different for the hydrogenation of propene, cyclohexene, and benzene and for the dehydrogenation of 2-propanol and cyclohexene. This new selective poisoning effect may be a new tool for modifying certain metal catalysts.

Suppression of Fast Transient Overvoltage during Gas Disconnector Switching in GIS

This paper describes the suppression of the transient overvoltage caused by gas disconnector switching of a small capacitive charging current in a gas insulated switchgear substation. The overvoltage is suppressed by the insertion of a resistor with an appropriate value during the switching. A scale model gas disconnector with the resistor is developed. The overvoltage suppression effect and the charging current breaking capability of the gas disconnector are experimentally confirmed. A prototype ultra high voltage gas disconnector is trial manufactured and tested.