A Versatile Rock Melting System For the Formation ... - The Black Vault

Survfyor't Tronlf-OitfngSFl-• Continues the two previous stepsuntil HFA is out of hole.• Secures all equipment.If required, the hole can then be surveyedby visual observation or instrumentation toevaluate straightness, glass-casing thickness,etc.VII.CONCLDSIONS AND DISCUSSIONFig. 23. Establishing the hole center line.• Stops advancing pressure and releasesthe rear stem-advancing clamp,returning this clamp to the full-outposition.o Releases bladder pressure in quickdisconnectservice head (QDSH).• Slips off QDSH and unplugs signalleads.• Adds stem section and tightensconnection after plugging-in signalleads.• Slips on QDSH, replugs signal leadsto console and repressures bladder.• Raises power and coolant flow toprevious values.• Regrips stem and applies previousload.The stem is retracted (when the holeis finished or for any other reason) withthe following steps; the operator:• Reduces stem load to zero.• Reduces power to zero.• Reverses thrust load to retract mode.• Maintains coolant flow until thestem pulls freely (stem drag only).• Shuts off retraction force.• Reduces coolant flow to zero andremoves QDSH.• Pulls out stem until the next stemconnection is accessible. Loosensand unscrews connection.• Unplugs signal leads and racks stemsection.The development of small-diameter Subterrenerock-melting penetrators has reachedthe stage where the design of a 75-mm (3-in.)-diam system for forming horizontal, glasslinedholes is possible. Contacts withutility companies and requests for informationfrom industrial firms have indicatedthe need for such a device.A comprehensive development programwould have to address two major areas:• The development of an alignmentcontrolsubsystem.• The conduct of an economic studyand a market survey.A most attractive feature of horizontalhole-melting Subterrene systems is the capabilityof varying the accuracy of holestraightness to match job requirements.This is achieved by including or omittingthe appropriate sections in the hole-formingassembly.The information and experience gainedfrom the development and commercializationof the horizontal hole-melting system willbe of value to other Subterrene system developments.The benefit derived can be anticipatedto be:• Field data on service life andreliability of components, particularlypenetrators.• Extension of the technology to themelting of holes with curved paths.• Experience that will lead to horizontalhole-melting systems withincreased diameter and range.• Adaptation of the perfected alignment-controlscheme to verticalhole-melting systems.17