E.i. Dupont De Nemours and Company

Eti Explosives Technologies International Inc.

Conoco Inc.

Other

Explosives Technologies International Inc.

Malak E Yunan

Dennis R Wilson

Larry K Moran

Michael J McGowan

Wilber R Moyer

Hardin D Mitchell, Jr

Philip E Adams

Casing conveyed perforator

In a non-electric system for initiating explosives, a shock tube is initiated by the detonation of a low-energy detonating cord (LEDC) whose wall has been placed adjacent to an initiation-sensitive region of a thin membrane in the shock tube, or in a capping member to an open end of a shock tube or in a capping member to the detonator itself, wherein the inner surface of the bore of the shock tube or the end-capping member is coated with a reactive composition of an explosive or a deflagrating compound. The end capping member fits over and seals the open end of the shock tube or fits in and seals a detonator with or without a shock tube in it, acting as a shock tube itself. The thin membrane accepts the detonation from the LEDC, whereby the shock tube or capping member is initiated and relays a pressure pulse to the shock tube or the detonator affixed thereto. Novel shock tubes, shock tube/detonator units, and a detonator for use in the hybrid shock tube/LEDC system are disclosed.

Hybrid shock tube/LEDC system for initiating explosives

Fluid activated detonating system

An improved plastic-bonded explosive composition which includes from 2 wt. % up to 30 wt. % of a nitrocellulose binder and comprises incorporating into the composition during preparation from about 0.0025 wt. % up to a value less than 2 wt. % of fibrillatable polytetrafluoroethylene (PTFE) and mixing the composition thoroughly and with sufficient shearing action whereby the PTFE fibrillates and becomes substantially uniformly distributed throughout the finished composition.

Fibrillatable PTFE in plastic-bonded explosives

An improved connector for holding low energy detonating cord adjacent the percussion-actuation and surface of a detonator comprises a plastic tube having a detonator-receiving bore and one or more cord receiving transverse bores between a plastic end closure for the tube and the end of the bore of the tube. The transverse bore(s) form channels which permit the cord segments therein to span the actuation end surface of the detonator and result in improved reliability of initiation of the detonator.

Connector and detonator/connector assembly for initiating explosive

An explosive primer unit adapted to be initiated instantaneously by low energy detonating cord when the unit comprises an explosive primer and an explosive coupler which operatively joins the low energy detonating cord to the primer.

Explosive primer unit for instantaneous initiation by low-energy

A primer assembly for use in the non-electric initiation of cap-insensitive explosives, especially of deck-loaded explosive charges by means of a single downline of low-energy detonating cord (LEDC), includes a percussion-actuated detonator seated in a cavity in a high-energy primer, and an explosive coupler in which a coupling explosive charge, housed in a plastic connecting block, is in initiating proximity to the detonator's percussion-sensitive ignition charge and sufficiently close to a cord-receiving perforation or conduit in or adjacent the primer as to be initiatable by the detonation of LEDC threaded therethrough. A preferred connecting block has means for engaging the detonator, and means for attaching the block to the primer. Preferably the explosive coupler is seated within a block-like cavity in the primer.

Primer assembly

An explosive primer unit in which the degree of energy coupling between a low-energy detonating cord (LEDC) and an explosive coupling element in a cast explosive primer is maximized; the unit contains (a) a substantially cylindrical charge of cast explosive having a perforation therein aligned substantially parallel to the charge's cylindrical axis, and sized to slidably receive a length of LEDC and (b) embedded in the cast explosive charge along the LEDC-receiving perforation, an explosive coupling element containing a shock-sensitive high-velocity detonating explosive having a tubular body having a wall that surrounds, and a bore that forms, the LEDC-receiving perforation over at least a portion of the perforation's length, the size of the bore of the coupling element's tubular body that forms the LEDC-receiving perforation in the cylindrical charge of cast explosive closely matching the outer diameter of a length of LEDC to be received therein.

Cast explosive primer initiatable by low-energy detonating cord

A non-electric detonator device having a tubular shell that is closed at its bottom end and containing

Non-electric detonators without a percussion element

A primer assembly for use in the non-electric initiation of cap-insensitive explosives, especially of deck-loaded explosive charges by means of a single downline of low-energy detonating cord (LEDC), includes a percussion-actuated detonator seated in a cavity in a high-energy primer, and an explosive coupler in which a coupling explosive charge, housed in a plastic connecting block, is in initiating proximity to the detonator's percussion-sensitive ignition charge and sufficiently close to a cord-receiving perforation or conduit in or adjacent the primer as to be initiatable by the detonation of LEDC threaded therethrough. A preferred connecting block has a U-shaped channel for engaging the detonator, and a connecting block arm for attaching the block to the primer. Preferably the explosive coupler is seated within a block-like cavity in the primer.

A carrier for supporting a primer explosive charge in operative relationship to initiating means therefor comprises a cup having a recessed portion in its closed bottom end for engaging an explosive-containing plastic connecting block, used to explosively couple a low-energy detonating cord (LEDC), threaded through a tunnel in the cup, to a percussion-actuated detonator seated in a cavity (cap well) in the cup. A number of such primers can be made to slide on a single LEDC downline for placement in decked explosive charges in a borehole. Two tubular members project into the cup from the recessed portion, forming one or two cord-threading tunnels and a cap well. Besides initiation of a detonator by an LEDC downline via the explosive coupler, the carrier allows the primer charge to be initiated by a high-energy detonating cord or an electric detonator in an axial tunnel in the cup, or by a length of LEDC threaded through a tunnel and connected to a non-electric detonator seated in the cap well.

Explosive primer and carrier therefor

An assembly for initiating a detonating explosive charge, e.g., a surface seismic charge, by low-energy detonating cord (LEDC) has a cord-connector fitted around a percussion-actuated detonator or booster, and a means of piercing a frangible package to enable the assembly to be embedded in the charge. In a preferred assembly, the connector is a plastic tube which fits over the actuation end of a booster shell whose opposite end is notched or serrated. A detonator preferably is fitted in a plastic cord-connecting tube whose end surface is tapered, or which has a pointed extension member, forming a spike. LEDC does not pose the fire hazard encountered with heavier cords in surface seismic operations in wooded or grassy areas.

Assembly for initiating explosives with low-energy detonating cord

An explosive booster, useful as a starter for one or more low-energy explosive connecting cords, e.g., low-energy detonating cord (LEDC), comprises a detonating explosive charge in the form of a rod having at least one longitudinal perforation for threading one or more (receiver) cords to be initiated by the booster explosive charge, which in turn is initiated by a blasting cap or preferably by the side-output of a (donor) detonating cord in contact therewith. A preferred rod has multiple perforations for threading multiple receiver cords, and is housed within a rigid plastic connector having a portion of its wall circumferentially cut out to allow a donor cord to contact the thereby-exposed rod therein. A trunkline cord is thereby adapted to initiate multiple downlines via a single booster.

Field-connected explosive booster for initiating low-energy explosive

Improved uniformity of timing, and particularly reduced sensitivity of timing to minor variations in delay charge size, are achieved in delay detonators by placing a loose load of a flame-sensitive ignition composition between a pressed delay charge and an ignition assembly, e.g., a percussion primer, at the actuation end of the detonator. The loose ignition charge has a free surface and is adapted to be ignited in response to direct contact with flame emitted from the ignition of a charge in the ignition assembly. Preferably, the delay charge is pressed into a plastic carrier which, in a non-electric detonator, has an open end terminating between the walls of the detonator shell and a primer shell that closes the actuation end of the detonator, and the ignition charge is loosely loaded into a metal capsule seated against the delay charge.

Delay detonator

A detonator closed at one end by a primer shell whose integrally closed end has a percussion-sensitive primer charge supported adjacent its inside surface, and its outside surface disposed across the end of the detonator shell, is actuated by the detonation of one or two lengths of low-energy detonating cord (LEDC) adjacent the primer shell's outside end surface, a single length of LEDC being arrayed in a manner such that a pair of axially separated segments thereof, or two lengths arrayed in a manner such that a segment from each length, is anchored in place in side-by-side relationship adjacent said surface. This cord array assures reliable ignition of a center- or rim-fired percussion primer by means of the side-output of LEDC even with explosive core loadings at the low end of the LEDC loading range. A preferred detonator has a sleeve having a loop-like projection, most preferably M-shaped, diametrically disposed beyond the primer shell end through which a looped length of LEDC can be threaded in various ways to hold the pair of segments adjacent the primer shell.

Growing community of inventors

Boonton Township, NJ, United States of America

Malak E Yunan