Water impervious detonator

Claim 1

IN AN ELECTRICAL INITIATOR COMPRISING AN IMPERFORATE TUBULAR SHELL HAVING ONE OPEN AND ONE CLOSED END, EXPLOSIVE CHARGES WITHIN THE SHELL, AND LEAD WIRES EXTENDING THROUGH AND FROM AN INSULATING PLUG WHICH SEALS THE OPEN END OF THE SHELL, MEANS OPERATING IN CONJUNCTION WITH THE INSULATING PLUG TO PROVIDE AN EFFECTIVE HYDRAULIC SEAL BETWEEN THE EXPLOSIVE CHARGES AND THE OPEN END OF THE SHELL UNDER SUCH CONDITIONS OF TEMPERATURE AND PRESSURE THAT SAID PLUG IS PLASTIC COMPRISING: (A) A RIGID TUBULAR SHELL LINER FIXEDLY POSITIONED BETWEEN THE CLOSED END OF THE SHELL AND THE INSULATING PLUG, AND (B) A CLOSURE ELEMENT OF HEAT- AND PRESSURE-RESISTANT MATERIAL CLOSING AND BEING SUPPORTABLY SEATED ON THE END OF THE SHELL LINER NEAREST THE INSULATING PLUG IN A POSITION CONTIGUOUS TO SAID PLUG, THE CIRCUMFERENTIAL SURFACE OF THE CLOSURE ELEMENT CONFORMING SUBSTANTIALLY TO AND BEING IN PERIPHERAL ENGAGEMENT WITH THE INTERNAL SURFACE OF THE SHELL, SAID CLOSURE ELEMENT BEING PROVIDED WITH OPENINGS THERETHROUGH FOR SAID LEAD WIRES, SAID EXPLOSIVE CHARGES BEING BETWEEN SAID CLOSED END OF THE SHELL AND THE CLOSURE ELEMENT.