Abstract: A seal bore is provided in a modular form so that a desired length of continuous seal bore can be provided with modules that are preferably secured to each other with threads. The modular concept allows overall seal bore lengths to go beyond the 20 meter limit that previously existing that could be attained with honing equipment entering opposed ends of a tubular. The modules abut each other as the threaded connection is made up. A transition zone extends in opposed direction on opposed sides of a connection that retracts the contact location between modules far enough so that even if the dimensional tolerances all go to the extreme in the pin and box that make the connection, a surface irregularity will be sufficiently small as to avoid seal stack contact that can result in potential seal damage. The seal stack length spans the transition zone to preserve sealing integrity.

Abstract: A high-voltage type photoflash lamp filled with a filamentary combustible material and oxygen and having an ignition structure comprising a pair of spaced apart lead-in wires bridged at their inner ends by a mass of primer material. An insulating sleeve encloses one of the wires, with the inner end of that wire and the top of the sleeve having a melted down configuration with a smooth and rounded surface. The other lead-in wire lies outside the sleeve and is formed to terminate and make contact with the exterior of the sleeve at or near its top end. The primer material is disposed to cover the top end of the sleeve and bridge the ends of the lead-in wires. Also disclosed is a method of making the lamp including the step of applying a flame to melt down a protruding end of the sleeve lead-in wire prior to sealing the ignition mount into the glass tubing to be formed into the lamp envelope.