Reverse acting rupture disc with laser-defined electropolished line of weakness and method of forming the line of weakness

Abstract

A reverse acting rupture disc is provided having a laser defined electropolished line-of-weakness recess, and an improved method of forming an electropolished line-of-weakness recess in a reverse acting rupture disc that assures full opening of the disc upon reversal. A rupture disc blank is pre-bulged, final bulged, and then provided with a layer of resist material. A laser is used to remove at least a portion of the layer of resist material corresponding to a desired line-of-weakness recess in the concave face of the bulged rupture disc. The disc is then subjected to an electropolishing operation to remove metal from the lased area of the rupture disc, thereby forming a lustrous polished line-of-weakness recess in the disc of desired configuration and of a predetermined depth that is related to material thickness. The electropolished line of weakness is defined by spaced opposed channel portions separated by a central raised crown portion wherein the channel portions are of greater depth than the crown portion. The burst/reversal pressure of the disc having an electropolished line-of-weakness recess may be selectively controlled by varying the pre-bulging pressure on the disc.