Method and apparatus for protecting a steel riser from chemical cutters

Abstract

A sleeve member constructed of material, preferably aluminum metal, nonreactive with chemicals from a chemical cutter, including a ringed collar around its upper end, the ring collar secured to the upper end of the sleeve, and defining a base for hanging the sleeve within a bore of a steel riser positioned in as part of a wellhead assembly, the sleeve having an o.d. slightly smaller than the i.d. of the steel riser, and an internal bore of sufficient interior diameter so as to allow a chemical cutter to be positioned there within, the sleeve being of sufficient length to allow the entire chemical cutter to be positioned therein, while the chemical cutter is positioned within the wellhead assembly. The sleeve would further include a plurality of centralizers at its lower end, for maintaining the sleeve positioned equidistant at all points along its length between itself and the steel riser. There may be further included an additional sleeve positioned flush against the upper end of the first aluminum sleeve so as to provide an extended sleeve within the steel riser, the sleeve serving to receive the impact of an inadvertent firing of the chemical cutter as it is housed within the sleeve, so that the aluminum metal within the sleeve does not react with the chemical compound within the cutter, and therefore would not be eroded away, and would protect the steel riser from the chemical compound of the cutter. Further, there may be included a fluid housed within the wall of the steel riser and the wall of the aluminum sleeve so as to provide further protection between the chemical compound of the cutter when fired and the steel riser wall.

Dependencies are inferred from the claim text.