A containment system and method for creating a confined space around a portion of a piping circuit, and for maintaining the confined space at a designated pressure with a pressurized blanketing gas. The confined spaced with its controlled environment protects against process upsets or icing when insulation is removed from sections in extreme temperature services. The containment system includes a shroud assembly that is made up of a cover configured into a tubular shape, and end plates on axial ends of the cover that mount onto the piping. Support rings are set within the cover that also mount to the pipe, and which provide radial support for the cover along the span between the end plates. Ports are formed through a sidewall of the cover that provide operations personnel access to the piping. Lines carrying the pressurized blanketing gas connect to inlets formed in the cover sidewall.