The Down Hole Expansion Tool is positioned inside the Expandable Steel Patch. The inflatable packer section is then inflated enough to grip the inside of the Patch (not enough to start expansion). The assembly is Run In Hole to the setting zone. The packer is inflated using pressure from surface to expand the top of the Patch, anchoring it in place. The packer is then deflated, run in 3 ft / 1 m, and the next section is expanded. This is repeated as often as necessary until the full length is expanded, and BHA is pulled back to surface.
The setting procedures for Saltel Patches are very different from those used with other expandable systems. The steel is not pushed out to a pre-determined diameter by a cone, but is expanded using an inflatable element which will ensure the patch is pushed out to seal effectively against the inside of the existing casing, irrespective of the precise casing ID, shape or form.