Abstract: A formation saver sub or pump out sub incorporating an anti-surge feature. The sub includes a body, a mandrel, a piston (or an annulus fluid pressure chamber and a tubular pressure chamber), a sleeve, a spring, a releasable seat, and a plug. The plug and seat are released from the sub when one or more dogs releasably positioning the seat in the mandrel bore disengages from the seat due to a bleed off of fluid pressure in the well bore.

Abstract: A formation saver sub or pump out sub incorporating an anti-surge feature. The sub includes a body, a mandrel, a piston (or an annulus fluid pressure chamber and a tubular pressure chamber), a sleeve, a spring, a releasable seat, and a plug. The plug and seat are released from the sub when one or more dogs releasably positioning the seat in the mandrel bore disengages from the seat due to a bleed off of fluid pressure in the well bore.

Abstract: A formation saver sub or pump out sub incorporating an anti-surge feature. The sub includes a body, a mandrel, a piston, a sleeve, a spring, a releasable seat, and a plug. In an alternative embodiment, the sub includes a body, a mandrel, a piston, an annulus fluid pressure chamber, a tubular pressure chamber, a sleeve, a releasable seat, and a plug. The plug and seat are released from the sub when one or more dogs releasably positioning the seat in the mandrel bore disengages from the seat due to a bleed off of fluid pressure in the well bore.

Abstract: A fully collapsible box with four sidewalls comprising vertical slats, horizontal cleats and interconnected wires at the ends of the cleats at the corners of the box, wherein the ends of the cleats have reverse miters so that the box may be hingedly collapsed along these corners when not in use. Hinged collapsing of this box does not require disconnection of the wires and does not adversely affect the tightness of the wire interconnections between adjacently located cleats. Because the reverse miters allow the box to be hingedly collapsed while the sidewalls remain interconnected, this invention assures a sturdy box over a period of use, while eliminating the need to connect and disconnect the cleats at the corners of the box during assembly and disassembly, respectively. In one embodiment the wire internconnection comprises a single loop extending completely around the box and secured to the cleats.