Improvements in and relating to sifting screens

Abstract From the Canadian patent

A frame over which woven wire mesh is to be stretched and secured to form a sieving screen and which can be used to screen solids from drilling mud recovered from downhole when drilling for oil or gas. The frame comprises a rectilinear moulded plastic frame having edge regions by which it is secured in place in a shaker. Within the frame is a plurality of rectilinear windows formed by an orthogonal array of interesting ribs also of moulded plastics material. Some of the ribs are internally reinforced by a structure comprising two spaced apart layers of orthogonal intersecting spaced apart wires running , parallel to the length and breadth of the rectilinear shape of the frame within …