Collapse-resistant corrugated filter element

A corrugated tubular filter element resistant to corrugation collapse under high differential pressure, although formed of filter sheet material susceptible to such collapse, comprising, in combination, filter sheet material enclosed in a dual layer of more open foraminous sheet material and formed in a tubular corrugated configuration having axial corrugation folds arranged in groups with adjacent side surfaces in supporting contact with each other;

• and, interposed between said groups, solid wedge support elements extending axially of the corrugation folds from end to end of the element and having side surfaces in substantially complete supporting contact with and from end to end of the element and from side to side and from end to end of the external side surfaces of the end folds of each group, substantially filling the spaces between the end folds of adjacent groups, and confining the folds of each group in substantially parallel array against lateral movement;
• and a foraminous support sheath disposed at least one of externally and internally of the filter sheet material in supporting contact with adjacent fold ends and retaining the wedge support elements and folds against one of outward and inward movement.