A structure in which no shearing force acts on each member is desired to be used at a welded part where a stress is liable to be concentrated. To solve this problem, the flange member includes a cap member, a ring member, and sheet-shaped thermoplastic resin member. At least one end of the thermoplastic resin member includes a protruding part that protrudes from an end surface of the cap member and from an end surface of the ring member. The protruding part is welded to the end surface of the cap member and to the end surface of the ring member.

A filter element for fluid filtration, in particular for hydraulic fluid, has element components, such as pleated and multi-layer filter material (10) that extends between two end caps (26) and has a fluid-permeable supporting tube (14) forming a hollow cylinder. At least one element component of the filter element is provided at least partially with at least one luminescent material or marker such that the material or marker is excited to a characteristic, detectable wave emission when exposed to a certain exciter wave or wave spectrum.

[Subject] To provide a novel liquid filter allowed for cleaning of adhered, foreign matter, and reusable after cleaned up,

[Solving Means] A liquid filter has a liquid-receiving space 3d formed at the center; a plurality of ridge parts 3a vertically juxtaposed so as to be exposed individually to the front, back, left side and right side; and a plurality of valley parts 3b each formed on the sides opposite to the individual positions of formation of the ridge parts 3a the liquid filter can be unfolded from a folded state into a rectangular sheet body 5, and the sheet body 5 in the folded state has its left end and right end overlapped.

The invention relates to a filter element for fluid filtration, in particular for hydraulic fluid, consisting of element components, such as a preferably pleated and multi-layer filter material (10) that extends between two end caps (26) and at least partially comprises a fluid-permeable supporting tube (14) forming a hollow cylinder, characterized in that at least one element component of the filter element is provided at least partially with at least one luminescent material or another marker in such a manner that said material or marker is excited to a characteristic, detectable wave emission when exposed to a certain exciter wave or wave spectrum.