Abstract: A pocket filter assembly includes a frame structure having a plurality of filter pocket openings and a corresponding plurality of filter pockets, each filter pocket having a pocket mouth securely sealed in a corresponding filter pocket opening. The frame structure includes an outer subframe and a corresponding inner subframe connected and locked to each other by means of locking elements at locking positions distributed along opening portions of the subframes defining the filter pocket openings. At each locking position, the filter pocket mouths are sealed clamped and sealed between co-operating opening portions of the subframes. The locking elements include an undercut hook-shaped projection on the inner subframe and a co-operating receiving hole on the outer subframe, such that an interlock of the subframes to each other is obtained, while including filter pocket mouth material of the associated filter pocket between said projection and said aperture such that said interlock is sealed thereby.