We provides both perforated stainless steel tubes and filter socks for white liquor filtration. In this application it is important to achieve a leak free filter sock installation which improves a clear filtrate. This is obtained with a welded filter sock that is thoroughly sealed in both ends combined with a sealing rubber o-ring. Precise tailoring of the filter sock provides an easy installation and the durable filter sock fabric in 100% polypropylene provides a long service life with minimum breakage.