All sewer, soil and waste pipes must be as direct as possible. Changes in direction must be made with fittings, "Y's", combination Y and eighth bends, or half "Y's", or one-eighth bends. Offsets in soil or waste pipes will not be permitted when they can be avoided; nor, in any case, unless suitable provision is made to prevent accumulation of rust or other obstruction. Offsets shall be made with forty-five degree bends, or similar fittings. The use of T's or sanitary T's will be permitted on upright lines only. Saddle hubs when bolted or strapped on are prohibited.
53 P.S. § 4625