Prohibited Joints and Connections in Drainage Systems

Section 890 Section 890.370  Prohibited Joints and Connections in Drainage Systems Drainage System.  Any fitting or connection which has an enlargement, chamber, or recess with a ledge, shoulder, or reduction of pipe area that offers an obstruction to flow through the drain is prohibited. No fitting or connection that obstructs flow shall be used.  In existing buildings only a flow control valve or device may be connected to the fixture drain and shall not be considered as an obstruction.  The enlargement of a three (3) inch closet bend or stub to four (4) inches shall not be considered an obstruction.