Foreword This supplement covers changes for API Std 7B (Tenth Edition): Specification for Rotary Drilling Equipment as adopted by the Committee on the Standardization of Rotary Drilling Equipment at the 1947 and 1948 meetings and previously published in Sup. 2; also changes adopted at the 1949 and 1950 meetings and subsequently ratified by letter ballot. These changes include, among others, the revision of stipulations on tool joints, drill collars, kellys, rotary drilling and vibrator, hose, rotary-drilling-bit connections, gaging practice for rotary tool joints, and the addition of five new sizes of slush pump liners.