The problem of tube collapse by external pressure has been investigated experimentally. A graphical solution developed to simplify inelastic collapse design problems was shown to agree with the test results. The von Karman reduced modulus was used in the graphical solution to correct for the stress redistribution caused by yielding. The effects of the geometric imperfections of ovality and wall thickness variations on collapse pressure were shown to be related to the stress-strain behavior of the material. The concept of a critical time'' was discussed in regard to creep-buckling phenomenon. (auth)