WRC Bulletin 443 reports the research on two separate projects on external pressure. The bulletin includes three separate reports@ such that the first covers one project and the last two cover the other project: Report 1: The Effect of Initial Imperfections on the Buckling of Cylinder Subjected to External Pressure by C. D. Miller. This report presents a new method for estimating the effects of deviations from a true circular form on external pressure capacity of cylinders. The new@ improved method is based on analytical work and test results that have become available since earlier Code rules were developed. The new method is based on a more rational basis than earlier rules@ and the new method provides better correlation with test results. The method could be adopted by ASME Code Committees as a replacement for the existing rules and as a means of providing some flexibility on specified tolerances@ so that a reduced allowable external pressure may be calculated if tolerance limits are exceeded. Report 2: Temperature Limits for ASME Boiler and Pressure Vessel Code External Pressure Design Charts by D. S. Griffin. Report 3: Temperature Limits for ASME Boiler and Pressure Vessel Code Section VIII Application of External Pressure Charts by D. S. Griffin. These two reports establish temperature limits for the ASME Boiler and Pressure Vessel Code External Pressure Design Charts. The methodology is based on classical stability theory developed by Gerard and simplified by Griffin by replacing the constant strain rate stress-strain curves with isochronous stress-strain curves for determining the tangent and secant moduli. The theory has been validated by both test and analysis methods. The method is applied to develop temperature limits that define the limits of applicability of external pressure design charts without consideration of creep. Design charts for three load cases are presented: cylinders under axial compression; spheres under external pressure; cylinders under external pressure. Four elevated temperature materials are included; type 304 and 316 stainless steel@ Alloy 800H and 2 ? Cr-1 Mo. Additional materials include 9Cr@ SA-533@ 2 ? Cr ?C 1Mo annealed@ 2 ? Cr ?C 1Mo NT and SA-516/55