ASME B18.13 pdf download Screw and Washer Assemblies – SEMS (Inch Series) 1 INTRODUCTION 1.1 Scope This Standard covers general and dimensional data pertinent to the various types of screw and captive washer assemblies, otherwise known as SEMS. SEMS products may include screws, tapping screws, or bolts in sizes No. 0 through 1 ⁄ 2 in. diameters in various grades...