ASME B18.13:2017 pdf free download

ASME B18.13:2017 pdf free download.Screw and Washer Assemblies – SEMS(Inch Series).
2.4 Hex Cap Screws for SEMS
The hex head cap screws component of SEMS shall conform to the specifications for cap screws published in ASME 818,2.1, except for the following:
(a) The maximum diameter of the unthreaded shank shall be sufficient to allow free assembly and i-otation of the washer relative to the screw.
(b) On hexagon cap screws threaded full length, the unthreaded length is the distance measured parallel to the axis of the screw from the underside of the washer to the face of a nonchamfered or noncounterbored standard GO ring gage. The unthreaded length is a maximum of two thread pitches (see Fig. 1). When required, threads extending closer than two pitches to the contacting face of the washer may be negotiated between the manufacturer and purchaser.
2.5 ApplicabIlity of Screw Sizes
To the extent that coverage is provided in the respectue dimensional tables, numbered nominal sizes shall apply to all types of screws, including Type A tapping screws, and fractional nominal sizes shall apply to all types of screws except Type A tapping screws.
2.6 Washers for SEMS
The washer components of SEMS shall conform with the dimensions and specifications given for the various types in this Standard. It should he noted that the washers for SEMS may differ dimensionally from the equivalent over-the-thread washers as specified in ASMIE B18.21.l. Except for helical spring lock washers where the inside diameters are included for manufacturing purposes, the holes in the SEMS washers are not specified inasmuch as the washers shall be assembled onto the screw blanks before the threads are rolled. The edge contour of the hole on the head side of the washer and the size relationship between the washer inside diameter and the diameter of the unthreaded shank on the screw shall be such that the washer will be retained on the screw after the threads are rolled, and shall be free to rotate after assembly.
2.7 Finish
2.7.1 General. Unless otherwise specified by the purchaser, SEMS shall be supplied with a natural (as- processed) finish, unplated or uncoated. Where corrosion preventive treatment is required, SEMS shall be plated or coated as specified by the purchaser. The application of heavy coating deposits or supplemental treatments entailing organic compounds may result in a bonding of the SEMS components at points that abut.