ASME B18.2.1:2010 pdf download

ASME B18.2.1:2010 pdf download Square, Hex, Heavy Hex, and Askew Head Bolts and Hex, Heavy Hex, Hex Flange, Lobed Head, and Lag Screws (Inch Series)
2.5 Threads 2.5.1 Thread Standard. Threads on all products in this Standard, except lag screws, shall meet the require- ments of ASME B1.1. Lag screw thread dimensions are specified in Table 16. 2.5.2 Thread Class. Unless otherwise specified, size limits for standard external thread Class 2A apply prior to coating. The external thread allowance may be used to accommodate the coating thickness on plated or coated parts, provided that the maximum coating thickness is no more than one-fourth of the allowance. Thus, the thread after plating or coating is subject to acceptance using a basic size Class 3A GO size thread gage and a Class 2A NOT GO size thread gage.
2.5.3 Thread Series. Thread series on all bolts and screws may be coarse (UNC), fine (UNF), or 8 thread series (8 UN), except askew head bolts, which shall be unified coarse (UNC) only, and lag screws, which are specified in Table 16.
2.5.4 Incomplete Thread Diameter. The major diameter of incomplete thread shall not exceed the actual major diameter of the full form thread.
2.5.5 Thread Acceptability. Unless otherwise specified by the purchaser, dimensional acceptability ofscrew threads shall be determined using thread gaging System 21 in ASME B1.3.
2.6 Straightness Shanks of bolts and screws shall be straight within the followinglimits atmaximummaterial condition(MMC). For bolts with nominal lengths up to and including 12 in., the maximum camber shall be 0.006 in. per inch (0.006L) of bolt or screw length. For bolts and screws with nominal lengths over 12 in. up to and including 24 in., the maximum camber shall be 0.008 in. per inch (0.008L) of bolt or screw length. A typical gage and gaging procedure for checking bolt and screw straightness are given in ASME B18.2.9.
2.7 Countersunk Center Holes For parts that require machining, it may be necessary to provide support with a countersunk center hole in the threaded end. Unless otherwise specified by the pur- chaser, the drill size and depth shall be in accordance with Nonmandatory Appendix C.
2.8 Materials Standard materials for various configurations of bolts and screws are identified in paras. 3.9, 4.9, and 5.7. When materials and/or grades, other than those in the applica- ble notes, are required, the purchaser must clearly spec- ify them in the purchase documents. 3 2.9 Finish Unless otherwise specified, bolts and screws shall be supplied with a plain (as processed) finish, unplated, or uncoated. Light oil on the surface is permissible to avoid corrosion during transportation, packaging, and further handling.
2.10 Workmanship Surface discontinuities shall be in accordance with the requirements of the applicable fastener material stan- dard. The purchaser may specify additional surface dis- continuity requirements for screws and bolts when tighter control of surface discontinuities is required or when discontinuity limits are not specified in the appli- cable fastener material standard.
2.11 Designation 2.11.1 Bolts and screws shall be designated by the following data in the sequence shown: product name; nominal size (fractional or decimal equivalent); threads per inch (omit for lag screws); product length (fractional or two-place decimal equivalent); material, including specification where necessary; and protective finish, if required. See the following examples: EXAMPLES: (1) Square Bolt per ASME B18.2.1, 3 ⁄ 8 – 16  1 1 ⁄ 2 . Steel per ASTM A 307 Grade A, Zinc plated per ASTM F 1941 Fe/Zn 3A (2) Hex Cap Screw per ASME B18.2.1. 1 ⁄ 2 – 13  4. ASTM A 354 Grade BD, plain finish (3) Hex Lag Screw per ASME B18.2.1, 0.75  5.00, Stainless Steel per ASTM F 593, Group 1, Condition CW (304) 2.11.2 For a recommended part identification number (PIN) system for B18 fasteners, see ASME B18.24.
2.12 Grade and Manufacturer’s Identification 2.12.1 Identification Symbols. Identification mark- ing symbols on products included in this Standard shall be raised or indented at the manufacturer’s option unless otherwise specified. Markings shall be legible to the unaided eye with the exception of corrective lenses. When raised, the height of the marking may not exceed 0.015 in. over the specified maximum head height for bolts 5 ⁄ 8 in. and smaller. For bolts larger than 5 ⁄ 8 in., the marking may not project more than 0.030 in. over the specified maximum head height. When indented, the depth of the marking shall not reduce the load-carrying capacity of the fastener.
2.12.2 Grade Symbols. Each of the products included in this Standard shall be marked in accordance with the requirements of the applicable specification for its material, mechanical, or performance requirements.