ASME B18.21.3-2008 pdf download.Double Coil Helical Spring Lock Washers for Wood Structures.
1 INTRODUCTORY NOTES 1.1 Scope This Standard covers the dimensional and physical properties and methods of testing for double coil helical spring lock washers for wood structures. NOTE: The word lock appearing in the name of the product in this Standard is a generic term historically associated with the product’s identification and is not intended to imply an indefinite permanency of fixity in attachments where the fasteners are used. 1.2 Comparison to ISO Standards No comparable ISO standards exist for this part. 1.3 Dimensions All dimensions in this Standard are in inches and apply to unplated or uncoated product. 1.4 Options Options, if required, shall be agreed upon by the pur- chaser and the manufacturer or distributor. 1.5 Terminology For definitions ofterminology not specifically defined in this Standard, refer to ASME B18.12. 1.6 Referenced Standards Unless otherwise specified, the standards referenced shall be the most recent at the time of the order placement. ASME B18.12, Glossary of Terms for Mechanical Fasteners ASME B18.18.1, Inspection and Quality Assurance for General Purpose Fasteners ASME B18.21.1, Lock Washers (Inch Series) ASME B18.24, Part Identifying Number (PIN) Code System Standard for B18 Fastener Products Publisher: The American Society of Mechanical Engineers (ASME), Three Park Avenue, New York, NY 10016-5990; Order Department: 22 Law Drive, P.O. Box 2300, Fairfield, NJ 07007-2300 ASTM B 117, Standard Practice for Operating Salt Spray (Fog) Apparatus ASTM E 140, Standard Hardness Conversion Tables of Metals (Relationship Among Brinell Hardness,
Vickers Hardness, Rockwell Hardness, Rockwell Superficial Hardness, Knoop Hardness, and Scleroscope Hardness) Publisher: ASTM International (ASTM), 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken, PA 19428-2959 SAE J403, Chemical Composition of SAE Carbon Steels SAE J411, Carbon and Alloy Steels SAE J419, Methods of Measuring Decarburization Publisher: The Society of Automotive Engineers (SAE), 400 Commonwealth Drive, Warrendale, PA 15096- 0001 1.7 Related Standards Related lock washers and tests are included in ASME B18.21.1. 1.8 Designation Nominal washer sizes are intended for use with com- parable nominal screw, bolt, and/or nut sizes. Fasteners conforming to this Standard shall be designated by the following data and sequence: (a) product name (b) ASME document number (c) nominal size EXAMPLE: Double coil helical spring lock washers for wood structures, ASME B18.21.3, 5 ⁄ 8 in. 1.9 Part Identifying Number For a part identifying number, refer to ASME B18.24. 2 GENERAL DATA 2.1 Application The double coil helical spring lock washers for wood structures covered in this Standard are intended to be used with a curved flat washer or the standard hardware practice of the user against the wood. While not essen- tial, it is a good practice to use a standard round washer between the double coil helical spring lock washer and the nut, then tighten the nut in accordance with the users’ standard practice, and back off the nut 1 ⁄ 4 (90 deg) turn. This is important to maintain an acceptable pres- sure on the hardware and the wood fibers which may shrink or swell during varying weather conditions.
2.2 Dimensions The dimensions of standard and extended travel dou- ble coil helical spring lock washers for wood structures are specified in Tables 1 and 2 and are before coating. Selections should be made from standard or extended travel series in Tables 1 and 2, respectively, to suit design requirements. 2.3 Material and Hardness 2.3.1 Material Composition. Washers shall be made from material meeting the chemical composition requirements of the following standards: (a) up to and including 3 ⁄ 4 in. carbon steel — SAE J403 1055-1065 (UNS G10550-G10650) (b) 7 ⁄ 8 in. and above boron steel — SAE J411 10B55- 10B65 2.3.2 Hardness. All washer section hardness requirements are 38 HRC to 46 HRC, 372 HV to 458 HV. To prepare washers for checking the material hardness, cut washer approximately in half so only one coil is used. Cold (water) grind or file both sides sufficiently flatand parallel to ensure a correctreading. Ifapplicable, be sure to remove the decarburized and coated surface. During this operation, care shall be exercised to prevent the surface temperature from exceeding 250°F. Refer to ASTM E 140 for hardness conversion. 2.3.3 Decarburization. Carbon steel and boron steel shall meet the limits for decarburization shown in Table 3. The method for testing limits shall conform to SAE J419.