ASME B18.21.3:2008 pdf download Double Coil Helical Spring Lock Washers for Wood Structures
1 INTRODUCTORY NOTES1.1 Scope
This Standard covers the dimensional and physicalproperties and methods of testing for double coil helicalspring lock washers for wood structures.
NOTE:The word lock appearing in the name of the product inthis Standard is a generic term historically associated with theproduct’s identification and is not intended to imply an indefinite
permanency of fixity in attachments where the fasteners are used.
1.2 Comparison to lso Standards
No comparable ISO standards exist for this part.1.3 Dimensions
All dimensions in this Standard are in inches andapply 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 of terminology not specifically definedin this Standard, refer to ASME B18.i2.
1.6 Referenced Standards
Unless otherwise specified, the standards referencedshall be the most recent at the time of the orderplacement.
ASME B18.12,Glossary of Terms for MechanicalFasteners
ASME B18.18.1,Inspection and Quality Assurance forGeneral Purpose Fasteners
ASME B18.21.i,Lock Washers (Inch Series)
ASME B18.24,Part ldentifying Number (PIN) CodeSystem Standard for B18 Fastener Products
Publisher: The American Society of MechanicalEngineers (ASME)，Three Park Avenue,New York,NY 10016-5990; Order Department: 22 Law Drive,P.O.Box 2300,Fairfield,NJ 07007-2300
ASTM B117,Standard Practice for Operating Salt Spray(Fog)Apparatus
ASTME i40,Standard Hardness Conversion Tables ofMetals (Relationship Among Brinell Hardness,
Vickers Hardness, Rockwell Hardness,RockwellSuperficial Hardness,Knoop Hardness,andScleroscope Hardness)
Publisher: ASTM International(ASTM),100 Barr HarborDrive,P.O. Box C700，West Conshohocken,PA19428-2959
SAE J403,Chemical Composition of SAE Carbon SteelsSAE J411,Carbon and Ailoy Steels
SAE j419, Methods of Measuring DecarburizationPublisher: The Society of Automotive Engineers (SAE),400 Commonwealth Drive, Warrendale,PA 15096-0001
1.7 Related Standards
Related lock washers and tests are included inASME B18.21.1.
1.8 Designation
Nominal washer sizes are intended for use with com-parable nominal screw, bolt, and / or nut sizes.Fastenersconforming to this Standard shall be designated by thefollowing data and sequence:
(a) product name
b) ASME document number(c) nominal size
EXAMPLE: Double coil helical spring lock washers for woodstructures,ASME B18.21.3,5%in.
1.9 Part ldentifying Number
For a part identifying number, refer to ASME B18.24.
GENERAL DATA
2.1 Application
The double coil helical spring lock washers for woodstructures covered in this Standard are intended to beused with a curved flat washer or the standard hardwarepractice of the user against the wood. While not essen-tial, it is a good practice to use a standard round washerbetween the double coil helical spring lock washer andthe nut,then tighten the nut in accordance with theusers’ 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 mayshrink or swell during varying weather conditions.
Although these washers were designed specifically foruse on bolts in wooden assemblies (poles,crossarms,etc.), they can also be used for general applicationswhere a heavy duty double coil washer is needed.
2.2 Dimensions
The dimensions of standard and extended travel dou-ble coil helical spring lock washers for wood structuresare specified in Tables 1 and 2 and are before coating.Selections should be made from standard or extendedtravel series in Tables 1 and 2, respectively, to suit designrequirements.
2.3 Material and Hardness
2.3.1 Material Composition. Washers shall be madefrom material meeting the chemical compositionrequirements of the following standards:
a) up to and including 3/ in.carbon steel -SAE J4031055-1065 (UNS G10550-G10650)
b春in. and above boron steel -SAE J411 10B55-10B65
2.3.2 Hardness.All washer section hardnessrequirements 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 isused. Cold (water) grind or file both sides sufficientlyflat and parallel to ensure a correct reading. If applicable,be sure to remove the decarburized and coated surface.During this operation, care shall be exercised to preventthe surface temperature from exceeding 250°F. Refer toASTM E 140 for hardness conversion.
2.3.3 Decarburization. Carbon steel and boron steelshall meet the limits for decarburization shown inTable 3. The method for testing limits shall conform toSAE J419.
2.4 Washer Section
The corners at the inner and outer peripheries of thewashers shall be slightly rounded. The section of thefinished washer shall be slightly trapezoidal with thick-ness at the inner periphery greater than the thicknessat the outer periphery by a minimum of 0.0005 in. to amaximum of o.0o1 in.per 0.0156 in.of the section width.The minimum section thickness specified in the dimen-sional tables represents the nominal mean thickness,T,of the trapezoid. The tolerance on the nominal meanthickness of the trapezoid shall be subject to thefollowing:
ASME B18.21.3:2008 pdf download
