Work Item
ASTM WK67534

Revision of F436/F436M-18a Standard Specification for Hardened Steel Washers Inch and Metric Dimensions

Rationale

Recent changes to hole diameters and installed bolt loads cup washers for the larger sizes. The cupping increases surface contact pressure and induces galling. The holes historically were nominal +1/16 and now they are +1/8, essentially parallel with the 105 to 120 ksi increase in minimum installed conditions. Most of the rational supplied for the increase in hole sizes cited global metric standards, where +3mm hole clearance is normal (approximately +1/8). But, in those metric construction standards the washers in the appropriate standards are noticeably thicker to transfer the load across the larger hole size. Refer to John Bickfords Handbook of Bolted Joints and the flat washer effective load transmission calculation. One steel gauge increase is warranted to restore the historical surface contact pressure. A second ballot item under the same WK# for reducing the ID of the washer will also be submitted with the same rational, to stiffen the washer and prevent cupping.

Details

Developed by Subcommittee: F16.02

Committee: F16

Staff Manager: Jennifer Rodgers

Work Item Status

Date Initiated: 03-20-2019

Technical Contact: Jordan Richardson

Item: 002

Ballot: F16.02 (19-03)

Status: Will Reballot Item

Item: 003

Ballot: F16 (20-01)

Status: Will Reballot Item