THE EFFECT OF GALVANIZING AND OF OTHER SURFACE TREATMENTS ON HIGH TENSILE BOLTS AND BOLTED JOINTS

THE EFFECT OF GALVANIZING AND OTHER SURFACE TREATMENTS ON BOLTED JOINTS WERE REVIEWED. IT IS THOUGHT THAT GALVANIZING STRUCTURAL JOINTS WILL AFFECT THE TIGHTENING OF THE BOLTS AND ALSO CHANGE THE SLIP CHARACTERISTICS OF THE JOINT. THESE TWO PROBLEMS WERE STUDIED, FIRST, BOLT CALIBRATION TESTS TO GATHER INFORMATION ON THE EFFECTS OF GALVANIZATION UPON THE PHYSICAL BEHAVIOR OF HIGH TENSILE BOLTS, AND SECOND, STATIC TESTS TO DETERMINE THE NOMINAL COEFFICIENT OF FRICTION OF VARIOUS TREATMENTS TO THE FAYING SURFACES IN JOINTS ASSEMBLED WITH THE ABOVE BOLTS. THE BOLT CALIBRATION TESTS WERE CARRIED OUT ON 3/4-INCH AND 1-INCH DIAMETER ASTM A325 AND A490 BOLTS WITH AND WITHOUT GALVANIZING AND WITH AND WITHOUT LUBRICATION. THE STATIC TESTS WERE MADE WITH THE FOLLOWING TYPES OF SURFACE TREATMENT ON THE CONNECTED PARTS, HOT-DIP ZINC GALVANIZED, ZINC PAINTED WITH GALVICON, HOT- ZINC SPRAYED, VINYL WASH, AND RUST BAN. TESTS WERE ALSO MADE WITH BARE PARTS AND GALVANIZED BOLTS. A325 AND A490 GALVANIZED BOLTS APPEAR TO BE SUITABLE AS STRUCTURAL FASTENERS PROVIDED SPECIAL CARE IS OBSERVED IN APPLYING TORQUE TO THEM. THE AUTHORS FEEL THAT THE TURN-OF-THE-NUT METHOD CARRIED OUT BY POWER WRENCH WILL INSURE THE REQUIRED CLAMPING ACTION. LUBRICANTS HELP IN REDUCING THE AMOUNT OF TORQUE REQUIRED TO TURN THE NUT, IN CASES OF BOTH GALVANIZED AND BLACK BOLTS. THE AVERAGE COEFFICIENT OF FRICTION IS NOT SIGNIFICANTLY REDUCED FOR ANY OF THE JOINT SURFACE TREATMENTS AND SEEMS TO IMPROVE FOR ONE OR TWO OF THE TREATMENTS. IT IS YET TO BE DETERMINED IF ZINC-COATED SURFACES CREEP OVER A LONG PERIOD OF TIME. /BPR/

  • Supplemental Notes:
    • Hpr-1/3/, HR 256
  • Corporate Authors:

    University of Washington, Seattle

    Seattle, WA  USA  98195

    Washington State Department of Highways

    Olympia, WA  USA 
  • Authors:
    • Brookhart, G C
    • Siddiqi, I H
    • Vasarhelyi, D D
  • Publication Date: 1967-1

Subject/Index Terms

Filing Info

  • Accession Number: 00215849
  • Record Type: Publication
  • Source Agency: Bureau of Public Roads /US
  • Files: TRIS, STATEDOT
  • Created Date: Aug 4 1994 12:00AM