ASTM F959 covers the requirements for compressible washer type direct tension indicators in diameters ranging from 1/2” to 1-1/2” inclusive. These washers are capable of indicating the achievement of a specified minimum bolt tension. They are available in two grades for use with A325 and A490 structural bolts and are also available in a weathering steel option for both grades.
F959 Types
| Type 325 and 325-3 | For use with A325, F1852 and A325-3, F1852-3 structural bolts |
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| Type 490 and 490-3 | For use with A490, F2280 and A490-3, F2280-3 structural bolts |
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F959 Acceptable Compression Load Range
| Diameter | Type 325 and 325-3, in kips | Type 490 and 490-3, in kips |
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| 1/2 | 12 – 14 | 15 – 18 |
| 5/8 | 19 – 23 | 24 – 29 |
| 3/4 | 28 – 34 | 35 – 42 |
| 7/8 | 39 – 47 | 49 – 59 |
| 1 | 51 – 61 | 64 – 77 |
| 1-1/8 | 64 – 77 | 80 – 96 |
| 1-1/4 | 81 – 98 | 102 – 122 |
| 1-3/8 | 97 – 117 | 121 – 145 |
| 1-1/2 | 118 – 143 | 148 – 178 |
F959 Chemical Requirements, Heat Analysis
| Element | Type 325 and 490 | Type 325-3 and 490-3 |
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| Carbon | 0.30 - 0.55% | |
| Manganese | 0.50 – 0.90% | |
| Phosphorous, max | 0.040% | 0.040% |
| Sulfur, max | 0.045% | 0.050% |
| Silicon | 0.15 – 0.35% | 0.15 – 0.35% |
| Chromium | | 0.45 – 0.65% |
| Nickel | | 0.25 – 0.45% |
| Copper | | 0.25 – 0.45% |
- Weathering steel DTIs may also be made from any of the type 3 steels listed in A325 and F436
- Weathering Steel DTIs having Copper, Sulfur, and Phosphorous conforming to the above, and having a Corrosion Resistance Index of 6 or higher calculated on the basis of the heat analysis as described in Guide 101 Predictive Method based on the data of Larabee and Coburn shall be considered acceptable.
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