Standard North American DTIs are made to ASTM F959 or F959M (metric), which define the chemical, mechanical (read compression load vs. residual DTI gap), and dimensional requirements. Complete F959 specifications are available from ASTM or you can contact Applied Bolting and we will send you a photocopy. The following is a summary of ASTM F959.
Do we make all these sizes and grades? See our LINECARD here.
Chemical Requirements(%) Product Analysis
|Carbon||.27 - .53|
|Manganese||.47 - .93|
|Silicon||.13 - .37|
DTI's are made to compress in proportion to the applied load or bolt tension. A sample of the lot must demonstrate a compression load range at a residual gap of .015" within the following values (the minimum is based on 70% of the minimum ultimate tensile strength of the applicable bolt grade, and the maximum is 20% higher than that). Note that F959 stipulates that the compression load test gap of .015" be the same whether the DTI is plain finish, galvanized, or epoxy coated. Note that the laboratory certification compression load tests for DTI's DO NOT involve bolts, but rather the tests are performed with the DTI's compressed between hardened mandrels.
The compression load test ranges stipulated by ASTM F959 are as follows:
|DTI Size Inch Series||Type A325 (000 lb)||Type A490 (000 lb)|
|DTI Size Metric Series||Type 8.8 (kN)||Type 10.9 (kN)|
Dimensions of Applied Bolting DTI's
|Inch Series (Dimensions in Inches)|
|(NOM DIA OF BOLT)||OD MAX||NO OF BUMPS||THICKNESS AFTER COMPRESSION||OD MAX||NO OF BUMPS||THICKNESS AFTER COMPRESSION||ID MAX|
|Metric Series (Dimensions in mm)|
F959 only allows for mechanical galvanizing (to ASTM B695) and epoxy coating on top of mechanical galvanizing. Other coatings are allowed with the approval of both the manufacturer and the purchaser. Coating of DTI's by anyone other than the manufacturer is prohibited because all compression testing and certification must be done after coating.
ASTM F959 requires that compression test certifications be issued which show the results of 29 pieces selected at random from the manufactured lot and compression tested according to the F959 Appendix A1. The compression load of all 29 pieces must be within the range stipulated above. Applied Bolting makes all product certifications available from this website by .pdf download.
All DTIs are stamped with an individual unique lot mark, which can be related to the lot number. Through the lot number, all DTI lots are traceable to date of manufacture and compression load properties.