1.1 This specification covers the requirements for carbon and alloy steel compressible-washer-type direct tension indicators capable of indicating a specified bolt tension in cap screws, bolts, anchors, and studs.

1.2 Direct tension indicators in nominal diameter sizes ¹/₄ through 2¹/₂ in. are covered.

1.3 There are two Types of DTIs covered by this specification, Type 1 and Type 2.

1.3.1 Type 1 DTIs are suitable for comparatively large bearing surfaces.² Type 1 DTIs are available in Grades 55 and 105, which differ in the amount of tension they indicate at a prescribed gap (see Table 1).

TABLE 1 Acceptable Range of Compression Load^A

DTI Nominal Diameter (in.)	Mean Compression Load^B Range in Pounds (lbs)		Mean Compression Load^C Range in Pounds (lbs)
DTI Nominal Diameter (in.)	Grade 5	Grade 8	Grade 55	Grade 105
¹/₄	2200 to 2450	3100 to 3450	...	...
⁵/₁₆	3500 to 3850	4950 to 5500	...	...
³/₈	5300 to 5850	7500 to 8300	...	...
⁷/₁₆	7200 to 7900	10100 to 11200	...	...
¹/₂	9700 to 10700	13700 to 15340	4450 to 4900	8500 to 9400
⁹/₁₆	12350 to 13600	17400 to 19200	5700 to 6300	10900 to 12050
⁵/₈	15550 to 17200	21850 to 24200	7050 to 7800	13500 to 15000
³/₄	22600 to 25000	31900 to 35300	10500 to 11600	20000 to 22150
⁷/₈	30850 to 34100	43550 to 48100	14500 to 16000	27650 to 30550
1	40200 to 44400	56700 to 62700	19000 to 21000	36250 to 40100
1¹/₈	45,100 to 49850	73150 to 80900	23950 to 26450	47300 to 52300
1¹/₄	56550 to 62550	91750 to 101450	30400 to 33600	59850 to 66150
1³/₈	69350 to 79750	112450 to 124250	38550 to 42600	73800 to 81600
1¹/₂	83350 to 92150	135150 to 149400	44050 to 48700	89300 to 98700
1⁵/₈	...	...	55800 to 61700	106200 to 117400
1³/₄	121850 to 134650	177850 to 196500	59550 to 65850	124600 to 137750
1⁷/₈	154550 to 170800	206050 to 227750	75550 to 83500	144500 to 159700
2	160050 to 177200	236850 to 261750	78 650 to 86 950	165800 to 183300
2¹/₄	208400 to 230350	277900 to 307100	102050 to 112750	212900 to 235350
2¹/₂	256500 to 283500	379600 to 419600	125400 to 138600	240550 to 265850

^ACompression load requirements establish the capability of the direct tension indicators to satisfy typical tension requirements for these grades. The user is not obliged to install fasteners and DTIs to these tensions, and is free to specify installation to lower tension values. When so specified, the DTI supplier shall provide a load-gap curve in accordance with 15.2 to enable the user to select the appropriate gap criteria for the intended target tension of the application.

^BMean compression load values for Grades 5 and 8 are based upon 75% of the proof load for SAE J429 cap screws.

^CMean compression load values for Grades 55 and 105 are based upon 60% of the yield strength for the matching fasteners on which they are used.

1.3.2 Type 2 DTIs are suitable for comparatively smaller bearing surfaces.³ Type 2 DTIs are available in Grades 5 and 8, which differ in the amount of tension they indicate at a prescribed gap (see Table 1).

1.4 Direct tension indicators are intended for installation under a bolt or cap screw head, a hex nut, or against a hardened washer or other flat hardened surface.

1.5 The following precautionary statement pertains only to the test method portions, Section 12 and Appendix XI of this specification: This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.