UDC 621’882’211 [ 669’14’018’291] - ( First Reprint JULY 1990) Indian Standard IS : 3757 - 1985 ( Reaffirmed 1998 ) SPECIFICATION FOR HIGH STRENGTH STRUCTURAL ( Second Revision ) BOLTS I. Scope and Field of Application - Covers the requirements for large series hexagon, high strength structural steel bolts in property classes 8’8 and 10’9 and in the size range Ml 8 to M36 with short thread lengths suitable for use in both friction-type and bearing-type structural steel joints. Bolts to this standard when matched with the appropriate nuts have been designed to provide an assembly with a high level of assurance against failure by thread stripping on overtightening. Note - Attention to be obtained. 2. Dimensions is drawn to the importance of ensuring that the bolts arecorrectly used if satisfactory results are and Tolerances 2.1 The dimensions or the bolts shall be as given in Table 1. 2.2 The recommended length-size combinations shall be as given in Table 2. 23 ~Threads shall conform to tolerance class 6g of IS : 4218 ( Part 6 )-1978 ‘ISO. metric screw threads: Part 6 Limits of sizes for commercial bolts and nuts ( diameter range 1 to 52 mm) ( first revision )‘. In case of hot-dip galvanized bolts, the specified tolerance class shall apply before hot-dip galvanizing. 3. Grade - Unless otherwise specified, the bolts shall be of product grade C as specified~in IS : 1367 ( Part 2 )-1979 ‘Technical supply conditions for threaded steel fasteners: Part 2 Product grades and tolerarans ( second revision )‘. 4. p~~chanicat Properties - The bolts shall be of property class 8’8 or 10’9 as specified in IS : 1367 ( Part 3 )-1979 ‘Technical supply conditions for threaded steel fasteners: Part 3 Mechanical properties and test methods for bolts, screws and studs with full loadability ( second revision )‘. 4.1 For tensile, proof load and wedge loading test on full size bolts only four threads shall be exposed between the grips. This is obtained by freely running the nut or fixture to the fullest extent and then unscrewing the specimen four full turns. 4.2 For test purposes, the screw threads on hot-dip galvanized bolts shall be chemically permit assembly with a standard threaded grip or nut, that is, thread class 6H. 5. Finish 5.1 Unless specified otherwise; the bolts shall be supplied with a residual coating of light oil. in the dull black heat-treated condition stripped to 5.2 Where property class 88 bolts are required to be hot-dip galvanized, they shall be galvanized in accordance with the requirements of IS : 1367 ( Part 13)-1983 ‘Technical supply conditions for threaded steel fasteners: Part 13 Hot-dip galvanized coatings on threaded fasteners ( second revision)‘. For fasteners with hot-dip galvanized coatings, the bolts or the mating nuts shall be provided with a suitable lubricant which shall be clean’and dry to the touch to ensure that seizure shall not take place in assembly. The hot-dip galvanized bolts shall be subjected to the anti-seizing test as specified in Appendix A. Note - Bolts 6. General or property class 10’9 should not be hot-dip galvanized since this may cause hydrogen embrittlement. Requirements 6.1 !n regard to permissible surface discontinuities, the bolts shall conform to IS : 1367 ( Pari 9 )1979 ‘Technical supply conditions for threaded steel fasteners: Part 9 Surface discontinuities on bolts, screws and studs ( second revision ).‘. 6.2 In regard to requirements not covered in the standard, the bolts shall conform to IS : 1367 -( Part 1 J-1 980 ‘Technical supplv conditions for threaded steel fasteners: Part 1 Introduction and general information ( second revision )‘. Adopted 26 July 1985 I BUREAU MANAK 0 December 1985,,kIS OF INDIAN SlAPiDARDS ZAFAR I MARG Gr 3 BHAVAN, 9 BAHADUR SHAH NEW DELHI 110002 55 19’75 -21’45 17’65 -.5 18.16’10 11’3 1’2 46 45 4’5 I?&----55’37 _ --0’8 0’4 34’24 30’84 29’16 Thread Size d Ml6 M20 (M22)* 2’5 38 45 0. 23. Max SHALL NOT BE LESS THAN I ‘tip M24 3 (M27)’ 3 M30 3’5 M36 4 56 63 0’8 0’4 31’24 27..__ -0‘0 04 0’4 18.29 12’5 13’40 11’60 8’1 0’8 34 33 --35- t 33’3 39’55 --p 14 14’90 13’10 I t 38’0 46’20 15 15’90 14’10 --’ -.2 0’8 36 I 9'9 1’0 1 .00 Max Min Min Nom Max Min Min Min Min Msx t I I 24’9 29’@6 10 ’ 10’75 9’25 6’6 0’6 27 26’16 t I 1 31’4 37.8 -_. .2 50 49 5’3 s Chamfer length 2 Note - -3’8 41 40 4’5 1 3 1 3’8 ( Sizes shown in brackets are at second preference.I i 1 I 12’4 i. 15’0 1’5 60--__ 58’8 6 9.1985 TABLE 1 DlMiNSlONS FOR HIGH STRENGTH ?TRUCTURAL ( Clause 2.37’00 35.-__ 0’4 I P Pitch of thread braf For length I Nom%1 Max Min Max Max Min dw I ii 2 I 2’5 36 43 I 1 1 I 41 48 0’8 0’4 27’64 24’84 23’16 0’8 -2% .84 26’16 4:‘8 50’85 17 __ 17’90. Max = s actual. BOLTS DETAIL X DETAIL ROUNDED BOLT END Y HEAD TYPE FOR BOLTS OF THREAD SIZE d >20 ALTERNATIVES DIFFERENCE BETWEEN IS. dimensions apply before galvanitin& t dw. _. *For galvanized bolts. IS : 3757 .16. 2 .. Min AND la. I._.- t 55’9 e k k’ I 86’44 -22.1 ) All dimensions in millimetres.70 15’30 A23’24 20’84 19’16 I I 1 i 1 25’24 22’84 21’16 41’00 ---.7 .7 --_. 148 : 156 .5 68. 137 147 167 167 177 187 197 g.5 26’5 31’5 36% 41’6 46.5 D7’B :3:5” 37’5 . . .5 99’6 K6” 29’5 39’5 t::: 69’5 79’5 89’6 99. bref 3 P = Is. - Thread Size d -_ Ml6 M20 (M22) 1s Min B - - I Min M24 M30 M36 . Min lengths are below the bold stepped line.5 17’S’ 11’5 4: 50 55 :: 55” 8”: 90 w 109: 110 120 130 140 150 160 170 % 200 210 220 230 240 ts6: :3x 41’2! 38’7! 5 43’71 i 46’21 51’2! 48’7! 5 56’5 53’5 58’5 x::: 63’5 71. 98’25 .8 -i4 149..304 24 :94 5 :72 2 :: Z 2294 . 1KY 108’25 i I 11:7: i I %“” : Z”” : 138 :. : 176 l! :: 186 04 196 $! 206 :44 216 $ 34 226 . 37’9 77’5 t7.X 19’5 24’5 29’6 34’5 39’5 44’5 49.: 2 % 44 49 E E 9”: 102 112 122 132 142 152 162 172 182 192 % $fi 46 :: :: 79 :Zt 109 119 129 139 149 159 169 179 189 199 209 219 229 239 249 1:.TABLE 2 RECOMMENDED LENGTH-SIZE COMBINATIONS ( Clause All dimefisions 2.Z 175 185 195 206 21s 225 6 :.. 156 !66 !76 :: 22. Max - Formulae: I For bolts with lengths above the bold line.: 9”: 106 116 126 136 146 156 166 176 186 196 206 216 t3t 246 256 2 E z 72 t22 ::: 122 132 142 152 162 :Zf 192 202 212 t:3 242 262 262 1t.:._Is Max Ma. g’: 03’5 13’5 23’5 33’6 :::5 63’5 73’5 83’5 93’5 K5” f$6” 4”.5 17. 6”. - % 49’5 Note Note 1 2 Recommended lu. 93’25 . 4.l Min Length I Nom Min Max Min Max -9 : ::: :8” $94 5.5 51’9 56’5 59’5 69’5 79.. :t 38 43 :: :: . 123 133 143 153 163 173 183 193 % 223 2234x 33: :84 :: 39 44 “6:: 7677 87 lo93 :. Max Is. $6” 9855 105 115 125 135 145 155 165 I75 185 195 !05 !15 !25 !35 !35 !46 40 2: s533 Z . :23t 22:.294 . 11.5 54’5 57’5 67’5 77’6 37’5 37. XT. 117’ 117 127 157 67 77 .5 17. . Z :: 64 344 1% 114 124 134 144 :x Z 75 2 :E 12s :Z i: 184 $4 114 !24 !34 !44 :.2 ) FOR HIGH STRENGTH STRUCTURAL BOLTS in millimetres. lnom = lg.5 )7’5 17. hfin e 1’5 P and 10.5 19’5 3tB 4 Min 43 Max Ja Max 1s Min Max Max I- -. Max . 237 ..5 15’5 52::: 30’5 35’6 ZX 53’5 63’5 73’5 16’5 .5 09.5 76’5 73’5 81’5 78’5 86’75 83’2E i 91’75 88’25 .5 !7.: 166.:. IS. Min + 3 P Sizes shown in brackets are of second preference.5 89.56 16’5 21. 22 i: :2’ :. :4 :! !t i !84 . Designation . Sampling .4 Hardened and tempered washers to be used with these bolts shall conform to the requirements of lS : 6649-1985 ‘Hardened and tempered washers for high strength structural bolts and nuts ( firsr revision ) ‘.and criteria of acceptance shall be in accordance ‘Methods for sampling of fasteners ( first reV/SiOn 1’. IS : 2814-1959 symbols on the top Minimum height of markings shall be 4’0 mm. 10. 9.name. the letter N shall be added to the designation as follows: High Strength Structural Bolt M24 . hot-dip galvanized 10’9S. size. 0 XYZ 8S . length 140 mm.3. dull black \ Nut Property Class and Finish 8s or lOS. In case of hot dip galvanized bolts. hot-dip galvanized lOS. the number of this standard and the property class identification symbol 8’8s or 10’9S-the sl:ffix letter S denotes a high strength structural bolt with a larga series hexagon head.Sampling’. dull black 1 OS. 11. Mode of Delivery .The bolts shall be delivered in accordance with IS : 1367 ( Part 18 )-I 979 ‘Technical supply conditions for threaded steel fasteners: Part 18 Marking and mode of delivery ( second revision ) ‘.Details available with the Bureau of Indian 4 Standards. When embossed.1 These nuts shall be of the property class and finish for each type of bolt as follows: Bolt Property Chess and Finish 8’8S. as shown below: a) The manufacturer’s identification b) The property class indetification symbol.3 The high strength structural nuts to be used with these bolts shall conform to the requirements lS : 8623-l 985 ‘High strength structural nuts ( first reViSiOfJ 1’.: 140 N IS : 3757-8’88 galvanized with 8.1985 6.Is : 3757 . dull black 8’8S. and symbol 8s for 8’8s or 10s for 10’9s. property class 8’8 and galvanized shall be designated as: High Strength Structural Bolt M24 x 140 IS : 3757-8’8s galvanized structural nut 7. marking shall project not less than 0’3 mm above the surface of the head and total head height ( head plus markings ) shall not exceed the specified maximum head height plus 0’4 mm. the word ‘galvanized’ shall be added to the designation.High strength structural bolts shall be marked with the following surface of the bolt head.High strength structural bolts shall be designated by . dull black of 1 8.1 If the bolt in the above example is required with a hot-dip galvanized high strength ( see IS : 6623-1985 ). 6. nominal lenqth. Example : A high strength structural bolt of size M24. either embossed or indented. 7. Certification Marking a. Marking . rer. In the present revision of IS : 3757. from 32 to 34 mm in line with (S : 9519-1980 ‘Width across flats for hexagon head bolts and nuts’. The nut shall be initially tightened to produce a load in the bolt not less than 10 percent of the specified proof load. these shall be subject to the following anti-seizing test for testing the effectiveness of the lubricant coating applied to the hot-dip galvanized bolts or nuts: a) The test shall be carried out on bolts. It is. shorter thread lengths have been provided to ensure no same bolting installation procedure. There shall be no other lubricant applied for the purpose of this test. and the final tensioning shall be completed without stopping the motion of the nut.ral bolts’ to enable them to be used for both friction-type and bearing type of. the width across flats for M20 size has been changed connections. ( Min) b) cl EXPLANATO-kY NOTE IS : 3757 ‘Specification for high tensile friction grip fasteners for structural engineering purposes’ The first revision of IS f 3767 catered for high tensile friction grip was originally published in 1986. bolts only. ? The bolt with nut and washer selected for testing shall be placed with the washer directly under the nut in a steel joint with total thickness sothat three to five full threads of the bolt are located between the bearing surfaces of the bolt head and nut. or stripping of the bolt or nut thread.2. 6 . structural steel. and include a lubricant coating as required by 5. Where bolts and the mating nuts and washers with hot-dip galvanized coating are specified. recognized that some transition period would be essential during which the new across flat size would be introduced and the old across flat size phased out. the bolt and the nut position shall be marked to provide the starting point for the rotational movement to be measured. nuts and washers from the manufact. the title of the standard has been changed to ‘High strength structu. The nut shall be rotated in accordance with the requirements of Table 3 from the initial tightening position without fracture of the bolt. separate standards.2 ) ANTI-SEIZING TEST FOR HOT-DIP A FASTENERS GALVANIZED A-l. The diameter of the holes in the assembly shall have the same nominal diameter as the hole in the washer. During this transition period. the corresponding nuts and washers were covered. nuts and washers in the condition as supplied by the manufacturer and shall be in accordance with. If the test is performed by the user it s II be carried out immediately after receipt of the bolts. however. TABLE 3 NUT ROTATION REQUIREMENTS Bolt Length ( Nominal ) I< 2dclC3d 3d<lC4d 4dclCEd I> Ed 2d Nut Rotation 180’ 240” 300” 360’ 420. thread protrusion in the shear plane so-that higher working stresses can be . connections with the Further. During nut rotation the bolt head shall be restrained from turning. by.1985 APPENDIX ( Clause 5. After this initial tightening.adopted for bearing-type Also due to technical reasons.IS : 3757 . 1985 the bolts may be supplied with the old across flat size and other related dimensions as mentioned below as being functionally equivalent. bolts with old across flat site should not be supplied with nuts with new across flat size and vice-versa. New Delhi. kll dimensions in millimetres. MS. Thread Size d I e Min 35’03 The standard is based on ISOlDlS 7412 ‘High strength structural bolts ( short thread length type )’ issued by the International Organization for Standardization. India .IS : 3757 . 6 Reprography Unit. However. . ALTERNATIVES .n -k y------ ‘9 ----y. Min must nor be leas than 1’5 P.-- I (bl- / -k' ~-----I------ HEAD TYPE OF THREAD FOR BOLTS SIZE d > M20 ROUNDED BOLT END Note -The difference betweer. /c. Max and Ig.