IS 13096 : 2000 IS0 898-6 : 1994 Indian Standard FASTENERS - HEXAGON NUTS WITH SPECIFIE:D PROOF LOAD VALilES - FINE PITCH THREAD MECHANICAL PROPERTIES ( First Revision ) ICS 21.060.10 0 BIS 2000 BUREAU OF INDIAN STANDARDS M A N A K B H A V A N , 9 ~BAHADUR SHAH ZAFAR M A R G NEW DELHI 110002 July 2000 Price Group 5 Bolts, Nuts and Fasteners Accessories Sectional Committee, BP 33 NATIONAL FOREWORD This Indian Standard ( First Revision ) which is identical with IS0 898-6 : 1994 `Mechanical properties of fasteners - Part 6 : Nuts with specified proof load values - Fine pitch thread' issued by the International Organization for Standardization ( IS0 ) was adopted by the Bureau of Indian Standards on the recommendation of the Bolts, Nuts and Fasteners Accessories Sectional Committee and approval of the Basic and Production Engineering Division Council. This standard was originally published in 1991 by adopting IS0 898-6 : 1988. This first revision has been taken up consequent upon the revision of IS0 898-6 : 1988, to keep it in line with the latest version. In the adopted standard, certain terminology and conventions are not identical to those used in Indian Standards. Attention isdrawn especially to the following: a) Wherever the words `International Standard' appear referring to this standard, they should be read as `Indian Standard'. b) Comma ( , ) has been used as decimal marker while in Indian Standards the current practice is to use a full point ( . ) as the decimal marker. In the adopted standard, reference appears to certain International Standards for which Indian Standards also exist. The corresponding Indian Standards which are to be substituted in their place are listed below along with their degree of equivalence for the editions indicated: international Standard IS0 68 : 1973') Corresponding Indian Standard IS 4218 ( Part 1 ) IS0 General purpose metric screw threads : Part 1 Basic profile ( second revision ) ( under preparation ) IS 4218 ( Part 2 ) IS0 General purpose metric screw threads : Part 2 General plan ( second revision ) ( under preparation ) IS 4218 ( Part 4 ) IS0 General purpose metric screw threads : Part 4 Selected sizes of bolts, screws and nuts ( second revision ) ( under preparation ) IS 9519 : 1980 Dimensions for width across flats for hexagon head bolts and nuts IS 919 ( Part 2 ) : 1993 IS0 System of limits : Part 2 Table of standard tolerance grades and limit deviation for hole and shaft ( first revision ) General IS 4218 ( Part 3 ) : 1999 IS0 purpose metric screw threads : Part 3 Basic dimensions ( second revision ) Degree of Equivalence Identical IS0 261 : 19732) do IS0 262 : 1973s do IS0 272 : 1982 IS0 286-2 : 1988 Modified Identical IS0 724 : 1993 do I) Revised in 1998 in two parts. Part 1 is applicable and being adopted as second revision of IS 4218 ( Part 1). 2, Revised in 1998 and being adopted as second revision of IS 4218 ( Part 2 ). 3, Revised in 1998. ( Continued on third cover) IS 13096 : 2000 IS0 898-6 : 1994 Indian Standard FASTENERS - HEXAGON NUTS WITH SPECIFIED PROOF LOAD VALUES - FINE PITCH THREAD MECHANICAL PROPERTIES ( First Revision ) 1 Scope This part of IS0 898 specifies the mechanical properties of nuts with specified proof load values when tested at an ambient temperature range of + 10 "C to + 35 "C. Mechanical and physical properties will vary with respect to temperature and property class. Products conforming to the requirements of this part of IS0 898 are evaluated only at the ambient temperature range and may not retain the specified physical properties at higher and lower temperatures. At temperatures higher or lower than the ambient temperature range, a significant change in properties may occur. When fasteners are to be used above or below the ambient temperature range, it is the responsibility of the user to ensure that the mechanical and physical properties are suitable for his ~particular service conditions. This part of IS0 898 applies to nuts - with nominal thread diameters, d, from 8 mm up to and including 39 mm (fine pitch thread); - of triangular IS0 thread and with diameters and pitches in accordance with IS0 68 and IS0 262 (fine pitch thread); - with diameter/pitch combinations in accordance with IS0 261 (fine pitch thread); - with thread tolerances 6H in accordance with IS0 965-l and 965-2 (see note 2); - with specific mechanical requirements; - with widths across flats as specified in IS0 272; - with nominal heights greater than or equal to 0,5d"; - made of carbon steel or alloy steel (see note I). It does not apply to nuts requiring special properties such as - weldability; - prevailing torque performance (see IS0 2320); - corrosion resistance (see IS0 3506); - ability to withstand temperatures above + 300 "C or below - 50 "C. (However, see note 1.) NOTES 1 Nuts made from free-cutting steel should not be used above + 250 "C. 2 With thread tolerances other or larger than 6H, a decrease in the stripping strength should be considered (see table I). 1) In IS0 898:1988, the symbol D was used. 1 IS 13096 : 2000 IS0 6968 : 1994 Table 1 - Reduction in thread strength Test load, 96 d IS0 965-2:1,980, IS0 general purpose metric screw threads - Tolerances - Part 2: Limits of sizes for general purpose bolt and nut threads - Medium quality. IS0 4964: 1984, Steel - Hardness conversions. Thread tolerances 6H 100 100 7H 96 98 6G 97,5 98,5 mm 8~ d< 16 16 0,8d Mating bolts style 1 Prqperty class of nut Property class 3.6; 4.6; 4.8 5 6 8 10 12 " 5.6; 5.8 6.8 8.8 Nominal thread diameter range mm d< 39 d< 39 d< 39 d< 39 d,< 16 Nuta style 2 Nominal thread diameter range mm d< 39 d,< 39 d< 39 d< 16 d< 16 d< 39 d< 16 10.9 12.9 NOTE - In general, nuts of a higher property class can replace nuts of a lower property class. This is advisable for a bolt/nut assembly going Into a stress higher than the yield stress or the stress under proof load of the bolt. However, should tightening beyond bolt proof load take place, the nut design is intended to ensure at least 10 % of the over-tightened assemblies fail through bolt breakage in order to warn the user that the installation practice is not appropriate. NOTE 3 For more detailed information on the strength of screw thread assemblies and for the styles of nuts, see IS0 898-2:1992, annex A. 3.2 Nuts with nominal heights 2 0,5d and < 0,8d (effective heights of thread 2 0,4d and < O&W Nuts with nominal heights 3 0,5d and -C 0,8d (effective height of thread 2 0,4d and < 0,6d) are desig- nated by a combination of two numbers: the second indicates the nominal stress under proof load on a hardened test mandrel, while the first indicates that the loadability of a bolt-nut assembly is reduced in comparison with the loadability on a hardened test mandrel and also in comparison with a bolt-nut assembly described in 3.1. The effective loading capacity is not only determined by the hardness of the nut and the effective height of thread but alsG by the tensile strength of the bolt with which the nut is assembled. Table3 gives the designation system and the stresses under proof IGad of the nuts. Proof loads are shown in table6. A guide for minimum expected stripping strengths of the joints when these nuts are assembled with bolts of various property classes is shown in table7. 3 IS 13096 : 2000 IS0 898-6 : 1 9 9 4 Table 3 - Designation system and stresses under proof load for nuts with nominal heights 2 0,5d and < 0,W Property class of nut oa 05 Nominal stress under pro&f load Nuts of property classes 05, 8 (style 11, 10 and 12 shall be hardened and tempered. Actual stress under proof load N/mm2 400 500 N/mm2 380 500 5 Mechanical properties When tested by the methods described in clause 8, the nuts shall have the mechanical properties set out in table5. 4 Materiais Nuts shall be made of steel conforming to the chemical composition limits specified in table4. The chemical composition shall be analysed in accordance with relevant International Standards. Table 4 - Limits of chemical composition 6 Proof load values Proof load values are given in table6. The nominal stress area, $, is calculated as follows: where 4') 1) Nuts of this property class may be manufactured from free-cutting steel unless otherwise agreed between the purchaser and the manufacturer. In such cases, the following maximum sulfur, phosphorus and lead contents are permissible: sulfur 0,34 %; phosphorus 0,ll %; lead 0,35 % 2) Alloying elements may be added, if necessary, to develop the mechanical properties of the nuts. 4 is the basic pitch diameter of the external thread; is the minor diameter of the external thread h=d, -f where d,lJ is the basic minor diameter of the external thread; H is the height of the fundamental triangle of the thread. l ) See IS0 724. 4 Stress under Stress under Nominal thread diameter d mm 86 d< 10 lO 16 mm may be quenched and tempered at the discretion of the manufacturer. Ml2 x 125 Ml2 x 1.5 Ml4 x 1.5 Ml6 x 1.5 Ml6 x 1.5 M18x2 M20 x 115 M20x2 M22 x 1,5 M22x2 M24x2 M27 x2 M30x2 M33x2 M36x3 M39x3 92.1 88.1 125 167 215 204 272 258 333 318 384 496 621 761 865 1 030 35 000 33 500 47 500 63 500 81 700 77 500 103400 98 000 126 500 120 800 145900 188 500 236 000 289 200 328 700 391 400 46 000 44000 62 500 83 500 107 500 102 000 136 000 129 000 166 500 159 000 192 000 248 000 310 500 380 500 432 500 515 000 63 500 60 800 86 300 115200 154 800 146 900 195800 185 800 239 800 229 000 276 500 351 100 447 100 547 900 622 800 741 600 71 800 68 700 97 500 130 300 187 000 177 500 236600 224 500 289 700 276 700 334100 431 500 540 300 662 100 804 400 957 900 88 000 84100 119 400 159 500 221 210100 280200 265jOO 343000 327500 395500 510900 639600 783800 942800 1123000 500 82 000 78400 111 200 148 600 - 102 200 97 800 138 800 185 400 - 97 200 92 900 131 900 176 200 232200 220300 293800 278600 359600 343400 414 700 535700 670700 821 934200 1112000 900 110 500 105700 150 000 200400 - IS 13096: 2ooo IS0 898-8 : 1 9 9 4 7 Failure loads for nuts with nominal heights of 3 0,5d and -=I 0,8d The values of failure loads given for guidance in table 7 apply to different bolt classes. Bolt stripping is the expected failure mode for lower strength bolts, while nut stripping can be expected for bolts of higher property classes. Table 7 - Minimum stripping strength of nuts as a percentage of the proof load of bolts :iEz the nut 04 05 Minimum stripping strength of nuts as a percentage of the proof load of bolts with property classes 6.9 I 8.8 I 10.9 I 12.9 85 100 65 85 45 60 40 50 8 Test methods 8.1 Proof load test The proof load test shall be used wherever the capacity of available testing equipment permits, and shall be the referee method. The nut shall be assembled on a hardened and threaded test mandrel as shown in figures 1 and 2. For referee purposes, the axial tensile test is decisive. The proof load shall be applied against the nut in an axial direction, and shall be held for 15 s. The nut shall resist the load without failure by stripping or rupture, and shall be removable by the fingers after the load is released. If the thread of the mandrei is damaged during the test, the test should be discarded. It may be necessary to use a manual wrench to start the nut in motion. Such wrenching is permissible provided that it is restricted to one half turn and that the nut is then removable by the fingers. The hardness of the test mandrel shall be 45 HRC minimum. Mandrels used shall be threaded to tolerance class 5h6g except that the tolerance of the major diameter shall be the last quarter of the 6g range on the minimum material side. 'I DllbtaImfromI9Da862. Figure 1 - Axial tensile test Figure 2 - Axial compressive test 7 IS 13096 : 2000 Iso 698-6 : 1994 8.2 Hardness test For routine inspection, hardness tests shall be carried out on one bearing surface of the nut and the hardness shall be taken as the mean of three values spaced 120" apart. In case of dispute, the hardness tests shall be carried out on a longitudinal section through the nut axis and with impressions placed as close as possible to the nominal major diameter of the nut thread. The Vickers hardness test is the referee test, and where practicable a load of HV 30 shall be applied. If Brine11 or Rockwell hardness tests are applied, the conversion tables in accordance with IS0 4964 shall be used. The Vickers hardness test shall be carried out in accordance with the requirements of IS0 6507-I. The Brine11 hardness test shall be carried out in accordance with the requirements of IS0 6506. The Rockwell hardness test shall be carried out in accordance with the requirements of IS0 6508. 8.3 Surface integrity test For the surface integrity test, see IS0 6157-2. Figure 4 - Examples of marking with code symbol (clock-face system) Marking dot may be replaced c by manufacturer's mark hem Figure 3 - Examples Of marking with designation symbol 9.3 Marking of left-hand thread Nuts with left-hand thread shall be marked as shown in figure5 on one bearing surface of the nut by indenting. The alternative marking for left-hand thread shown in figure6 may also be used. 9 Marking 9.1 Symbols Marking symbols are shown in tables 8 and 9. 9 . 2 Ldentification Hexagon nuts of all property classes shall be marked in accordance with the designation system described in clause 3, by indenting on the side or bearing surface, or by embossing on the chamfer. See figures 3 and 4. Embossed marks shall not protrude beyond the bearing surface of the nut. -Figure 5 - Left-hand thread marking 8 IS 13096 : 2oocl IS0 898-6 : 1994 9.4 Alternative marking Alternative or optional permitted marking as stated in 9.1 to 9.3, is left to the choice of the manufacturer. 9.5 Trade (identification) marking 11 s = uAdnlacrolmfla~. Figure 6 - Alternative left-hand thread marking The trade (identification) marking of the manufacturer is mandaton/ on all products covered by the obligatory marking requirements for property classes, provided this is possible for technical reasons. Packages, however, shall be marked in all cases. Table 8 - Marking for nuts with property classes in accordance with 3.1 Property class either designation symbol . 5 5 6 6 8 8 F z t E P g E 8 u or code symbol (clock-face sys- tern) 1) Indication of the 12 o'clock position with the manufacturer's mark is not possible. Table 9 - Marking for nuts with property classes in accordance with 3.2 Property class 04 05 Marking _@ @._ ( Continued from second cover ) International Standard Corresponding Indian Standard IS 1367 ( Part 6 ) : 1994 Technical supply conditions for threaded steel fasteners : Part 6 Mechanical properties and test methods for nuts with specified proof loads ( third revision ) IS - IS0 General purpose metric screw threads - Tolerances : Part 1 Principles and basic data ( under preparation ) Degree of Equivalence Identical IS0 898-2 : 1992 IS0 965-l : 1980') do IS0 965-2 : 1980*) IS - IS0 General purpose metric screw threads - Tolerances : Part 2 Limits of sizes for general purpose external and internal screw threads - Medium quality ( under preparation ) IS 4258 : 1982 Hardness conversion for metallic materials ( first revision ) IS 1367 ( Part 10 ) : 1979 Technical supply conditions for threaded steel fasteners : Part 10 Surface discontinuities on nuts ( second revision ) IS 1500 : 1983 Method for Brine11 hardness test for metallic materials ( second revision ) IS 1501 ( Part 1 ) : 1984 Method for Vickers hardness test for metallic materials : Part 1 HV 5 to HV 100 ( second revision ) IS 1586 : 1988 Method for Rockwell hardness test for metallic material ( Scales A-B-C-D-EF-G-H-K ) ( second revision ) do IS0 4964 : 1984 IS0 61 57-23) Modified do IS0 6506 : 1981 IS0 6507-l : 1982') do do IS0 6508 : 1986 do In reporting the results of a test or analysis made in accordance with this standard, if the final value, observed or calculated, is to be rounded off, it shall be done in accordance with IS 2 : 1960 `Rules for rounding off numerical values ( revised)`. `) Revised in 1998. *) Revised in 1998. a) Published in 1995. `) Revised in 1997. 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