Torque Tightening Values for Structural Steel Bolts Below is a list of the recommended tightening torques for 12 9 10 9 8 8 zinc plated finish bolts Maximum Recommended Tightening Torques Metric Course Pitch Grade 12 9 Plated Metric Course Pitch Grade 10 9 Plated Metric Course Pitch Grade 8 8 Plated

3 Tensile strength min psi of all Grade 7 bolts is 133 000 Proof load is 105 000 psi 4 Tensile strength min psi of all Grade 8 bolts is 150 000 psi Proof load is 120 000 psi Ref Fastening Reference Machine Design Nov 1977 Bolt Clamping Force vs Tightening Torque for Unlubricated Steel Bolts 5/16 18 3/8 16 1/2 13 5/8

Bolts and Set Screws AS1111 Ajax Metric Hexagon Precision 32 34 Bolts and Set Screws AS1110 Property Class 8 8 Fine Pitch Threads 35 BOLT SHEAR CAPACITY OF AJAX BOLTS AND SET SCREWS 7 37 40 DESIGN OF BOLTED JOINTS FOR GENERAL ENGINEERING 8 41 46 TIGHTENING OF BOLTED JOINTS 9 47 60 ISSUE 99 PAGE 4 90138AjxH/bk99IndexPgs1 8 10

Grade 2 calculations only cover fasteners 1 ⁄ 4 3 ⁄ 4 in diameter up to 6″ long for longer fasteners the torque is reduced significantly Clamp loads are based on 75 of the minimum proof loads for each grade

Tightening Torque SAE J429 Grade 5 K = 0 15 K = 0 17 103 121 128 171 105 120 141 3706 245 1817 2371 2688 3162 278 1363 46 82 92 109 K = 0 20 FNL Grade 9 Clamp Tightening Torque Load Tightening Torque SAE J429 Grade 8 K = 0 15 4169 K = 0 15 K = 0 17 K = 0 20 Unified Coarse Thread Series Fine Thread Series 3544 K = 0 15 383 91 325 78 287 68 327

Bolt torque chart reference guides include Grade 2 B7 A307 A325 Grade 8 A490 and Grade 5 AFT Fasteners is your trusted source for fastener information

Bolt grade 3 6 4 6 4 8 5 8 8 8 10 9 12 9 Nm As mentioned above the tightening torque is for practical reasons the criteria normally used to specify the pre stress in the screw The torque or the moment of force can be requirements On the other hand a nut for securing the length

Title Metric Bolts Screws Nuts Tightening Torques Author Fastener Mart Created Date 8/12/2006 10 22 23 PM

Torque Tightening Values for Structural Steel Bolts Below is a list of the recommended tightening torques for 12 9 10 9 8 8 zinc plated finish bolts Maximum Recommended Tightening Torques Metric Course Pitch Grade 12 9 Plated Metric Course Pitch Grade 10 9 Plated Metric Course Pitch Grade 8 8

per foot of diameter and flange bolt holes must be aligned to within 1/8 maximum offset 6 Adjust the position of the nuts to insure that 2 3 threads are visible above the top of the nut Recommended Tightening Procedures Up to 8 Bolts– Use 4 Pass Method Pass 1 Set the torque wrench to the 30 torque value and apply the

Too low a torque will cause the fastener to pick up more load more often and eventually cycle it to failure or metric 8 8 and 10 9 Information and online shopping for grade 8 nuts bolts and assortments in fine and coarse thread A grade 8 bolt is stronger than the more commonly used grade 5

The following suggested tightening torques provide an excellent starting point for determining torque requirements Remember you may need to vary these numbers somewhat based on the individual joint or the amount of fastener lubrication

Tightening Torque Guide for Grade 5 8 Hex Cap Screws This table is based on IFI 5th Edition Technical Data N 12/N 16 using Equation 1 and a torque coefficient K=0 20 for non plated steel fasteners and K=0 15 for plated fasteners These Figures represent an estimate of torque torque being the measurement of friction not tension required to induce given preload clamp load in a bolt

Tightening Torque Hex Bolts UNC Hex Bolt Properties UNCRECOMMENDED TIGHTENING TORQUE Nominal Size TPI Recommended Tightening Torque Recommended Tightening Torque Grade 5 Grade 8 mm Nm lbft Nm lbft 1/4ʺ 20 9 5 7 14 0 10 5/16ʺ 18 20 0 15 28 5 21 3/8ʺ 16 36 0 27 51 5 38 7/16ʺ 14 59 0 43 81 0 60 1/2ʺ 13 90 0 66 125 0 92

The tightening torques below are for imperial US bolts with tension approximately 70 of yield strength Size in Torque lbf ft SAE Grade 2 SAE Grade 5 SAE Grade 8 18 8 S/S Coarse

Grade 2 calculations only cover fasteners 1 ⁄ 4 3 ⁄ 4 in diameter up to 6″ long for longer fasteners the torque is reduced significantly Clamp loads are based on 75 of the minimum proof loads for each grade and size

Grade B Nuts Strength is similar to Grade 5 Grade B7 Threaded Stud Rod Same as Grade 5 Use with Grade 2H and Grade C nuts Grade C Nuts Strength exceeds Grade 5 Use with heat treated medium strength steel fasteners like ASTM A325 structural bolts Grade G Nuts Strength is similar to Grade 8 Use with ASTM A325 structural bolts Grade 2

properties of grade 8 8 bolt nut iso bolt size pitch stress area mm2 bolt/stud/screw iso 898 1 gr 8 8 nut iso 898 2 gr 8 proof stress n/mm2 proof load kn tensile stress n/mm2 tour que n m hard ness hrc elonga tion# proof stress n/mm2 proof load kn hard ness hrc m6 1 20 1 580 11 7 800 0 9 4 22 32 12 0 855 17 2 30 max

Structural Bolts Installation AS WORKING DEFINITIONS Torque is not used as a measure for the tensioning of structural bolting Bolt torque values are not shown in AS4100 TORQUE The energy taken to twist the nut up the thread of the bolt Measured in Nm TENSION The force generated in the bolt to

correct torque table B Self Locking Nuts When torquing a self locking nut the nut should be run down on the threads of the bolt until the nut almost contacts the mating surface The amount of torque required to run the nut down friction drag torque should be measured and added to the amount of torque specified for the fastener

Bolt Diameter x Pitch Thread Stress Area mm 2 When μ = 0 10 Results in When μ = 0 14 Results in Tightening Torque Nm Pre load kN Tightening Torque Nm

1 3/8 12 1 1/2 12 SAE Grades 5 8 Bolts Screws1 SAE 1 SAE TPI Grade 5 14 Grade 8 14 Surface Condition Torque Adjustment Factors Plain Steel as supplied X 1 0 Plain Steel degreased X 2 0 Zinc Plated as supplied X 1 0 Zinc Plated lightly oiled X 0 9 Galvanised degreased X 2 1 Galvanised lightly oiled X 1 1 Heavily greased X 0 7

If lubrication is to be applied to the nut/bolt multiply the recommended torque by the appropriate factor shown in the table on page 7 Alternatively use the Torque/Tension Calculator on the Norbar website which enables fastener and friction conditions to be modified with ease Bolt Grade 3 6 4 6 5 6 5 8 6 8 8 8 9 8 10 9 12 9

Steel Grade SAE 5 SAE 8 Socket Head Cap Screws Property Class 8 8 10 9 12 9 Socket Head Cap Screw Torque in Pound Foot or Pound Inch Torque in Newton MeterNm Lubed means cleaned dry bolts lubricated with standard medium viscosity machine oil Lubricate all contact areas of the bolts and washers Lubricating the bolts is the suggested method

7/8 9 429 322 606 455 682 511 7/8 14 474 355 669 502 752 564 1 8 644 483 909 681 1022 767 1 12 722 542 1020 765 1147 860 Inch SAE J429 Grade 4 8 4 6 5 8 Tensile 1220MPa Grade ASTM A574 120 000 psi 150 000 psi 170 000 psi 120 350 psi 150 800 psi 176 900 psi Bolt Torque Specs in Foot Pounds or Inch Pounds Tensile 830MPa Tensile 1040MPa

A 1/4 20 grade 2 bolt can only handle 6 foot pounds of torque A 1 8 grade 5 bolt can withstand up to 530 foot pounds of torque One of the most industrial bolts is the 2 4 5 grade 8 which is capable of withstanding up to 8 200 foot pounds of torque The torque applicable to the majority of bolts ranges between 12 and 400 foot pounds of torque

Bolt grade 3 6 4 6 4 8 5 8 8 8 10 9 12 9 Nm As mentioned above the tightening torque is for practical reasons the criteria normally used to specify the pre stress in the screw The torque or the moment of force can be requirements On the other hand a nut for securing the length

TORQUE TENSION RELATIONSHIP FOR A307A GRADE 5 8 9 BOLTS Locknut Size Threads per inch Steel Hex Locknut Steel Hex Flange Nut Grade C FNL Grade 9 Grade F Grade G Clamp Load lbs Tightening Torque Clamp Load lbs Tightening Torque Clamp Load lbs Tightening Torque Clamp Load lbs Tightening Torque min max min max min max min max

The most common grading system used for bolts in the U S is the SAE system but you can find metric grading systems as well There are several grades of bolts but the three common grades for SAE are 2 5 and 8 The common class grades for metric are 5 8 8 8 10 9 and 12 9 Each grade has a specific bolt

Suggested Assembly Torque Values The tapped hole or nut must have an equal or greater proof load than the stud s minimum ultimate tensile strength Generally the full effort of an ironworker with a ordinary spud wrench is sufficient to tighten the nuts on anchor bolts Consult the design engineer to determine the proper tightening torque or

3 Tensile strength min psi of all Grade 7 bolts is 133 000 Proof load is 105 000 psi 4 Tensile strength min psi of all Grade 8 bolts is 150 000 psi Proof load is 120 000 psi Ref Fastening Reference Machine Design Nov 1977 Bolt Clamping Force vs Tightening Torque for Unlubricated Steel Bolts 5/16 18 3/8 16 1/2 13 5/8 11 3

occurs when a given amount Of tightening torque is applied The first factor is the bolt s diameter It takes more force to tighten a 3/4 10 bolt than to tighten a 3/8 16 bolt it is larger in diameter The second factor is the bolt s grade It takes more force to stretch an SAE Grade 8 bolt than it does to stretch an SAE Grade 5 bolt because Of

Bolts and Set Screws AS1111 Ajax Metric Hexagon Precision 32 34 Bolts and Set Screws AS1110 Property Class 8 8 Fine Pitch Threads 35 BOLT SHEAR CAPACITY OF AJAX BOLTS AND SET SCREWS 7 37 40 DESIGN OF BOLTED JOINTS FOR GENERAL ENGINEERING 8 41 46 TIGHTENING OF BOLTED JOINTS 9 47 60 ISSUE 99 PAGE 4 90138AjxH/bk99IndexPgs1 8 10 13/7/00 10 11 AM

MATERIAL Sy KSI LUBR µ TIGHTENING TORQUE in Lbs ft Multiply by 1 356 to obtain N m GRADE 1 36 NL 0 20 4 8 14 22 34 49 68 120 194 291 412 581 762 1012 1253 1596 1944 2398 3507 4799 6513 8593 C 36 L 0 15 3 6 10 17 26 37 51 90 145 218 309 436 572 759 940 1197 1458 1799 2631 3599 4885 6445 O GRADE 2 57 NL 0 20 6 107191

k Class K2 using Torque Method Torque method uses a torque wrench in two steps of assembling km figure is required for calculating first tightening torque value and Vk is required for calculating final tightening torque Andrews Fasteners HR assemblies according to EN 2005 k Class K2 are supplied with km and Vk figures Engineers follow the formula from EN 1090 2 to calculate