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• 2018-05-07

A minimum thread protrusion length is given to ensure that all the threads are engaged This is required to ensure a full strength fastener Equipment component drawings should specify the type length and size of bolt stud bolt stud etc to be Use AISC anchor rod and base plate hole recommendations Use the recommended hole sizes for base plates shown in AISC Design Guide 1 or in Table 14 2 of the 3rd Edition Manual This will allow for even more tolerance in the founda tion for anchor rod placement Make sure to use a heavy plate washer over the hole 82022 03 09 nbsp 0183 32 Hence the potential of thread stripping of both the internal and external threads must be avoided if a reliable design is to be achieved When specifying nuts and bolts it must always be ensured that the appropriate grade of nut is matched to the bolt grade Having the top of the bolt thread flush with the nut results in the chamfer being present within the nut Never let thread length get the best of you with our help from ASMC We ve put together a handy thread length chart that is certain to make quick work of confusion and increase work production 215 SIGN UP FOR OUR NEWSLETTER TO RECEIVE SPECIAL OFFERS SIGN UP Contact Us 888 660 0334 19087 W Casey Rd Libertyville IL 60048 CAGE Code 8CZU4 Accounts amp 2007 04 18 nbsp 0183 32 075 7 5 1 MINIMUM THREAD PROTRUSION A minimum thread protrusion length is given to ensure that all the threads are engaged This is required to ensure a full strength fastener Equipment component drawings should specify the type length and size of bolt stud bolt stud etc to be used to obtain the proper thread protrusion

2018 12 12 nbsp 0183 32 They consist of fasteners that capture and join other parts and are secured with the mating of screw threads As per AISC We have 3 type of bolts which are commonly used ASTM A325 Structural Bolts Fully tensioned amp snug tight 70 of tensile strength of bolt ASTM A490 Structural bolts Fully tensioned amp snug tight 70 of tensile strength of bolt ASTM A307 In bolted connections minimum edge distances from the centre of any bolt to the edge of a plate or the flange of a rolled section should be used as specified below taken from the Australian Standard 4100 Steel structures Rolled edge of a rolled section – 1 25df Sheared or hand flamecut edge – 1 75df Rolled plate machine flamecut sawn or planed edge – 1 50df Note What is the minimum thread for 3 8 eye bolt What are the acceptable bolting methods per AISC There are four acceptable installation methods to obtain the pretension values for bolting turn of nut method with or without match marking calibrated wrench method twist off type tension control bolt method and direct tension indicator method Each of these methods is Open Minimum ISO Thread Engagement Calculator Threaded Hole Fastener Ratio Open ISO Thread Fastener Ratio and Length Calculator This assumes that the male and thread materials have the same strength If the Material strength is lower i e J as calculated below is greater than 1 then the length of engagement must be increased to the threads included in the shear plane AISC amp NISD 2000 Threads in the Shear Plane Threads Included In The Shear Plane Threads Excluded From The Shear Plane 12 In a slip critical joint the bolts must be fully pretensioned to cause a clamping force between the connected elements This force develops frictional resistance between the connected

2002 08 30 nbsp 0183 32 AISC has changed its terminology to anchor quot rod quot to eliminate confusion between Yes The use of either rolled cut or ground threads is permitted in ASTM F1554 Section 6 2 Rolled threads are formed by pressing threading dies into the shank to displace the surplus of the metal outward The original rod diameter must be slightly less than the nominal diameter 2021 11 01 nbsp 0183 32 There is a NASA standard MSFC STD 486B available online free that contains requirements for minimum thread protrusion If you look this standard up it is given in Table XII Personally I don t want some highway sign dangling over my head with nuts only half engaged Perhaps there s a paper trail with calculations that say this condition is acceptable The ratio of stress area to nominal bolt area ranges from 0 75 for 190 in diameter to 0 79 for 11⁄8 in diameter per the Guide to Design Criteria for Bolted and Riveted Joints Accordingly to simplify calculations the lower bound reduction of 0 75 is incorporated in AISC tabulated nominal strength values for use with nominal bolt areas minimum bolt pretension T m as described in Section 5 4 1 F n Nominal strength per unit area ksi F u Specified minimum tensile strength per unit area ksi I Moment of inertia of the built up member about the axis of buckling see the Commentary to Section 5 4 in 4 L Total length of the built up member see the Commentary to Section 5 4 How to determine A325 Structural Bolt Length If you are looking to determine the optimal length for your Structural Bolts on your project You will need to calculate the sum of Grip Thickness of materials clamped together Corresponding number on the table below Depending on number of F436 Washers used and bolt diameter Bolt Diameter

This includes stock sizes available in the market place length tolerances short thread lengths and the actual head dimensions are the same as any heavy hex head bolt Dimensions per ASME B18 2 6 2011 Available Sizes Although technically any size A325 can be custom manufactured there are certain restrictions as well as common lengths which are more readily 2011 07 31 nbsp 0183 32 Thread protrusion requirementsA special plate washer of minimum thickness 4 mm shall be used under the nut if the hole diameter is larger than the bolt diameter by 3 mm or more Oversize hole shall not exceed 1 25 d or d 8 mm in diameter where d is the nominal diameter of the bolt in mm A short slotted hole shall not exceed the appropriate hole size in width and 1 33 d in length A long slotted hole AISC amp NISD 2000 Threads Excluded From The Shear Plane BMA Engineering Inc – 6000 Slip Critical Joints In a slip critical joint the bolts must be fully pretensioned to cause a clamping force between the connected elements Thisforce develops frictional resistance between the connected elements The frictional resistance allows the joint to withstand loading without 2022 02 11 nbsp 0183 32 To ensure that bolt threads are fully engaged in the nut BS EN 1090 2 clause 8 2 2 specifies that the protrusion must be at least one thread pitch This is because the very end of the bolt may be slightly convex leading to a reduced resistance if threads are not fully effective The same clause specifies the necessary numbers of threads within the grip length between

3 2 1 The minimum thread protrusion for each male threaded fastener must be one full thread beyond the face of the nut The maximum thread protrusion for each male threaded fastener is 10 full threads beyond the face of the nut 3 2 2 For self locking plastic insert nut installations the minimum thread protrusion for bolt or stud end may be flush with the face of the nut B 6 Thread Protrusion A minimum thread protrusion length is given to ensure that all the threads are engaged This will ensure a full strength bolt The bolt should protrude a distance of at least one thread beyond the top of the nut Excessive protrusion should be avoided particularly when necessary clearances accessi bility safety and potential corrosion are impossible to exclude the threads from the shear plane and the design must be based upon the threads included strength val ues Fully threaded A325 bolts are marked on the head of the bolt with A325T instead of A325 so that they can be identi fied even after installation 6 3 Verification Testing 6 3 1 minimum yield strength and two classes denoting thread class as follows Description Grade Tensile Strength ksi MPa Yield Strength min ksi MPa Size Range in mm 36A 58–80 400–558 36 248 1⁄ 4 –4 6 4–102 55 75–95 517–655 55 380 1⁄ 4 –4 6 4–102 105 125–150 862–1034 105 724 1⁄ 4 –3 6 4–76 Class 1A anchor bolts with Class 1A threads Thread protrusion engagement Fastener Substitutions Running torque Fasteners in good condition No lube Allows all fasteners in a joint to take the load evenly Prevents uneven tightness Extremely important in soft goods Why we use torque Pattern Incremental torque final value Incremental –2 less than 250 –3 250 or greater Final torque –Midrange