Bolt preload table


We manufacture and galvanize headed, bent, and threaded fasteners from 1/2" to 6" in diameter. Failure to do so will result in inadequate bolt pretension and loose connections. The capacity of a bolt is the same regardless of the number of plates being connected together. Torque and Tension in Bolts: Bolt, one of the most widely used fasteners in the industry, is usually tightened by applying torque to the head and/or nut. 14, which requires a good quality lubricant. Table 8 and 9 shows the assembly torque and preload values in torque-angle strategy for M12 Cadmium plated and Aluminium IVD and MoS 2 coated bolt with hexagonal nut and Nylock hexagonal nut combinations. The computed seating load on the gasket is increased to the average of the required bolt strength and the available bolt strength. 5 to 50 percent (preload and operating) safety margins. On the other hand, excessive CF may produce damages in the structural members such as excessive distortion or breakage. BS 8100 - Lattice Towers and Masts BS EN 1993 - Design of Steel Structures. : i) Torque Control ii) Part Turn of Nut iii) Direct Tension Measurement Torque Wrench Tightening torque to preload a bolt Metric thread : M1 M1. TESTING Preload (Tension in Bolt) Clamping Force Torque (Nm) www.


the quality control engineer will be able to check bolt preload on assembled machines. Rumpf as fulfillment of the course require­ ments of C. As an alternative to the typical nut factor method of determining preload, the torque-preload relationships can be determined experimentally. 8 9. 5 of 2007 ASME VIII a loadcase with a factor of 2. Since the quality assurance and integrity of the bolted connection is determined by the bolting assembly itself, visual inspection of the bolt spline removal is sufficient. (1) With reference to Table 2-1 through Table 2-7 , locate the specific table that carries the primary bolt part number (designation) and the part number of the nut. MARYLAND METRICS Technical Data Chart Standard tightening torque for metric screw threads Standard tightening torque [N•m] (Reference value) [N•m] = Newton meter Bolt Torque Calculator. 9% 25. See the instructions within the documentation for more details on performing this analysis. Remember that the Generalized torque coefficients and a universal torque table give engineers an easier path to accurate bolt preloading A simpler way to predict bolt preload | Machine Design the threaded portion of the bolt.


Bickford does admit that this argument of stiffer or less stiffer bolts should be looked at for every individual case. 2 Table 9 Heavy Hex Effect of Bolted Joint Preload on Structural Damping by Weiwei Xu A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Mechanical Engineering Department of Mechanical Engineering College of Engineering University of South Florida Major Professor: Daniel P. (3) Hydrogen embrittlement is a problem with most BOLT TORQUE K FACTORS CHART. PRINCIPLES OF BELLEVILLE SPRINGS 2. loads to be achieved (see Table 1). The preload requirement chart shows the variability that was expected in the bolt's preload, assuming that the torque tightening method was being used. , preload (N); d, nominal bolt diameter (m). The calculation is designed for a geometrical design and strength check of a prestressed bolt connection, loaded by static or cyclic loading resp. Tightening control and operation is easy. A Bolt in Tension. As the bolt is tightened, it is stretched (preloaded).


Fb = force in the bolt (due to preload and external load) Fm = clamp load in the members. 2. 0 Why Does a Bolt Loose n? 2. 8 10. 5ksi. total bolt force preload tensile force Figure 2. EXPERIMENTAL & NUMERICAL STUDY OF DYNAMICALLY LOADED BOLTED & HYBRID (BOLTED/BONDED) JOINTS By Aiswarya Venkadachalam Joining of composite materials is commonly achieved by bolting, bonding, or a combination of the two methods (hybrid) in engineering structures such as aircraft, marine and automotive. The hard contact was used for the connection between bolt-head/nut and plate elements. The mechanics of a bolt in tension are less complicated than for a bolt in shear. 3a shows axial bolt stress variation by tightening as per sequenceat the completion of -1 last –And, for the #10, the nut is stronger than the bolt, which may lead to reduced fatigue life •For all other combinations listed above, the nut or insert is the weak link. ) Min.


Typically expressed as “positive” even though it is a compressive load. (3) Thread size of bolt (10-32, 1/4-28, 5/16-24, 3/8-24, etc. 0. 9 (Eurocode 3) per EN 1993‐1‐8 Section 3 Table 3. 8 6. Use the dimensions of your bolt to determine the appropriate size nut. EN 1090-2:2018 Bolt tightening is controlled by the torque value. D. For a successful assembly, tightening should be carried out with a slow smooth action. Lubrication added to a dry bolt will typically reduce the torque value 15-25%. are given in Table 1.


ii. Results and Discussion 4. The bolted joint works by inducing an initial clamping force ("preload") on the joint by threading the fastener into either a nut or into threads that have been tapped into one of the parts. Calculator - Tightening torque to preload a bolt use the tightening torque specified in the table for the bolt. by Stephen T. The preload requirement inthis case consisted of two elements. This code disaster greatly increases the required thickness of flanges far beyond the loads that the gasket can handle. For P = 0; Fm = Fb = Fi = change in length kb, km – stiffness of bolt and of members, respectively (remember, everything is a spring) A simpler way to predict bolt preload Generalized torque coefficients and a universal torque table give engineers an easier path to accurate bolt preloading. define bolt load on an imported cylinder. When installing a bolt, a common prac-tice is to find a torque table and look up the Total required preload F = S x L (3) Selection of Bolt Material, Bolt Size, Number of Bolts. For easy identification and selection, all Preload Indicating Washers are color-coded by stress level.


2 AISC Design Tables • Table 7-10 on page 7-33 of the AISC Manual gives the design shear of one Engineer’s Guide to Finite Element Analysis of Part-to-Part Connections 6 / i. By selecting a suitable bolt size and bolt material, the required number of bolts can be determined from – N = F f Where N is the number of bolts, F is the total required preload and f is the recommended preload (see Tables 18-23) on the bolt for the Hexagon-Head Bolt Hexagon-head bolts are one of the most common for engineering applications Standard dimensions are included in Table A–29 W is usually about 1. The ±25 to 30 percent accuracy range of using torque to preload bolts and nuts should be considered when determining the suitability of 20. Match your hardware strength-wise! discussing bolt installation. ” The RCSC specification requires bolt preten-sions to be at least 70% of the specified minimum tensile strength, as shown in Table 8. Size Recommended Torque; Grade 2 Grade 5 Grade 8 18-8 S/S Bronze Brass; Coarse Fine Coarse Fine Coarse Fine Coarse Fine Coarse Fine Coarse Fine #4*-----5. 1% Torque reference values for bolt tightening Bolt design preload bolt effective area in threaded region bolt diameter ‐ d by the fastener manufacturer Bolt Preloading Force - Classes 8. 9 column in the table on right, M8, 3116[N] {318[kgf]} , should be selected. If correct make-up is Table -2: Analysis Results for Stress Values in MPa Size- 1M4 M5 M6 Conditions Stress in MPa With No washer 1170 1198 1198 With plain washer 1227 1247 1263 With Spring washer 1270 1280 1298 3. Results showed that after the running-in test, the bolt lengths increased and then decreased due to the stress relaxation. D, table 3.


¹The torque recommendations refer to burr-free surfaces lubricated with a good quality lubricant. Unfortunately there is no low cost means of tightening a bolt and knowing, precisely, the preload value. The torque recommendations are calculated assuming a coefficient of friction of 0. Pinjar1, Prof. Bolt Preload Tension Force: In the tension joint, the bolt and clamped components of the joint are pre-load designed to transfer the external tension load through the joint by way of the clamped components through the design of a proper balance of joint and bolt stiffness. The bolt is stressed up to the proofload value, and if there is no deformation, elongation, or fracture, then the bolt is deemed to have passed. 4 Diagram of internal forces in joint with preloaded bolt loaded by tensile forces, according to [Bickford, 1995] Q&A 2. See how to define preloaded bolts meshed with solid elements using Femap. The value of K depends on the bolt material and size. Varma - Lc = clear distance, in the direction of the force, between the edge of the hole and the edge of the adjacent hole or edge of the material (in. The table below lists a typical range for the "K Factor" as well as the values used in calculating the RepairEngineering Bolt Torque Chart.


Dr. 8-4. Preload relaxation may result over a period of minutes to hours after the first application of the preload due to: 1) Excess bearing stress under nuts and bolt heads caused by UNC threaded fasteners, Screw joint calculator. Most of it is used to overcome the resistive effect of friction, which opposes the rotation of the fastener. The thread angle is the included angle between the flanks of a screw thread. 36, which was determined from a separate nut factor test for this bolt/insert flight configuration. If not on a torque/preload UF of 0. 9 12. siemens. Failure may be relatively brittle, and the analyst may not think to check anything other than the bolt. If your application requires a higher or lower load, usually the standard product torque can be increased or decreased proportionally.


Imposed initial strain iii. Check the loosening performance of nut with bolt at various stages during the rotation of machine. M12 Cd+ Table -8: Assembly torque and preload values for Cd plated fastener in torque-angle strategy 0. As discussed above in the section on Bolt Preloading, torqueing is a very inaccurate method for achieving bolt preload. E. However, you mal until the working load exceeds preload. bolting torque table 1a - cold service astm a193 and astm a320 grade b8, cl2 stud bolts. 9) By finding a value greater than the allowable load of 1960N {200 kgf} in the Strength Class 10. Keywords— Bolted joints, bolt test rig, loosening of bolted joints, preload decay, self-loosening, stress analysis An Experimental Investigation of Bolt Preload Decay in Socket Head Cap Screw by Transverse Vibration Test Rig Mr. Preload tension is necessary to keep the bolt tight, increase join strength, create friction between parts, and improve fatigue resistance. The bolt is inserting in two plate of test rig and nut is tight.


Hexagon Headed Bolt, Stud Bolt (Unit: N·m {ft. Table 2. Both Norton and Shigley tabulate proof strengths for various bolt grades. ) of threaded section of each bolt size. Our metric stud bolt to nut table is meant to help determine the correct size bolt or nut for your purpose. 2a) 3. For bolting specifications that do not have a published proofload, it is usually calculated at 92% of minimum yield strength. snug-tightened. However, only a small amount of the input torque serves to pre-tension the bolt. The instrument will allow measurement to be made with access to only one end of the bolt and will not require either prior knowledge of the original bolt length or disturbance of the bolted joint. lbs, kgf·m}) Strength 4T 7T 8T Identification symbol Nominal diameter (Stud) (Stud) (Stud) M5 2 to 3 A torque specification chart explains the correct torque for a variety of nut and bolt types.


Property Class: 8. This is the most widely used method. The concept of higher preloads resulting in increased fatigue perform-ance may be counterintuitive, which might otherwise sug-gest that increasing the tightening force of a bolt may Up to five shear sections Verification both in shear and friction modes Bolt preload parameters Verification of the joint cover to tension Force definition (Ultimate Limit State and Serviceability Limit State) Quick summary table Joint verification as per Category A, B, C and D to shear, tension, combined effect in shear and friction mode. 5. ) 5/8” 27100 19000 200 3/4” 40100 28000 355 7/8” 55500 39000 570 1” 72800 51000 850 1 1/8” 80100 56000 1060 1 1/4” 101750 71000 1495 1 3/8” 121300 85000 1960 1 1/2” 147550 103000 2600 a490 torque specifications bolt diameter ultimate tensile (lbs. In the absence of data from manufacturers or detailed analysis, values for K are given in the table below for a variety of materials and bolt sizes: Example question: Pre-load and tightening torques for stainless steel fasteners - Coarse Metric Threads Bolt Preload Tension Force Equation & Calculator. 3 Movement in Flanged Joints 2. If there is an access to the head and the end of the bolt, bolt elongation can be measured by using micrometers or dial indicators. 8 5. 1. Mean values of reported nut factors K in ( 2a) are tabulated here to give an appreciation of the beneficial effect of proper lubrication of thread and nut face on preload.


Relationship between bolt fatigue life and bolt preload. "* Use closure lid design which minimizes the prying actions of applied loads. The calculator below can be used to calculate the torque required to achieve a given axial bolt force or load. Area of hub flange fillet is selected around 360° after which elements attached to this area are selected. The agreement between the calculation and the actual application depends Try our free and simple bolt load calculator to approximate your bolt stress at installation. Method to Determine the Slip Coefficient for Coatings used in Bolted Joints. Rough contact type (PTYPE=4) was defined between beam and spacer block to ensure no sliding between the contact surfaces, yet allow contact areas to open or Clamp load is also known as preload or initial load in tension on bolt. 70% of this value gives me a preload stress of 80. The bolt preload requirement was specified by my customer (they have also specified a minimum gasket preload stress of 20ksi). This is the manufacturer specified axial load the bolt must withstand without permanent set. Preload Variation: In an ideal world the preload provided by the bolt would be known to an exact value and would be the same for every bolt tightened.


Defining Bolt Regions before using the bolt preload command is slower, but allows you to more easily name/label each region, allowing you to keep your model The primary components of a bolted joint include the threaded fastener as well as the parts to be joined together (the clamped parts). 3. Rasim Guldiken, Ph. Table 1: Specimens for bolt preload tests (*with additional glass fabric on outer surfaces: 2 x 0. The minimum preload can be calculated by dividing the maximum preload through the tightening factor α A – see table on page F. 1 on all loads (including self-restraining load cases) should be analysed. II, Pt. bolting torque table 2 - astm 193 grade b7 and astm 193 grade b16 stud bolts. bolt bolt model on stiffness values of the element fastened in the bolted joint has been examined. Hess, Ph. .


Higher grade materials, such as carbon alloy steel, allow for greater torque strength in the threads of the bolt. This thesis focuses on the different causes for bolt relaxation and their relation to joint design. d. Do not use for Stainless Steel clamps . 0 What is a Belleville Spring? 2. In this case there is no slip to consider. 2649743 LM Guide NR and NRS — Ultra A-225 A-IV Permissible moment In types NR and NRS, a single LM block can bear moments in all directions. I L4 Moment of inertia Je nd Factor used in the computation of thread tear out K nd Nut factor. (See page 10). 4 Bolt Stress Area. Rotation angle method Torque and Tension in Bolts: Bolt, one of the most widely used fasteners in the industry, is usually tightened by applying torque to the head and/or nut.


High surface pressures under the bolt head can also be a cause of excessive embedding. (See 6. The advantage of having adequate bolt preload (although it sometimes causes a much higher bolt stress) is, the bolt stress does not fluctuate nearly as much, when the applied load fluctuates Relaxation of ASTM A325 Bolted Assemblies Standard EN 1090-2 and the minimum preload is either part of Table 1. Since the torque value does not change because of the bolt length, standardization is easy. Contact interference if the bolt head/nut are modeled iv. bolting torque table 1 - astm a193 and astm a320 grade b8, cl2 stud bolts. Example: For installations with commercial, modern torque wrenches, tightened in a uniform, uninterrupted fashion, with an estimated friction coefficient, a tightening factor α A = 1,6 to 2,0 must be applied. Analysis of Bolted Connections in Creo Simulate type of load introduction and offers 96 accordant values in a table total bolt load – preload The stress area is the effective cross-sectional area of the bolt that resists bolt fracture. Test Matrix Bolt length (mm) Bolt diameter For a real bolted connection, the bolt preload creates forces in the bolt and the members. ” This second, updated, edition has been prepared and approved by the Research Council. The preload is applied on bolt head, and then the machine is start.


The specification is based on existing information concerning the structural behavior, analysis, and design of bolted joints. As a designer, when the seating loads are too large and are caused by extra bolt area, Table 1 — Systems of bolt/nut/washer assemblies specified preload can be achieved when the average gap remaining after tightening (compressed protrusions) Preload Relaxation. Increased bolt torques/preload values in points 3 & 4 above apply for Low Alloy steel clamps with B7/B7M bolting (or equivalent). TABLE 2 - Torque, Stress and Load Data for Bolts with: Min Minor Diameter (in. bolting torque table 2a - cold service astm a320 grade l7 stud bolts separation and bolt fatigue may occur. Use these values in case no information available from bolt manufacturers and suppliers for bolt K factor values. When he compared the preload decay of a bolt & split washer combo to bolt by its as seen in the table below. lbs Such embedding results in a loss of bolt extension and hence preload. K Factor is a torque coefficient between bolt and receptacle. If the turn-to-tension procedure is used to establish clamping load, it is necessary to know both the spring rate of the bolt and the spring rate of the clamped components, since turning the bolt stretches the Fp F Bolt preload Fpr F Bolt proof load. 7 4.


com/plm/femap. 1) the equivalent stress is a result of the stress by tension and torsion. Firstly, a small amount of preload was anticipated being lost as a result of embedding. 14 Preload Indicating Washers for use with re-worked joints (see the availability chart on Pages 10-11) and “specials” for loads not listed in this literature (contact the SPS Technologies Product Engineering Dept. bolt tension (lbs. Exceeding the bolt loads detailed above may cause clamp/hub distortions. 9. DESCRIPTION This section contains information on the correct usage and identification of bolts, flat washers, lock wash- The Bolted Joint Analysis calculator allows for stress analysis of a bolted joint, accounting for preload, applied axial load, and applied shear load. 2 Clampload is calculated at 75% of proofload. Table footnotes. By using the elongation value of the bolt and bolt material properties, the bolt preload can TABLE OF CONTENTS 1.


Empirical preload values can be obtained from proven designs and can be applied to similar designs. High strength friction grip bolts and nuts require to be tensioned in accordance with BS 4604 which specifies min. Preload and its control in threaded fasteners. 4. ). The target preload was 480 kN. The tangential contact between bolt-shank and bolt-hole was considered to be frictionless; see Figures 3(c) and 3(d). Let’s define L f as the deformed length of bolt which corresponds to the settlement of the connecting parts due to pre-stress. The test can be performed on the locking mechanism forming part of a nut, and on a bolt or a washer. Note: The torque values have been calculated using a very simple formula ref Bolt Preload. PRELOAD N.


Stress relaxations were calculated and are shown in Table 21. 10 Tricks Engineers Need to Know About Fasteners. S. 2-4. Most charts identify bolts or nuts by size and the number of threads per inch. 6 4. The charts tell mechanics, builders and assembly workers how to tighten each nut and bolt for maximum efficacy. This causes the bolt to stretch, while parts are compressed. The bolts are usually more rigid than hot-rolled steel member, and they are usually denoted as a master surface in the contact pairs; see Flange Bolting Guide GASKET INSTALLATION age of the short-term bolt preload loss occurs within All nuts are in accordance with ANSI B18. Section 9. lbs.


TORQUE Nm. - t = thickness of connected material 5. Bolt Preload Scatter 4. Before using a given torque table, these assumptions should be verified to insure they are appropriate for the specific application. P = external applied load to the joint. To quantify the importance of torque on a nut/bolt combination it must first be understood what operation Relating Bolt Torque to Bolt Tension Best way to measure bolt preload is by relating measured bolt elongation and calculated stiffness Usually, measuring bolt elongation is not practical Measuring applied torque is common, using a torque wrench Need to find relation between applied torque and bolt preload Relating Bolt Torque to Bolt Tension Best way to measure bolt preload is by relating measured bolt elongation and calculated stiffness Usually, measuring bolt elongation is not practical Measuring applied torque is common, using a torque wrench Need to find relation between applied torque and bolt preload Force Sensing Bolts/Studs General Product Information Strainsert fasteners utilize an exclusive internal gaging method (U. Over the last fifty years great improvements have been made by the fastener industry in improving the design and reliability of their products. Notice the constant slope or straight-line relationship between the force and elongation. 2 Using Belleville Springs to Maintain Bolt Preload 2. A. F m.


. See the reference section for details on the methodology and the equations used. The calculator is generic an can used for imperial and metric units as long as the use of units are consistent. Interference fit was done in a similar way, by modeling a bolt with a larger diameter than the hole. PDF | Preload loss in pretensioned bolts is an inevitable phenomenon. 5 times nominal diameter Bolt length L is measured from below the head Shigley’s Mechanical Engineering Design Hexagon-Head Bolt Hexagon-head bolts are one of the most common for engineering applications Standard dimensions are included in Table A–29 W is usually about 1. The following precautions are to be noted: (1) The bolt plating material is usually the limiting factor on maximum service temperature. 1 The Joint Diagram 2. If there is no bolt preload in loaded bolt joint, the bolt load is equal to the joint load. The tension devel-oped within the bolt has an equal and oppo-site reaction 1 on the bolted components, which creates the all-important clamp force, the compressive force holding the bolted joint members together. The stretch of a bolt or metal rod loaded in tension is calculated by use of the following equation.


1 Measurement: Preload 1 tensioning 1 st pass During pre-installation BoltSafe nr. Table 1: Figures Preload 1 tensioning 1 st pass BoltSafe Force (kN) Mean (kN) Difference with mean (%) Double Shear Bolt . Bolt preload scatter and relaxation behaviour during tightening a 4 in-900# flange joint with spiral wound gasket. Torque = K. The result of actions described in the paper is proposal distribution of the preload on nodes belonging to the bolt head which guarantees the best effects of spider bolt model application. Proper torque spec varies depending on the material, bolt grade or wether lubrication is used such as oil, wax, or anti-seize Always go to the manufacturer for proper torque specs if needed. (2) Carbon steel and alloy steel are unsatisfactory (become brittle) at temperatures below –65 “F. Effect of Different Flange Sizes (6 and 8 inch) Fig. 9 Preload is the tension load developed in a fastener while tightening. For new designs, SKF recommends calculating the appropriate preload range by using SKF SimPro Quick or SKF SimPro Expert and then checking it by testing in the application. also known as preload.


resistant section mm2 friction coefficient; COARSE THREAD. "* When choosing a bolt preload, pay special attention to the interactions between the preload Metric Bolt Torque Table, torque specs estimated with clamp load as 75% of proof load as specified in ISO 898-1. Several discussions in this technical section stress the importance of preload to maintaining joint integrity. Investigating bolt A partial listing of bolt materials is given in table I. Formed in 1947 and formerly known as the Research Council on Riveted and Bolted Structural Connections, the Research Council on Structural Connections is a LOAD DISTRIBUTION IN BOLTED JOINTS. It is a function of the materials' frictional characteristics, which are based on surface finish, coatings and so on. 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 for non-critical applications only. BS 5400 - Steel, Concrete and Composite Bridges. For critical or special applications where greater control is desired this should be experimentally determined. One of the most critical factors when it comes to reliability of a threaded-fastener joint is preload—the force the tightened fastener exerts on an assembly. The greater the resistance to turning, the greater the torque or force required to turn the item.


When all three of the above values are known, refer to Table 2-1 through Table 2-7, as applicable. Investigating bolt relaxation is relevant because there is a direct relation between the bolt preload and the resistance of the connection. Reference values for bolt torque K factors are given in the following bolt torque K factors chart. 1 bolt classes recommended by the Eurocode; per EN 1993‐1‐8 3. 5 times nominal diameter Bolt length L is measured from below the head Shigley’s Mechanical Engineering Design development of preload in the anchor bolt sufficient to provide adequate resistance to fatigue failure. 096 Ts+α F 120 62. 809 To convert lbft to Nm above increase bolt torque/preload by 2. Since the structure is not infinitely stiff, one result of a preload is that the structure deforms and relieves a portion of the preload. The bolt chart provides both US and metric stud sizes. INTRODUCTION 1. 8.


"* Lubricate bolt threads to reduce required preload torque and to increase the predictability of the achieved preload. ) suggested tightening torque (ft. , acting both in the axis of the bolt and in the plane of the connected parts. Here, the torque-preload relationships are determined by direct measurements taken from instrumented joint specimens. On the go? Download our Bolt Load Calculator app instead. 1 shall not be cause for rejection. lbs, kgf·m}) Hexagon Headed Flange Bolt (Unit: N·m {ft. The CF is generated by the superposition of the individual tension of the bolts. 4 Maximum bolt end and edge distances What is the background to the maximum spacing p1 and p2 of 14 t or 200 mm given in Table 3. 6 M2 M3 M4 M5 M6 M8 M10 M12 M14 M16 M20 M24 M30 M36 M42 - 3. Strain gauges and This report specifies the requirements and criteria for stress analysis of closure bolts for shipping casks containing nuclear spent fuels or high level radioactive materials.


PRELOAD N If the external tension forces overcome the clamp load (bolt preload) the clamped joint components will separate, allowing relative motion of the components. In FEA, the beam element has an initial force but the members have 0 force. It also specifies three methods of determining bolt tension, i. The specificity of bolt and nut assemblies with a calibrated preload, compared with the system HR as defined in EN 14399-3, is the preload in the bolt which is controlled during tightening by the fracture of the spline-end of the bolt under Notes for applications engineering with Superbolt® products. Patent #2,873,341) to indicate bolt tension due to preload with strain gage accuracy. Marcin Submitted to Professor John L. b. 103, "Special Problems" Fritz Engineering Laboratory Department of Civil Engin~ering Lehigh University Bethlehem, pennsylvania May 1960 \-. Fatigue life of a bolt is determined by the magnitudes of mean and alternating stress imposed on the bolt by external cyclic loads. ) required min. com.


It increases with the number of joint surfaces being clamped and with the roughness of those surfaces. Thus, for a condition where cyclic loads are smaller than preload, lit-tle or no cyclic damage occurs to the fastener. 1 mm) For each layup two specimens with two or three bolts are prepared, one specimen for the test at RT and one at a temperature of 70 °C. }' I think this may be the case, as the sealing preload in the bolt might be considered a self-restraining loadcase (notation T in ASME VIII part5). Bolt Preloading 4. 9 Socket Head. Table 1 shows the measured values by in digit and in figure 4 in diagram. 2 M1. In many cases, the known preload is the final load in the bolt and member (F'), so the above formulas can be used to calculate the preload P to apply to the beam elements. 6 115 65 120 2 52 The bolt tensile stress will always be higher with preload, when you apply the applied tensile load, not lower (assuming the bolted plates do not gap). 1496 Preload in Loaded Joint 1496 Preload In Shear 1497 General Application of Preload 1498 Preload Adjustments 1498 Coefficients of Friction 1499 Preload Relaxation 1499 Measuring Preload TORQUE AND TENSION IN (Continued) FASTENERS 1500 Bolt Preload Application Methods 1500 Elongation Measurement 1502 Tensile Stress Area 1503 Torque and which specify high-strength structural bolting for preloading; it belongs to the system HR.


other bolting torque tables. EXPERIMENTAL INVESTIGATION OF BOLT PRELOAD DECAY. Preload loss in pretensioned bolts is an inevitable phenomenon. 6. Norton recommends that maximum preload be 90% and 75% of a bolt's for statically- and dynamically-loaded assemblies, respectively. TABLE OF PRELOADS AND TIGHTENING APPROXIMATE VALUES. 3, prEN1993-1-8? RECOMMENDED ASSEMBLY TORQUES SAE Grade 5 Bolts & Screws - UNF Thread Bolt Tension Recommended Corresponding to Assembly 65% of Proof Load Torque lbf lbft 2010 8 3180 17 4840 30 6560 48 8840 74 11240 105 14170 148 20600 258 28100 410 36600 610 41100 771 51600 1075 63200 1448 To convert lbf to kN: Multiply kN by 224. 4. Clamp load (lb) is calculated by arbitrarily assuming usable bolt strength is 75% of bolt proof load(psi) times tensile stress area(sq in. There are many methods for measuring preload (see Table 12). The dispersion band of the axial tension is wide and bolt effi ciency is low.


2) the torsional stress may vanish by relaxation CE 405: Design of Steel Structures – Prof. 1 NeiNastran A preload of 4,200 lbs was applied to the two cut mid-sections of the bolt in opposite directions as depicted in Figure 1. Therefore according to Table 5. 13 was broken, this was not a BoltSafe failure. To take full advantage of strength properties, the preferred design would be to position the full shank body in the shear planes as illustrated with the joint on the right. TURN-OF-NUT BOLTING METHOD AISC & RCSC Turn-of-Nut (Part Turn) Note: As with every bolt pretensioning method, Turn-of-Nut may only be performed after all steel plies in a connection have been drawn into firm contact, i. Preload is a function of many Methods of setting bolt preload /tension. Most accurate bolt torque calculator given its geometry and thread diameter, using vdi 2230 standard, Screw Clearance through the specific tool 3D model TIGHTENING TORQUES FOR METRIC BOLTS of yield strength (Sy) MÉTRIQUE Diameter (mm) 6 8 10 12 14 16 18 20 22 24 27 30 33 36 39 42 45 48 52 56 60 64 68 M6 M8 M10 M12 M14 M16 M18 M20 M22 M24 M27 M30 M33 M36 M39 M42 M45 M48 M52 M56 M60 M64 M68 Table 1 – Material Properties 4. Frictional resistance is highly dependent on the surface conditions. Preload, for example, was developed by creating a bolt head which physically overlapped the washer; then the ERROR tolerance on the contact table was used to force the head and washer faces into place, thereby pre-stressing the bolt. This is done to allow a Bolt Preload Theory and Application Bolt Regions Bolt Regions are user defined regions that can be defined using either bar or beam elements.


Torque reference values calculator for EN 14399-1 Preload bolt assemblies with specified k-Class (K2 for Torque Method, K1 for Combined - part-turn method) Metric Stud Bolt To Nut Size Chart. S m is the design stress intensity for the bolt material per the ASME B & PV Code. Impact wrenches or air powered screw drivers are not recommended. Since shear strength is directly related to the net sectional area, a smaller area will result in lower bolt shear strength. The resulting preload changes on the bolt and joint are. The following table gives bolt geometry and thread engagement data for UNC bolts from 1/4 The below chart refers to usage in steel. (3) Hydrogen embrittlement is a problem with most A partial listing of bolt materials is given in table I. 6 5. The torque and preload (bolt load) values given in the catalog tables are the “standard” values for common uses. All of those factors are summarized in single variable that is known as the nut "K Factor". Total Preload UF for Flight Joints After Re-torque Coupon Retorque Max Preload (lbf) % Preload Loss from CF after 24 hrs after 5 years after 13 years Flight-1 Y 354.


Jahid P. The tensile force thus induced in bolt, creates a compressive force in the bolted joint this is called clamp force. CIRRUS AIRPLANE MAINTENANCE MANUAL MODEL SR22 20-60 Page 1 All EFFECTIVITY: FASTENER IDENTIFICATION AND TORQUE DATA 1. 8 and 10. How friction affects torque and preload Grade 8 Bolts: Strength and Durability The factor that makes a grade 8 bolt different from a lower grade bolt is its preload strength. overlap. au Torque, by definition, is a force caused by turning. Preload should be measured by a turn-of-the-nut method. 2 is a constant from Machinery's Handbook for thread and collar friction coefficient =0,15 d = nominal diameter (m) F m = Maximimum Bolt tension (0,85. donhad. If you need more control over the preload application location, the bolt load can be scoped to a single body Prelax = axial bolt preload loss, lb, about 5% of Po,min.


See Torque Force Design Equations webpage and torque chart page for recommended fastener torque and equation data. To simplify After the spline of the bolt has sheared, the assembly preload should be equal to or greater than those values as required by the specification (see table 1). The bolt, screw or nut shall not be reworked in any manner; this includes drilling, filing, cutting, using a tap or die, or any other mutilation, unless approved by the cognizant engineer, reidentified and inspected The minimum preload can be calculated by dividing the maximum preload through the tightening factor α A – see table on page F. The studs have UNC threads. to the bottom area of the bolt shank to pre-stress each bolt to the target stress, is given in 4 Table for both 6 and 8 inch flange sizes. Typically, preload loss due to embedding is in the region of 10%. Bolt lengths during the test were measured by the ultrasonic device. The clamp force in an unloaded bolted is assumed to be equal and opposite of the preload. (Equation 1) Ke L Length of engaged threads needed to avoid tear-out in using high tensile There are several factors that affect the relationship between the applied bolt torque and the resulting bolt tension. Prestressed bolt connection. 046.


Flange Bolt-Up Bolting Torque Table 2 The torque tables are built on specific assumptions regarding bolt and nut factor. The level of preload in a bolt is governed by three things: The tensile strength of the bolt material, the ‘property class’; The thread size of the bolt; The extent to which the bolt is strained (extended) during the installation and tightening process. Constraint equations (The bolt is split into two elements and a relative overlap is induced to create tensile forces in the beams) Figure 2). View more tips and tricks videos at http://www. Also there are no shear planes. The deformation of the parts connected through the bolt is calculated and is used to determine the bolt's length at zero stress state L 0. 8 8. The second type of bolted joint transfers the applied load in shear of the bolt shank and relies on the shear strength of the bolt. For example, when L/d is 2, the preload to apply to the beam elements is 1. Various K Factors FASTENERS The Torquing of Stainless Steel Fasteners your guarantee of quality industrial fasteners Stainless steel threads are notorious for galling or seizing during tightening. 1 of the RCSC specification states “a pretension that is greater than the value specified in Table 8.


35 times the final preload in the bolt and members. I have found the yield stress of the studs to be 115ksi, as per sect. Why Bolt Preload is Important. d - diameter of bolt (m, in) F - axial bolt force or load (N, lb) The Importance of Preload - The Joint Decompression Point Bolt Crosstalk and the need for a Tightening Sequence Tightening the Nut or the Bolt Head Use of Two Nuts to Prevent Self Loosening Tutorial on the theory of Bolted Joints Why is a bolt's preload force vital? How a bolted joint sustains an applied force - Proper preload - Controlling joint-bolt stiffness ratio - Achieving correct preload In my research, I tend to think that the joint-bolt stiffness ratio holds the key in many issues. The torque wrench is used to apply preload calculated for different dimensionsof bolts. This fastener bolt torque calculator will Estimate the unknown torque, diameter, axial force applied and coefficient of turning friction for the given conditions. According to the specified tightening sequences and bolt preload values, during bolt up, yielding is observed at hub flange fillet in different flange sizes, resulting in their failure. Bolt preload (kN) Target bolt stress (MPa) Average Bolt preload table Japanese Patent Nos. Due to the internal forces resisting the elongation, a tension force or preload is produced (Fp). The transverse vibration test rig is used to predict the bolt preload decay. Bolt root areas are used to calculate the preloads listed herein.


In addition an BOLT LENGTHS (GRIP LENGTHS) FOR PRELOAD FASTENERS There are three standards for the design of steelwork – BS 5950 - Structural use of steelwork in buildings. 9% 22. 4 Bus Conductors and Differential Thermal Expansion 3. 5 Bolts, Screws and Nuts. Tension loads on such a joint are only incidental. K = 0. Kalje 2 1M. The simulation tool will then use the middle of the selected face for the mesh division and pretension element creation. The following table gives several results. Bolt preload direc-tion is determined automatically, as shown in Figure 1. In “Bolted Joint Diagram 1”, as the bolt is tightened, the bolt elongates (∆B).


Thermal load is applied by a temperature chamber. • Where the property class differs between the nut and bolt (or stud bolt), use the tightening torque specified in the table for the bolt. e. This is done by defining a maximum preload (PLDmax) and a minimum preload Bolt Elongation Measurements with Micrometer: A technique to control preload by measuring elongation with a micrometer. The third is the torque necessary to produce a specified tensile load in a bolt. Proof load) stripper bolt made of 4137 Alloy Steel, 33 to 38 HRC, strength class 10. preload and the effects of external loads. The changes in lengths were symmetric. 3 In preparing this guide to torque values, the following basic assumptions have been made: (a) bolts and nuts are new, standard finish, uncoated and not lubricated* (b) the load will be 90% of the bolt yield strength (c) the coefficient of friction (µ) is 0. Table-3: Decay in Preload of Portland Bolt provides anchor bolts and nonstandard construction fasteners directly to contractors, steel fabricators, OEMs, and other construction-related companies worldwide. Definitions of terms are located below the chart.


Lamps the topmovable 3. TIGHTENING TORQUES AND THE TORQUE-TENSION RELATIONSHIP All of the analysis and design work done in advance will have little meaning if the proper preload is not achieved. Friction Factor Friction Factor Bolted Joints and Bolt Preload Overview The bolt strength criteria, the bolt fatigue and fracture criteria, and the joint separation criteria do not require that the preload be multiplied by yield, ultimate or joint separation factors of safety, yet any uncertainty in the preload must be taken into account. K - constant. The bolt tension, also referred as bolt preload, is the actual force that is stretching the bolt body. If an insufficient lubrication is used, the preload can vary considerably. The bolt’s length at zero stress is then calculated from: L 0 = L f / (1+(P The fastener preload decay graphs produced can allow an assessment to be made of a fastener’s resistance to self-loosening. Abhay Kumar M. bolt preload table

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