|
|
| Line 1: |
Line 1: |
| '''Multi-jackbolt tensioners''' ('''MJT''') provide an alternative to traditional [[bolted joint]]s Rather than needing to tighten one large bolt, MJTs use several smaller jackbolts to drastically reduce the [[torque]] required to attain a certain [[Preload (engineering)|preload]]. MJTs range in [[Screw thread|thread]] sizes from 3/4” to 32” and can achieve up to 20 million pounds of [[force]] and greater. MJTs only require hand-held tools, such as [[torque wrench]]es or air/electric impacts, for loading and unloading bolted joints.<ref name="Bolted Joints">Steinbock, Rolf. "The Multi-Jackbolt Tensioning System." ''Handbook of Bolts and Bolted Joints.'' Ed. John H. Bickford and Sayed Nassar. New York: Marcel Dekker, Inc., 1998. 507-533.</ref>
| | Missouri lottery is a issue of chance. A lot of folks have lost their income to con artists who promise them functional suggestions on how to get. The use facets like specific figures and how or when to decide them, chilly numbers and hot quantities. These strategies never ever work and folks ought to steer clear of tricksters like these who are only after their cash.nThe most important thing to keep in mind about these game titles is that the figures are random with no likelihood of prediction. The authorities that sanction this sort of game titles have to make certain there is no opportunity of cheating or predicting the successful numbers. These kinds of possibilities direct to unfair edge to those with a indicates of predicting the quantities.nThat getting explained however, there are a quantity of genuine ideas that may possibly support individuals improve their probabilities of successful the lottery. A single of these is selecting on a standard sample of taking part in. 1 could make a decision to purchase at least 5 [http://Www.Reddit.com/r/howto/search?q=tickets tickets] for each week and these are the number of chances he or she has that week.nChoosing the very best game is also yet another way to boost the odds of profitable. Even with the sum of income on the jackpot, a game with several gamers lowers the possibilities of a specific person successful. One need to pick the recreation with the the very least gamers.nThough it is challenging to pick the quantity most likely to get, one might boost his or her winnings by selecting the numbers the very least likely to be picked by other players. This will help enhance the amount received. This means that should the amount win, he or she will have less folks to break up the wins with. nHow to earn the lottery.nnBasic typical feeling dictates that the person with far more tickets stands a much better opportunity of profitable that the 1 with less. 1 ought to therefore acquire as a lot of as attainable. However, individuals have to watch their spending given that the game may possibly be addictive.nOne may enhance the odds by playing less usually. An person who plays five tickets a week might improve by actively playing ten tickets every two weeks or twenty each and every month. This has more entries per [http://www.google.co.uk/search?hl=en&gl=us&tbm=nws&q=perform&gs_l=news perform] and as a result much better possibility of winning.nnnA syndicate assists people improve their chances by a huge share. People join syndicates of like-minded men and women and these aid improve their probabilities. They share the winnings of every personal among the members. However the winnings are lower, enjoying is much more affordable and fun. It also offers people a likelihood to acquire more than as soon as and socialize while at it.nLotteries vary in nature. Therefore, the ideas that aid an person get a specific one particular could not assist him or her acquire every subsequent sport he or she participates in. Men and women need to study posts online about how they can enhance their possibilities of winning the Missouri lottery. Computer software is obtainable that analyses the traits and makes an attempt to predict the successful tickets. Nevertheless, people must not rely on this given that the actions of a complicated method is not predictable. Possibility and luck are the principal determinants of the winner.<br><br>If you loved this article and you would like to collect more info about lotto texas ([http://valv.im/ASIvO click through the up coming website page]) please visit the web site. |
| | |
| ==Basics of multi-jackbolt tensioners==
| |
| Multi-jackbolt tensioners (MJTs), registered under the [[trademark]] Superbolt or Supernut, are designed to decrease the torque required to tighten large bolted joints. One of the major problems associated with traditional bolt tightening methods is as the diameter of the bolt increases, the amount of torque required to tighten it increases in the third power of the diameter.<ref name="Bolted Joints"/> Because of this, the largest size bolt a person can typically tighten by hand is 1".<ref name="Rolf 4">Steinbock, Rolf. "Mechanical Tensioners Tame High-temperature Joint Failures." ''Power Engineering.'' August 1997, p. 46-50.</ref>
| |
| Multi-jackbolt tensioners reduce the amount of torque required to clamp the joint by using multiple jackbolts threaded through the nut or bolt head.<ref name="Kane 5">Kane, Joe. "Revisiting Superbolt's Super Torquenut: Since Our Last Visit, Many More Compressor Related Applications of the Torquenut Have Been Uncovered." ''Compressor Tech Two.'' September, 2004.</ref>
| |
| The jackbolts, which are small enough to be tightened by simple hand tools, [[thrust]] against a hardened [[Washer (hardware)|washer]] and generate clamping force on the joint. [[Structural load|Loads]] up to 20,000,000 pounds and greater are attainable using only [[hand tool]]s. MJTs and related products are produced by Superbolt, Inc. in [[Carnegie, Pennsylvania|Carnegie, PA.]]
| |
| | |
| ===Types of tensioners=== | |
| *'''Nut type'''
| |
| **[[Nut (hardware)|Nut]] type MJTs, otherwise known as Torquenuts, can be [[retrofit]]ted onto existing bolts or [[Screw|studs]].<ref name="Kane 3">Kane, Joe. "Superbolt - A Sure and Safe Bolting System." ''Compressor Tech Two.'' May/June 1997. p. 50-52.</ref> Because of this, they are the most common type of MJT.
| |
| *'''Bolt type'''
| |
| **Bolt type MJTs, otherwise known as Torquebolts, have a ring of jackbolts almost touching the bolt shank. They typically have a smaller outside diameter than Torquenuts. With Torquebolts, it is possible to have very close spacing even at high preloads.<ref name="Bolted Joints"/>
| |
| *'''Thrust-collar type'''
| |
| **Thrust-collar type MJTs are used in applications where it is difficult to use threaded tensioners, such as on [[rolling mill]]s where the joint would typically need to be tightened by [[Crane (machine)|crane]] wrenching. Jackbolts push a threadless nut against a [[Retaining ring|retainer ring]], which is fitted into a groove and transfers the jacking force to the main bolt or stud. Because there are no threads, they can also be used in [[Machine press|press]] column applications, eliminating the problems and hassles associated with large nut threads.<ref name ="Bolted Joints"/>
| |
| | |
| ==Mechanical advantage==
| |
| MJTs have a high [[mechanical advantage]] for tightening large nuts. To calculate mechanical advantage over standard [[hex nuts]], the following formula is used:<ref name="Bolted Joints"/>
| |
| | |
| <math>MA = \frac {T}{T_j}= \frac {nDA}{d} </math>
| |
| | |
| Where:
| |
| | |
| :{| border="0"
| |
| |-
| |
| |MA ||= overall mechanical advantage
| |
| |-
| |
| |T ||= main thread torque
| |
| |-
| |
| |T<sub>j</sub> ||= jackbolt torque
| |
| |-
| |
| |n ||= number of jackbolts
| |
| |-
| |
| |D ||= main thread pitch [[diameter]]
| |
| |-
| |
| |d ||= jackbolt pitch diameter
| |
| |-
| |
| |A ||= torque advantage of jackbolts over tension bolts (with [[graphite]] lube A=1.37)
| |
| |}
| |
| | |
| ==Safety==
| |
| MJTs are a relatively safe bolting method because only small hand or air tools are required for tightening. Other methods, including [[Thermal energy|thermal]] tightening, [[Overhead crane|crane]] wrenching, [[Hydraulic torque wrench|hydraulic wrenches]] and [[sledgehammer]]s, can cause serious worker injuries due to heat, electricity, highly pressurized [[Hydraulic fluid#Safety|hydraulic fluid]] and brute force. Back and other injuries can also be avoided because no heavy tightening equipment needs to be lifted onto the bolt. Safety is also increased because MJTs prevent parts from becoming loose.<ref name="Kane 3"/>
| |
| | |
| ==Downtime==
| |
| Due to [[Dynamics (physics)|dynamic]] loads, bolted joints have a tendency to loosen. Downtime is significantly reduced because MJTs are able to easily achieve the large clamping forces required to prevent bolted components from vibrating loose. Therefore, less time is spent tightening joints repeatedly and fixing problems caused by loose joints.<ref name="Kane 3"/> MJTs also reduce the likelihood the bolted joint will [[Structural failure|fail]], which reduces downtime caused by needing to replace damaged components.
| |
| | |
| ==Installation time==
| |
| Even though more individual jackbolts must be tightened, installation is still fast in comparison to other methods. Because the torque required to tighten each small jackbolt is exponentially less than the torque required to tighten one large nut, it takes less time and effort overall to tighten the larger number of jackbolts. Also, no additional time is spent moving around heavy equipment to tighten each nut. Installation processes have been developed using air tools, which also greatly reduces installation time. Additionally, multiple workers can work on a joint simultaneously since the tooling required is inexpensive. Another common method, thermal tightening, can take a long time because the stud must be heated, and clamping force is not obtained and cannot be checked until it is cooled since it depends on shrinkage. If the stud is not at proper stretch, the heating process must be repeated.
| |
| | |
| ==Versatility==
| |
| {{prose|date=October 2010}}
| |
| | |
| *MJTs can be used in tight spaces because no bulky equipment is required to tighten the bolts.
| |
| *MJTs can also be engineered to specifications for almost any application. There are few size limitations, and they can be used with extremely large thread sizes (as high as 32" thread diameter).<ref name="Bolted Joints"/> They can also be used effectively in high temperature applications, given proper materials are used. Overall, the unique properties of MJTs created by the use of jackbolts can simplify complicated applications, especially for large thread sizes.<ref name="Rolf 4"/>
| |
| | |
| ==Joint integrity== | |
| {{prose|date=October 2010}}
| |
| | |
| *Thread [[galling]] and seizing is significantly reduced because mating bolts/studs are loaded in pure [[Tension (physics)|tension]] without [[Torsion (mechanics)|twisting]].<ref name="Kane 3"/>
| |
| *In many applications, [[Elasticity (physics)|elasticity]] in a bolt significantly helps to keep a joint held together.<ref name="Rolf 4"/> Tests have shown turbine-type MJTs increase the elasticity of the average bolting system by the equivalent of four stud diameters, and nut-type MJTs increase the elasticity by 4 to 12 diameter equivalents, which would triple or quadruple the elasticity of the bolting system.<ref name="Bolted Joints"/> In other words, MJTs increase elasticity by adding up to 2 to 4 equivalent bolt effective lengths. This is particularly advantageous in high-temperature bolting applications where bolts are subject to [[Creep (deformation)|creep]], because elastic bolting systems will take longer to reach a given relaxation stress than in a rigid system.<ref name="Bolted Joints"/> Elastic bolting systems can also improve the integrity of [[gasket]]ed joints by compensating for temperature changes, joint movement and changes in internal pressure.<ref name="Kane 2">Kane, Joe. "Multi-Jackbolt Tensioners Designed for Superior Tightening." ''Diesel & Gas Turbine Worldwide.'' November 1997. p. 49-50.</ref>
| |
| *Stress relief—Most bolts fail at the bottom of the nut in the first two or three threads. [[Hoop stress]]es on the nut in MJTs cause an increase in diameter at the bottom and decrease at the top, distributing thread stress more evenly and reducing the likelihood the stud or bolt will fail.<ref name="Bolted Joints"/>
| |
| | |
| ==Disadvantages==
| |
| MJTs may not be cost effective for bolts smaller than 1" diameter, low-[[Stress (physics)|stress]] applications, and in plants where the number of studs/bolts to retrofit is difficult to justify versus prior investment in existing tightening equipment.
| |
| | |
| ==Common applications==
| |
| | |
| ===Presses===
| |
| Multi-jackbolt tensioners can be used on many press column applications, especially where large thread sizes are required. [[Multi-jackbolt tensioner#Thrust-collar type|Thrust collars]] ease assembly and disassembly on large press columns, while greatly reducing critical problems such as thread galling and seizing. Multi-jackbolt tensioners are also used on [[Tie rod|tie-rods]], bearing blocks, high-pressure piping, die cushions, cylinder ram bolting, and [[anchor bolt]]s.
| |
| | |
| ===Mining===
| |
| Mining applications often require high preloads, and joints encounter high dynamic forces, which can cause joints to loosen. MJTs can keep joints tight on boom points, [[ring gear]]s, side frames, [[Hoist (device)|hoist]] motors, [[Dragline|drag lines]], [[pinion]] gears, split gears, and [[excavator]] bearing caps, because the joint is loaded in pure tension without twisting. Some applications, such as toothed rims, require short bolts – MJTs can be useful in these applications because they greatly improve the [[Multi-jackbolt tensioner#Joint integrity|elasticity]] of the joint.
| |
| | |
| ===Hydro Power===
| |
| Multi-jackbolt tensioners are used in several hydro applications, including [[turbine]] [[coupling]]s, blade bolts, turbine wheel to shaft bolting, [[pelton turbine]] nozzles, servo piston nuts, [[Bearing (mechanical)|bearing]] housings, and [[ball valve]]s. Multi-jackbolt expansion bolts provide additional benefit for shaft couplings, because they generate both radial and axial forces, creating the interference fit necessary. MJTs can also easily achieve the high preloads required on Kaplan turbine crossheads and servo piston rods.
| |
| | |
| ===Steam Power===
| |
| In steam power plants, MJTs are used on boiler feed pump head and barrel casings, boiler circ pump main flanges, [[stop valve]]s, [[control valve]]s, turbine couplings, stay rods, [[manway]] doors, inlet [[flange]]s, and [[feedwater heater]]s. MJTs can save a lot of time during scheduled downtime or maintenance because they require less time to install and remove than other bolting methods.
| |
| | |
| ===Steel Mill===
| |
| Multi-jackbolt tensioners have a number of uses in the Steel industry. Thrust collars can be used on rolling mills, which makes changing the rolls much easier than other methods, and frees up crane time because only hand tools are required. Other MJTs are used on mill motors, bearings, shaft mounts, anchor bolts, and [[slitter]] knives.
| |
| | |
| ===Petrochemical===
| |
| In the [[petrochemical]] industry, multi-jackbolt tensioners have been used on [[Chemical reactor|reactor]] vessels, [[heat exchanger]] heads, turbine [[control valves]], turbine joints, pipe flanges, anchor bolts, couplings, [[Gas compressor|compressors]], and [[pumps]].
| |
| | |
| ===Gas Compression===
| |
| Special multi-jackbolt [[piston]] end nuts and [[crosshead]] jamnuts are used to ease the installation of piston rods, especially considering space limitations. Other applications include anchor bolts, flexible disk couplings, dehydration towers, compressor cylinders, compressor doghouse bolting, end plates, and gas compression engines.
| |
| | |
| ==References==
| |
| {{reflist}}
| |
| | |
| {{DEFAULTSORT:Multi-Jackbolt Tensioner}}
| |
| [[Category:Fasteners]]
| |
| [[Category:Screws]]
| |
| [[Category:Structural connectors]]
| |
Missouri lottery is a issue of chance. A lot of folks have lost their income to con artists who promise them functional suggestions on how to get. The use facets like specific figures and how or when to decide them, chilly numbers and hot quantities. These strategies never ever work and folks ought to steer clear of tricksters like these who are only after their cash.nThe most important thing to keep in mind about these game titles is that the figures are random with no likelihood of prediction. The authorities that sanction this sort of game titles have to make certain there is no opportunity of cheating or predicting the successful numbers. These kinds of possibilities direct to unfair edge to those with a indicates of predicting the quantities.nThat getting explained however, there are a quantity of genuine ideas that may possibly support individuals improve their probabilities of successful the lottery. A single of these is selecting on a standard sample of taking part in. 1 could make a decision to purchase at least 5 tickets for each week and these are the number of chances he or she has that week.nChoosing the very best game is also yet another way to boost the odds of profitable. Even with the sum of income on the jackpot, a game with several gamers lowers the possibilities of a specific person successful. One need to pick the recreation with the the very least gamers.nThough it is challenging to pick the quantity most likely to get, one might boost his or her winnings by selecting the numbers the very least likely to be picked by other players. This will help enhance the amount received. This means that should the amount win, he or she will have less folks to break up the wins with. nHow to earn the lottery.nnBasic typical feeling dictates that the person with far more tickets stands a much better opportunity of profitable that the 1 with less. 1 ought to therefore acquire as a lot of as attainable. However, individuals have to watch their spending given that the game may possibly be addictive.nOne may enhance the odds by playing less usually. An person who plays five tickets a week might improve by actively playing ten tickets every two weeks or twenty each and every month. This has more entries per perform and as a result much better possibility of winning.nnnA syndicate assists people improve their chances by a huge share. People join syndicates of like-minded men and women and these aid improve their probabilities. They share the winnings of every personal among the members. However the winnings are lower, enjoying is much more affordable and fun. It also offers people a likelihood to acquire more than as soon as and socialize while at it.nLotteries vary in nature. Therefore, the ideas that aid an person get a specific one particular could not assist him or her acquire every subsequent sport he or she participates in. Men and women need to study posts online about how they can enhance their possibilities of winning the Missouri lottery. Computer software is obtainable that analyses the traits and makes an attempt to predict the successful tickets. Nevertheless, people must not rely on this given that the actions of a complicated method is not predictable. Possibility and luck are the principal determinants of the winner.
If you loved this article and you would like to collect more info about lotto texas (click through the up coming website page) please visit the web site.