Spherical Pressure Vessel

Consider a spherical pressure vessel with radius r and wall thickness t subjected to an internal gage pressure p.
For reasons of symmetry, all four normal stresses on a small stress element in the wall must be identical. Furthermore, there can be no shear stress.

The normal stresses s can be related to the pressure p by inspecting a free body diagram of the pressure vessel. To simplify the analysis, we cut the vessel in half as illustrated.



Since the vessel is under static equilibrium, it must satisfy Newton's first law of motion. In other words, the stress around the wall must have a net resultant to balance the internal pressure across the cross-section.







Cylindrical Pressure Vessel

Consider a cylindrical pressure vessel with radius r and wall thickness t subjected to an internal gage pressure p.

The coordinates used to describe the cylindrical vessel can take advantage of its axial symmetry. It is natural to align one coordinate along the axis of the vessel (i.e. in the longitudinal direction). To analyze the stress state in the vessel wall, a second coordinate is then aligned along the hoop direction.

With this choice of axisymmetric coordinates, there is no shear stress. The hoop stress sh and the longitudinal stress sl are the principal stresses.
To determine the longitudinal stress sl, we make a cut across the cylinder similar to analyzing the spherical pressure vessel. The free body, illustrated on the left, is in static equilibrium. This implies that the stress around the wall must have a resultant to balance the internal pressure across the cross-section.

Applying Newton's first law of motion, we have,

To determine the hoop stress sh, we make a cut along the longitudinal axis and construct a small slice as illustrated on the right.

The free body is in static equilibrium. According to Newton's first law of motion, the hoop stress yields,


Remarks
• The above formulas are good for thin-walled pressure vessels. Generally, a pressure vessel is considered to be "thin-walled" if its radius r is larger than 5 times its wall thickness t (r > 5 · t).
• When a pressure vessel is subjected to external pressure, the above formulas are still valid. However, the stresses are now negative since the wall is now in compression instead of tension.
• The hoop stress is twice as much as the longitudinal stress for the cylindrical pressure vessel. This is why an overcooked hotdog usually cracks along the longitudinal direction first (i.e. its skin fails from hoop stress, generated by internal steam pressure).

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The majority of the electric cars on the streets today are home-made conversion cars. It is very possible to easily do an electric car conversion right in your own garage. There are many online communities where you will find recommendation and complete instructions on doing an electric car conversion yourself for a comparatively reduced cost. If you're concerned about your emission output and the environmental damage caused by carbon dioxide, then an electric automobile could be just the choice for you.
DC controllers and DC motors are the usual base parts of an electric car conversion. The first step is to select the voltage you would like the motor to run on.

96-192 volts is the normal range. Forklift providers often carry the perfect motors and controllers for electric conversion cars. Most folks use manual transmission vehicles as the donor car. You may need to choose a donor automobile with a fair unimpaired body. You need to also choose a fairly common model auto or the donor, as you will need to find spare parts with small difficulty and cost. there are many kinds of battery technology you can select from. The subsequent choice is to decide on the kind of electrolyte. The good thing about a flooded battery is that it is minimal cost, but the top power of them is low as well .
If you select a pre-packaged conversion kit you are able to save plenty of time. These kits are compiled with the best components you will need by folks who have great experience building electric conversions. They have been tested and proven to be effective .
when you have the kit, you will need to get a roomy and clean work area to start the project. You must also be sure that you have all the parts ordered and that they will be shipped inside a fair time period. To prepare the donor vehicle, you need to steam clean the engine compartment to clear away any residual grease. If you're using a kit, then it will come with an instruction book which you need to study and follow fastidiously throughout .

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The most important safety riding gears that you should wear is motorcycle helmets. It’s used as protective gears for the head to avoid severe injuries brought about accidents. Basically, the motorcycle helmets protect the head, skull or brain. There are many riders that not in favor of wearing this safety gears, that make it very controversial compared to the rest of motorcycle apparel. However, as for me, I will never compromise my safety by not wearing a good helmet.

Besides protection your head from critical injuries, the thing that you must also consider in purchasing a motorcycle helmets is comfort to use. Helmet must make you feel safe yet comfy. You can have the fiber glass shell helmet if you want your helmet to be high-impact resistant and durable. Safety and comfort liners can also be restored to in order to have a cooler ride.

There are different kinds of motorcycle helmets. They are full face helmets, half face helmets or open face helmets, and hybrid helmets. Full face helmets are identifiable because of their protection around the chin thus, face, and all parts of your head. Half face helmet, this motorcycle helmets protects the side of the face and the ears. Often, its visors are detachable. The drawback of these helmets is that it offers no protection for the chin. Hybrid helmets, this helmet can be opened on the chin part. More over, it is advantageous to those who wear glasses.

The kind of motorcycle helmet that gives maximum protection for your head is that of a full-face helmet. These kind of motorcycle helmets recommended by manufacturers, professional riders and testing authorities. Nevertheless, other kinds of helmet likes half face helmet, open face helmet are also good provided they pass the DOT or SNELL testing standards. The DOT and SNELL are two most trusted helmets testing authorities in the United States.

The DOT helmets testing authorities has a set of standards for motorcycle helmets. When buying a helmet, you need to look for the DOT logo on the helmet, usually at the back of your helmet. The helmet should also have a label that includes the manufacturer’s name, date of manufacture, size, model and materials.

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An understanding of the benefits and drawbacks of each form of nondestructive examination can help you choose the best method for your application

The philosophy that often guides the fabrication of welded assemblies and structures is "to assure weld quality." However, the term "weld quality" is relative. The application determines what is good or bad. Generally, any weld is of good quality if it meets appearance requirements and will continue indefinitely to do the job for which it is intended. The first step in assuring weld quality is to determine the degree required by the application. A standard should be established based on the service requirements.

Standards designed to impart weld quality may differ from job to job, but the use of appropriate weld techniques can provide assurance that the applicable standards are being met. Whatever the standard of quality, all welds should be inspected, even if the inspection involves nothing more than the welder looking after his own work after each weld pass. A good-looking weld surface appearance is many times considered indicative of high weld quality. However, surface appearance alone does not assure good workmanship or internal quality.

Nondestructive examination (NDE) methods of inspection make it possible to verify compliance to the standards on an ongoing basis by examining the surface and subsurface of the weld and surrounding base material. Five basic methods are commonly used to examine finished welds: visual, liquid penetrant, magnetic particle, ultra-sonic and radiographic (X-ray). The growing use of computerization with some methods provides added image enhancement, and allows real-time or near real-time viewing, comparative inspections and archival capabilities. A review of each method will help in deciding which process or combination of processes to use for a specific job and in performing the examination most effectively.

Visual Inspection (VT)
Visual inspection is often the most cost-effective method, but it must take place prior to, during and after welding. Many standards require its use before other methods, because there is no point in submitting an obviously bad weld to sophisticated inspection techniques. The ANSI/AWS D1.1, Structural Welding Code - Steel, states, "Welds subject to nondestructive examination shall have been found acceptable by visual inspection." Visual inspection requires little equipment. Aside from good eyesight and sufficient light, all it takes is a pocket rule, a weld size gauge, a magnifying glass, and possibly a straight edge and square for checking straightness, alignment and perpendicularity.

Before the first welding arc is struck, materials should be examined to see if they meet specifications for quality, type, size, cleanliness and freedom from defects. Grease, paint, oil, oxide film or heavy scale should be removed. The pieces to be joined should be checked for flatness, straightness and dimensional accuracy. Likewise, alignment, fit-up and joint preparation should be examined. Finally, process and procedure variables should be verified, including electrode size and type, equipment settings and provisions for preheat or postheat. All of these precautions apply regardless of the inspection method being used.

During fabrication, visual examination of a weld bead and the end crater may reveal problems such as cracks, inadequate penetration, and gas or slag inclusions. Among the weld defects that can be recognized visually are cracking, surface slag inclusions, surface porosity and undercut.

On simple welds, inspecting at the beginning of each operation and periodically as work progresses may be adequate. Where more than one layer of metal filler is being deposited, however, it may be desirable to inspect each layer before depositing the next. The root pass of a multipass is most critical to weld soundness. It is especially susceptible to cracking, and because it solidifies quickly, it may trap gas and slag. On subsequent passes, conditions caused by the shape of the weld bead or changes in the joint configuration can cause further cracking, as well as undercut and slag trapping. Repair costs can be minimized if visual inspection detects these flaws before welding progresses.

Visual inspection at an early stage of production can also prevent underwelding and overwelding. Welds that are smaller than called for in the specifications cannot be tolerated. Beads that are too large increase costs unnecessarily and can cause distortion through added shrinkage stress.

After welding, visual inspection can detect a variety of surface flaws, including cracks, porosity and unfilled craters, regardless of subsequent inspection procedures. Dimensional variances, warpage and appearance flaws, as well as weld size characteristics, can be evaluated.

Before checking for surface flaws, welds must be cleaned of slag. Shotblasting should not be done before examination, because the peening action may seal fine cracks and make them invisible. The AWS D1.1 Structural Welding Code, for example, does not allow peening "on the root or surface layer of the weld or the base metal at the edges of the weld."

Visual inspection can only locate defects in the weld surface. Specifications or applicable codes may require that the internal portion of the weld and adjoining metal zones also be examined. Nondestructive examinations may be used to determine the presence of a flaw, but they cannot measure its influence on the serviceability of the product unless they are based on a correlation between the flaw and some characteristic that affects service. Otherwise, destructive tests are the only sure way to determine weld serviceability.

Radiographic Inspection
Radiography (X-ray) is one of the most important, versatile and widely accepted of all the nondestructive examination methods - Fig. 1. X-ray is used to determine internal soundness of the welds. The term "X-ray quality," widely used to indicate high quality in welds, arises from this inspection method

Radiography is based on the ability of X-rays and gamma rays to pass through metal and other materials opaque to ordinary light, and produce photographic records of the transmitted radiant energy. All materials will absorb known amounts of this radiant energy and, therefore, X-rays and gamma rays can be used to show discontinuities and inclusions within the opaque material. The permanent film record of the internal conditions will show the basic information by which weld soundness and be determined.

X-rays are produced by high-voltage generators. As the high voltage applied to an X-ray tube is increased, the wavelength of the emitted X-ray becomes shorter , providing more penetrating power. Gamma rays are produced by the atomic disintegration of radioisotopes. The radioactive isotopes most widely used in industrial radiography are Cobalt 60 and Iridium 192. Gamma rays emitted from these isotopes are similar to X-rays, except their wavelengths are usually shorter. This allows them to penetrate to greater depths than X-rays of the same power, however, exposure times are considerably longer due to the longer intensity.

When X-rays or gamma rays are directed at a section of weldment , not all of the radiation passes are through the metal. Different materials, depending on their density, thickness and atomic number, will absorb different wavelengths of radiant energy.

The degree to which the different materials absorb these rays determines the intensity of the rays penetrating through the material. When variations of these rays are recorded, a means of seeing inside the material is available. The image on a developed photo-sensitized film is known as a radiograph. Thicker areas of the specimen or higher density material (tungsten inclusion), will absorb more radiation and their corresponding areas on the radiograph will be lighter - Fig 2.

Whether in the shop or in the field, the reliability and interpretive value of radiographic images are a function of their sharpness and contrast. The ability of an observer to detect a flaw depends on the sharpness of its image and its contrast with the background. To be sure that a radiographic exposure produces acceptable results, a gauge known as an Image Quality Indicator (IQI) is placed on the part so that its image will be produced on the radiograph.

IQI's used to determine radiographic quality are also called penetrameters. A standard hole-type penetrameter is a rectangular piece of metal with three drilled holes of set diameters. The thickness of the piece of metal is a percentage of the thickness of the specimen being radiographed. The diameter of each hole is different and is a given multiple of the penetrameter thickness. Wire-type penetrameters are also widely used, especially outside the United States. They consist of several pieces of wire, each of a different diameter. Sensitivity is determined by the smallest diameter of wire that can be clearly seen on the radiograph.

A penetrameter is not an indicator or gauge to measure the size of a discontinuity or the minimum detectable flaw size. It is an indicator of the quality of the radiographic technique.

Radiographic images are not always easy to interpret. Film handling marks and streaks, fog and spots caused by developing errors may make it difficult to identify defects. Such film artifacts may mask weld discontinuities.

Surface defects will show up on the film and must be recognized. Because the angle of exposure will also influence the radiograph, it is difficult or impossible to analyze fillet welds by this method. Because a radiograph compresses all the defects that occur throughout the thickness of the weld into one plane, it tends to give an exaggerated impression of scattered type defects such as porosity or inclusions.

An X-ray image of the interior of the weld may be viewed on a fluorescent screen, as well as on developed film. This makes it possible to inspect parts faster and at a lower cost, but the image definition is poorer. Computerization has made it possible to overcome many of the shortcomings of radiographic imaging by linking the fluorescent screen with a video camera. Instead of waiting for film to be developed, the images can be viewed in real time. This can improve quality and reduce costs on production applications such as pipe welding, where a problem can be identified and corrected quickly.

By digitizing the image and loading it into a computer, the image can be enhanced and analyzed to a degree never before possible. Multiple images can be superimposed. Pixel values can be adjusted to change shading and contrast, bringing out small flaws and discontinuities that would not show up on film. Colors can be assigned to the various shades of gray to further enhance the image and make flaws stand out better. The process of digitizing an image taken from the fluorescent screen - having that image computer enhanced and transferred to a viewing monitor - takes only a few seconds. However, because there is a time delay, we can no longer consider this "real time." It is called "radioscopy imagery."

Existing films can be digitized to achieve the same results and improve the analysis process. Another advantage is the ability to archive images on laser optical disks, which take up far less space than vaults of old films and are much easier to recall when needed.

Industrial radiography, then, is an inspection method using X-rays and gamma rays as a penetrating medium, and densitized film as a recording medium, to obtain a photographic record of internal quality. Generally, defects in welds consist either of a void in the weld metal itself or an inclusion that differs in density from the surrounding weld metal.

Radiographic equipment produces radiation that can be harmful to body tissue in excessive amounts, so all safety precautions should be followed closely. All instructions should be followed carefully to achieve satisfactory results. Only personnel who are trained in radiation safety and qualified as industrial radiographers should be permitted to do radiographic testing.
Magnetic Particle Inspection (MT)
Magnetic particle inspection is a method of locating and defining discontinuities in magnetic materials. It is excellent for detecting surface defects in welds, including discontinuities that are too small to be seen with the naked eye, and those that are slightly subsurface.

This method may be used to inspect plate edges prior to welding, in process inspection of each weld pass or layer, postweld evaluation and to inspect repairs - Fig. 3.

It is a good method for detecting surface cracks of all sizes in both the weld and adjacent base metal, subsurface cracks, incomplete fusion, undercut and inadequate penetration in the weld, as well as defects on the repaired edges of the base metal. Although magnetic particle testing should not be a substitute for radiography or ultrasonics for subsurface evaluations, it may present an advantage over their methods in detecting tight cracks and surface discontinuities.

With this method, probes are usually placed on each side of the area to be inspected, and a high amperage is passed through the workplace between them. A magnetic flux is produced at right angles to the flow of current - Fig. 3. When these lines of force encounter a discontinuity, such as a longitudinal crack, they are diverted and leak through the surface, creating magnetic poles or points of attraction. A magnetic powder dusted onto the surface will cling to the leakage area more tenaciously than elsewhere, forming an indication of the discontinuity.

For this indication to develop, the discontinuity must be angled against the magnetic lines of force. Thus, when current is passed longitudinally through a workpiece, only longitudinal flaws will show. Putting the workpiece inside a solenoid coil will create longitudinal lines of force (Fig. 3) that cause transverse and angular cracks to become visible when the magnetic powder is applied.

Although much simpler to use than radiographic inspection, the magnetic particle method is limited to use with ferromagnetic materials and cannot be used with austenitic steels. A joint between a base metal and a weld of different magnetic characteristics will create magnetic discontinuities that may falsely be interpreted as unsound. On the other hand, a true defect can be obscured by the powder clinging over the harmless magnetic discontinuity. Sensitivity decreases with the size of the defect and is also less with round cracks such as gas pockets. It is best with elongated forms, such as cracks, and is limited to surface flaws and some subsurface flaws, mostly on thinner materials.

Because the field must be distorted sufficiently to create the external leakage required to identify flaws, the fine, elongated discontinuities, such as hairline cracks, seams or inclusions that are parallel to the magnetic field, will not show up. They can be developed by changing the direction of the field, and it is advisable to apply the field from two directions, preferably at right angles to each other.

Magnetic powders maybe applied dry or wet. The dry powder method is popular for inspecting heavy weldments, while the wet method is often used in inspecting aircraft components. Dry powder is dusted uniformly over the work with a spray gun, dusting bag or atomizer. The finely divided magnetic particles are coated to increase their mobility and are available in gray, black and red colors to improve visibility. In the wet method, very fine red or black particles are suspended in water or light petroleum distillate. This can be flowed or sprayed on, or the part may be dipped into the liquid. The wet method is more sensitive than the dry method, because it allows the use of finer particles that can detect exceedingly fine defects. Fluorescent powders may be used for further sensitivity and are especially useful for locating discontinuities in corners, keyways, splines and deep holes.

Liquid Penetrant Inspection (PT)
Surface cracks and pinholes that are not visible to the naked eye can be located by the liquid penetrant inspection. It is widely used to locate leaks in welds and can be applied with austentic steels and nonferrous materials where magnetic particle inspection would be useless.

Liquid penetrant inspection is often referred to as an extension of the visual inspection method. Many standards, such as the AWS D.1. Code, say that "welds subject to liquid penetrant testing·shall be evaluated on the basis of the requirements for visual inspection."

Two types of penetrating liquids are used - fluorescent and visible dye. With fluorescent penetrant inspection, a highly fluorescent liquid with good penetrating qualities is applied to the surface of the part to be examined. Capillary action draws the liquid into the surface openings, and the excess is then removed. A "developer" is used to draw the penetrant to the surface, and the resulting indication is viewed by ultraviolet (black) light. The high contrast between the fluorescent material and the object makes it possible to detect minute traces of penetrant that indicate surface defects.

Dye penetrant inspection is similar, except that vividly colored dyes visible under ordinary light are used - Fig. 4. Normally, a white developer is used with the dye penetrants that creates a sharply contrasting background to the vivid dye color. This allows greater portability by eliminating the need for ultraviolet light.

The part to be inspected must be clean and dry, because any foreign matter could close the cracks or pinholes and exclude the penetrant. Penetrants can be applied by dipping, spraying or brushing, but sufficient time must be allowed for the liquid to be fully absorbed into the discontinuities. This may take an hour or more in very exacting work.

Liquid penetrant inspection is widely used for leak detection. A common procedure is to apply fluorescent material to one side of a joint, wait an adequate time for capillary action to take place, and then view the other side with ultraviolet light. In thin-walled vessels, this technique will identify leaks that ordinarily would not be located by the usual air test with pressures of 5-20 lb/in.2 When wall thickness exceeds ¹ in., however, sensitivity of the leak test decreases.

Ultrasonic Inspection (UT)
Ultrasonic inspection is a method of detecting discontinuities by directing a high-frequency sound beam through the base plate and weld on a predictable path. When the sound beam's plate path strikes an interruption in the material continuity, some of the sound is reflected back. The sound is collected by the instrument, amplified and displayed as a vertical trance on a video screen - Fig. 5.

Both surface and subsurface detects in metals can be detected, located and measured by ultrasonic inspection, including flaws too small to be detected by other methods.

The ultrasonic unit contains a crystal of quartz or other piezoelectric material encapsulated in a transducer or probe. When a voltage is applied, the crystal vibrates rapidly. As an ultrasonic transducer is held against the metal to be inspected, it imparts mechanical vibrations of the same frequency as the crystal through a couplet material into the base metal and weld. These vibrational waves are propagated through the material until they reach a discontinuity or change in density. At these points, some of the vibrational energy is reflected back. As the current that causes the vibration is shut off and on at 60-1000 times per second, the quartz crystal intermittently acts as a receiver to pick up the reflected vibrations. These cause pressure on the crystal and generate an electrical current. Fed to a video screen, this current produces vertical deflections on the horizontal base line. The resulting pattern on the face of the tube represents the reflected signal and the discontinuity. Compact portable ultrasonic equipment is available for field inspection and is commonly used on bridge and structural work.

Ultrasonic testing is less suitable than other NDE methods for determining porosity in welds, because round gas pores respond to ultrasonic tests as a series of single point reflectors. This results in low-amplitude responses that are easily confused with "base-line noise" inherent with testing parameters. However, it is the preferred test method for detecting plainer-type discontinuities and lamination.

Portable ultrasonic equipment is available with digital operation and microprocessor controls. These instruments may have built-in memory and can provide hard-copy printouts or video monitoring and recording. They can be interfaced with computers, which allows further analysis, documentation and archiving, much as with radiographic data. Ultrasonic examination requires expert interpretation from highly skilled and extensively trained personnel.

Choices Control Quality
A good NDE inspection program must recognize the inherent limitations of each process. For example, both radiography and ultrasound have distinct orientation factors that may guide the choice of which process to use for a particular job. Their strengths and weaknesses tend to compliment each other. While radiography is unable to reliably detect lamination-like defects, ultrasound is much better at it. On the other hand, ultrasound is poorly suited to detecting scattered porosity, while radiography is very good.

Whatever inspection techniques are used, paying attention to the "Five P's" of weld quality will help reduce subsequent inspection to a routine checking activity. Then, the proper use of NDE methods will serve as a check to keep variables in line and weld quality within standards.

The Five P's are:
1) Process Selection. The process must be right for the job.
2) Preparation. The joint configuration must be right and compatible with the welding process.
3) Procedures. The procedures must be spelled out in detail and followed religiously during welding.
4) Pretesting. Full-scale mockups or simulated specimens should be used to prove that the process and procedures give the desired standard of quality.
5) Personnel. Qualified people must be assigned to the job.

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One of the easiest and simplest ways to make the car have the fuel economy and power you want is by installing a new Toyota performance chip. The selection of Toyota performance chips is the best on the Internet that gives you more options. When someone really needs to make the car become more powerful then he/she will have to make the engine of the vehicle more flexible, the only answer to this is a new power chip added to the vehicle that is Toyota.

The Toyota performance chip would allow one to make more powerful at the turn of a knob. The Surge Engineering Toyota power performance chip is made so that it can be installed by the customer. You can install one of these power chips in just in some minutes and the car will be more responsive to all of inputs for this process one should simply switch up the power delivery with the given supplied knob. A turn towards the right direction and one would be doing bigger tearing up and burnouts of the track. When one reaches their home, he/she can turn the knob towards the left side to get the car up to four more miles to the gallon.

There are various advantages of using the Toyota performance chip which could be said as increases power, expands the time duration between expensive tune ups, aids the spark plugs life that is installed in the engine, very good for the manual or the auto transmissions for fasting shifting, increases torque, Has the performance that is insane which actually does not hurt the gasoline, has better capacity for towing and it increases the top speed as well as acceleration. Making most of the car's engine is not just down for the Toyota ECU chip. One can also change the Toyota oxygen sensor to make more power if they wish to do so. The Toyota O2 power sensors would redirect the sensor readout to make the car run with more power. A new Toyota performance oxygen sensor would make the engine perform much better in every types of condition. The performance chips for the Toyota are considered to be one of the best upgrades any of the company’s could ever make. These chips of Toyota would actually indulge you to think seriously that you have two cars .In one you would feel as if one has a fuel miser on the highway and has a tire burner on the track in the other one.

The new Toyota Performance chip makes your car look attractive and gives it a very new appearance. These Performance Chips make the motor run at its best. There is no other better way to enhance the performance of one’s Toyota vehicle than by installing the Performance Chip of the Toyota today itself without any hurdles. Go on to become a performance-minded and install the Performance Chips of Toyota, and the vehicle would give you a very quick response and would actually reward you with a greater horsepower. One has various options to choose from different varieties of performance chips for Toyota. Whatever the needs are of the customers, the brand Toyota provides the Performance Chips which are the best for them and their vehicle.

The Toyota Performance Chip upgrades the current running condition of the vehicle’s engine. Plug in a performance chip for Toyota and one can see their engine’s power that actually gets rev up. And one could know that they are always getting a great deal with the installation of the performance chips of Toyota, because this top-brand of Performance Chips come with a 1-year lower price guarantee from Toyota.

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4130 Chromoly tubing is used for all kinds of applications, but 2 of the main ones are for airplanes and for racing just about anything from motorcycles, to mountain bikes, to go-carts.

AISI 4130 tubing is strong. It's real strong. So the reason it is so popular among race car and airplane builders can use thinner tubing and that translates into speed and less weight.

Welding 4130 steel tubing is not that hard. There seems to be some mystique around it but it actually welds better than plain carbon steel.

So then whats all the fuss about? Well there is one thing. If it cools too quickly, 4130 chromoly tubing will be hard and brittle in the heat affected zone of the weld.

Thats the main thing to be concerned about. So how do you prevent the weld area from cooling too quickly?

1. Make sure the ambient temperature is above 60 degrees F.
2. Use a small propane torch to preheat weld area to about 100-150 F. 300 degrees F if room air is below 60 degrees.
3. Weld a little bit slower than you would for plain carbon steel.
4. Dont use 4130 tig welding rods. Use E70S2.
5. Never speed cool anything.

Some frequently asked questions about tig welding 4130 steel tubing are:

Q. Do I need to heat treat the weld when I am done welding?

A. No, the term heat treat is often misused. What is usually meant when it comes to welding chromoly is "stress relief". A stress relief can be done with an oxyfuel torch and a 900 degree F temp stick or a digital pyrometer. But it is usually unnecessary unless the thickness exceeds one eighth inch.

Q. Do I need to back purge my Chromoly welds with argon gas?

A. It always helps, but think about how many oxy acetylene welds there are out there doing fine that were done with no purge.

Q. What about using 308 stainless for welding chromoly?

A. there is a bunch of discussion on Baja Racing forums on this subject. I can tell you that lots of welders are using er308 tig welding rod with success, but for airplanes, E70S2 is the way to go. One thing that might not occur to you that you should consider is that if you ever needed to weld repair something and all you had was a gas welding torch, the E70s2 would be easily welded over with an oxyfuel rig. The 308 stainless welds? Not so much.

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However all vehicles should be maintained regularly to keep fit, cars need more attention from their owners to give them the luxury drive with pride. Unlike other cars whose service intervals are based purely on mileage traveled, BMW's service interval based system measures maintenance requirements based on actual use of the car and the conditions in which it has operated. The Recommended Service intervals for older BMWs are shorter, and the owners of older cars often benefit in more frequent servicing.

When it comes to care for your luxury car like BMW, you can’t trust upon anybody else except experts in the field. Trained technicians of BMW Repair Mesa put their expertise to work on restoring your BMW to peak performance. Their technicians are not only specially trained in the care of all BMW vehicles, but they also use only genuine BMW parts, ensuring that your BMW gets the professional, quality care it deserves. They also have expertise in other expensive cars like Audi and Porsche etc.

If your car is in need of any repair, start looking for a qualified professional to handle your concerns. The correct service interval for your car depends upon many factors including the specific year and model of the car, particular driving habits and the type of engine oil you are using. Porsche Service Phoenix looks forward to serving all your Porsche needs. They give you the high quality services in reasonable prices.

Regular preventative maintenance is critical to significantly maximizing the life of a vehicle. As a car owner it is your responsibility to keep up routine maintenance on your vehicle. By ensuring the right service at the right time you not only save you from the headache but also costly repairs that can be easily prevented. If you're looking for someone to service your Audi, Audi Repair Chandler can be a huge help. They have all the experience and expertise to give your car the best treatment.

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Now our youth have a variety of career options to choose from. A career in heavy equipment repair is one such opportunity and an ideal choice for youngsters who have a mechanical inclination and who like to deal with this machinery that is used for construction or mining industries.

Machinery like bulldozers, cranes, forklifts, excavators and many others fall into the category of heavy equipment because of size and strength. This machinery can only operated by well-trained and skilled operators. Heavy equipment operators undergo training for operating as well as repairing these expensive machines.

There is a huge demand for operators as well as heavy equipment repair technicians due to industrial growth in transportation, trucking, construction etc. Employers are unable to recruit highly specialized repair technicians due to a shortage of trained technicians. So if you are keen in making a career in this field then you can join any of the heavy equipment training colleges to become an accredited repair technician.

These training schools design programs educate the candidates with details of the equipment as well as train them in repair and maintenance of the heavy equipments like wheel loaders, backhoes, forklifts, bulldozers, skid steers and excavators.

Training courses guide you through the repair and maintenance prospects and show you the right way to grow in this career. Such courses are highly practical and provide hands on training. This career can provide you a start from $10-$25 per hour and as you gain experience in this field you can surely expect a high pay scale. After gaining five years experience in this field, you can surely expect a hike of $70,000 per annum.

Repair training courses are available throughout the year and some colleges offer courses in the evening, while some offer regular daytime courses to enable you to adjust your schedules accordingly. The demand is ever increasing in the field of heavy equipment repair technicians in the field of transportation technology and those who love hands on work experience as well as those who are mechanically skilled can choose this field. This repair course allows you to flourish in this field and avail of many opportunities. You can even learn to impart your skills and you can expect a pay scale of $10-$25 per hour or more. Career prospects in this area include automotive, aviation, heavy equipment operation, equipment repair, truck driving and collision repair.

If you have an interest in heavy equipment repair, then you can take up an accredited training. Once you are trained, you can surely grow in this field and get many credentials and become a professional technician.

Growth prospects range from service technicians to service mangers or you can start your own repair shop some day. This can be achieved with an academic career-training program provided by various training schools. The jobs provide job satisfaction as well as help you to earn an attractive pay package. Initially the pay scale may be modest, but it is bound to increase with experience and expertise.

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If welding with a solid wire is satisfactory, why use a higher priced flux-cored wire? A flux-cored wire is optimized to obtain performance not possible with a solid wire. For many welding applications like vertical-up welding, flat welding, welding over galvanized, or welding hard-to-weld steels, a flux-cored wire can do it better and faster.

Although gas metal arc welding (GMAW) with a solid mild steel wire is popular, easy-to-use, and effective for many applications, it does have limitations and drawbacks. For example, GMAW is slow for out-of-position welding. It is either limited to short-circuit transfer, which is restricted by many welding codes due to the tendency for lack-of-fusion, or pulse transfer, requiring a special welding power source. It also requires very clean steel.

The ability to add a variety of materials to the core of the welding wire allows many performance enhancements to be made. Slag formers are added to shield the weld pool and shape and support the weld. Iron powder is used to increase deposition rates. Powdered alloys are added to produce low-alloy deposits or improving the mechanical properties. Scavengers and fluxing agents are used to refine the weld metal.

Flux-cored arc welding gas-shielded (FCAW-G) wires were introduced to the market around 1957. The flux-cored arc welding self-shielded (FCAW-S) wires were introduced to the market later, around 1961.

The core ingredients for FCAW-G wires have been formulated to obtain performance impossible to achieve with a solid GMAW wire. As all of shielding is provided by the shielding gas, the core materials may be carefully selected to maximize a certain area of welding performance, such as obtaining smooth spray-type transfer with 100% carbon dioxide shielding gas and welding speeds twice as fast in the vertical position.

The FCAW-S wires on the other hand, the core materials must provide all of the shielding. The core materials generate its own shielding gases, slag formers, and compounds to refine the weld pool. The benefits of self-shielded flux-cored wires lie in its simplicity. They may be used outdoors in heavy winds without tenting and the additional equipment required for gas shielding.

Now, we're going to discuss several popular types of flux-cored wires and how they can increase welding productivity.

For semi-automatic out-of-position welding, E71T-1 wires offer unsurpassed performance. Its fast freezing rutile slag provides the highest deposition rates in the vertical-up position, up to 7 pounds per hour, unmatched by any other semi-automatic arc welding process. In addition, the E71T-1 wires also offer an exceptionally smooth welding arc and minimal spatter, even with 100% carbon dioxide shielding gas. Argon/carbon dioxide blends are used for the smoothest arc and best out-of-position performance. These are reasons why E71T-1 is the world's most popular flux-cored wire. It is a top choice for shipbuilding, structural steel, and general steel fabrication applications.

For semi-automatic out-of-position welding without shielding gas, E71T-8 wires offer the highest deposition rates. Lincoln Electric's NR®-232 can deposit 4.5 lbs./hr. in the vertical-up position, 50% faster than other E71T-8 wires. Since this wire is self-shielded, it is widely used outdoors and in field erection of structural steel.

For semi-automatic welding in the flat position, the fastest way to join thick steel plate is with an E70T-4. It offers the highest semi-automatic deposition rates, up to 40 pounds per hour. This wire is widely used to join thick steels where there is no Charpy impact toughness requirement. This wire is also self-shielded, allowing it to be easily used outdoors.

The highest deposition rate gas-shielded flux-cored wire is E70T-1. Compared to E70T-4, they offer slightly lower deposition rates of up to 30 pounds per hour, but they offer a smoother welding arc and Charpy impact toughness properties. It offers higher deposition rates than GMAW, handles dirtier plates, and uses lower cost 100% carbon dioxide shielding gas. E70T-1s are widely used in structural steel fabrication shops.

For welding coated and galvanized sheet steels, E71T-14 is the wire of choice. The self-shielded E71T-14 wire has core materials which explode in the arc, volatizing the steel coating, minimizing cracking and porosity. The result is higher quality welds and fast welding speeds. E71T-14 wires are widely used in the automotive industry for fabricating galvanized steels.

What is the fastest way to weld hard-to-weld steels? E70T-5 gas shielded wire offer excellent crack resistance on hard-to-weld steels, such as T-1 quench and tempered steels, abrasion resistant steels, and free machining steels. E70T-5 has a basic slag system, similar to 7018 stick electrode, which removes phosphorus and sulfur from the weld metal, which can cause cracking, porosity, and poor toughness. E70T-5s have lowest diffusible hydrogen levels among the flux-cored wires, resulting in excellent resistance to delayed hydrogen cracking, as. In addition, they offer exceptional Charpy impact toughness properties.

Flux-cored wires offer higher productivity for many mild steel semi-automatic welding applications:

E71T-1 (FCAW-G): Highest deposition rates out-of-position.
E71T-8 (FCAW-S): Highest deposition rates out-of-position without a shielding gas.
E70T-4 (FCAW-S): Highest deposition rates in the flat position.
E70T-1 (FCAW-G): Highest deposition rates in the flat position with Charpy properties.
E71T-14 (FCAW-S): Fastest travel speed on galvanized and coated steels.
E70T-5 (FCAW-G): Fastest way to weld hard-to-weld steels.

Why be limited by a solid wire when a flux-cored wire can do it better and faster? Select the flux-cored wire optimized for your welding application. Use it and increase your productivity and lower your welding costs.

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The characteristic loud, continued accent of a locomotive's admonishing arresting is amid the best calmly apparent sounds around. Play a band with a agglomeration of two-second complete snippets and best bodies will be able to calmly analyze which is the blare of a locomotive. For abounding bodies it is additionally a activate for addicted memories, abnormally if they grew up abreast a base or the railroad tracks. Imagine that aforementioned conspicuously loud complete advancing from your auto or SUV and there isn't a abuse alley in sight. All you charge to do to accomplish that dream a absoluteness is booty a attending at the abounding alternation horns for trucks that are accessible as an aftermarket accessory.

The loud bawl of an abutting adaptable was developed to active pedestrians and motorists that they bare to break off the advance so the alternation could canyon after hitting anyone or anything. It was additionally acclimated as a advice apparatus amid the architect and railway and base workers. The aboriginal whistles were powered by the beef engine's exhaust. However, as agent engines began to alter beef the activating air horn became the accessory of choice. Train horns for trucks are the aforementioned as those acclimated on locomotives, except they accept been scaled bottomward in size. The 25-gallon air catchbasin frequently acclimated on the railway is aloof too big, and bluntly overkill, for use on commuter vehicles. Those accessories about accept tanks that ambit in admeasurement from one to bristles gallons. The added apparatus accommodate an air compressor that's appropriately powered to ample the tank, air hoses, valves, trumpet-shaped horns, and all the accouterments appropriate to put it all together.

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Motorbikes are becoming a more and more popular method of commuting in cities throughout the UK as roads become grid-locked with cars, trucks, buses and roadworks! Yet motorbikes still manage to weave their way through traffic and reach their destination on time - highlighting another benefit that biking has in comparison to driving a car. Not only can a motorbike traverse spaces that would be impossible in a car, motorbikes are also cheaper to maintain, have better fuel economy and it is much easier to find parking spaces in busy areas. In 2006 there were over 1.1million motorbikes registered in the UK, a figure which has gradually grown as popularity for biking rises.

In the UK, it is a legal requirement to be insured when driving on public roads. So, whether you’re a commuter who uses a motorbike to squeeze past gridlocked cars to get to your work on time, or a recreational rider exploring the UK’s country roads at the weekends, you’ll need adequate insurance cover to keep yourself and others protected while on the road.

However, it's not only when driving a motorbike that you need motorbike insurance. Due to the design and size of motorbikes, they can be stolen and removed by thieves far more easily than a car, and as a result most general insurance companies deem insuring motorbikes as a high risk. However some companies specialise in motorbike insurance and appreciate that this is not necessarily the case. In fact, providing the owner implements some basic security measures a motorbike can be as low risk to own as a car.

For example, motorbikes should be parked in well lit areas and the frame should be secured to a fixed object with a sturdy security chain. To further deter would-be thieves, fit an approved immobiliser to prevent the engine being started without the key, and install a Thatcham approved alarm. You could also have a tracking device fitted to help the Police track your motorbike in the event it should it be taken.

Owners should also buy an ultraviolet pen to mark their motorbike with personal details and keep a copy of the serial number of their motorbike, so that if their motorbike is stolen it can be traced back to the theives by the authorities. By taking precautions such as these, you can reduce your motorbike insurance premium.

The most common type of insurance chosen by owners is a comprehensive policy. This level of cover ensures that in the event of an accident the policy holder will be fully insured for the market value of their motorbike, as well as the repair cost of any damage caused to a third party by the policy holder. Some policies even cover policy holders for personal claims against them, which in today's litigious climate is certainly a comforting safeguard. This ensures that if you are unfortunate enough to have an accident, you won't have to cope with a huge financial burden too.

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Caring for the clear coat on your car is not easy with all the challenges our cars face every day. After all, we are merely one shopping cart away from permanent damage. To properly maintain the clear coat of your car you need to keep a good coat of wax and sealant on it. This may not sound like a big deal, but the way in which you wax your car does matter, as you can damage the clear coat if you do not do it properly.

For instance, if you hire an auto detail who does not know how to use a buffer, or does not use the right type of application pad when putting on the wax, he can actually damage your car's clearcoat rather than helping you protect it. Also if you go to a carwash and the brushes are not clean they can cause tiny scratches in the clearcoat, which can start the clearcoat decaying.

It's best to wash the car with soap and water by hand using a lamb's wool mitt, gently removing the dirt, then carefully chamois off the remaining water. When completing the job it makes sense to inspect to make sure there is no damage to the clear coat of your car, and then applying a coat of wax. There are special clear-coat-waxes made that are also sealant coatings, many of these are specially made for clear-coat cars.

Once you have a strong sealant coat on your car it makes sense to wax it with regular wax many times over again. This will protect your car from scratches and therefore, protect your automobile's clear-coat from harm. Please consider all this.

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