Kamis, 09 April 2015

Welding heat treatment effect on stress corrosion resistance of welded steel pipe

Welded steel stress corrosion can occur only under certain circumstances, it has the following characteristics: only the presence of stress (tensile stress in particular) is to stress corrosion cracking. This stress can be applied stress or residual stress introduced during the welding and processing of T, it can be expanded to stress corrosion products caused by the wedge effect. Stress corrosion cracking is a time lag of about destruction, which delayed cracking and hydrogen completely similar. Stress corrosion cracking is a low-stress brittle fracture.

Stress corrosion is the damage under tensile stress, caused by metal corrosion medium. This corrosion generally across the grain, which is called transgranular corrosion. Strain the combined effects of stress corrosion and corrosion by the residual or applied stress generated by the destruction caused by the process. Cause stress corrosion fracture of materials known as stress corrosion cracking. Stress corrosion is generally considered the anodic dissolution and hydrogen induced cracking two kinds. Stress corrosion is a common mechanism: the parts or in the medium under the action of stress and corrosion, the surface of the oxide film is etched and damaged, and does not damage the surface of the surface damage formed in the anode and cathode, respectively, at the anode metal ion is Be dissolved, resulting in a current to the cathode. Since the anode is much smaller area than the cathode, the anode current density is large, the destroyed surface further corrosion. Plus tensile stress the role of the destruction of the gradual formation of cracks, crack over time gradually extended until it breaks. Such cracks can not only develop along the metal grain boundaries, but also across the grain development. Stress corrosion cracking is a petrochemical equipment, especially oil pipeline is a common cause of failure of welded steel pipe. Due to the unpredictability of stress corrosion cracking occurred, and therefore the largest petrochemical industry hazards. A necessary condition for the occurrence of stress corrosion cracking and corrosion medium tensile stress coexistence, the tensile stress is an important condition for stress corrosion. In the petrochemical and nuclear industries equipment, most of the stress caused by stress corrosion cracking is caused by the residual tensile stress, it is often superimposed on job stress. Mainly from tensile residual stress generated in the device residual stresses during welding. Currently, the project is widely used to eliminate residual stress annealed after welding cooling, and cooling after welding residual stress is an important process, this approach is not a waste of energy and easy to produce larger welding residual stresses. Post weld heat treatment is a new technique to eliminate residual stress. After the material is preheated before welding to heat treatment temperature and the welding process to maintain continuous heating of the weld member that temperature after soldering using its thermal insulation cotton allowed to cool slowly. This method can effectively reduce the welding residual stress, improve resistance to stress corrosion of metals.
Post weld heat treatment can effectively reduce the welding residual stress, and heat treatment temperature is higher, the residual stress better. Heat treatment after welding can be effectively improved stress corrosion resistance welded steel pipe, the higher the heat treatment temperatureScience Articles, stress corrosion resistance increased more significant.
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Kamis, 02 April 2015

Welding Tools- All You Need To Know

Welding Tools - All You Need To Know - Tools are specifically used for some purpose to achieve or produce something and the weldors need a proper welding tool to acquire a good control over the work.
Due to advancement in technology, welding products with portable and comfortable sizes are available and it enables the weldors to weld the metals soon. To become a good weldor or to become a famous entrepreneur in welding industry, knowledge about the welding tools is must. There are different types of welding such as mig, tig, stick and submerged arc, and each type of welding use different welding tools. Each type of welding uses different tools, so it is always better to have equipment that best suits and do all kinds of work.

From the decade, welding has been developed a lot with new welding technologies and with advanced welding equipment and systems. The weldors should be aware of the latest welding technology and should be equipped with welding accessories and tools. Also, the welding industry should be equipped with modern tools such as welding electrodes, welding torches, welding consumables and welding guns and should follow the proper welding system with appropriate welding technology. The basic tool the weldor use is a welding gun, it is a tool that does spot weld, tack weld and burns holes in metals and you can drill faster and make a spot within a second.

Welding torch is used to weld metals and the cutting torch is used to cut metals, rose-bud torch is used to heat metals for bending and straightening and injector torch is used to mix the two gases. If you are a tig weldor, then know about the tig welder machines that is focused on user convenience and it exists in different types such as power tig 200DX, 250EX, 315DX, 225LX and power 1-tig 200. They are designed to weld any types of steel and stainless materials and it is easy to repair in the field and garage. Power arc welder exists in two types such as 200 welders and 160 welders. Smooth dc arc, low power consumption, high duty cycle with digital display and adaptive arc force control are its special features.

Mig welder exists in four types such as 160 welder, 200 welder, 205 welder and 250 p welder. They are Convenient and portable, with the help of this unit, you can go any where to get to the repair. Multi process units are completely redesigned for greater portability and convenience, the power ultra is ideal for using in the field for the spot repairs and quick fab jobs requiring basic tig, stick and/ or plasma processes. These units exists in six types such as powerultra 164, 185, 205 and powerpro 205, 226 and 256. The process of welding cannot be successful unless there are no proper accessories and parts. Accessories such as guns and torches, spool guns, welding helmets and gloves, welding carts and parts are important accessories in welding.
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Sabtu, 28 Maret 2015

Plastic pipe preheating temperature control

Preheat plastic pipe coating stage, preheat temperature control at 150 , after half an hour you can paint processing. Painting can be used when spraying or dip, high-voltage electrostatic spray painting is by way of the epoxy powder coated steel surface, dip is directly immersed in the well pipe, filling epoxy powder.
Plastic pipe having excellent corrosion resistance and a relatively small frictional resistance. Epoxy coated steel pipes for conveying water supply and drainage, water, warm water, oil, gas and other media, PVC plastic pipe for conveying drainage, water, oil, gas and other media. Plastic pipe is the use of PE (polyethylene modified) or hot dip EP (epoxy) coated inside and outside of the product, has excellent corrosion resistance. Meanwhile coating itself also has good electrical insulation, does not produce galvanic corrosion. Low water absorption, high mechanical strength, low coefficient of friction, can achieve the purpose of long-term use. Can effectively prevent the destruction of plant roots and soil environmental stresses. Connection convenient, easy maintenance.

Hot dip steel can be called hot dip coated steel, the different nature of it and electrostatic spraying, the polymer coating is corrosion by high-pressure electrostatic plastic powder coated steel surface sprinkled in, and dip is put directly into the pipe Plastic wells polymer powder, processing the same purpose of these two are so welded at high temperature plastic powder in the surface of the pipe to form a composite tubular body. Diameter steel pipe is guaranteed due to the existing ordinary ordinary galvanized steel lined with plastic, so its actual diameter composite pipe significantly less than the specified diameter, coupled with its joints to achieve corrosion requirements, the actual path lined after its less than the specified diameter of 1/3. Lined steel reinforcement embedded within the outer layer of galvanized steel is specially processed, so its actual diameter composite pipe is fully consistent with the provisions of diameter, and pipe joints no path loss.
Inner pollution prevention measures to improve: the use of ordinary steel pipe fittings to connect the traditional way, will cause secondary pollution of water after fitting threaded outer rust. Steel bars embedded in the plastic-lined using quick connect fittings, interior fittings in his possession were all lined handle, when connected to the pipe, the pipe system is not any metal material portion of the fluid in contact with the transmissionArticle Submission, it is possible to effectively prevent the water quality secondary pollution.
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Jumat, 20 Maret 2015

Mig Welding: Techniques And Application

Mig Welding: Techniques And Application - If there is one group of elements that has played a significant role in shaping human civilization, it is the metals. One good quality of metals is that they are easy to shape, whether they are molten, hot or cold. Another quality is they can be joined together to merge or to form different shapes. Most metals can be joined by a process called welding.
In welding, the edges of two metal pieces are held together and melted with a gas flame or a powerful electric spark called an electric arc. That is why welding is commonly referred to as arc welding of more specifically Metal Inert Gas welding or MIG welding. The molten metals then fuse together and form a strong joint as they cool.

The technique used in MIG welding is simple. A consumable wire electrode and a shielding gas are fed through a welding gun onto the metal pieces to be welded. When cooled, the bond becomes very strong which can later be finished by grinding, cleaning, polishing and painting. Four primary techniques in MIG welding include globular, short-circuiting, spray and pulse spray.

MIG Welding was initially developed for welding aluminium and other non-ferrous metals and alloys such as brass, copper and bronze. Later developments found it suitable for iron and steel as well because it allowed for lesser welding time compared to other welding processes. Since then, MIG welding has become the most the most preferred and prevalent welding process. MIG welders usually come in between 150 to 450 amperes electrical capacity. Along with welding equipment come a number of welding accessories that include tool balancers, gouging torches, electrodes, connectors, clamps, and welding aid tools such as chipping hammers, electrode holders and pliers.

Today, MIG welding has application in almost all goods manufactured goods from metals. You may not know, but frames of your bicycle and motorcycle, chassis of your car and sides of your refrigerator are made by welding together iron or steel pipes, angles or sheets. Many of the welding processes in mass production industries have now been automated. For example, the entire car body including doors are now made and assembled by robotic arms. The versatility of welding process enables one to create numerous shapes and profiles, in that context it can be said that welding is both an art as well as a science. Current developments include laser welding, friction welding, electron beam welding and ultrasonic welding. Perhaps future developments may make it possible to weld non-metal items as well.
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Rabu, 18 Maret 2015

A Quick Guide To Welding

There are many ways that humans build things. From sticking stones together with mud, to hammering nails to join wooden boards, to welding together two metals, humans have developed their method of shaping the world around them over time, and now what do we have to show for it? Skyscrapers, ocean liners, construction cranes, and much more. If you are in need of some welding supply in NYC, you can probably benefit from some more information on welding itself.
Welding is a method in construction that involves connecting two materials together. The materials are usually metals, but welding is sometimes used for other materials as well, such as thermoplastics. Rather than tie the two or more pieces together, or bind them to one another with some sort of glue, the materials are actually meant to coalesce; that is to say, join together as one mass. But to do this with metals involves making them melt, and that, in turn, requires intense heat in most cases. Once the metal pieces are melted into a weld pool, either by using a laser, a flame, or an electric arc (among other things), a filler material is added, and then the mixture is allowed to cool into a strong joint which is one mass. This process differs from soldering, in which the workpieces are not melted. Only the filler material is melted, and this forms the bond between the two workpieces. This method often produces a less powerful joint than with actual welding.

Welding supply in NYC companies can have a wide knowledge of welding technique, procedure, and history. Early welding was known as forge welding, which consisted of heating two metals in a forge and then hammering them together once they are hot enough to not be completely solid. Nowadays, welding technology lets welders make a much stronger bond between the two workpieces, and the process of heating the metals to the appropriate temperature is usually a lot shorter as well. The presence of these high temperatures makes welding a potentially dangerous process, and modern welders usually take care to protect themselves from heat with fire-retardant jackets, heavy gloves, etc. Also, the bright light emitted by the heat source in the welding process can easily burn the human retinaPsychology Articles, and so protective goggles or masks with UV-filtering material are used to protect the eyes. Welding supply in NYC companies can probably hook you up with any safety equipment you may need.

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