flange fittings pipes

Flat welding flange is only applicable to pressure levels low stainless steel flange, threaded connections. The fatigue life of flat welding flange is only about a third of the butt welding flange, subjected to inteal pressure and the performance of flat welding flange, stainless steel flat welding flange though the price is cheaper than stainless steel threaded flange. Easy to damage the flange surface and cause the deformation of the flange surface, cannot be used in under the action of alteating stress, stainless steel threaded flange is used in the occasion of galvanized steel pipe and cast iron flanges can't welding.

Stainless steel threaded flange this kind of flange is in the socket of flat welding flange pipe thread tube and pipe connection, the flange material does not necessarily consistent with pipes. One of the flange is fitting. So, this kind of flange. Therefore has been widely used, the thickness of the section of the high neck through the high neck gradually transition to the wall thickness, thus increasing the intensity of stainless steel threaded flange. Worse than butt welding flange, pipe material must be consistent with the pipe material. Not necessarily cheaper than butt welding flanges, generally used for small diameter pipe (() and the following. Welded tubes inserted into the flanges. Mainly used for connection of the pipe and pipe fittings, valves, equipment, fatigue strength 50% larger than flat welding flange, butt welding flange your of the same pressure temperature rating. Alloy steel flange has enough strength, stainless steel threaded flange can be used for high pressure conditions, due to the cheap material can use different material of flange. The gap between flange and pipe sometimes prone to corrosion; Hence reduces the discontinuity of stress, when using this kind of flange. The intensity of flat welding flange approximately two-thirds of the corresponding butt welding flange, pipe and flange pipe butt welding, such as. Static strength are the same. Also, instead of welding.

 www.wilsonpipeline.com

Stainless steel flange is also called the loose flange, rotating with flange. The inner diameter of the butt welding flanges shall be in accordance with the connection pipe diameter, but with the pipe connection on both sides of the fillet weld; Due to the combined with flanging tube joint, and cheaper prices. If the inside and outside welding, pressure or temperature fluctuations of pipeline or high temperature, high pressure and piping of sub-zero temperatures, flange set outside the flanging pipe joint; In order to avoid because of the flange joint leakage or damage can lead to bad consequences, its advantage is flange can rotate, but not easy to welding, general and flanging tube joint combination. Combined, such as the cost of raw materials and construction costs, there is a seam on the back of the flange, butt weld stainless steel flange bolt hole easily. Less important on the pipeline, pipe flange flanging activities can also be applied to need frequent disassembly for cleaning or inspection, due to thermal expansion pipe or other load and make the stress of the flange of the larger or stress changes repeatedly, its diameter should be consistent with pipe diameter, easy to leak. Should not be used in place of temperature fluctuation repeatedly. But for your pipes in particular, on the spot annealing is difficult, therefore. Butt welding flange can also be used to deal with expensive, inflammable, explosive fluid; If the inside welded again on one can avoid the corrosion, stainless steel flange when using this kind of flange. Socket welding flange its basic shape the same as the flat welding flange, flange and pipe connection in the form of butt welding, welding, thread, socket welding and flanging activity type (also called loose flange), etc;

Stainless steel flange easier due to the pressure fluctuations, temperature fluctuations, vibrations and shocks are not serious occasions during welding assembly line, or only when the alignment flange bolt holes in the rotation method Portland rather than the rotation of the tube. Calculated according to the inteal pressure, generally used for pressure, low temperature, construction costs cheaper.

Only 10% of the fatigue life of welded flange. Because in the vicinity of the welding flange. Welded flange for applications that require more severe cases, petrochemical enterprises in the process piping commonly used welding, than the same diameter. The use of large-diameter pipeline is easy to install, welded flange and other different flange that flange and pipe welding with a circle of high long and lean neck (neck). In the petrochemical business in public works mostly for the pipeline.

When countries facing the world opening, merchandise exports and imports has become one of the most common communication content. A lot of goods to the world have a better development, flange for this commodity is no exception. But this kind of goods for China, the market prospect is not optimistic, in the first is how export flange with overseas stock traders get close contact as soon as possible do a simple introduction:
First of all, the exporter should pay attention to, not can use the way of writing or respects is the way to establish close contact with overseas suppliers. Because for merchants to import flange, received many letters every day, but in fact these letters tend to be handled with as rubbish. Because this way will waste precious time in the history of replenish onr's stock, because these overseas stock traders like to use more direct and more convenient way. , of course, if there are any business urgently needs to find a partner, your way of writing are also likely to be successful, but the hope too slim.
Second, most can communicate is set up for the market of the country for a friendly visit, and then to interview you want to establish business relations company. For the two cities went to Sydney or Melboue goods access, usually in the area of outlet flange can have more chance to meet major importers. Need to do is to remind here, must make appointments before the meeting, this is also an aspect of etiquette.
Once get the chance to meet the importer, the first to use the price of a product attract purchase business in Australia. Because of Australian businessmen don't like to bargain, as long as they think the price is more appropriate, they will be willing to go to the next link exchanges. But it also from another side, let us know that all the businessmen care most about a problem is the price of the product. Once the commodity price recognised by the Australian businessman, they in the production process of suppliers after investigation, will decide whether place and merchants have long-term business relations.

Finally, in terms of export flange. Exporters also note that if you want to get in touch with the importer with the fastest speed, the best way is to find a purchasing agent in country, because the importer and purchasing agent contact opportunities is more, once you find the importers to trust purchasing agent will make things more quickly.

It is due to the use of stainless steel material production and become the widespread use of flange, so led to this kind of material in the supply of the flange it is good for the manufacturer to a message. Although the number of production is very important, but the importance of quality seems better, this requires manufacturers in the production of stainless steel flange well below these considerations, in order to guarantee the use effect.
The first point, easy to avoid corrosion of stainless steel material
For stainless steel the material on the surface of the the most important thing is to keep it clean, once after corrosion of the stainless steel surface will change the appearance, not so bright and clean. So all those who have the ability of stainless steel corrosion things will be far away from the production. Both acidic and alkaline gases or liquids are far away from the production environment.
The second point, chosen the collocation of flange gasket
The effect of flange connecting pipe above is indeed great, but little also not of gasket. A good helper in the collocation of use of stainless steel flange is asbestos gasket. Asbestos the material itself has very good properties, it can resist acid, either gas or liquid can be well absorbed by asbestos, so as not to affect the stainless steel. A little on special occasions, of course, also use other materials to the production of gaskets, this time to choose and with complementary ability of stainless steel gasket.
The third point, to consider the connection flange production
In there are different ways of connecting pipe, the pipe is thin can tu directly using the thread flange screw connection, some stainless steel flange facing some there is a big pressure pipeline, you will need to use to the welding, so that more solid and reliable. Material made of stainless steel flange still had better choose welding connection, both for the pipe pressure is big or small. Stainless steel welded connection is very convenient, is also easier.

The diameter of the flange plate size, flange thickness is and will face the pressure of the pipeline is big or small. General situation, the more pressure big stainless steel flange thickness is also thick. If the pressure of the pipe is small, then a thin layer of stainless steel flange and disc can get different pipe connection problem.

Source: wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Reciprocating piston compressor, the most commonly used positive displacement compressor, has the advantages of mature technology, wide range of pressure, high thermal efficiency, strong adaptability, large range of exhaust volume regulation, low material requirements, and is widely used in various gas compression airports in the fields of petroleum and chemical industry.
The weldolet is often used for the transition connection between the main pipe and branch pipe of the safety valve, and the threaded weldolet is often used for the transition connection between the main pipe and the temperature and pressure measurement end.
Compared with the traditional connection type, the branch connection has many outstanding advantages, such as safety and reliability, cost reduction, simple construction, improvement of medium flow channel, series standardization, and convenient design and selection.
However, the special structure and weld form of the weldolet increase the difficulty of detection and the complexity of the process. The lack of penetration in the welding process is difficult to detect scientifically and repair effectively. The lack of penetration in the joint has a great influence on the structure. It reduces the effective bearing area of the weld, reduces the strength of the welded joint, causes stress concentration, and increases the safety risk of the unit.

Observation and analysis of inteal appearance of welding joint of weldolet

The appearance of welds on weldolet and main pipe of a unit is shown in Figure 1, and the inteal section is shown in Figure 2.

Figure 1

Figure 2

It can be seen from Fig. 2 that there are a large number of incomplete penetration in the connection weld of weldolet abutment in the actual production process. The possible causes of incomplete penetration are irregular opening, too small assembly gap, improper welding position, too small current, too fast running speed, arc blowing deviation, etc.

Cause analysis

Irregular opening

The weld appearance with mechanical opening is shown in Figure 3. It can be seen from the figure that under the condition that other factors remain unchanged, a large part of the root area of the weld still has incomplete penetration when the mechanical opening is adopted, indicating that the irregular opening is not the main reason for the incomplete penetration of the weld.

Figure 3

Adjust the group clearance

The weld appearance of flame opening mode is shown in Figure 4 after adjusting the assembly clearance, and that of mechanical opening mode is shown in Figure 5. It can be seen from Fig. 4 and Fig. 5 that most areas have been fully welded, indicating that the main reason for lack of penetration is the assembly gap.

Figure 4

Figure 5

The penetration effect of vertical welding and overhead welding position is not good, because these two positions can not promote the droplet away from the end of the welding wire under the same gravity as that of the flat welding position, which is conducive to the weld pool transition.
Manual TIG welding is used for backing, the accessibility of welding gun at the flat position is better, and the weld pool is easy to observe. The welder is more likely to adopt short arc welding, the heat is more concentrated, the heat affected zone is smaller, and the deformation is smaller, which is conducive to improving the welding quality.

The relationship between gap and penetration rate of different pairs is shown in Table 1. It can be seen from table 1 that too small gap and too much gap are not conducive to penetration. The gap is too small, the welding gun is not easy to penetrate into the root of the weld, and the arc can not be well transited to the back of the weld through the gap.

Table 1 Gap and penetration of different pairs

The gap is too large, the melting hole is too large, it is easy to bu through, the back of the weld is too convex, which is not conducive to the gas flow, and is not conducive to the connection of temperature measurement, pressure measurement and other parts. When the gap is 2.5-5mm, the penetration length ratio of single weldolet can be greatly increased.
Under the reasonable clearance, the penetration length of a single weldolet with mechanical opening is slightly longer than that with flame opening, and the weld appearance quality is also better than that with flame opening. This is because adopting mechanical opening is conducive to ensuring the uniform clearance of assembly, and the difference in weld width and residual height is relatively low.

Ensure welding position

On the basis of machining the groove and ensuring the assembly clearance, adjust the welding position and weld the weldment in the flat welding position. The results are shown in Fig. 6 and Fig. 7. It can be seen from the figure that the penetration area of the same weldolet is 100%.

Fig. 6

Fig. 7

The complete sample is radiographed, all areas meet the requirements of domain level, indicating that all welding is complete, and there is no incomplete and inclusion defects.

Parameter validation

The microstructure of the weld after cutting, grinding and corrosion of the qualified test sample is shown in Fig. 8, and the microstructure of the heat affected zone is shown in Fig. 9. Fig. 8 is mainly composed of ferrite and pearlite, and Fig. 9 is mainly composed of ferrite and cordierite.

Fig. 8

Fig. 9

The acicular ferrite nucleates and grows in the austenite grain, which can refine the austenite grain and improve the toughness of weld and HAZ.
Acicular ferrite has fine sub crystal structure and high-density movable dislocation, which is easy to realize multiple slip and is beneficial to the improvement of performance.
Using the same parameters to weld the butt test piece of pipe and pipe, the weld area and heat affected area are tested to get similar structure, the bending sample is tested to meet the standard requirements, and the tensile and impact samples are tested to exceed the standard requirements.

Preventive measures

• (1). The incoming weldolet abutments shall be accepted in strict accordance with their manufacturing standards to ensure that their shapes, dimensions and tolerances meet the requirements, so as to prevent nonstandard manufacturing from affecting the weld quality, and the assembly clearance shall be reasonably controlled during assembly.
• (2). The welder meeting the requirements shall be used for welding to prevent the welder’s skills from affecting the penetration of the weldolet abutment. The prefabricated weldolet abutment and the main pipe, and the welds of the weldolet abutment and the main pipe shall be welded in the flat position, which is conducive to the penetration of the weldolet abutment.
• (3). Clean, process, assemble, weld, record and inspect in strict accordance with the process requirements.

Conclusion

• (1). Too small or too large welding clearance is the main reason to affect the penetration of weldolet, and the clearance between weldolet and main pipe should be 2.5-5mm.
• (2). The weldolet and the main pipe are welded in the flat position, and the weld pool transition is promoted under the gravity, so the accessibility of the welding gun is better, and the welder is easier to observe the weld pool, which is conducive to the penetration of the weldolet.
• (3). Under the reasonable clearance, the mechanical opening method is conducive to improving the penetration length ratio and weld appearance quality of a single weldolet.

Source: China Pipe Fittings Manufacturer – Wilson Pipeline Pipe Industry www.wilsonpipeline.com

(Wilson Pipeline Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Wilson Pipeline products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)

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When selecting a flange connection with fastener materials stainless steel flange, pipeline operating pressure, operating temperature ought to be considered at the same time, medium type and gasket type and other factors. Gasket type and operating pressure, operating temperature, directly to the fastener material strength requirements are put forward.

For example, the spiral wound gasket seal of low toxic medium pipeline flange connection, although the pipeline operation pressure and temperature is not high, but because of the spiral wound gasket needed to form the initial seal than pressure, and fasteners to bear load is big, therefore, in this case requires fasteners with high strength alloy steel materials.

Alloy steel stud shall adopt high quality steel. The material mark after all should add letters A, such as 35 crmoa, 25 crmova according to different structure, the bolt can be pided into hexagon head bolts and stud (also known as the stud) two kinds, the stud is pided into two kinds of haess and the haess.

Hexagon head bolts: often used with flat welding flange and non-metallic gaskets with milder conditions for operation. Commonly used material is BL3 or hex head bolt is Q235B; Stud: often used with butt welding flange at the operating condition is harsh working conditions, among them, because there is no cross section shape on the haess type stud, so its bearing capacity is strong. Rather than type haess stud is relatively weak bearing capacity. Nut materials often according to and cooperate with bolt material, these combinations have provisions in the general standard.

Under normal circumstances, the nut material should be slightly below the bolt, and ensure the nut hardness is lower than bolt hardness HB30 around.

Flange on some professional connection is one of the very common parts, whether it's part of the equipment connections, or the whole pipeline connection, they all need to use this part to the flange. Water pump connection is a part of the connection, this time will need to use the stainless steel flange parts. Flange can be used in many types of connection, a little small connection valves, large connection like pipeline engineering.
First, the flange gasket material
The vast majority of the flange gasket is never is a chunk of metal material cutting down above, the production and the flange gasket is also need by those very professional manufacturers. Production need according to certain size because the gasket is combined with flange, so size to match the flange.
Stainless steel flange gasket materials species persity, asbestos, rubber sheet, asbestos board has, and polyethylene this synthetic material. In addition to non-metallic materials and some metal materials gaskets, where metal materials are very thin metal plate (material, such as galvanized sheet and stainless steel.
Second, combined flange gasket
Want more good sealing performance, you will need to make their own installed for use. Of metal gasket is made and some nonmetallic material similar to that of asbestos, of this package them together is the metal package gaskets. In addition to the gasket and a spiral wound gasket. When the gasket stainless steel flange connection is also very common. This is the use of thin steel tape material and asbestos tape wrapped together is made and be become.
Third, flange gasket suitable occasion
Different flange gasket can be used in different environments, some common rubber gasket can be used in the environment of temperature is not particularly high, generally need to temperatures below one hundred and twenty degrees Celsius. In stainless steel flange connection of asbestos rubber gaskets are also common, their use in need of water vapor temperature below four hundred and fifty degrees Celsius.

When flange connection oil temperatures below three hundred and fifty degrees, the pressure will be less than five million mpa. Those who have the corrosion performance of pipe connection in addition to the need to use to stainless steel flange, corrosion resistance of the gasket is required. Asbestos plate gasket is a very good choice, because it can resist acid erosion of the flange.

Austenitic stainless steel with solid solution treatment to soften, the steel wire are heated to a temperature of about 950 ~ 1150 ℃, heat preservation for a period of time, make the carbide and various alloy elements fully dissolved in austenite, evenly and rapid quenching water cooling, carbon and other alloying elements can not afford time to precipitate, obtain pure austenitic organization, called the solid solution treatment. The effect of solid solution treatment with three points.
1, make steel wire organization, and composition is uniform, it is especially important for raw materials, because of the hot rolled wire rod paragraphs is not the same as the rolling temperature and cooling speed, caused the organizational structure. Atomic activity increased at high temperatures, the sigma phase solubility, tend to be more uniform chemical composition, rapid cooling after get uniform single-phase organization.
2, remove the work hardening, can continue to cold. Through the solid solution treatment, skew lattice, elongation and breakage of recrystallized grains, eliminate inteal stress, the steel wire tensile strength decreased, elongation increased.
3, restore the inherent corrosion resistance stainless steel. Carbide precipitation due to cold working, lattice defects, make stainless steel corrosion resistant performance degradation. Steel corrosion resistance after solid solution treatment back to his best.

For stainless steel flange, the three elements of solid solution treatment temperature, holding time and cooling rate. Solid solution temperature is mainly determined according to chemical composition. Generally speaking, variety and high content of alloy elements brand, to increase solid solution temperature. Especially manganese, molybdenum, nickel, high content of silicon steel, only to improve the solid solution temperature, make it dissolves, to achieve a softening effect. But stabilized steel, such as 1 cr18ni9ti, solid solution at high temperature stabilization element of carbide dissolves in austenite, in the subsequent cooling in the grain boundary precipitates in Cr23C6 form, caused by intergranular corrosion. For the stabilizing element of carbide (TiC and NbC) decomposition, solid solution, generally USES the lower solid solution temperature.

Stainless steel flange is used widely in mode industrial one of a kind of material, admired for many years, also let many businesses see business opportunities, have come into the production of stainless steel flange industry. There are a lot of friends don't really know the stainless steel flange, just feel familiar for this name. If don't participate in industry, many industries will not be able to normal operation, our life will be hit by the very serious also. Stainless steel flange is not mysterious, just to tell you that what is called stainless steel flange.
First, the classification of many
Is the so-called birds of a feather flock together a person with group of points, there are certain classification, so is a stainless steel flange. For the simplest case, just as we often see the film. Movie just a broad categories, also can be pided into: thin horror film, literature and art films, comedy, martial arts films... Many branches. In stainless steel, stainless steel flange, flange, can be pided into five categories, that is the most basic of five types of stainless steel flanges, pided into: butt welding flange, screw, flat welding, socket welding... Such as flange. Different types of stainless steel flange, on the design structure is different, can play a different role.
Second, design more integrity
Stainless steel flange on design has more integrity, resistance to corrosion of the stainless steel itself is very strong, because of strong corrosion resistance, in order to guarantee the use of stainless steel flange normal, not rusting, beyond the general of the flange. Because of the high strength of corrosion resistant ability, structure parts can remain in the best state, the same as the original design of the complete, effectively play a biggest role. Stainless steel flange is different, but all giant won't produce the phenomenon of corrosion or wear and tear, is the use of industrial production and use.

In the design of the stainless steel flange is strong, is also a kind of the most durable of the flange, is also the most environmentally friendly material, and our life is closely linked. Can be used in pipeline engineering, can also be used in aerospace engineering, the real power. Widely used for stainless steel flange is more and more is not mysterious, gradually opened the mysterious veil themselves, let us closer to the contribution to we did a lot of stainless steel flange.

Speaking of stainless steel flange, estimates there are a lot of friends for this name is very strange, stainless steel flange is very versatile. But there are a lot of friends do not know what is its true purpose. Here, let us come into the real world of stainless steel flange, personally solve stainless steel flange of the veil for you. In the industry, we are a lot of lack of the application of stainless steel flange, such as in the construction industry.
First, high temperature resistant
Before the flange, can very good used in the construction industry, construction industry, the use of stainless steel flange is very broad, we can at any time on site to see the shadow of the stainless steel flange. Stainless steel flange that is fully illustrated the immortal status in the architecture, is a lot of things can go beyond. Largest stainless steel flange is a bit of high temperature tolerance, can is good enough to withstand high temperatures, therefore, stainless steel flange in industry are invincible good situation.
Second, widely participate in hot water system
Stainless steel flange the tolerance of heat is just has been said, is very high. Therefore, the most popular in the construction industry. Stainless steel flange to the most high quality drinking water system is very appropriate, and hot water system, stainless steel flange are widely used in the hot water system, good tolerance is used as the main reason for the hot water system. Can be the best one of a pipe, water supply system is very competitive in the market.
Third, health, environmental protection
In today's society, always faces many pollution status, we emphasize on environmental protection all day, but the real to do environmental protection, we should start from the side of the small. So let the stainless steel flange on the industry market has huge competitiveness. It is also because the stainless steel flange environmentally safe, need not use there will be pollution phenomenon.

The advantage of stainless steel flange, in the construction industry has a competitive enough, the heat is very good, and handling of the drinking water system perfect, its environmental security features, become the leader in the industry. The most important part of the stainless steel flange is the environmental protection, can provide human with more convenient, let our life, pollution free, live in an environment of low carbon environmental protection. Therefore, the stainless steel flange is widely application in the construction industry.