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In the field of widely used, the corrosion resistance of stainless steel are satisfactory. From experience, in addition to the mechanical failure, the corrosion of stainless steel mainly displays in: the a serious corrosion of stainless steel in the form of local corrosion (i.e. stress corrosion cracking, pitting corrosion, intergranular corrosion, crevice corrosion and corrosion fatigue). A lot of stainless steel corrosion failure accidents is actually can be avoid by reasonable selection and. Stress corrosion cracking (SCC) Stress corrosion cracking refers to stainless steel under stress because of crack extension and failure in the corrosive environment. Stress corrosion cracking of brittle fracture morphology and toughness of material can also occur in. Stress corrosion cracking of the necessary factors is to have a tensile stress, residual stress, and stress) and the corresponding corrosive medium. Crack formation and propagation is roughly and vertical tensile stress direction. This leads to stress value of the stress corrosion cracking than when there are no corrosive medium stress value of the material fracture need much smaller. In the micro level, through the crack in grain called transgranular crack, and the cracks along the grain boundary expansion graph called the intergranular crack, when the stress corrosion cracking extended to one depth (here, the load stress on the section of materials to achieve its fracture stress) in the air, the material is according to the normal crack (in ductile material, usually through microscopic defect aggregation) and disconnect. Therefore, as a result of the stress corrosion cracking and failure parts section, will contain area has the characteristics of the stress corrosion cracking and polymerization with micro defects have associated “toughening nest” area. Pitting corrosion Corrosion is a form of local corrosion. Intergranular corrosion Grain boundary are crystal orientation in different intergranular disorder malocclusion boundaries, so they are stainless steel of various elements of solute segregation or metal compounds (e.g., carbide and delta facies) precipitate out the favorable area. In some corrosive medium, grain boundary may first be corrosion is not surprising. This type of corrosion is known as intergranular corrosion, most of the metal and stainless steel in specific corrosive medium are intergranular corrosion may occur. Crevice corrosion Crevice corrosion is a kind of local corrosion performance, it may occur in the gap of stagnation of solution or in a surface. Metal and metal or metal and non-metal joint can form such a gap, for example, with rivets, bolts, gaskets, valve seat, the surface of the loose sediment and Marine biological phase formation. General corrosion General corrosion refers to the entire stainless steel surface corrosion phenomenon in the form of comparison are a spoon. Is general corrosion, the village of material thinning due to corrosion, and even the final failure due to corrosion. Stainless steel in strong acid and strong alkali corrosion is likely to be comprehensive. All kinds of stainless steel corrosion resistance 304 stainless steel is a kind of common stainless steel, is widely used in production requirements with good comprehensive performance, corrosion resistance and formability of equipment and parts. 301 stainless steel during deformation presents obvious work hardening phenomenon, a high intensity was used for various occasions. 302 stainless steel is essentially higher variations of 304 stainless steel, the carbon content by cold rolling can make its higher strength. 302 b is a kind of high silicon content in stainless steel, it has high resistance to high temperature oxidation performance. Se is 303 and 303 respectively containing sulfur and selenium free cutting stainless steel, used for main requirements with high degrees of free cutting and table light hao occasion. 303 se stainless steel is also used to make part of the need of hot upsetting, because in such conditions, the stainless steel has good hot workability. 304 l is a variation of carbon content lower 304 stainless steel, welding is applied to the occasion. Low carbon content is made in the heat affected zone near the weld in the precipitation of carbide to a minimum, because of the carbide precipitation may result in stainless steel intergranular corrosion in some environments (welding erosion). 304 n is a kind of nitrogenous stainless steel, and the effect of nitrogen is to improve the strength of the stainless steel. In 305 and 384 stainless steel containing high nickel, the work hardening rate is low, suitable for various occasions requiring cold formability. 308 stainless steel are mainly used for making electrode. 309, 310, 314 and 330 stainless steel and nickel, chromium content is higher, mainly for stainless steel in high temperature oxidation resistance and creep strength. And 30 s5 and 310 s was 309 and 310 stainless steel varieties, the difference is only carbon content is low, in order to minimize the carbide precipitation near the weld. 330 stainless steel has a particularly high carburizing resistance and thermal shock resistance. 317 and 316 stainless steel containing aluminum, thus in the ocean of pitting corrosion resistance and chemical industrial environment is greatly better than that of 304 stainless steel. Among them, the varieties, including low carbon type 316l stainless steel, nitrogen stainless steel of high strength 316 n and high sulfur content of free cutting stainless steel 316 f. 321, 347 and 348 was on titanium, niobium and tantalum and niobium, stabilization of stainless steel, suitable for high temperature use welded components. 348 is a stainless steel is suitable for the nuclear power industry, has a certain restrictions on the content of tantalum and drilling. Source: wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

The forming process of high pressure alloy elbow is complicated and needs to be welded according to different materials and uses. The forming of high pressure alloy elbow needs to be carried out according to a certain procedure, and the corresponding process is strictly observed. Otherwise, the production of high pressure alloy elbow will produce quality problems. Alloy high pressure bend forming technique of the basic process is: first of all welding a cross-sectional polygon polygon ring shell or closed at both ends of the multiple edges of fan-shaped shells, when interior flushes the full pressure medium, subjected to internal pressure, internal pressure under the effect of cross section by the polygon gradually became round, eventually to become the a circular ring shells. This is the process of high pressure alloy elbow forming process. The advantages of the forming process of high pressure alloy elbow are mainly manifested in the following aspects: (1) without the need of pipe blank as raw material, the cost of pipe making equipment and die can be saved, and the high pressure alloy elbow with a relatively thin wall thickness can be obtained. The raw material of the high pressure alloy elbow is special, and the raw material of the pipe blank is not needed to be added in the process of processing. (2) processing of high pressure alloy elbow blank is flat or developable surface, and thus a simple material, to ensure accuracy. Assembly welding is convenient, in the processing of easy control of raw materials, simple operation, no complicated process and welding and assembly is convenient. (3) due to the above two reasons, the high pressure alloy elbow can shorten the manufacturing cycle, and the production cost is greatly reduced. Because no special equipment is needed, the high pressure alloy elbow is especially suitable for the field processing. Source: wilsonpipeline Pipe Industry(www.wilsonpipeline.com)

Resistance welding is short of ERW steel pipe with number of advantages, such as high productivity, low cost, good dimensional accuracy, beautiful appearance. However, in the past, due to the poor reliability of the weld, great limitations on the use. The proportion of small pipe production. ERW steel pipe welding mechanism made ​​gratifying achievements, and this theory as a guide to optimize. Automatic control technology to optimize the parameters given to ensure the weld quality greatly improved; due to the improvement of ultrasonic detection technology, ultrasonic flaw detector Wong stack trace detection can be achieved in the production line; due to the improvement of the level of automation. The annealing of the weld (normalizing) treatment step in the production line. The weld performance improvement. Above several technical applications, greatly improved the reliability of ERW steel pipe welds. Making it increasingly wide range of applications. Currently, some of the world’s production of ERW steel pipes pipe plant can be applied in cold areas, and many countries have been building ERW pipe production line. From countries ERW pipe production, in addition to the earlier high productivity, low into surgery, dimensional accuracy from the outside, the tensile strength of the weld. Elongation off and shrinkage, bending test at room temperature impact toughness values ​​can meet the specification requirements. But there are a lot of manufacturers of ERW steel pipe welds poor low-temperature toughness, which limits their use in cold areas. The amount of heat input, the welding speed, the convergence angle and other factors are associated with the low temperature toughness of the weld, a large number of useful work has been done in this regard. Weld on both sides of the welding surface speed should be close to each other in the molding process, cold welding, and weld two, due to metal melt is poured to the surface separate speed, such as the former speed occurs if the latter speed is large will more foreign invasion FATT value increased, the literature recommended convergence angle of 5 to 6. Better welding speed to 20m/min specific circumstances specific analysis, I believe that after several tests to find the best welding process, thus improving the low temperature toughness of the weld.

Socket pipe fittings, mainly by the round steel or steel ingot mould forging blank molding, and then the lathe machining molding of a high pressure pipeline connection fittings. Socket pipe fittings’ wall often will produce the amount of corruption, the are good inspection and management, guarantee to ensure the good application features and value of socket pipe, in accordance with accurate method and way for application and promotion. Socket pipe corrosion to in accordance with certain ways and means of disposal and cozy, guaranteed to according to certain principle is applied, so the bearing in the application of pipe has good corrosion. Produce corruption, usually said the wall plug fittings for bearing is thinner and has local pits and pitting. The connecting pipe can be pided into three forms: socket weld connections, welded connections, threaded connections. Intubation conditions to withstand the pressure rating, the general bearing in welding, butt welding connection form pipe fitting pressure level is pided into 3000LB SCH80, 6000LB SCH160, 9000 XXS). Thread connection pipe fittings pressure level is pided into 2000LB, 3000LB, 6000LB. Socket pipe fittings are mainly used in oil, chemical industry, medicine and health, electric power, aerospace, military, fire protection, metallurgy, shipbuilding, gas, nuclear power, and environmental protection requirements under high pressure, size precision and other departments and fields. Source: wilsonpipeline Pipe Industry(www.wilsonpipeline.com)

With the development of the national economy, all kinds of seamless steel pipes are widely used in petrochemical, boiler manufacturing industry, especially the harsh working conditions such as high temperature, high pressure, seamless steel pipe quality higher requirements.  Seamless steel pipe generally made after smelting, casting, cogging, rolling and drawing processes, defects in addition to the the various metallurgical defects on the slab during the forming process, along the pipe axially extending circumferential points laminar imperfections in the various stages of the production process, but also because of the improper process of machining operations, roll or drawing mold design improper reasons in the steel pipe caused the crack, folding, warping, scratches, or strained surface and internal defects.  In order to ensure seamless steel pipe quality, in accordance with the technical standards for products, the seamless steel pipe production line required nondestructive testing of surface and interior. Seamless steel pipe often used NDT eddy current testing and magnetic flux leakage testing two technologies, they have their own characteristics and scope of application. Principles and characteristics of the eddy current testing Eddy current testing is the establishment of a non-destructive detection method on the basis of the electromagnetic induction, it sine current excitation probe coil, the coil surrounding the alternating magnetic field generated in the pipe surface when the probe near the Seamless surface induced electromotive force generates an induction current, i.e. vortex. The eddy current and generates an induction magnetic field acting on the coil, thereby changing the electrical parameters of the coil. The loss resistance of the vortex channel and the eddy-current generation of anti-flux, but also reflected to the probe coil, changing the size and phase of the current in the coil, which changes the impedance of the coil. The probe in the seamless steel surface is moved relative defects encountered, so that the reaction of the eddy current magnetic field of the coil, causing the change of coil impedance, thereby measuring the amount of change identified seamless steel pipe surface defects. The eddy-current flaw detection method of one of the hydrostatic test may be substituted. All conductive seamless steel pipe, whether ferromagnetic or non-ferromagnetic, as long as the outer diameter greater than 2 mm, the wall thickness is not less than 011mm, the eddy current method may flaw. The eddy current test results can be directly output as an electrical signal, easy to automate testing. The eddy-current flaw detection using non-contact manner, the fast testing. Eddy current testing can detect defects limited depth, generally not more than 5 mm, and the test results are often affected by the function of testing instruments and testing conditions affect. Principles and characteristics of the magnetic flux leakage testing Seamless steel pipe of the basic principle of the magnetic flux leakage inspection is built on top of this feature of the high magnetic permeability of the ferromagnetic material, a seamless steel pipe of the ferromagnetism is magnetized, its surface and near surface defects in the surface of the seamless steel pipe to form a leakage magnetic field , by detecting the leakage magnetic field change signal can be detected in the presence of a defect. The seamless steel defects permeability much smaller than the magnetic permeability of the steel pipe. Seamless pipelined manner into the steel pipe detection wire, quickly passes through the detection zone will be subject to DC coils produce horizontal and vertical magnetic field magnetization. If seamless steel no defects, the most of the magnetic lines of force through the seamless steel pipe, the uniform distribution of magnetic field lines; if seamless steel defects, the magnetic lines is curved, and has a part of the leak magnetic field lines to a seamless steel pipe surface. Lateral and longitudinal coil probe (sensor) to detect the leakage magnetic field of the seamless steel pipe surface escape, then based on Faraday’s law of electromagnetic induction, the leakage magnetic field is converted to the defect signal (the induced voltage generated by the detection coil in the probe), and further processing of the defect signal. and analysis, you can determine whether a defect exists and defect size parameters. The pipeline detection method comparison Pipeline eddy current flaw detection, through the coil to the outer surface of the flaw, the inner surface flaw detection using the interpolation formula coil method. The outer surface flaw Top coil fixed subject seamless steel axial feeding and the coil fixed to the subject seamless steel screw feed two methods. The mechanical transmission of the testing equipment is relatively simple. Pipeline magnetic flux leakage flaw detection method the probe rotation seamless steel pipe straight forward and probe fixed seamless steel pipe spiral forward in two ways. Flaw detection equipment, mechanical transmission is more complex. Compare eddy current detection performance Detecting the surface detection of the seamless steel pipe applicable to a variety of conductive materials, regardless Seamless is ferromagnetic or non-ferromagnetic, and regardless of whether it is black metal, or non-ferrous metal or a nonmetal, Seamless is conductive and the outside diameter and wall thickness to meet certain conditions can be detected using the eddy current method. It is more appropriate in the ordinary thin-walled seamless steel pipe outer surface defect detection, widely used in carbon steel, alloy steel and stainless seamless steel pipe surface defect detection. Seamless steel pipes for the two surface-line testing methods have their own advantages and limitations, seamless steel pipe production line depending on the particular circumstances choose. The eddy-current flaw applies to various conductive seamless pipe testing, either stainless steel or carbon steel seamless steel pipes are suitable for detecting the influence of the surface of the oil and other impurities from seamless steel. Detection speed and high sensitivity. The magnetic flux leakage test can be detected not only the inner and outer surfaces, and subcutaneous defects, and without measurement from the established electrical signal amplitude and defect parameters relationship can informed of the defect depth and length characteristics such as size and whether the level of the set reject . Detection ability, speed detection. Seamless steel pipe, but it only applies to the ferromagnetic detection equipment investment, the lower the sensitivity of the detection of defects.

Effect of Nickel on Stainless Steel Adding nickel in stainless steel will form austenitic crystal structure, can improve the plasticity of stainless steel, toughness, weldability and other properties, so the nickel is called austenite forming elements. Carbon steel structure is ferrite, the body-centered cubic (BCC) structure, by adding nickel can promote the crystal structure from the body-centered cubic (BCC) structure into a face-centered cubic (FCC) structure, known as the Austrian Body stainless steel. However, this nature of nickel is not unique. Austenite formation of the more common elements are: nickel, nitrogen, manganese, carbon, copper. Now people have a lot of formulas to express the relative importance of austenite forming elements, the following is the most famous formula: Austenite forming ability = Ni% + 30C% + 30N% + 0.5Mn% + 0.25Cu% From this formula, it is seen that carbon is 30 times more potent for forming austenite than nickel, but it can not be added to corrosion-resistant stainless steels because after soldering this leads to sensitized corrosion and subsequent intergranular corrosion problem. The effect of nitrogen on the formation of austenite is also 30 times the nickel, but it is a gas, adding too much nitrogen will cause porous problems. In addition, the addition of manganese and copper can lead to problems of refractory life reduction and welding during the steelmaking process. Although the addition of manganese is not conducive to the formation of austenite, but the addition of manganese can help more nitrogen dissolved in stainless steel, and nitrogen is very conducive to the formation of austenite. In the 200 series stainless steel, the amount of manganese and nitrogen is substituted for the nickel element to form a 100% austenitic structure, and the lower the nickel content is, the higher the amount of manganese and nitrogen is. For example, in 201 stainless steel, containing only 4.5% nickel, but also contains 0.25% nitrogen. By the above formula, it can be seen that the nitrogen element is equivalent to 7.5% of nickel in the ability to form austenite, and therefore can also form a 100% austenitic structure. 200 series of stainless steel is the resulting Health. Part of the non-compliance 200 series stainless steel, due to the inability to add a sufficient amount of manganese and nitrogen, but for 100% of the austenitic structure, by deliberately reducing the amount of chromium added, which led to the stainless steel corrosion resistance. In stainless steel, ferrite-forming elements continue to form ferrite, austenite-forming elements continue to form austenite. And the final crystal structure depends on the relative amount of the two elements added. Where chromium is a ferrite forming element, so in the formation of stainless steel crystal structure of chromium and austenite formation element is competitive. Since both iron and chromium are ferrite-forming elements, the 400-series stainless steel is completely ferritic stainless steel and is magnetic. In the process of adding the austenite forming element-nickel to the iron-chrome stainless steel, the austenite formed gradually increases as the nickel element increases until all the ferrite structures are transformed into austenite Structure, and ultimately the formation of 300 series stainless steel. However, if only half of the amount of nickel is added, 50% of the ferrite and 50% of the austenite will be formed, that is, duplex stainless steel. 400 series stainless steel is an alloy of iron, carbon and chromium. It is a martensite structure and an iron element with normal magnetic properties. And also has a strong resistance to high temperature oxidation, but compared with carbon steel, 400 series stainless steel physical properties and mechanical properties have improved space. 400 series stainless steel heat treatment can be done. 300 series stainless steel contains iron, carbon, nickel and chromium and other elements, there is no magnetic, malleable features better than the 400 series of stainless steel. Because of the austenitic structure of the 300 series stainless steel, its corrosion resistance is strong in many environments and the fracture properties caused by the corrosion resistance caused by the metal over stress are also good, and the material properties of the 300 series stainless steel are not subjected to heat treatment Impact. Source: wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

When selecting a marine flange, you need to pay attention to the following points: 1, marine flange bolt preload: A, the pre tightening force of the marine flange can not be too large, it can not be too small. (large: the gasket Yahuai or extrusion; too small: not up to the initial seal gasket compression and implementation conditions.) B, appropriate to improve the pre tightening of the marine flange, you can increase the sealing capacity of the gasket. (because the capillary porosity of the porous material is reduced) C, the pre tightening force of the marine flange can be used on the pad, which can be used to reduce the bolt diameter and increase the number of bolts. 2, the use of the ship’s surface (sealing surface) type A, plane type compression surface The surface of the compression surface of a marine flange is a plane or a plane with a groove. Advantages: simple structure, easy processing. Disadvantages: large contact area, the need for a large preload ratio, bolt bearing large, so the flange and other parts of the requirements of high, bulky, easy to squeeze out of the gasket, sealing performance is poor. The use of P pressure less than 2.5Mpa, not the use of toxic, flammable and explosive medium. B, concave and convex type Marine flange is composed of a concave surface and a convex surface with the composition. Put in the concave washer. Advantages: easy to medium, can prevent gasket extrusion. Available in P = 6.4Mpa, DN = 800mm C, trapezoidal groove pressing surface Marine flange at the bottom of the groove can not afford the sealing effect is groove inside and outside cone and gasket contact trapezoidal form a seal, and elliptic or octagonal cross section of the metal gasket with. D, conical compression surface Usually used for high-pressure sealing, the disadvantage is that the required size accuracy and surface roughness requirements are high. Must be matched with lens gasket, commonly used in high-pressure pipeline. E, groove A tenon groove sealing surface, the utility model has the advantages of neutral good, the seal pretightening pressure small, gasket is not easy extrusion is not affected by the medium erosion for flammable and explosive sealing requirements high. The disadvantage is the replacement is difficult, easy to damage the tenon. Source: wilsonpipeline Pipe Industry(www.wilsonpipeline.com)

Quality inspection of alloy elbow: 1, the alloy elbow according to the relevant technical documents provided for the project and the requirements of the inspection; 2, when the mechanical properties of the alloy elbow is not qualified, it can be repeated heat treatment, but the number of repeated quenching or solid solution is generally not more than two times. Supplementary tempering of the workpiece does not count as repeated treatment; 3, after the quenching state or low temperature tempered alloy elbow, repeated quenching should be carried out before the preheating, annealing or high temperature tempering; 4, heat treatment records should be kept for future reference. Alloy elbow cleaning: 1, according to the requirements of the alloy elbow and the surface condition of the alkali wash, water soluble cleaning agent, chlorine solvent blasting, shot blasting and other methods to clean up; 2, alloy elbow generally do not use pickling method to clean up. Alloy elbow correction: 1, the alloy elbow static load is used to correct, it is generally not suitable for local percussion; 2, the alloy elbow should be annealed at less than the original tempering temperature; Source: wilsonpipeline Pipe Industry(www.wilsonpipeline.com)

Crevice corrosion is a form of localized corrosion crack in the surface sediments or shielded area surface passivation layer destruction.  The processing or design cracks in the welding of stainless steel pipe fittings mouth at the other junction. In effective corrosion places, the cracks must be wide enough to allow corrosion electrolyte into the stagnation zone. Corrosion crack width reach several meters wide, but not absolute, and the critical crack size cause corrosion occurred.  Especially very reactive with the negatively charged chloride ions, therefore, if there is crack external bulk solution, it is easy then positively charged metal ions attracted into the narrow cracks, the crack in the formed metal chlorides (typically chromium) reacts with water to form hydrochloric acid, reducing the pH value to the depassivation pH, then the cracks in the passivation film is destroyed, pitting will further. Event to passivation, corrosion will be fast and be able to self-sustaining, especially in the case of bulk solution has provided chlorine ions.  Elements to avoid crevice corrosion in stainless steel seamless pipe The chromium, nickel, support the stability of the passivation layer can promote the stability of the stainless steel passivation layer. Although chromium metal ions is more supportive than the ion or nickel anode reaction in the crevice corrosion, improve the chromium content of the alloy is more resistant to crevice corrosion. For specific chromium content steel, austenitic stainless steel seems more tolerant than low nickel ferritic steel erosion. Molybdenum and nitrogen is very significant for improving the corrosion resistance. Generally, stainless steel, such as 6% Mo austenitic stainless steel, to provide the best corrosion resistance to crack. Ordinary stainless steel, has a good effect to reduce the resistance to crack corrosive. The cracks can not implemented completely infiltrated the place of welding beads generated in the welding manufacturing process.  Completely root dissolved permeability is essential, as round and smooth weld bead, in the internal bead to the metal region of the substrate is not the bottom groove.

Frequently steel pipe is used metal structural engineering, its dimensions are very important. Steel pipe quality directly affects the quality of component processing, or eventually directly affect the overall quality of the project. However, in the the usual steel pipe procurement, often encounter serious bent of some steel pipes (particularly in larger diameter steel pipe) duration and other aspects of the pressure, but sometimes forced, received or will steel pipe down, so it must be Steel Pipe corrected as soon as possible. Bending deformation analysis Generated by the thermal processing deformation principle known, thermal processing (welding), the compressive plastic deformation is generated due to the unevenness of the heating temperature, the high temperature region, cooling the parts of the contraction by the other parts of the blocking of the (low-temperature region or the first cooling portion) , resulting in the residual stress and deformation. After thermal processing on the steel market steel pipe (welded pipe or heat pipe expansion) mainly to bending deformation. Treatment program The pipe diameter is small, relatively thick wall, you can take the the mechanical correction method (such as the use of the bending machine, jack and the corresponding fixture) corrected, the method is simple. Steel pipe diameter, the wall is relatively thin, it is inappropriate to use mechanical correction method, not only because it requires huge machinery and equipment and complex fixture, and likely to cause steel pipe local depression. Flame straightening operation, although a certain degree of difficulty, but the method is simple and good results.

Seamless steel pipe is a kind of hollow section, and the peripheral no joint of strip steel. Seamless steel pipeis no seam, hot or cold drawing process molding. Characteristic is confined good. Spiral steel pipe features: straight seam welding pipe production process is simple, high production efficiency, low cost. the strength of the spiral welded pipe is usually better than straight seam welding pipe is high, which can use a narrow billet production of larger diameter welded pipe, still can use the same width of the billet production pipe diameter different welded pipe. But with the same length straight seam pipe, compared to weld length increases 30 ~ 100%, and the production speed is low. Therefore, a small-bore pipe welding mostly adopts the straight seam welding, large diameter welded pipe is mostly using spiral welded. Spiral steel pipe‘s type is made by strip, seamless steel pipe type is made by round steel, difference is very big, production process different: Spiral steel pipe is to use strip steel welding, can see the weld; Seamless steel pipe is made with round steel punched, Spiral steel pipe wall thickness difference under very big, and Seamless steel pipe small pipe under basic no difference, the difference for bassoon and will not many.

Pipe Cap and dished head are similar in shape, material for stainless steel is more, pipe cap size is relatively small, forging; a little more dished head size, generally with the pressing of steel, pipe cap is generally used for the end of the pipe, head for container equipment (vertical) equipment parts or left and right ends (horizontal). The convex cap includes a hemispherical, oval disc cap, pipe cap and spherical cap. Look at the convex cap from the hemispherical force from the angle of. Pipe Cap is directly welded to die at the end of the pipeline; at the end of the pipeline can also welding flange, then with a blind flange to death, when necessary can open the blind flange, pipeline check inside. The conventional cap holder with pressure pressing made by thick wall; forging; by spinning large diameter. The need for maintenance or even after the connecting line, with blind, not later, with a pipe cap. With the blind plate has the possibility of leakage, there is a long time, and screw rust died, as useless, the heat pipe is not very easy to heat insulation. wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)