Search Results

The high frequency vibration of high pressure piping has strict requirements on the assembly of the lens gasket of the high pressure flange. Before the assembly should be inside pipeline, pipe threaded end and tapered sealing surface, gaskets, high pressure flange and bolts, nuts and all the clean up, and check the appearance, when necessary, then coloring, magnetic or ultrasonic flaw detection. Any seals shall have crack; surface defects, which the pipe threaded end, high pressure flange, bolt and nut thread of the effective part of tooth high corrosion and wear shall not exceed 10% of the standard tooth height, each lap mechanical damage length should not be more than 1 / 5 of the perimeter, each circle and not larger than the circumference of a circle, bolt rod section shall not corrosion or mechanical damage; overproofed defects should be replaced in a timely manner. In the assembly process, attention should be paid to maintain a clean sealing surface, and strictly control the bolt of flange preload, the hydraulic tightening device or measuring torque wrench symmetric fastening. Stud bolt tightening after the elongation control in general is not more than 3 / 10 000 bolt length, high temperature control between the 3 / 10 000 ~ 5 / 10 000 bolt length, bolt ends exposed outside the nut thread length should be equal as far as possible and not less than 2 times the pitch, to remove more than twice the bolt pre tightening force of around 6% increase. Installation shall not use forced assembly and a requirement to keep two flanges parallel to the end surface, the parallel deviation control within 0.3mm, keep the two flanges on the axial center line of the coaxial, coaxiality error depending on the diameter size control in less than 0.3 ~ 0.5mm range, to really confidential cover good contact and prevent bad moment. Keep a good surrounding environment, do a good job of dampproof, dustproof and anti rust and other maintenance work, and according to the working temperature of the level of discretion in the high pressure bolt coated powder lubricating oil or grease molybdenum disulfide. Pipeline running at high temperatures, the general should be in keeping the temperature test operation 24h after, tube pressure relief to 0.5MPa (gauge) following then moderate fastening force will flange bolts in hot tight to seal the pretightening force; pipeline running at low temperatures, in keeping the temperature test operation 24h after unloading despite internal pressure and with methanol on the surface of the bolts of flanges. Source: wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

While preparing the purchase requisition/inquiry of any piping component there are various points which need to be checked and confirmed with the vendor. The responsible requisition engineer should include all the technical points & clauses applicable to the piping components in the requisition/inquiry & subsequent technical queries (TQ). The requisition engineer should refer all the project specific standards and specifications along with the applicable international codes and standards while preparing the inquiry requisition of the piping components. In this article few general technical requirements for pipes & pipe fittings are listed for information. Note that these requirements may vary depending upon the project requirements. General requirements: Pipe and Pipe Fitting Material supplied must be strictly in accordance with the latest codes and standards, mentioned in the Material Requisition (MR or PR: Purchase Requisition) Scope of supply. This specification for pipes and pipe fittings as detailed in subsequent points shall supplement the codes and other project specifications. All items must be supplied in accordance with proper wall thickness/ schedule as stated in the Purchase Requisition (PR). Wall thickness thinner or heavier than specified tolerance shall not be accepted. Vendor must specify the material type and grade together with NPS and schedule / wall thickness / class within the Material requisition – Scope of Supply for all piping components. Butt weld end preparation for pipes, pipe fittings and flanges shall be as per ASME B16.25. 100% radiography has to be performed for all welded items to give a joint factor of 1.0. If not specified, Pipes and pipe fitting shall be supplied seamless. Seamless is an acceptable alternative for welded pipe and pipe fittings but vice-versa is not acceptable. The chemical analysis of Carbon Steel (CS) & Low Temperature Carbon Steel (LTCS) pipes and pipe fittings, forgings, plates shall be in accordance with the applicable product standard with the following limitations: Carbon 0.23 Maximum wt% (pipes) Carbon 0.23 Maximum wt% (forgings) Carbon Equivalent (CE) shall not exceed 0.43% Where CE = C + Mn/6 + (Cr+Mo+V)/5 + (Cu+Ni)/15 The above formula for CE is applicable when the carbon content is greater than 0.12% CS & LTCS materials shall be fully killed and fine grained and shall be produced by a low sulphur and low phosphorous refining process. The components must be supplied in normalized or normalized and tempered condition. All Austenitic stainless steel, duplex stainless steel items must be supplied in solution annealed and quenched condition as per corresponding ASTM standard. Repair welding for parent plate / weld end flange is not accepted. The carbon content of SS 316 must be limited to 0.03%. All SS Materials specified as F 316 / WP 316/ Type 316 may be dual certified for both SS 316 & 316L, if specifically mentioned in the project specification. Austenitic stainless steel has to be capable of passing an inter-granular corrosion test in accordance with ASTM A262, Practice E. All duplex stainless steel shall have ferrite content between 35% – 65% (volume fraction) on base metal and on heat affected zone to 35% – 70 % as per ASTM E562 four point count method. Requirements for Pipes: Dimensions of CS / SS and Alloy steel (AS) pipe shall comply with ASME B36.10M or ASME B36.19M as applicable. CS pipes shall be supplied in double random lengths (11 to 13m) for pipe sizes 2” to 36”, and in single random lengths (5 to 7m) for pipe sizes 1.5” and smaller. SS, Duplex Stainless Steel (DSS) and Carbon Steel galvanized pipes shall be supplied in single random lengths (5 to 7m) for all pipe sizes. It is not permitted to join lengths of pipe by circumferential welds to make single or double random lengths. Plain end pipes must have square ends cut with burrs removed. All stainless steel pipes shall be supplied in solution annealed condition. All threaded & coupled pipes shall be supplied with ends threaded in accordance with ASME B1.20.1 (NPT). Each length of the threaded pipe shall be supplied with full coupling screwed hand tight at one end. Galvanizing of pipes shall be in accordance with ASTM A153. Threaded portion of pipes shall be free of galvanizing. Pipes shall be heat treated in accordance with product specification requirements after completion of all forming and welding operations. Carbon Steel & Low Temperature Carbon Steel (LTCS) Pipes shall be fully killed fine grained and shall be supplied in normalized or normalized and tempered condition. Welded pipe shall be supplied with single straight seam for sizes up to 36” and double straight seam for sizes greater than 36” subjected to approval from the contractor. Spiral seam welds are not acceptable. All DSS welded pipes with a wall thickness greater than 30 mm must be 100% ultrasonically examined. Requirements for Pipe Fittings: Dimensions of butt welded pipe fittings must be in accordance with ASME B16.9. Forged, threaded and socket welded pipe fittings shall be in accordance with ASME B16.11. Other pipe fittings dimensions shall comply with MSS SP-75, MSS SP-95, MSS SP-97 or BS 3799 as applicable. Vendor shall provide calculations as per ASME B31.3 for the pipe fittings not covered under the above mentioned standards. Union dimensions shall be in accordance with BS 3799. All screwed pipe fittings shall be threaded NPT in accordance with ASME B1.20.1. Branch reinforcing pipe fittings (i.e. Elbowlets, Sockolets, weldolets, etc.) shall be designed in accordance with the requirements of ASME B31.3. The vendor shall submit drawings during bid stage and calculations for review and approval after award of contract. Butt weld elbows shall be long radius type (radius =1.5 nominal pipe size). Short radius elbows are not permitted. For reducing pipe fittings specified with two schedules in the Inquiry / Purchase description, the first schedule refers to the larger end or run pipe, the second schedule refers to the smaller end or branch pipe. Pipe Fittings shall be forged to the final shape and size. Pipe Fittings shall not be machined from bar stock or solid forged billets without specific approval. Galvanizing of pipe fittings shall be in accordance with ASTM A153. Threaded portion of pipe fittings shall be supplied with threads free of galvanizing. Swage nipple shall be pipe swaged by forging only. Machining of bar stock, forgings or heavy wall pipe not permitted. Dimensions shall be in accordance with MSS-SP-95. All reduction sizes for tees and reducers to be in accordance with ASME B16.9. CS & LTCS pipe fittings shall be fully killed and fine grained and shall be supplied in normalized or normalized and tempered condition. 100% of CS & LTCS welded pipe fittings, with wall thickness greater than Sch 80 shall be examined by Magnetic Particle Examination for weld bevel ends. Acceptance standards shall be in accordance with ASME VIII Division 1, Appendix 6. This shall be done after final heat treatment. 100% of SS & DSS wrought pipe fittings having wall thickness more than 20mm shall have the bevel and weld end over a width of 25mm, examined by Dye penetrant Method. Acceptance standards shall be in accordance with ASME VIII Division 1, Appendix 8. 100% of DSS welded pipe fittings with a wall thickness greater than 30mm shall be 100% ultrasonically examined in accordance with ASME VIII Division 1. 100% of DSS forged pipe fittings weld bevels shall be examined by Dye Penetrant inspection. 100% of CS, LTCS & SS forged pipe fittings, with wall thickness greater than Sch 80 shall be examined by Magnetic Particle / Dye penetrant examination. Acceptance standards shall be in accordance with ASME VIII Division 1, Appendix 6 / 8. This shall be done after final heat treatment. Positive material identification: Positive Material Identification (PMI) shall be conducted for all SS / CRA alloy piping items as per the project specification included in the Inquiry / Purchase requisition. Special Requirements: Sour service requirements: All materials specified for sour service shall, as a minimum, meet the requirements of NACE MR0175 / ISO 15156 – latest edition. All welded pipes / pipe fittings in sour service shall be HIC tested, if required by the project specification. It shall be conducted for one pipe / pipe fitting per heat in accordance with NACE TM-0284 Solution – A with acceptance criteria as specified in NACE MR-0175. Impact test requirements: All CS, LTCS, welded austenitic and duplex stainless steel piping components shall be impact tested (for using in low temperature services) in accordance with ASME B31.3. For carbon steel pipes and pipe fittings, the impact test temperature shall be the ‘minimum metal temperature’ as defined in the project. The impact test requirement and acceptance criteria shall be as per Cl. 323.2.2 and Cl. 323.3.5 of ASME B31.3 respectively. For welded SS and DSS items, the impact test temperature shall be the ‘minimum metal temperature’ as defined in the project but not more than (-101 Deg. C) and (-50 Deg. C) respectively. For SS items, the acceptance criteria shall be as per Cl. 323.3.5 of ASME B 31.3. For DSS items, test results shall be at least 40 joules in transverse direction (for standard specimen 10 x 10 mm) as an average of three tests, one result may be lower but not less than 30 joules. For LTCS items, the impact test temperature shall be (-46 Deg. C). Test results shall be at least 27 joules as an average of three tests (for standard specimen 10 x 10 mm), one result may be lower, but not lower than 21 joules.

What is butt welding mean? The strategy of butt welding is often a welding joint.When butt welding, material together two parts in a single lines are parallel over the edge.Butt welded joints can be produced with a large continuous or portable welding machine operation.Butt welded joint is surely an economical and reliable technique of joining materials without any additional components. In wilsonpipeline.Com, a lot of butt welding joints in our products. 1.Our main pipe fittings products are butt welding pipe fittings products, their ends are plain end or bevel end for butt welding connection.  2.Large size pipe fittings products are produced from steel plate, they are welded in body, not seamless.Those pipe fittings are produced in butt welding method. 3.The weld neck flange, when a weld neck flange is welded to the pipes, the welding joint is butt welding. 4.Piping prefabrication, for such fabrication products, when we design it, we perfer to use joints of butt welding method. Because butt welding joints is very strong and secure for materials. Source: wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Welding to choose the right welding material. The chemical composition of the wire has an important effect on the corrosion resistance of the weld. The electrode should have a chemical composition similar to that of the base metal. This allows the weld metal to have a similar chemical composition to the base metal and is generally considered to be the best Corrosion resistance. Stainless steel welding characteristics As the resistance coefficient of stainless steel is much larger than the low-carbon steel, welding and welding of the base metal are more likely to be heated lead to melting, will melt around the base overheating, making the welding zone deformation and grain coarsening. Stainless steel linear expansion coefficient, and the thermal conductivity of small, easy to transfer heat, and welding depth of penetration, welding heat will cause the expansion of the structure, there are relatively large cooling shrinkage and tensile stress, easy to cause thermal cracking. After the welding of stainless steel, it is easy to cause intergranular corrosion in the heat affected zone. Because in the heat affected zone, at the sensitization temperature (450 ℃ -850 ℃) interval, the substrate is partially poor chromium, it is difficult to passivation, resulting in corrosion resistance was significantly reduced, so will be the first corrosion, stainless steel grain boundary corrosion width. At this point the corrosion of stainless steel parts of the plasticity and strength has been seriously missing, there will be cracks in the cold bend, brittle fracture, corrosion of metal parts floor landing sound. Precautions against welding of stainless steel Control welding current The current magnitude of the welding stainless steel is smaller than the low carbon steel, the current capacity is about 80% of the low carbon steel. Speed ​​up the welding speed Welding speed to be faster, thus reducing the width of the heat affected zone, shortening the weld in the sensible temperature range of residence time, so that the weld in a stable state, and refine the weld structure. Reasonable selection of welding materials Select the appropriate welding material and shielding gas. As the chemical composition of the wire will significantly affect the corrosion resistance of the weld, so the chemical composition of the electrode should be similar with the base metal, which will help the weld show the best corrosion resistance. Welding before and after cleaning The surface of the material must be cleaned before welding and the weld residue removed after welding. Source: wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Because stainless steel pipe fitting is their condition in a number of different joint made to work, and so has to pick a suitable pipe fitting type, to get the very best usage of join performance. Mainly reflected inside the characteristics of pipe fitting types, namely, the development of the liquid leaving the pipe of the shape as well as its operating performance. pipe selection factors flow, pressure, liquid angle, coverage, impact, temperature, materials, applications, and the factors in many cases are implicated the other, mutual restraint. The stainless steel pipe fitting you can pick: metal grease fitting material should be in line with the chemical properties with the bath to discover: 1, for non-corrosive bath in accordance with the futility of processing, the use of alloy steel pipe fitting 2, to avoid corrosion, stainless steel pipe fitting can be utilized 3, sulfuric acid, hydrochloric acid and also other strong corrosive bath, may be seamless pipe fitting 4, to the phosphate bath pipe materials frequently used acid-resistant stainless steel 5, to stop corrosion from the pipe fitting can even be directly created from metal or nylon production. Source: wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Due to the site of the arrival of the The wall thickness of elbow exceeds bid badly, need to be done according to the actual measurement of pipeline stress calculation, the calculation of wall thickness to exceed bid, pipes, pipe stress on device interface thrust and torque is qualified, and whether to set up reasonable pipe rack. In the pipeline stress calculation procedures, bend the wall thickness of the default for the connection pipe wall thickness, calculating the stress strengthening coefficient of elbow and flexible coefficient. To accounting need to select the wall thickness of the pipe connected to the elbow. By the weight of the elbow to convert in this wall thickness, the bend along the centerline and diameter into a straight pipe (straight pipe length equals the bend axis length), the weight unfolds the straight pipe and elbow weight is consistent, the straight tube wall thickness for the bend in the form of weight reduced wall thickness. The elbow convert of calculated thickness back to piping stress calculation model, can be bend the impact on the pipeline after the wall thickness of paint. 1. The stress influence of the pipes The wall thickness of elbow change before and after the pipe elbow in a stress and secondary stress calculation results. Elbow bend wall thickness increase after a stress most showed a trend of decrease, and the secondary stress showed a trend of increase, but a change of stress and secondary stress were not more than 20%. According to the specification, in the case of not consider accidental loading, a stress piping shall be conducted by the pipe pressure, gravity and other continuous load. Internal pressure is constant, there is no external load cases, the increase of thickness, stress strengthening coefficient decreases, and will cause the bend of a lower stress. Inpidual point due to the elbow wall weight increase, reduce the impact of the offset the stress strengthening coefficient, makes a stress rose slightly. And in the absence of other secondary stress under the influence of cyclic loading is mainly caused by thermal expansion the joint torque generated in the cross section. As a result of the The wall thickness of elbow increases, the bend of the flexible coefficient K value is reduced, makes on the cross section of torque increase, so the secondary stress will increase. 2. The effects on thrust torque device interface The wall thickness of elbow change push pipe of equipment interface of thrust and torque changes, pipe of high the influence of interface are discussed here. By the calculation results can be seen that as a result of the The wall thickness of elbow increased, under the thermal state of resultant force and torque will increase, the biggest increase of 52.18%, the smallest is 14.76%. The reason is due to the changes of bend flexible coefficient. Flexible coefficient said bent pipe relative to the straight pipe under the bending moment increase flexible degree, its value is equal to the same deformation conditions, in accordance with the general and the bending moment and bending theory considering the bent pipe cross section to calculate the bending moment of the ratio of flat effect. 3. The impact on pipe, lifting point load After The wall thickness of elbow change, in the piping of lifting point loading will change too. By the calculation results can be seen that elastic bearing point of the steam extraction pipeline hot rate reached 15%, and drain piping hot load change rate is not more than 5%, the difference is mainly due to the different piping within the medium. Due to the drain pipe medium is water, bend weight is small, the proportion in the whole piping weight change not for piping lifting point load is too big change. But medium for steam of the steam extraction pipeline, density is small, elbow weight is bigger, the proportion in piping wall thickness change, will cause the tube department bearing load must be changed. But no matter how to load variation, spring support in terms of piping size spring jump phenomenon happens. Source: wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

The application of butt welding pipe fittings:

A butt welding pipe fitting means the pipe fitting which has the connecting end for butt welding.Commonly the butt welding pipe fitting products includes elbows,tees,reducers, caps,paddles,stub ends,crosses,hot induction bends.The butt welding pipe fitting products are widely used in Industry field,like Oil,Gas & Petrochemical,Energy & Power plant,Chemical industrial,Shipbuilding & Offshore Development. Our butt welding pipe fittings products commonly according to standard ANSI/ASME B16.9 and ANSI/ASME B16.28,there are other standards about butt welding pipe fittings such as:EN 10253,DIN,JIS,MSS SP-43,MSS SP-75,GOST.We also manufacture the butt welding pipe fittings as per client’s requirements.The butt welding pipe fitting tolerance within the scope of the following: Butt Welding Pipe Fitting General: Cross-sectional tolerances for all butt welding pipe fittings (ASME/ANSI B16.9 and B16.28): Alignment tolerances are concerned with the way that the ends of a fitting are cut. Exaggerated distortions are shown for clarity in the diagram below. Alignment tolerances (ASME/ANSI B16.9 and B16.28): Tolerances for Specific Fittings Dimensional tolerances for elbows and returns (ASME/ANSI B16.9 and B16.28): Dimensional tolerances for reducers, caps and stub ends (ASME/ANSI B16.9): wilsonpipeline manufacture forged pipe fittings,pipe flanges,steel pipes according to international standards or customer’s requirements.If you have any requirements about the butt welding pipe fittings, welcome to contact us. Source: wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Since its inception in the early 20th century, with the continuous development of its research and development and production technology, the standard of stainless steel has been gradually established in various industrialized countries, and the establishment and perfection of stainless steel standard has promoted the progress of stainless steel production technology. Raw Materials Stainless steels are made of some of the basic elements found in the earth: iron ore, chromium, silicon, nickel, carbon, nitrogen, and manganese. Properties of the final alloy are tailored by varying the amounts of these elements. Nitrogen, for instance, improves tensile properties like ductility. It also improves corrosion resistance, which makes it valuable for use in duplex stainless steels. The Manufacturing Process The manufacture of stainless steel involves a series of processes. First, the steel is melted, and then it is cast into solid form. After various forming steps, the steel is heat treated and then cleaned and polished to give it the desired finish. Next, it is packaged and sent to manufacturers, who weld and join the steel to produce the desired shapes. Melting and casting 1 The raw materials are first melted together in an electric furnace. This step usually requires 8 to 12 hours of intense heat. When the melting is finished, the molten steel is cast into semi-finished forms. These include blooms (rectangular shapes), billets (round or square shapes 1.5 inches or 3.8 centimeters in thickness), slabs, rods, and tube rounds. Forming 2 Next, the semi-finished steel goes through forming operations, beginning with hot rolling, in which the steel is heated and passed through huge rolls. Blooms and billets are formed into bar and wire, while slabs are formed into plate, strip, and sheet. Bars are available in all grades and come in rounds, squares, octagons, or hexagons 0.25 inch (.63 centimeter) in size. Wire is usually available up to 0.5 inch (1.27 centimeters) in diameter or size. Plate is more than 0.1875 inch (.47 centimeter) thick and over 10 inches (25.4 centimeters) wide. Strip is less than 0.185 inch (.47 centimeter) thick and less than 24 inches (61 centimeters) wide. Sheet is less than 0.1875 (.47 centimeter) thick and more than 24 (61 centimeters) wide. Heat treatment 3 After the stainless steel is formed, most types must go through an annealing step. Annealing is a heat treatment in which the steel is heated and cooled under controlled conditions to relieve internal stresses and soften the metal. Some steels are heat treated for higher strength. However, such a heat treatment—also known as age hardening —requires careful control, for even small changes from the recommended temperature, time, or cooling rate can seriously affect the properties. Lower aging temperatures produce high strength with low fracture toughness, while higher-temperature aging produces a lower strength, tougher material. Though the heating rate to reach the aging temperature (900 to 1000 degrees Fahrenheit or 482 to 537 degrees Celsius) does not effect the properties, the cooling rate does. A post-aging quenching (rapid cooling) treatment can increase the toughness without a significant loss in strength. One such process involves water quenching the material in a 35-degree Fahrenheit (1.6-degree Celsius) ice-water bath for a minimum of two hours. The type of heat treatment depends on the type of steel; in other words, whether it is austenitic, ferritic, or martensitic. Austenitic steels are heated to above 1900 degrees Fahrenheit (1037 degrees Celsius) for a time depending on the thickness. Water quenching is used for thick sections, whereas air cooling or air blasting is used for thin sections. If cooled too slowly, carbide precipitation can occur. This buildup can be eliminated by thermal stabilization. In this method, the steel is held for several hours at 1500 to 1600 degrees Fahrenheit (815 to 871 degrees Celsius). Cleaning part surfaces of contaminants before heat treatment is sometimes also necessary to achieve proper heat treatment. Descaling 4 Annealing causes a scale or build-up to form on the steel. The scale can be removed using several processes. One of the most common methods, pickling, uses a nitric-hydrofluoric acid bath to descale the steel. In another method, electrocleaning, an electric current is applied to the surface using a cathode and phosphoric acid, and the scale is removed. The annealing and descaling steps occur at different stages depending on the type of steel being worked. Bar and wire, for instance, go through further forming steps (more hot rolling, forging, or extruding) after the initial hot rolling before being annealed and descaled. Sheet and strip, on the other hand, go through an initial annealing and descaling step immediately after hot rolling. After cold rolling (passing through rolls at a relatively low temperature), which produces a further reduction in thickness, sheet and strip are annealed and descaled again. A final cold rolling step then prepares the steel for final processing. Cutting 5 Cutting operations are usually necessary to obtain the desired blank shape or size to trim the part to final size. Mechanical cutting is accomplished by a variety of methods, including straight shearing using guillotine knives, circle shearing using circular knives horizontally and vertically positioned, sawing using high speed steel blades, blanking, and nibbling. Blanking uses metal punches and dies to punch out the shape by shearing. Nibbling is a process of cutting by blanking out a series of overlapping holes and is ideally suited for irregular shapes. Stainless steel can also be cut using flame cutting, which involves a flame-fired torch using oxygen and propane in conjunction with iron powder. This method is clean and fast. Another cutting method is known as plasma jet cutting, in which an ionized gas column in conjunction with an electric arc through a small orifice makes the cut. The gas produces extremely high temperatures to melt the metal. Finishing 6 Surface finish is an important specification for stainless steel products and is critical in applications where appearance is also important. Certain surface finishes also make stainless steel easier to clean, which is obviously important for sanitary applications. A smooth surface as obtained by polishing also provides better corrosion resistance. On the other hand, rough finishes are often required for lubrication applications, as well as to facilitate further manufacturing steps. Surface finishes are the result of processes used in fabricating the various forms or are the result of further processing. There are a variety of methods used for finishing. A dull finish is produced by hot rolling, annealing, and descaling. A bright finish is obtained by first hot rolling and then cold rolling on polished rolls. A highly reflective finish is produced by cold rolling in combination with annealing in a controlled atmosphere furnace, by grinding with abrasives, or by buffing a finely ground surface. A mirror finish is produced by polishing with progressively finer abrasives, followed by extensive buffing. For grinding or polishing, grinding wheels or abrasive belts are normally used. Buffing uses cloth wheels in combination with cutting compounds containing very fine abrasive particles in bar or stick forms. Other finishing methods include tumbling, which forces movement of a tumbling material against surfaces of parts, dry etching (sandblasting), wet etching using acid solutions, and surface dulling. The latter uses sandblasting, wire brushing, or pickling techniques. The Smelting process of stainless steel production First to introduce the basic principles of stainless steel smelting. Stainless steel contains at least 10.5% Cr, which is different from carbon steel production. Therefore, in the decarburization reaction, reaction occurs: Cr3O4 + 4 [C] = 3 [Cr] + 4CO Reaction equilibrium constant Cr in the high chromium steel, Cr than C priority oxidation, in the normal smelting temperature, C below 0.03%, the balance of Cr is only about 4%; improve the temperature can improve the balance of Cr content, but refractory unbearable. Such as: 18% Cr of molten steel, the temperature to reach more than 1900 ℃, for the development of a partial pressure of CO to reduce the smelting method. Stainless steel commonly used refining methods: AOD, VOD, K-OBM-S, K-BOP and so on), RH-BMP method and so on, which can be used in the process of arc furnace, direct arc melting, AOD, VOD, OB method, in which the AOD method, VOD method dominant. Through the use of two-step and three-step process to produce smelting stainless steel, can produce large-scale low-carbon, ultra-low carbon stainless steel, but also can improve the recovery of Cr. 1) Several smelting methods of stainless steel: One step: EAF Original Electric Furnace Direct Production Process Two-step method: EAF + AOD EAF + VOD EAF + CLU LD-OB + VOD Three steps: EAF + K-OBM-S + VOD or AOD + (LF) EAF + AOD + VOD EAF + LD-OB + VOD 2) The advantages and disadvantages of AOD and VOD: AOD smelting has the advantages of low investment cost, high decarburization speed and high production efficiency, high thermal efficiency and low cost of smelting. It has good stirring effect and is easy to de-S and O. The equipment is relatively simple and the process is easy to grasp. AOD around the use of stainless steel production, the disadvantage is the production of low C, N steel difficult. VOD smelting off C, Cr-effective, good deoxidation effect; suitable for the production of low C, N steel and so on. Shortcomings High investment costs, equipment maintenance difficulties. The process hot rolling of stainless steel The strip accounts for about 70% of the total output of stainless steel. Stainless steel hot strip mainly by the hot rolling mill, steckel mill and other production, including hot rolling mill, which is characterized by large output, low cost, good quality, is widely used in many steel mills. However, the number of stainless steels produced by the improved Steckel Mill in the world is increasing, such as AVESTA and YUSCO. Heavy plate generally by the four-roll reversing mill-based production. The cold rolling process of Stainless steel Stainless steel is a high alloy steel, rolling deformation resistance, in order to carry out high-efficiency, high-precision rolling, rigidity should be used in large rolling mill, generally multi-roll cold rolling mill. The heat treatment process of stainless steel Stainless steel heat treatment through the use of the best performance, or create conditions for subsequent processing, the general stainless steel in the factory before the need for heat treatment. Martensitic stainless steel: softening (martensite → ferrite + carbide); carbide diffusion; degree. Ferritic stainless steel: to improve plasticity; adjust the grain size. Austenitic stainless steel: Carbide solid solution; Adjust grain size; Soften; Reduce δ ferrite. Duplex stainless steel: carbide solid solution; improve plasticity; reduce the brittle phase precipitation. The common standard of stainless steel Since its inception in the early 20th century, with the continuous development of its research and development and production technology, its standards are gradually established in the industrialized countries, the establishment and perfection of stainless steel standards, in turn, to promote the progress of stainless steel production technology, Promote the improvement of product quality, the development of stainless steel products in the market trade, play a very important role. China National (GB / T) standards: Hot – rolled stainless steel sheets and strip GB / T Cold – rolled stainless steel sheets and strips GB / T Heat – resisting steel plates and strips GB / T GB / T1220 stainless steel rods GB / T8165 stainless steel composite plate and strip Stainless steel and heat – resistant steel, designation and chemical composition GB / T Other special stainless steel standards, as well as the enterprise standards Commonly used foreign standard (international common standard): ASTM A240 (M) stainless steel plate (American Standard) ASME A 240 (M) Stainless Steel Plate (American Standard) ASTM A 480 (M) Stainless Steel Plate (American Standard) JIS4305 stainless steel cold rolled steel sheet (Japanese standard) JIS4304 stainless steel hot-rolled steel sheet (Japanese standard) EN10028 Stainless steel for pressure vessels (EU) EN10088 General purpose sheets, plates and strips with stainless steel (EU) Other European EN series standards

Large flange in assembly welding. To avoid in the condition of bearing or bearing welds, try to eliminate the influence of external forces of weld bead and prevent deformation of the flange. Take the following measures: (1) when conditions permit, the horizontal barrel level in roller frame assembly welding flange. After welding flange in the mouth of the first welding flanges outside the mouth. Welding current and voltage shoulds not be too big, in order to reduce the accumulation of heat. (2) when necessary, can give the flange stiffened plates equipped with process closed to resist deformation trend. Stiffened plates removed after welding process. And the welding scar left by the bridge polishing. (3) when the cylinder is in vertical position assembly welding equipment flange, should try to support cylinder, the flange in a suspended state, giving the function of weld bead is not affected by tube weight force. (4) if necessary, can be used on the bolts in the flange fixed another companion flange, then the normal assembly welding flange. After welding to remove companion flange. In short, as long as the welding process to take appropriate measures before four, even if again big, again weak flange can also ensure that will not happen deformation during welding. Source: wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Butt welding elbow is one of the pipe fittings, elbow pipe fittings are used in the process of pipeline engineering construction is becoming more common, this is largely due to its forming good, strong compression ability, simple welding form etc., to ensure the bearing capacity of the pipe, so in the process piping engineering especially in petrochemical and flammable and explosive pipe of high temperature and high pressure, the rational use of pipe and pipe fittings itself quality directly plays an important role. Butt welding elbow is applied to the butt welding of ring artifacts such as car rim and bicycle, motorcycle rims of butt welding, butt welding of various link, etc. Butt welding elbow is applied to parts of compound will be roughly rolling, forging, stamping or machined parts butt into major parts of the eve, with a low completion. Such as car mark purpose shaft shell and the rear axle shell butt welding, butt welding of various connecting rod, rod, as well as special parts of butt welding and so on. But in the process of application, prone to all kinds of problems: A, the uneven wall thickness of pipe fittings In pipe wall thickness uneven occurs mainly at the site of the largest pipe deformation. Such as wall thickness in other parts of the bend of the back; The nozzle and the pipe body wall thickness. Specified in the relevant national standards. Check for such problems, using measuring tools such as caliper, often difficult to find, at this time only can be measured using ultrasonic thickness gauge. Second, the hardness of paint Butt welding elbow hardness of overweight problems, mainly due to the heat treatment after forming process The solution is to use the correct heat treatment process for an additional heat treatment. Three, produced by the defects in materials and processing The defect of butt welding elbow harm the safety of the plant is the largest. Check up and more troublesome. Factors of defects are more complex, more it is a combination of material itself defects and processing manufacturing process and heat treatment process of defects caused by the incorrect. Source: wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

The forged pipe fittings are mean that pipes are through the technology of forging.Commonly the forged pipe fittings includes:socket weld pipe fittings and threaded pipe fittings. Forged Pipe Fittings Standard: We supply forged pipe fittings according to GB/T14383,SH3410,ASME B16.11,BS3799 and Custom-made.We supply a variety of forged pipe fittings to satisfy our customers’ specific requirements. Our products are produced strictly according to the required standard. Forged Pipe Fittings Size: wilsonpipeline supplies forged pipe fittings Dimension DN6-DN100.It has all kinds of size.They are generally small size.We can according to the size of production.In forging the purpose of each size is different.The customer wants to type can be booked. Forged Pipe Fittings Pressure: We under the pressure of production in 3000/6000/9000/10000 PSI.The PSI’s English is full of Pounds per square inch,which said the pressure of the forged pipe fittings. Forged Pipe Fittings Material: The forged pipe fittings could be Carbon Steel,Stainless Steel,Alloy Steel,20#,A105,20Mn,A350LF2,ASTM A182 F5,F9,F11,F12,F22,F91,F304L,F316L,F321,F347,F51. wilsonpipeline is mainly producing forged pipe fittings and other products in China.We supply a variety of pipe fittings to satisfy our customers’ specific requirements. Welcome to contact us when you have any need about all kinds of forged pipe fittings.