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Valve leakage, especially in check valves, presents a significant risk. Check valves play a crucial role in preventing backflow, ensuring fluid flows in only one direction.  Widely used in domestic water systems, sewage systems, marine, oil and gas industries, and heating systems, check valves are cost-effective solutions.  However, if these valves malfunction, the risk of backflow arises, potentially leading to disastrous consequences, particularly in sensitive systems like sewage treatment.  Addressing check valve leakage is paramount for the safety and reliability of industrial processes. Check Valve Leak Rate ANSI Standards define 6 distinct levels of check valve leakage rates, each indicating an acceptable range of leakage for a valve.  Varied check valves are manufactured with leakage rates tailored to specific requirements.  Let’s explore the details of these leakage rate levels: Class II Permissible leakage is 0.5% of the rated capacity. Capacity is assessed by pressurizing the valve inlet with the outlet open. Class III Permissible leakage is 0.1% of the rated capacity. Capacity is assessed by pressurizing the valve inlet with the outlet open. Class IV Permissible leakage is 0.01% of the rated capacity. Capacity is assessed by pressurizing the valve inlet with the outlet open. Class V Permissible leakage is 0.005 ml per minute of water per inch.  Capacity is assessed by pressurizing the valve inlet after filling the valve body, connecting the pipe with water, and keeping the valve plug closed. Types of Leaky Check Valves and How to Fix Them Check valve leakage can result from various factors, including improper installation, inadequate maintenance, or defects in valve manufacturing.  Precision and careful handling are crucial in check valve repair, often carried out by professionals.  This overview addresses common issues related to check valve leakage, explores their potential causes, and provides solutions for effective resolution. Check Valve Leaking Issue #1: Shut-off Failure Shut-off failure in check valves, occurring during zero flow, leads to potential leakage, posing risks in various environments.  Seizing issues in shut-off valves may compromise functionality and allow hazardous backflow. Possible Cause Aging internal components, like gaskets and washers losing their grip, or debris obstruction inside the valve, contribute to shut-off failure. How to Fix Inspect the industrial check valve, replace damaged washers, and clean the valve thoroughly to prevent future problems. Check Valve Leaking Issue #2: Leaks When Closing Incomplete closure of a check valve leads to leakage, a critical issue requiring attention.  Persistent leaks may signal the need for check valve replacement, especially when handling hazardous chemicals. Possible Causes Debris Blockage: Foreign particles obstructing valve closure result in leakage. Worn-out Washer: A deteriorated washer hinders proper check valve functioning, leading to leaks. Improper Installation: Incompatible check valve size for specific situations causes leakage. How to Fix Thorough Cleaning: Remove contaminants causing obstruction and ensure proper valve functionality. Washer Replacement: Worn-out washers should be replaced promptly to maintain a secure grip. Proper Installation: Ensure correct sizing during installation to prevent leakage issues. Opt for check valve replacement if size mismatches persist. Check Valve Leaking Issue #3: Leaking from Seat Seal The valve seat maintains airtightness in the check valve body, crucial for preventing air leakage.  Imperfect sealing of the check valve seat results in air and fluid leakage, causing system issues such as improper functioning and backflow. Detection is often performed through a bubble test. Possible Causes Improper Installation: Incorrectly placing the valve and seat can lead to air and fluid leakage. Wear and Tear: Sealing deterioration due to wear and tear can result in a leaky check valve seat. How to Fix Repair or Replacement: Address a leaky seat seal by repairing or replacing it. Proper Installation: Ensure accurate valve and seat placement during installation. Preventive Maintenance: Proper lubrication minimizes wear and tear on the valve seat, ensuring prolonged functionality. Check Valve Leaking Issue #4: Leaking from Stem While many check valves lack stems, specific types feature stems for external control.  Stem-related leakage in check valves, particularly stop-check valves, indicates malfunction and unregulated flow due to a damaged or improperly installed stem. Possible Causes Wear and Tear: Excessive wear and tear on the stem impairs its ability to control the valve disc. Improper Installation: Incorrect stem placement disrupts disc control, leading to unregulated flow. How to Fix Stem Replacement: Address leakage by replacing a damaged stem with the appropriate replacement. Maintenance Routine: Prevent check valve issues with regular maintenance and testing. Repairing Packing: Repairing the valve packing contributes to effective stem performance. Key Takeaway Detecting and addressing leakage in check valves, such as a bad check valve or when backflow leaking from the top occurs, is crucial.  Over time, check valves may go bad due to wear, leading to potential backflow issues.  Regular maintenance and prompt replacement of worn parts help ensure optimal valve performance and prevent leakage.

The primary difference between a wafer check valve and a flanged check valve lies in their installation methods.  Wafer check valves are sandwiched between flanges, offering a compact design for space-limited applications, while flanged check valves bolt directly to flanged piping, providing a more secure connection.  Both valves serve similar purposes but vary in installation and design, catering to different operational requirements and space constraints. What is the difference between a wafer check valve and a flanged check valve? The main difference between a wafer check valve and a flanged check valve is how they’re made and put in.  Wafer check valves are slim and light, fitting between two flanges in a pipe. They’re good for tight spaces or when weight matters.  Flanged check valves,also called flange insert check valves, are compact valves for flanged pipes.  They range from small to big and are bolted between flanges, which is a bit more complicated than installing wafer check valves.  Wafer check valves save space and seal well, making them good for fast-flowing situations.  Flanged check valves might slow down flow because of the valve body, which limits the disc’s movement, affecting how well the valve works. Wafer Check Valve and Flanged Check Valve: Similarities and Differences Wafer check valves and flanged check valves are both types of check valves used in piping systems to control the flow of fluids.  Despite serving similar functions, they have distinct designs and installation methods. Similarities Functionality: Both wafer check valves and flanged check valves are designed to allow fluid flow in one direction while preventing backflow. Check Valve Design: They both feature a hinged disc or flap that opens in the direction of flow and closes to prevent reverse flow. Material: Both types of valves are typically made from durable materials such as stainless steel, cast iron, or PVC, depending on the application requirements. Differences Design: Wafer check valves have a slim profile and are designed to fit between two flanges in a pipeline.  In contrast, flanged check valves have a more robust design and are installed by bolting between flanges. Installation: Installing a wafer check valve involves sandwiching it between two flanges, while a flanged check valve requires bolting it directly to flanged piping. Application: Wafer check valves are suitable for applications with space or weight limitations due to their lightweight and compact design.  Flanged check valves, on the other hand, are commonly used in-line and vary in size from small to large, making them suitable for a wide range of piping systems. Where Wafer Check Valve and Flanged Check Valve Are Commonly Used Wafer Check Valve Applications 1: HVAC Systems – Wafer check valves are commonly used in heating, ventilation, and air conditioning (HVAC) systems to prevent backflow in water and air lines. 2: Water Treatment Plants – They are also utilized in water treatment plants to maintain the flow of treated water in the desired direction. 3: Industrial Processes – In various industrial applications, such as chemical processing and manufacturing, wafer check valves help regulate fluid flow and prevent damage to equipment. Flanged Check Valve Applications 1: Municipal Water Distribution – Flanged check valves are often used in municipal water distribution systems to prevent water hammer and backflow. 2: Oil and Gas Industry – They find applications in the oil and gas industry for controlling the flow of crude oil, natural gas, and refined petroleum products. 3: Power Generation Plants – Flanged check valves play a critical role in power generation plants to maintain fluid flow in boilers, condensers, and other equipment. Key Takeaway While wafer check valves and flanged check valves serve similar functions as check valves, their differences in design and installation make them better suited for specific applications.  Wafer check valves are preferred for space-constrained installations, while flanged check valves offer robustness and versatility in a wide range of piping systems.  Understanding their similarities and differences helps in selecting the most suitable valve for various industrial and commercial applications.  

The difference between lug and flanged butterfly valves lies in their mounting mechanisms and applications. Lug-type butterfly valves feature threaded inserts or lugs on either side for easy installation and removal in systems requiring frequent maintenance. On the other hand, flanged butterfly valves are secured to pipelines via flanges, offering a more robust connection suitable for high-pressure applications. Understanding these differences enables informed decision-making when selecting valves for specific industrial or commercial piping systems. What is the use of a lug-type butterfly valve? A lug-type butterfly valve is primarily used in applications where space and weight are limited, as it can be installed without using a full flange set. It is commonly employed in industries such as HVAC, water treatment, and chemical processing for regulating or isolating flow in pipelines. The lugs on the valve body enable easy installation and removal without disrupting the entire piping system. What is the main function of a flange butterfly valve? The main function of a flanged butterfly valve is to regulate or isolate the flow of fluids in pipelines by using a disc mounted on a rotating shaft. This disc rotates perpendicular to the flow direction, allowing for precise control over flow rates and providing efficient shut-off capabilities when fully closed. Flanged Butterfly Valve vs Lug-Type: Differences in Usage or Working Principles Flanged butterfly valves and lug-type butterfly valves are two common types used in industrial applications, each with distinct characteristics and applications. Flanged Butterfly Valve Flanged butterfly valves are designed with flanges on both sides, allowing them to be bolted directly to flanged pipes or equipment. They are typically used in applications where space permits and where a secure, leak-proof connection is required. Flanged butterfly valves are ideal for high-pressure applications due to their robust construction and ability to withstand substantial forces. Lug-Type Butterfly Valve Lug-type butterfly valves, on the other hand, feature lugs or ears on the valve body. These lugs allow the valve to be bolted between two flanges without the need for additional hardware. Lug-type butterfly valves are commonly used in applications where frequent disassembly and reassembly are required, as they can be easily installed or removed without disturbing the surrounding piping.

When it comes to industrial valve selection, ball valves with flanged end connections offer a robust solution with some distinct benefits. While threaded and socket weld ends have their place, flanged ball valves rise above for many demanding services and critical applications.   The rugged flanged body design, easy maintenance, and versatility in materials/configurations make these valves a trusted choice across countless facilities. If you’re considering a new ball valve installation, it’s worth exploring if a flanged option is the optimal fit.   Flange Ball Valve – Key Benefits If you are wondering, “Are flange ball valves better?  ,” here are some of the key advantages that flanged ball valves can provide over alternative end connections: 1.Ability to Withstand Higher Pressures With their sturdy two-piece body construction, flanged ball valves can handle significantly higher pressure ratings compared to threaded units. The flanges create a blowout-proof design by containing forces within the rigid body assembly. Some flanged valves achieve pressure ratings above 5,800 psi for harsh, severe-duty applications. High-integrity pressure boundaries are critical for applications like oil/gas production, steam systems, chemical processing plants and more. Flanged connections provide the required safety margins. 2.Full Bore Design for Minimum Flow Restriction Flange end ball valve typically features a full-bore design where the inner ball cavity matches the pipe’s inner diameter.   This open area allows an unrestricted flow path when open with minimal pressure drop or flow resistance. Other end connection types may utilize reduced ports, venturi shapes or plugs which can impede flow and increase turbulence. The flanged full-bore configuration is ideal for slurries, high-volume utility services, and applications where head loss needs to be minimized. 3.Simplified Maintenance and Inline Removal Perhaps the biggest advantage of flanges is easy valve removal from the pipeline without hot-tapping or line breaks.   The bolted end connections enable quick disassembly for maintenance or replacement by simply unbolting the flanges. This eliminates the need for pipe cutting, threading, re-welding and other invasive & costly procedures. In-line maintainability is a major benefit for critical services, reducing costly downtime. Easy access also simplifies internal inspection, repacking, gasket replacement and part changeouts. 4.Ability to Handle Extreme Temps and Medias Flanged construction allows for a wide selection of valve body materials and trims to handle corrosive media and extreme temperatures. Options include carbon steel, stainless, high-nickel alloys, titanium and special metal/lining combinations. These robust metallurgy choices provide excellent chemical resistance and enable flanged ball valves to operate reliably in the harshest refinery, chemical and slurry applications. The flanged design avoids potential weaknesses from threaded connections in these services. Conclusion While there are applications where threaded or socket weld connections are suitable, flanged ball valves provide undeniable advantages for many industrial uses.   Their pressure containment, flow characteristics, maintainability and material flexibility make them an excellent choice for critical services.

When it comes to precisely regulating flow in pipelines and process equipment, few valve designs can match the versatility of flanged globe valves. These robust yet compact valves have become indispensable across countless industrial applications that require throttling capabilities. From oil/gas and chemical processing to power generation and high-purity manufacturing, flanged globe valves provide exceptional control combined with tight shutoff. Their unique contoured plug design offers advantages over other throttling valve types as well.  Contoured plug provides precise flow regulation and throttling Rugged body design with bidirectional shutoff Flanged ends allow easy installation between piping sections If your operations demand precision flow modulation along with reliable isolation, it’s hard to beat the performance of flanged globe valves. How Does a Flange Globe Valve Work? The defining component of a globe valve is the specially contoured throttling plug. As the plug’s profile varies, it edges in and out of the surrounding seat ring. This gradually expands or contracts the flow passage to modulate the volumetric flow rate. The shape of the plug’s guiding surfaces and seat ring determine flow characteristics. Popular trim styles include: Contoured/Cam Trim – Linear flow characteristic, easier throttling Port or Throttling Plug – Quick opening, then constant flow change V-Port Ball – Allows finer adjustments over wider range Stem-guided plugs move perpendicular to the flow path, while beam-guided types pivot instead. The materials and finishing of these precision-machined trim parts are critical. Rugged Body Construction The flanged globe valve body consists of three chambers separating the inlet, outlet, and bonnet regions. By design, the bonnet area containing the stem, plug, and guiding surfaces is fully isolated from the flow path. This protects components from erosion and process media exposure. It also allows inline maintenance by removing just the bonnet – no need to disconnect the valve body itself. Bidirectional Shutoff and Sealing Another key advantage of globe valves is their bidirectional sealing capability when closed. With the plug tightly seated, they can prevent flow and withstand pressure from either upstream or downstream directions. Spiral-wound gaskets, laminated rings, or other reinforced seals create the tight shutoff barrier necessary for this bidirectional sealing. As with other components, the sealing material selection is based on the temperature, pressure, and media properties. Flanged End Connections As the name suggests, flanged globe valves feature raised face or ring joint flange connections at the inlet and outlet ports. These bolt directly between mating pipe flanges for installation. Flanged ends make globe valves fairly easy to insert into new piping runs or remove for service without disconnecting excessive upstream/downstream sections. Common flange facing styles include raised face, flat face, grooved, and RTJ/ring joint types to match piping specs. Besides flanges, globe valves may also be available with other end styles such as: Threaded (NPT) Socket Weld Butt Weld Valve Body Material Selection To withstand the rigors of industrial service, globe valve bodies are constructed from high-strength metallic materials like: Carbon Steel – Economical general service option Stainless Steel – Exceptional corrosion resistance Nickel Alloys – Superior high-temperature capabilities Brass/Bronze – Durable choice for lower pressure services The body material provides the necessary structural integrity while also offering some chemical compatibility with the process media. Stainless steel flanged globe valves are very common in corrosive environments. Internal trim components utilize specialized alloys and materials designed to handle specific temperature/pressure/media conditions over long operating cycles. Industry Applications Thanks to their robust throttling abilities combined with reliable shutoff, flanged globe valves fill critical roles in many sectors, including: Oil and Gas – Wellheads, gathering lines, separators, and refineries Petrochemical Processing – Reactors, distillation, fractionation columns, compressors Power Generation – Steam lines, condensers, cooling water, fuel supply Pharmaceutical Manufacturing – Ingredient handling, clean utilities, WFI distribution Food and Beverage – Batching lines, CIP/SIP, pasteurization, fermentation Pulp and Paper – Chemical handling, washers, bleach plants General Process – Isolation, sampling, flow/pressure regulation Flanged globe valves can handle liquids, gasses, steam, slurries, and other media with a wide range of pressures and temperatures. They’re available in both standard and project-specific designs per application requirements. Where Flanged Globe Valves Shine? While very versatile, it’s important to understand where the strengths and limitations of flanged globe valves lie: Precise Flow Throttling  The contoured plug design excels at gradually metering and throttling flow rates. This makes globe valves ideal for regulation, mixing, process diversion, and other modulating services. Reliable Shutoff  When closed, flanged globe valves provide bidirectional Class VI shutoff to isolate equipment and prevent backflow. Not for Frequent Operation  While robust overall, flange globe valve parts are more prone to wear than some other valve types like ball or gate. This makes them less ideal for applications requiring frequent open/close cycling. Higher Pressure Drop  The multiple flow path turns and contours in globe valves create more resistance and turbulence compared to ball or gate designs. This results in higher pressure drops, limiting maximum flow capacity for a given valve size. Conclusion Whether your process involves throttling chemical feeds, regulating fluid temperature, or any other critical modulating service, a dependable flanged globe valve is essential. When you partner with a proven manufacturer like Xintai Valve, you can count on superior performance and long service life. Xintai offers an expansive lineup of flanged globe valves engineered to handle virtually any application: Standard and severe service trim options Advanced anti-cavitation and low-noise trims Project-specific designs per API, ASME, BS, and other codes Wide range of materials for temperature/corrosion resistance Actuator accessories including electric, pneumatic, and more From basic isolating and sampling duties to the most demanding process control, Xintai has the flanged globe valve solution you need. Their commitment to innovative engineering and rigorous quality control results in equipment you can stake your reputation on.

The production methods of seamless steel pipes can be roughly divided into oblique rolling method (Menesmann method) and extrusion method. The oblique rolling method (Menesmann method) is to first pierce the tube blank with oblique rolling rolls, and then extend it with a rolling mill. This method has a fast production speed, but requires high machinability of the pipe blank, and is mainly suitable for producing carbon steel and low alloy steel pipes. The extrusion method is to use a piercing machine to pierce the pipe blank or steel ingot, and then use an extrusion machine to extrude it into a steel pipe. This method is less efficient than the oblique rolling method and is suitable for producing high-strength alloy steel pipes. Both the oblique rolling method and the extrusion method must first heat the billet or ingot, and the steel pipe produced is called hot-rolled pipe. Steel pipes produced by hot working methods can sometimes be further cold worked as needed. There are two methods for cold working: one is the cold drawing method, which involves pulling steel pipes through a drawing die to gradually thin and elongate them; Another method is the cold rolling method, which applies the hot rolling machine invented by the Menesmann brothers to cold working. The cold processing of seamless steel pipes can improve the dimensional accuracy and processing smoothness of the pipes, and improve the mechanical properties of the materials.

It’s easy to be confused when it comes to gate and ball valves. Ball and gate valves vary in a few vital ways, even though they sound incredibly similar. Consumers are also confused about the difference between the two and which the better fit for their specific needs is. We’ll talk about what they are and what they needs better represent here. Valves for balls Ball valves, also known as “shut off valves,” are the only way to stop the flow of water immediately. Immediate redirection is impossible with gate valves. Machined stops prevent most ball valves from moving more than 90 degrees, except for 3-way ball valves. Ball valves are available in several settings. Valves for gateways A round knob on a gate valve is usually turned to control the water flow. To stop or start the water, this raises or lowers an internal gate. A spigot on garden hoses is an example of this. Rather than simply turning it off or on, gate valves give users control over the flow pressure. Gate valves provide users to significantly more control over water flow and pressure than ball valves but do not allow for an immediate stop of flow. Stainless steel gate valves are extremely hardy and no more prone to corrosion than ball valves for those aiming to use gate valves but concerned about corrosion. Why do you use a ball valve instead of a gate valve? With so many different valves on the market today, deciding which one is best for your application can be challenging. BM Engineering Supplies examines the advantages of ball valves over gate valves in this article. The valve you choose will make or break your machine. Both ball valves and gate valves are used to monitor and limit flow. Which, on the other hand, has a longer lifespan and prevents leaks? Continue reading to find out. What is the big distinction between gate and ball valves? The work of both ball and gate valves is the same. Their structural characteristics, however, are vastly different. Ball valves, also known as “rotational” valves, have a stem and a ball that rotate horizontally. They’re best for applications that need pressure-free on/off the power. Gate valves open by removing a round or rectangular gate from the fluid’s course. Since the sealing surfaces among the gate and seats are planar, gate valves are commonly used when a fluid flow in a straight line with minimal restriction is needed. Gate valves or ball valves: which is better? Ball valves are robust and reliable, working well after several cycles and closing tightly even after extended periods of inactivity. These characteristics make them an excellent choice for shutoff applications, where gates and globe valves are often favored. However, in throttling applications, they lack sufficient power. Although ball valves are slightly more expensive than gate valves of comparable quality, the small cost savings is not worth the potential problems. Furthermore, due to their 100% shut-off characteristics, ball valves close much tighter than gate valves and are therefore much less susceptible to leaks. Ball valves are more durable, have a lower failure rate, and are easier to use than gate valves. Is it true that ball valves are superior to gate valves? Ball valve’s advantage over a gate valve is that they close much tighter, preventing leakage better than gate valves. This is due to their ability to shut down completely. They’re much simpler to use than gate valves, with lower failure rates and longer life. Ball valves are a great option for shutoff applications because of their reliability. They have a high level of consistency over several cycles and durability, and the ability to close securely even after extended periods of inactivity. They are often favored over gate and globe valves for these reasons. Both types of valves limit and regulate flow, and you want the right type of valve for your plumbing project to ensure durability and leak prevention.    

Nowadays, most industries are using high-tech and modern types of valves to enhance production and operation. Out of all the other types of industrial valves, globe valves are widely used in the oil, gas and fuel industries. There are many uses of this type of valve as it works to stop as well as regulate the flow of liquids. If you want to know more about globe valves and their uses, follow this article. What Are Globe Valves? It is a type of linear motion valve which is used in different types of industries. It is designed in a way that you can use it for throttling as well.  It has a spherical shape like a globe and comes with a disc. The disc moves in order to block as well as allow the flow of substances. When you close the valve, the disc entirely covers the pathway to stop the flow of fluids. However, when you open the valve, the disc moves upwards in order to clear the pathway and allows substances to flow freely. It is mostly used for isolation and throttling purposes. This type of industrial valves has good shutoff capability. You can use it to prevent leakages. Apart from that, it also offers good throttling capacity. The stroke is shorter, which makes it easy to use and maintain. It is available in different types and designs.  Applications and Uses of Globe Valves: Globe valves have many applications. It is used for industrial as well as domestic purposes. The majority of the industries with plumbing needs use this type of valve. Here are some applications and uses of globe valves.  Cooling Water Systems: A globe valve helps maintain the heat and cooling of the system by regulating the flow. It helps in the adjustment of the temperature of the system in relation to the demand of heat or cool by taking the measurement of the changes in pressure. As a result, a valve regulates the amount of heat produced by the boiler.  Fuel Oil Systems:  A Globe Valve is a very important component of fuel oil systems. It helps to prevent and control the rate at which gasoline is burnt in an engine, thus enabling the engine to maintain a constant pressure of fuel at all times. It is usually found on the side of the engine near the firewall. It has a round-shaped body and has two cones on its side.  Chemical Feed Systems: A Globe valve is one of the important parts of chemical feed systems. It helps in the complete process of converting the feed mixture into a liquid, and it also helps in the separation of solids from the liquid mixture. A Globe valve has a piston, and it is rotatable. In this, the piston moves up and down due to the increase and decrease in pressure.  Boiler, Main Stem Vents and Drains: The globe valve is used in main steam and boiler rooms and drains as well. They can be used for controlling the amount of steam that enters a room from outside, regulate the water temperature in the boiler or condensate drain, or act as a thermostatic valve. It is commonly used in the hot water tank to prevent the loss of hot water from the tank through the pipes. Turbine Lube Oil System: A globe valve is used in a turbine lube oil system as it allows the flow of turbine oil to be limited to a single point. The oil is pumped by means of a turbine into a sump tank that is located above the turbine.

Inspection of Stainless Steel Reducers1. Geometry analyses of stainless steel reducersThe distribution trends of wall thickness of big and small concentric reducers are exactly the same. From the large end face to the section close to the small end face, the wall thickness changes from thin thickness to thick one. The inner hole of the small end has been turned after forming, and part of the wall thickness has been removed. However, the wall thickness of end faces of small ends is thinner than that of end faces of large ends, which is exactly the opposite of the eccentric reducer. This is caused by the manufacturing process. When the wall thickness of the axial section changes, there is obvious regularity for changes between the warp threads, but there is also a certain degree of dispersion. 2. Analyses of strengthThe distribution trends of surface hardness of the large and small eccentric reducers are roughly the same, but they are not completely the same. The main difference is the hardness of the small end. The hardness of the small end of small eccentric reducers is higher, while the hardness of that of large eccentric reducers is lower. The tensile strength of the sample is 6.1% and 11% higher than the estimated strength value of the empirical formula. The yield strength and tensile strength of the sample 1 were increased by 9.0% and 2.0% respectively before production, and those of the sample 2 were increased by 26.4% and 8.8% compared with before production). 3. Conclusion(1) The geometric dimensions of large and small ends of stainless steel reducers are more accurate, but the wall thickness is very uneven. As for stainless steel reducers with straight sections, the wall thickness of the small end of the eccentric reducer is thicker than that of the large end, while the wall thickness of the small end of the concentric reducer is thinner than that of the large end. The wall thickness of the reducing elbow is more uniform. Therefore, the geometric dimensions of the large and small ends must be measured when they are tested. (2) The wall thicknesses of the stainless steel reducers tested are all extremely thick. It is recommended that a comprehensive wall thickness inspection record should be performed before they are used. With a basis for online thickness measurement to determine the thinning, the corrosion rate can be accurately reflected so as to ensure the safe operation of the pipeline.(3) The ellipticity of the stainless steel reducer is less than 2%; the bending radius error of the reducing elbow is also small and can be ignored.(4) The surface hardness of the two ends of the stainless steel reducer is about 35% lower than that of the middle section on average.(5) After the final normalizing treatment, the yield strength and tensile strength of the stainless steel reducer made of large-diameter pipes by hot pressing are significantly improved.

Large-diameter seamless steel pipes can be divided into straight seam arc welded steel pipes and straight seam submerged arc welded steel pipes according to traditional processes. The production process of straight seam welded pipe is simple, low cost, rapid development, and high production efficiency. First, the steps to explain the large-diameter seamless steel pipe1. Large-diameter seamless steel pipes are made of a single piece of metal and have no seams on the surface. They are called seamless steel pipes. Seamless steel pipes have hollow sections and are suitable for transporting fluids such as oil, water, and some solid materials.2. Large-diameter seamless steel pipes are widely used to manufacture structural parts and mechanical parts, such as oil drill pipes, automobile drive shafts, bicycle frames, steel scaffolding, etc. Straight seam steel pipe refers to a steel pipe in which the weld seam is parallel to the longitudinal direction of the steel pipe. When seamless pipes and straight-seam pipes have the same diameter and wall thickness, the pressure and robustness of seamless pipes are much greater than that of straight-seam pipes.3. Large-diameter seamless steel pipes and welded steel pipes are steel pipes made by crimping steel plates or steel strips. Second, a complete list of methods for large-diameter seamless steel pipes1. Seamless steel pipes have much higher corrosion resistance, pressure resistance, and high-temperature resistance than welded steel pipes. When seamless pipes and straight-seam pipes have the same diameter and wall thickness, the pressure and robustness of seamless pipes are much greater than that of straight-seam pipes.2. Large-diameter seamless steel pipe has a hollow section and is suitable for transporting fluids, such as oil, water, and some solid materials. The production process of straight seam welded pipe is simple, low cost, rapid development, and high production efficiency.3. Seamless steel pipes have much higher corrosion resistance, pressure resistance, and high-temperature resistance than welded steel pipes. A welded steel pipe is a steel pipe made of steel plates or steel strips pressed together.

This technical specification is suitable for the bidding for the procurement of steel pipe projects. Executive standards The steel pipe shall meet the following standards: Quality standard like Spiral Welded Submerged Arc Welded Steel Pipes for Urban Heating CJ/T3022-1993 or Technical Delivery Conditions of Oil and Gas Industry Transportation Steel Pipes GB/T9711.1-2017 should be implemented for spiral welded pipes. Seamless Steel Pipe for Fluid Transportation GB/T8163-2008 should be carried out as quality standards for seamless steel pipes. Technical requirements for steel pipes Materials The steel pipe should be made of spiral seam welded steel pipes with Q235B.  The seamless steel pipe should adopt 20# steel. Technical specifications The quality and size of spiral seam welded steel pipes should conform to IS09330-1 or GB9711.1～2017 standards. Spiral seam welded steel pipes should ensure that the minimum yield strength is greater than 235N/mm2. Weld joints of steel pipes must meet the technical requirements of DIN1626 or GB3323-87. Specifications, weights and errors of steel pipes The supply of steel pipes shall comply with the relevant regulations in the latest GB9711.1-2017 or GB8163-2008. The normal supply length of the steel pipe should be 12m with a length deviation of 0/+25mm.  When the length of the steel pipe is less than 12m due to the valve, compensator or pipeline turning, it should be supplied according to the actual length on site. The thickness deviation requirements of the raw material steel plate of the steel pipe: when DN is 800mm, the negative thickness deviation should be smaller than or equal to 0mm.  When DN is greater than 800 and smaller than or equal to 1100mm, the thickness negative deviation should be less than or equal to 0mm.  When DN is greater than 1100 and smaller than or equal to 1200mm, the thickness negative deviation should be less than or equal to 3%. The end of the steel pipe should be grooved.  The groove angle should be 30° and the deviation 0°/5°.  The size of the blunt edge should be 1.6±0.8mm. The end surface of the steel pipe shall be perpendicular to the axis of the steel pipe.  When the nominal outer diameter is less than 508mm, the limit deviation shall not be greater than 1.5mm.  When the nominal outer diameter is greater than or equal to 508, the limit deviation shall not be greater than 2.0mm. The ovality of the steel pipe end within 100mm shall not exceed ±1%D. Requirements for manufacturers In order to ensure the quality of the project, the following requirements are put forward for the materials and manufacturers of steel pipes and fittings: The steel quality standards of steel pipes are equal to or higher than those of famous steel pipe manufacturers in China. The quality standard of the steel pipe is equal to or higher than the product standard produced by the bidder, and the selected manufacturer must be approved by the tenderer and indicate in the bidding document. At the same time, photocopies of the delivery quality certificate of the steel pipe raw materials, the quality certificate of the steel pipe, the special equipment manufacturing license (pressure pipe) that the manufacturer should have, and the inspection report issued by the local quality inspection department must be attached to the bidding documents.

Materials of alloy steel pipes Alloy steel pipes have good hardness, which are widely used for pipelines for transporting oil, natural gas, gas, water and certain solid materials. The common alloys are ferroalloys, ferro-chromium alloys, iron-nickel alloys, aluminum alloys(light weights) and copper alloys(good thermal conductivity). The main materials include 16-50Mn, 27SiMn, 20-40Cr, 12-42CrMo, 16Mn, 12Cr1MoV, T91, 27SiMn, 30CrMo, 15CrMo, 20G, Cr9Mo, 10CrMo910, etc. Alloy steel pipes made from 16Mn belong to low alloy steel pipes. Applications of alloy steel pipesAlloy steel pipes are mainly used for high-pressure and high temperature pipelines and equipment such as power plants, nuclear power, high-pressure boilers, high temperature superheaters and reheaters. Three expressions of alloy steel pipe specifications 1. The first one is the outer diameter plus wall thickness. For example, an alloy steel pipe with an outer diameter of 57mm can be indicated by 57x3. 2. The second one is using the inner diameter, that is, the nominal inner diameter. For example, an alloy steel pipe with an outer diameter of 57mm is indicated by DN50. 3. The third one is the inch. For example, an alloy steel pipe with an outer diameter of 57mm can be indicated by 2 inches (1 inch equals to 25.4mm.)  Specific welding steps of alloy steel pipesWelding processes of alloy steel pipes are heating before welding, quenching and tempering after welding. HeatingBefore welding the alloy steel pipe, it should be heated, and weld it after the temperature is controlled for 30 minutes. The heating and virtual beam temperature tempering of welding are actively operated by the temperature control cabinet for temperature adjustment. Adopt far infrared tracking heat treatment furnace plates. Intelligently and actively set the graph and record the graph, and use the thermal resistance to accurately measure the temperature. The thermal resistance measuring point is from 15mm to 20mm away from the edge of the weld during heating. Welding methods1. In order to prevent welding deformation of the alloy steel pipe, each column joint is welded symmetrically by two people, and the welding direction is from the middle to the two sides. After welding one to three layers, reverse planing should be carried out. After the carbon arc gouging is used, the welding equipment needs to be polished. The welding surface should be nitridation treated to show the metal texture and prevent the surface carbonization from causing cracks. The outer hole is welded once, and the remaining inner holes are welded once. 2. When welding alloy steel pipes with two layers, the welding direction should be opposite to that of the layer of alloy steel pipes. The butt welds of each layer are separated by 15 to 20mm.3. The welding current, welding speed and number of overlapping layers of multiple welding machines should be maintained.4. In welding, you must start welding from the pilot arc board and finish welding on the pilot arc board. Cut, polish and clean after welding.  Quenching and tempering after weldingAfter the seam are welded, it should be tempered within 12 hours. If the alloy steel pipe cannot be quenched and tempered immediately, heat preservation and slow cooling should be adopted. When the alloy steel pipe is tempered, temperatures of the two thermal resistances should be measured and the thermal resistance should be welded on both sides of the seam.