'easily mounted'

Half Round Tube Shield Ladhani Metal Corporation offers SS 304 Half Round Straight Tube Shields engineered to protect straight sections of boiler and heat exchanger tubes from erosion, scaling, and high-temperature wear. These shields are installed over exposed tube surfaces to serve as a physical barrier against hot flue gases, fly ash, and other abrasive or corrosive elements present in thermal processing systems. The half-round design ensures close contact with the tube, providing effective protection and extended service life. SS 304 Half Round Straight Tube Shield The SS 304 Half Round Straight Tube Shield is designed for use in environments where straight tubes face constant exposure to high-temperature gases and particulate matter. SS 304 is an austenitic stainless steel with excellent corrosion resistance, high-temperature strength, and formability. These properties make it a preferred material for shielding straight tube sections in boilers, waste heat recovery systems, and steam reformers. Ladhani Metal Corporation is a leading manufacturer, supplier, and exporter of SS 304 Half Round Straight Tube Shields, offering precision-fabricated shielding components for various industrial thermal systems. Material Grade SS 304 – Austenitic Stainless Steel with high chromium and nickel content for enhanced corrosion resistance. Chemical Composition of SS 304 • Carbon (C): ≤ 0.08% • Manganese (Mn): ≤ 2.00% • Phosphorus (P): ≤ 0.045% • Sulfur (S): ≤ 0.030% • Silicon (Si): ≤ 1.00% • Chromium (Cr): 18.0 – 20.0% • Nickel (Ni): 8.0 – 10.5% • Iron (Fe): Balance Applications: Ideal for environments with exposure to steam, hot gases, and corrosive particles where durability and corrosion resistance are essential. Uses • Protection of straight tube sections in boilers and superheaters • Shielding tubes in economizers and HRSG systems • Applied in chemical heat exchangers and refinery heaters • Used in pulp and paper industry recovery boilers • Suited for marine and coastal power plants facing chloride exposure Features • Corrosion resistance – Excellent protection against oxidation, steam, and flue gas attack • Thermal durability – Withstands continuous exposure to elevated temperatures without deformation • Wear resistance – Shields tube surface from impact, erosion, and ash impingement • Custom fabrication – Tailored to tube size, wall thickness, and system layout • Secure installation – Easily mounted with clamps, welding, or stainless-steel banding • Cost-effective – Reduces maintenance frequency and extends tube life Applications • thermal power stations – Prevents tube thinning and cracking in straight sections exposed to ash-laden gas streams • chemical and petrochemical plants – Provides robust shielding for exchanger tubes in corrosive processing environments • waste heat recovery units – Enhances protection in systems where temperature fluctuation and gas velocity are high • industrial boilers – Ensures system reliability and energy efficiency by maintaining tube wall integrity • marine and offshore boilers – Protects tubes from saline steam and acidic corrosion Conclusion The SS 304 Half Round Straight Tube Shield from Ladhani Metal Corporation is a reliable and durable solution for shielding straight tube sections in demanding thermal applications. Manufactured from corrosion-resistant stainless steel and designed for easy installation, these shields provide lasting protection that enhances boiler performance and reduces maintenance downtime. For detailed specifications, custom sizes, or technical support, please contact Ladhani Metal Corporation.

Half Round Tube Shield Half Round Tube Shields by Ladhani Metal Corporation are precision-engineered components designed to safeguard boiler and heat exchanger tubes from erosion, scaling, and thermal degradation. These shields are essential for industrial systems subjected to high-temperature flue gases, particulate abrasion, and corrosive atmospheres. The half-round design allows for simple installation over both straight and curved tube surfaces, enhancing tube longevity and reducing unplanned maintenance. SS 420 U Type Outer Half Round Tube Shield The SS 420 U Type Outer Half Round Tube Shield is manufactured from SS 420, a high-carbon martensitic stainless steel offering excellent hardness, strength, and moderate corrosion resistance. This outer U-type shield is designed specifically to protect the outer arc of U-bend tubes, where direct exposure to flame, slag, and abrasive gas streams accelerates wear. SS 420’s heat resistance and hard surface make it well-suited for shielding critical tube areas in high-wear, high-temperature applications. • Outer U Type Half Round Tube Shield – Provides robust coverage for the external curve of U-bend tubes, defending against mechanical erosion, scaling, and thermal fatigue. Ladhani Metal Corporation is a prominent manufacturer, supplier, and exporter of SS 420 U Type Outer Half Round Tube Shields, delivering reliable protection in harsh industrial operating environments. Chemical Composition of SS 420 – High-Carbon Martensitic Stainless Steel • Carbon (C): 0.15 – 0.40% • Manganese (Mn): ≤ 1.00% • Phosphorus (P): ≤ 0.040% • Sulfur (S): ≤ 0.030% • Silicon (Si): ≤ 1.00% • Chromium (Cr): 12.0 – 14.0% • Iron (Fe): Balance Applications: Best suited for high-temperature, abrasive environments where mechanical strength and surface durability are critical, with moderate corrosion exposure. Uses • Protection of U-bend outer surfaces in superheaters, reheaters, and economizers in thermal power plants • Shielding external curves in gas heaters, exhaust systems, and flue ducts prone to slag or particulate erosion • Applied in return bends of waste heat recovery systems and HRSGs to guard against high-velocity gas wear • Ideal for industrial furnaces, incinerators, and heat exchangers operating in high-heat and abrasive zones • Suitable for applications where resistance to scaling, mechanical stress, and oxidation is required Features • High hardness and wear resistance – Martensitic steel structure offers excellent protection against abrasion and mechanical impact • Thermal durability – Performs well under high-temperature conditions with good resistance to scaling and thermal fatigue • Outer arc shielding – Specifically designed to guard the most exposed curvature of U-bend tubes from direct flame and gas stream contact • Precision-engineered – Fabricated to exact tube radius and diameter for secure, vibration-resistant installation • Simple installation – Easily mounted using clamps, tack welds, or stainless banding without system disassembly • Cost-efficient protection – Provides a durable solution with a balance of strength and corrosion resistance at an economical price Applications • thermal power stations – Used to shield outer curves of U-bend tubes from flame impingement and gas erosion • industrial boilers and furnaces – Protects return bends in high-heat, high-wear zones prone to slag accumulation and scale formation • waste heat recovery boilers – Installed in WHRB and HRSG systems to extend tube life under hot gas and particulate exposure • chemical and petrochemical industries – Suitable for heaters and exchangers where thermal stress and gas impact degrade surfaces • process heating systems – Applied in equipment handling high-velocity gas or steam that contributes to tube wear and surface damage Conclusion The SS 420 U Type Outer Half Round Tube Shield by Ladhani Metal Corporation—manufacturer, supplier, and exporter—is a dependable and rugged solution for protecting the outer arcs of U-bend tubes in boilers, heat exchangers, and high-temperature processing systems. Its high strength, excellent wear resistance, and thermal durability make it ideal for applications where erosion and mechanical damage are frequent. Customizable and easy to install, it supports long-term reliability and reduced operational downtime in demanding industrial conditions. For technical consultation, custom orders, or quotations, please contact Ladhani Metal Corporation.

Half Round Tube Shield Half Round Tube Shields by Ladhani Metal Corporation are precision-engineered components used to protect boiler and heat exchanger tubes from erosion, scaling, and high-temperature corrosion. These shields are widely applied in industrial systems exposed to thermal cycling, aggressive gases, and particulate flow. Their half-round shape allows for simple and secure installation over straight or curved tube surfaces, extending tube life and reducing maintenance needs. SS 310S U Type Outer Half Round Tube Shield The SS 310S U Type Outer Half Round Tube Shield is designed using SS 310S, a low-carbon austenitic stainless steel known for its excellent resistance to oxidation, high-temperature strength, and enhanced weldability. This outer U-type shield is specifically engineered to cover and protect the outer arc of U-bend tube sections in superheaters, reheaters, waste heat recovery systems, and high-temperature heat exchangers. With its high chromium and nickel content, SS 310S provides superior performance in oxidizing and carburizing environments while maintaining structural stability during prolonged thermal cycling. • Outer U Type Half Round Tube Shield – Shields the external curvature of U-bend tubes from slag deposition, hot gas erosion, scale formation, and high-temperature fatigue. Ladhani Metal Corporation is a leading manufacturer, supplier, and exporter of SS 310S U Type Outer Half Round Tube Shields, offering high-performance solutions for critical thermal and process applications across industries. Chemical Composition of SS 310S – Low-Carbon Austenitic Stainless Steel • Carbon (C): ≤ 0.08% • Manganese (Mn): ≤ 2.00% • Phosphorus (P): ≤ 0.045% • Sulfur (S): ≤ 0.030% • Silicon (Si): ≤ 1.50% • Chromium (Cr): 24.0 – 26.0% • Nickel (Ni): 19.0 – 22.0% • Iron (Fe): Balance Applications: Best suited for high-temperature, oxidizing, and carburizing environments where thermal stability, scale resistance, and corrosion protection are essential. Uses • Outer surface protection of U-bend tubes in superheaters and reheaters of thermal and industrial power plants • Shielding of return bends in petrochemical reformers, process heaters, and high-temperature exchangers • Applied to outer arcs in WHRBs and HRSGs subjected to thermal cycling, slag erosion, and hot flue gas exposure • Suitable for use in chemical and gas processing units handling oxidizing or acidic exhausts at elevated temperatures • Ideal for incinerator tubes, radiant coils, and furnace bends operating under continuous or cyclic heat conditions Features • Outstanding high-temperature strength – Performs effectively up to 1150°C with excellent resistance to scaling and oxidation • Enhanced weldability – Low carbon content minimizes the risk of sensitization and intergranular corrosion after welding • Outer U-bend coverage – Designed for targeted protection where erosion and thermal impact are most severe • Precision fitment – Manufactured to exact tube radius and diameter specifications for tight, vibration-free installation • Quick installation – Easily mounted using clamps, tack welds, or stainless steel banding without system disassembly • Long-term durability – Resistant to cracking, scaling, and corrosion under thermal fatigue, reducing maintenance and downtime Applications • thermal power plants – Installed on U-bend tube outer curves in superheaters and reheaters for oxidation and erosion protection • petrochemical plants – Used in reformers and cracking furnaces exposed to high-temperature and oxidizing environments • waste heat recovery systems – Protects return bends in WHRBs and HRSGs from hot gas flow, slag buildup, and scaling • chemical and gas processing – Shields bends in high-temperature exchangers and preheaters from corrosive and oxidizing media • furnaces and industrial incinerators – Applied to radiant tubes and burner bends subjected to direct flame and thermal cycling Conclusion The SS 310S U Type Outer Half Round Tube Shield by Ladhani Metal Corporation—manufacturer, supplier, and exporter—is a premium solution for protecting U-bend tube outer arcs in boilers and heat exchangers exposed to severe heat and gas flow conditions. With excellent oxidation resistance, low carbon content for improved weldability, and precision design for long-lasting performance, this shield enhances the lifespan and reliability of thermal systems across a wide range of industrial sectors. For technical consultation, custom orders, or quotations, please contact Ladhani Metal Corporation.

Half Round Tube Shield Half Round Tube Shields by Ladhani Metal Corporation are precision-engineered components used to protect boiler and heat exchanger tubes from erosion, scaling, and high-temperature corrosion. These shields are widely applied in industrial systems exposed to thermal cycling, aggressive gases, and particulate flow. Their half-round shape allows for simple and secure installation over straight or curved tube surfaces, extending tube life and reducing maintenance needs. SS 420 U Type Half Round Tube Shield The SS 420 U Type Half Round Tube Shield is manufactured from hardenable martensitic stainless steel, providing robust mechanical strength, surface hardness, and oxidation resistance in high-temperature service environments. Designed specifically for U-bend sections in heat exchangers, boilers, and superheaters, this shield offers dependable protection against scaling, thermal fatigue, and particulate erosion. The U-type configuration enables targeted shielding of both the inner and outer arcs of tube bends—critical areas where temperature gradients and gas velocity are highest. • Outer U Type Half Round Tube Shield – Protects the outer curve of U-bends from slag accumulation, flame impingement, and surface wear caused by high-velocity gas flow. • Inner U Type Half Round Tube Shield – Shields the inner arc against turbulence-induced erosion, scaling, and corrosion under thermal stress conditions. Ladhani Metal Corporation supplies SS 420 U Type Half Round Tube Shields tailored to meet the demands of thermal power, petrochemical, and process industries operating in elevated temperature ranges with limited corrosive exposure. Chemical Composition of SS 420 – Hardenable Martensitic Stainless Steel • Carbon (C): 0.15 – 0.40% • Manganese (Mn): ≤ 1.00% • Phosphorus (P): ≤ 0.040% • Sulfur (S): ≤ 0.030% • Silicon (Si): ≤ 1.00% • Chromium (Cr): 12.0 – 14.0% • Nickel (Ni): ≤ 0.75% • Iron (Fe): Balance Applications: Ideal for systems requiring wear resistance, oxidation stability, and mechanical strength in dry, heat-intensive environments. Uses • Protection of U-bend tubes in thermal power plant superheaters and reheaters • Coverage for curved tube sections in WHRBs and HRSGs exposed to abrasive gas flow • Shielding tube bends in chemical reactors and reformers where thermal shock and particulate wear are common • Erosion prevention in return bends of condensers, evaporators, and economizers • Suitable for heat exchanger systems with low moisture and minimal chemical corrosion Features • Excellent surface hardness – SS 420 can be heat-treated for increased hardness and wear resistance, making it suitable for erosive and abrasive service. • Good oxidation resistance – Performs effectively in dry air at elevated temperatures, helping prevent surface scaling and material degradation. • Full bend protection – Offered in both inner and outer U-type forms to ensure total shielding of critical tube bend areas. • Tight and secure fit – Engineered to match tube radius and diameter, ensuring vibration-free performance and minimal exposure. • Simple installation – Can be easily mounted using banding, clamping, or light tack welding without requiring full system shutdown. • Cost-effective solution – Provides a balance of performance and affordability for moderately aggressive service conditions. Applications • thermal and captive power plants – Used on U-bends in reheaters and superheaters to combat flue gas erosion and temperature cycling. Ensures better tube life and heat retention. • refinery and process industries – Suitable for return bends in units with dry, high-temperature gas flow and minimal moisture-induced corrosion. • waste heat recovery systems – Shields U-shaped tubes in WHRBs from slag, particulate impact, and scale buildup. • cement and glass industries – Installed on high-temperature tubes exposed to solid-laden gas streams for wear resistance and surface stability. • chemical plants – Applied in select heat exchanger areas where scaling and erosion are more critical than chemical corrosion. Conclusion The SS 420 U Type Half Round Tube Shield by Ladhani Metal Corporation offers a rugged and efficient solution for protecting U-bend tubes exposed to heat, slag, and abrasive gas flow. With its ability to resist scaling, erosion, and surface fatigue, SS 420 is ideal for industries operating in dry, high-temperature environments. Precision fit, dual-arc protection, and easy installation make these shields a valuable addition to any boiler or heat exchanger system. For technical consultation, custom orders, or quotations, please contact Ladhani Metal Corporation.

Ladhani Metal Corporation offers Clip-On Tube Shields designed for quick installation and reliable protection of boiler tubes in power plants, refineries, petrochemical heaters, waste heat recovery boilers (WHRBs), and heat recovery steam generators (HRSGs). These shields feature a clip-on fastening mechanism that allows them to be mounted securely onto tube surfaces without welding, reducing installation time, labor, and downtime while still ensuring effective tube protection in high-wear areas. Function of Clip-On Tube Shields • Provide erosion and corrosion protection for boiler tubes in flue gas paths • Reduce downtime with fast, non-weld installation and removal • Shield tubes from soot blower jets, ash particle erosion, and hot flue gases • Extend service life of boiler components under high-temperature operation Ladhani Metal Corporation manufactures, supplies, and exports Clip-On Tube Shields in various sizes, thicknesses, and radii, catering to both domestic and international market requirements. Available Grades • SS 304 / SS 304L • SS 310 / SS 310S • SS 316 / SS 316L • SS 410 / SS 420 / SS 430 • 1Cr13 • 1Cr18Ni9Ti • 1Cr20Ni14Si2 • 1Cr25Ni20Si2 • Cr23Ni13 • Cr25Ni20 Applications: Widely used in reheater, superheater, economizer, and LTSH sections where high-velocity flue gases and abrasive particles cause localized tube erosion. Uses • Protects boiler tubes from erosion, oxidation, and mechanical wear • Shields against soot blower jet impingement • Reduces costly maintenance and tube replacement • Suitable for power plants, HRSGs, WHRBs, and refinery heaters Features • Clip-on design – Easy installation and removal without welding • Strong hold for reliable protection in high-velocity zones • Corrosion and oxidation resistance at elevated temperatures • Designed for accurate fit and long-term service Applications • Power generation boilers – Fast protection solution for reheater/superheater tubes • Waste heat recovery boilers – Guards tubes in erosive gas flows • HRSGs – Provides durable shielding with minimal downtime • Industrial and petrochemical steam systems – Reliable in high-temperature cycles Conclusion The Clip-On Tube Shield from Ladhani Metal Corporation offers a practical and efficient solution for protecting boiler tubes from erosion and corrosion without requiring welding. Available in a wide range of stainless steel and alloy grades, these shields deliver precision, durability, and global supply capability to meet the needs of power generation and process industries.

Product:Titanium stud m8 Material: Gr2 Gr5 Size: M3-M52*Length, or as customers' drawings Surface: Polished Technique: CNC Machined, Forged Titanium bolts are widely used in various industries such as automobiles,chemical industry. Different from welding and riveting, the biggest feature of bolts is that they can be easily removed even after tightening and can be reused by re-tightening Item name: Titanium Stud Bolt Material: GR2 GR5 Size: M3-M52 Pitch: 1.25/1.5mm Length: total length 5-300mm, the length of thread at both ends is based on your requirements Technique: CNC/Forged Surface: Polished Chemical composition (Wt%) ASTM No. Fe max O max N max C max H max Al V Bal Grade2 0.3 0.25 0.03 0.1 0.015 - - Ti Grade 5 0.3 0.2 0.05 0.08 0.015 5.5-6.75 3.5-4.5 Ti Physical Properties (Min) ASTM Grade Alloy Composition Tensile Strength Yield Strength Elongation min % ksi Mpa ksi Mpa Grade 2 Unalloyed Ti ("Pure") 35A -CP1 58 400 40 275 20 Grade 5 Ti6Al4V 130 895 120 825 10

Product Name: WN Titanium Flanges Standard: ANSI / ASME B16.5 Material: Gr1 Gr2 Gr5 Gr7 Gr12 Unit Price: $25usd/pc-$85usd/pc Sealing Surface: RF, FF, TG, RJ etc. Size: NPS 1/2 - NPS 24(DN 10 - 2000) Pressure: 150#-2500# Surface: Polished Technique: Forged and CNC Machined Inspection: UT% PT% Certificate: ISO9001, TUV etc. WN Titanium Flanges The titanium flange is a part made of pure titanium or titanium alloy, which connects the pipe to the pipe, and to the end of the pipe. Product Name: WN Titanium Flanges Standard: ANSI / ASME B16.5 Material: Gr1 Gr2 Gr5 Gr7 Gr12 Unit Price: $25usd/pc-$85usd/pc Sealing Surface: RF, FF, TG, RJ etc. Size: NPS 1/2 - NPS 24(DN 10 - 2000) Pressure: 150#-2500# Surface: Polished Technique: Forged and CNC Machined Inspection: UT% PT% Certificate: ISO9001, TUV etc. Differences between Weld neck titanium flange and slip on titanium flange 1. Different welding forms: The welding form of neck flat welded titanium flange pipe and titanium flange is fillet welding, while the welding form of the neck butt welded flange and pipe is girth welding; 2. Different materials: the material of the necked flat welding flange is made of ordinary titanium plate with a thickness that meets the requirements, while the material of the necked butt welding flange is mostly machined from titanium forgings; 3. the nominal pressure is different: the nominal pressure of the necked flat welding flange is: 0.6---4.0MPa, and the nominal pressure of the necked butt welding flange is: 1--25MPa; 4. Another point is that the welding seam between the necked butt-welded flange and the connection pipe belongs to type B seam, and the welding seam between the necked flat-welded flange and the connection pipe belongs to type C seam. And the non-destructive testing after welding is different; 5. The necked flat welding flange and the necked butt welding flange cannot be replaced at will. From a manufacturing perspective, the necked flat welding flange (SO is the abbreviation of Slip On) has a large inner diameter, which means that the weight is light and the cost is low. Neck butt welding flanges (WN is the abbreviation of Welding Neck) with a nominal diameter greater than 250mm need to be tested, and SO flanges do not need to be tested, so the cost is low.

Product Name: Titanium seamless pipe for heat exchanger Standard: ASTM B338 Material: Gr1, Gr2 Unit Price: $25usd/kg-$40usd/kg Type: Seamless Shape: Round Outer Diameter: 21.3mm-609.6mm etc. Wall Thickness: 1.24-30mm Length: Max 16000mm Surface: Bright Titanium seamless pipe for heat exchanger The grade 2 titanium tube consists of commercial pure titanium or Unalloyed titanium. The oxygen content of grade 2 is standard. ASTM b861 GR 2 pipes can be easily welded. It also has excellent strength and ductility. The natural strength of metal is used for applications requiring very high strength, and the corrosion resistance is used for long-term appliances. Although most use cases are in industrial standards, titanium grade 2 seamless pipes can also be used in aesthetic and home applications. Due to the cost of raw materials and production costs, the cost is very high. The content of titanium in commercial pure CP grade 2 titanium welded pipe exceeds 99%. It can be cold drawn into titanium seamless pipe or hot rolled into welded pipe. They are used in high temperature applications, such as titanium 2-stage exhaust pipes, which can maintain their shape due to their high thermal conductivity, low thermal expansion and high oxidation resistance at high temperatures.

Product name: Titanium alloy Tubes Standard:ASTM B338 ASTM B861 ASTM B862 Material:Titanium Gr7 Diameter:5-914mm Wall thickness:0.5-50mm Length:Max 16000mm Surface:Pickling surface/Polished Type:Seamless, welded Application:Heat Exchanger, chemical industry etc. Technique:Rolled Because stainless steel and other materials are inefficient in many cases, titanium tubes are increasingly used in various occasions. A common titanium grinding product is titanium tube. Because of its superior corrosion resistance and strength weight ratio, titanium tube is used in various products. The development of many different alloys has expanded the application of titanium in industry, chemical processing and power generation. Commodity Titanium Alloy Tube /Pipe/Tubing,titanium alloy seamless tube/pipe,titanium alloy welded tube pipe,ASTM B338 titanium tube,Titanium pipe price per kg Tube Shape Round Square Flat Coil Material Gr1,Gr2,Gr3,Gr4,Gr5(Ti-6Al-4V),Gr7,Gr9,Gr11,Gr12,Gr23(Ti-6Al-4V Eli) Standard ASTM B337 ASTM B338 ASTM B861 ASTM B862 Type Seamless Welded ERW Fabricated OD 5-914mm or as customized Wall Thickness 0.5-50mm or as customized Length Max 16000mm End Plain End, Beveled End, Threaded Certificate EN 10204/3.1B, Raw Materials Certificate 100% Radiography Test Report Third Party Inspection Report, etc Application Off-Shore Oil Drilling Companies Power Generation Petrochemicals Gas Processing Specialty Chemicals Pharmaceuticals Pharmaceutical Equipment Chemical Equipment Sea Water Equipment Heat Exchangers Condensers Pulp and Paper Industry Titanium alloy tubes can be divided into three categories according to phase composition: α Alloy（ α+β) Alloy and β alloy 1. α Stability of alloy containing a certain amount α The element of phase, in equilibrium, is mainly composed of α Phase composition. α The alloy has small specific gravity, good thermal strength, good weldability and excellent corrosion resistance. Its disadvantage is low strength at room temperature. It is usually used as heat-resistant and corrosion-resistant materials. α Alloys can usually be divided into complete alloys α Alloy (Gr7), near α Alloy (ti-8al-1mo-1v) and alloy with a small amount of compounds α Alloy (Ti-2.5Cu). 2. ( α+β) Stability of alloy containing a certain amount α Phase harmony β Phase elements, and the microstructure of the alloy in equilibrium is α Phase harmony β Phase. ( α+β) The alloy has medium strength and can be strengthened by heat treatment, but its weldability is poor. ( α+ β) Alloys are widely used, and the output of Ti-6Al-4V Alloy accounts for more than half of all titanium materials. 3. β The alloy contains a large amount of stable β Phase elements can be used at high temperature β All phases were retained to room temperature. β Alloys can usually be divided into heat treatable alloys β Alloy (metastable) β Alloy and near metastable β Alloy) and thermal stability β Alloy. Heat treatable β The alloy has excellent plasticity in quenched state, and the tensile strength can reach 130 ~ 140kgf / mm2 by aging treatment. β Alloys are usually used as high strength and high toughness materials. The disadvantages are large ratio, high cost, poor welding performance and difficult machining.