ASTM A782 Low Alloy Steel Flange, Class 3

1,We Manufacturing processes are primarily classified into four types: 1:Forging, 2:Casting, 3:Cutting, 4:Rolling. 2,We can manufacture in accordance with these standards. Standards: GB Series (Chinese Standards), JB Series (Machinery Standards), HG Series (Chemical Industry Standards), ASME B16.5 (American Standards), BS4504 (British Standards), DIN (German Standards), and JIS (Japanese Standards). Internationally, there are two primary systems of pipe flange standards: the European system, represented by the German DIN standards (including those of the former Soviet Union), and the American system, represented by the US ANSI pipe flange standards. Other common standards include: the Chinese Ministry of Machinery Industry standards (JB series), the Ministry of Chemical Industry standards (HG series), the Chinese National Standard *GB/T 9112–9124-2010 Steel Pipe Flanges*, as well as US standards (ASME B16.5), British standards (BS4504), German standards (DIN), Japanese standards (JIS), and marine standards (CBM), among others. The nominal pressure ratings for the PN series are designated by "PN" and comprise the following nine levels: PN2.5, PN6, PN10, PN16, PN25, PN40, PN63, PN100, and PN160. The nominal pressure ratings for the Class series are designated by "Class" and comprise the following six levels: Class150, Class300, Class600, Class900, Class1500, and Class2500. Flange Classification 1. **According to Chemical Industry Standards:** Flanges are classified as follows: Plate Flat Welding Flange (PL), Necked Flat Welding Flange (SO), Necked Butt Welding Flange (WN), Integral Flange (IF), Socket Welding Flange (SW), Threaded Flange (Th), Butt Welding Ring Loose Flange (PJ/SE), Blind Flange (BL), Flat Welding Ring Loose Flange (PJ/PJ), and Lined Blind Flange (BL(s)). 2. **According to Petrochemical (SH) Industry Standards:** Flanges are classified as follows: Threaded Flange (PL), Butt Welding Flange (WN), Flat Welding Flange (SO), Socket Welding Flange (SW), Loose Flange (LJ), and Blind Flange (no specific designation). 3. **According to Machinery (JB) Industry Standards:** Flanges are classified as follows: Integral Flange, Butt Welding Flange, Plate Flat Welding Flange, Butt Welding Ring Plate Loose Flange, Flat Welding Ring Plate Loose Flange, Lap Joint Ring Plate Loose Flange, and Blind Flange. 4. **According to Connection Method/Type:** Flanges are classified as follows: Plate Flat Welding Flange, Necked Flat Welding Flange, Necked Butt Welding Flange, Socket Welding Flange, Threaded Flange, Blind Flange, Necked Butt Welding Ring Loose Flange, Flat Welding Ring Loose Flange, Ring-Type Joint (RTJ) Flange and Blind Flange, Large-Diameter Plate Flange, Large-Diameter High-Neck Flange, Figure-8 Blind Plate, Butt Welding Ring Loose Flange, etc. 5. **According to the Component Being Connected:** Flanges can be classified into Vessel Flanges and Pipe Flanges. 6. **According to Structural Type:** Flanges include Integral Flanges, Threaded Flanges, Flat Welding Flanges, Butt Welding Flanges, Lap Joint (Loose/Swivel) Flanges, and Blind Flanges. A flange—also referred to as a flange plate or rim—is a component used to connect shafts to one another, or, more commonly, to join the ends of pipes. Flanges are also utilized at the inlet and outlet ports of equipment to facilitate connections between two devices—for instance, the flange on a speed reducer. A "flange connection" or "flanged joint" refers to a detachable joint assembly comprising three interconnected elements—a flange, a gasket, and bolts—that together form a sealed structural unit. In the context of piping systems, a "pipe flange" specifically denotes a flange used for plumbing within the installation; when applied to equipment, it refers to the inlet or outlet flange of that specific device. Flanges feature a series of holes through which bolts are inserted to securely fasten the two flanges together, while a gasket placed between the flanges ensures a leak-proof seal. Flanges are broadly categorized into three types: threaded (screw-in) flanges, welded flanges, and clamp-type flanges. Flanges are invariably used in pairs; threaded flanges are suitable for low-pressure piping applications, whereas welded flanges are required for systems operating at pressures exceeding 4 kilograms per square centimeter. A sealing gasket is inserted between the two flange plates, which are then firmly secured using bolts. The thickness of a flange—as well as the specifications of the bolts used to fasten it—vary depending on the specific pressure rating required for the application. When connecting equipment such as water pumps or valves to piping systems, the corresponding connection points on these devices are often manufactured in the shape of a matching flange; this method of attachment is also referred to as a "flange connection." Generally, any connecting component that utilizes bolts to join and seal the perimeters of two flat surfaces—such as the joints in ventilation ducts—is termed a "flange"; such components may collectively be classified as "flange-type parts." However, since such a connection often constitutes merely a *portion* of a larger device—for instance, the interface between a flange and a water pump—it would be inappropriate to classify the entire water pump itself as a "flange-type part." Conversely, smaller components—such as valves—that feature such flanged interfaces may indeed be appropriately categorized as "flange-type parts." -:- For detailed product information, please contact sales. -: ASTM A782 Low Alloy Steel Flange, Class 3 Product Information -:- For detailed product information, please contact sales. -: ASTM A782 Low Alloy Steel Flange, Class 3 Synonyms -:- For detailed product information, please contact sales. -:

ASTM A782 Low Alloy Steel, Class 3 Product Information -:- For detailed product information, please contact sales. -: # **Product Introduction: ASTM A782/A782M Class 3 High-Performance Weathering Steel** **ASTM A782/A782M Class 3** represents the premium grade within the A782 specification, designed for **the most demanding structural applications requiring exceptional atmospheric corrosion resistance coupled with high strength**. This **high-strength low-alloy (HSLA) weathering steel** is engineered to form a highly protective and stable patina, offering **corrosion resistance typically six to eight times greater than plain carbon steel** in atmospheric exposure. With a **minimum yield strength of 70 ksi (485 MPa)**, Class 3 provides superior strength-to-weight efficiency for exposed structures where long-term durability, minimal maintenance, and architectural distinction are paramount. It is typically supplied in the **normalized or quenched and tempered condition** to achieve the optimal combination of mechanical properties and microstructural uniformity. --- ## **International Standard & Key Specifications** * **Primary Standard:** **ASTM A782/A782M** - Standard Specification for Pressure Vessel Plates, Alloy Steel and High-Strength Low-Alloy Steel, for Moderate and Lower Temperature Service. * **Application Context:** Although classified under pressure vessel standards for quality assurance, this material is **predominantly utilized in high-end structural and architectural applications** due to its superior weathering characteristics and strength. The pressure vessel designation reflects its high-quality, defect-controlled manufacturing standard. * **Related Specifications:** * **ASTM A709/A709M** - Structural Steel for Bridges (Grades 70W). * **ASTM A6/A6M** - General Requirements for Rolled Structural Steel. * **AASHTO M270M/M270** - For bridge construction (when specified as Grade 70W). * **Governing Standard:** **ASTM A20/A20M** - Standard Specification for General Requirements for Steel Plates for Pressure Vessels (applicable to plate products). * **Heat Treatment:** Often supplied in **normalized (N)** or **normalized and tempered (N&T)** condition to ensure refined grain structure and consistent through-thickness properties, which are critical for both high strength and reliable weathering performance. --- ## **Chemical Composition (Weight %, max unless range is specified)** The chemical composition of Class 3 is precisely balanced with enhanced levels of key alloying elements to achieve superior strength while maximizing atmospheric corrosion resistance. The specific ranges may be proprietary to individual steel producers, but they typically build upon the weathering steel alloy system. | Element | Typical/Expected Composition Range (%) | Role in Performance for Class 3 | | :--- | :--- | :--- | | **Carbon (C)** | 0.15 - 0.21 | Carefully controlled to provide necessary strength foundation while maintaining good weldability and toughness. | | **Manganese (Mn)** | 0.80 - 1.60 | Essential for strength and hardenability, supporting the higher yield strength requirement. | | **Phosphorus (P)** | ≤ 0.04 | Enhances atmospheric corrosion resistance. | | **Sulfur (S)** | ≤ 0.05 | Impurity, minimized. | | **Silicon (Si)** | 0.15 - 0.65 | Deoxidizer and solid solution strengthener; contributes to patina formation. | | **Copper (Cu)** | **0.30 - 0.60** | **Fundamental weathering element.** Higher content than lower classes for more robust and rapid patina formation in varied atmospheres. | | **Chromium (Cr)** | **0.60 - 1.25** | **Significantly enhanced.** Critical for forming a dense, highly adherent, and protective chromium-rich oxide layer, offering superior resistance in aggressive (industrial, coastal) environments. | | **Nickel (Ni)** | **0.40 - 0.80** | **Elevated content.** Improves toughness significantly, enhances atmospheric corrosion resistance, and stabilizes the microstructure, especially beneficial in normalized conditions. | | **Molybdenum (Mo)** | **0.10 - 0.30** | Often added to increase strength (solid solution strengthening), improve hardenability, and enhance resistance to localized corrosion/pitting. | | **Vanadium (V)** | 0.02 - 0.10 | Microalloy for grain refinement and precipitation strengthening. | | **Niobium (Cb/Nb)** | 0.005 - 0.05 | Optional microalloy for grain refinement. | **Key Distinction:** Class 3 chemistry is characterized by **higher minimums and/or broader ranges for Cu, Cr, and Ni**, and may include **Molybdenum**. This advanced alloy design targets maximum durability in corrosive atmospheres while achieving 70 ksi yield strength through a combination of solid solution, precipitation, and grain refinement strengthening. --- ## **Typical Physical & Mechanical Properties** Properties are for normalized or normalized and tempered plates, which provide the best combination of strength, toughness, and weathering performance. | Property | Value / Description | | :--- | :--- | | **Tensile Strength** | **620 - 795 MPa (90,000 - 115,000 psi)** | | **Yield Strength (min)** | **485 MPa (70,000 psi)** | | **Elongation in 2-in (50 mm) (min)** | 18% | | **Modulus of Elasticity** | ~200 GPa (29 x 10⁶ psi) | | **Density** | ~7.85 g/cm³ (0.284 lb/in³) | | **Charpy V-Notch Impact Toughness** | **Test Temperature:** Often specified for critical structures at **0°F (-18°C)** or **-40°F (-40°C)** via supplementary requirements. **Minimum Avg. Energy:** Typically ≥ 20 ft-lbf (27 J) at the specified temperature, ensuring good fracture resistance. | | **Atmospheric Corrosion Resistance** | **6-8 times** greater than plain carbon steel. Engineered for excellent performance in severe marine and industrial atmospheres. | | **Brinell Hardness (typical)** | 210 - 250 HBW (Normalized condition) | --- ## **Product Applications** Class 3 is specified for landmark, long-span, or critical infrastructure projects where its premium performance justifies the investment, often in aggressive environments or where architectural expression is key. **Primary Structural Applications:** 1. **Signature & Long-Span Bridges:** * **Main cables, towers, and girders** of major cable-stayed and suspension bridges. * **Arch ribs** and **primary truss members** in iconic bridge designs. 2. **High-Profile Architecture:** * **Exposed structural systems** for museums, stadiums, and concert halls. * **Facade support systems** and **long-span cantilevers**. 3. **Critical & Severe Environment Infrastructure:** * **Offshore platform topsides** (in splash zone and above). * **Power plant structural components** in coastal locations. * **Transmission towers** in highly corrosive industrial or coastal zones. 4. **Specialized Engineering:** * **Large-scale public art** and **monuments**. * **Specialty transportation and marine structures**. --- ## **Advantages and Critical Fabrication & Design Considerations** * **Advantages:** * **Optimal Strength-Corrosion Resistance Balance:** 70 ksi yield strength with top-tier weathering performance. * **Exceptional Durability in Aggressive Environments:** Enhanced Cr, Ni, and optional Mo content provide superior resistance to coastal salt spray and industrial pollutants. * **Lifecycle Cost Effectiveness:** Eliminates perpetual painting cycles, offering tremendous savings over a 50-100 year service life. * **Architectural Prestige:** Provides a unique, evolving aesthetic that signifies permanence and quality. * **Critical Fabrication & Design Considerations:** * **Advanced Welding Protocols Required:** Higher alloy content and strength level demand **stringent low-hydrogen procedures** with qualified WPS. Matching or overmatching weathering-grade filler metals (e.g., AWS E10018-W) are essential. Preheat and interpass temperature control are mandatory. * **Non-Standard Heat Treatment:** Supplied in normalized condition; any post-fabrication thermal cutting or heating must be controlled to avoid degrading the optimized microstructure. * **Ultra-Critical Detailing:** **Design for complete drainage is non-negotiable.** Every detail must prevent water entrapment. Use of seal welds, continuous welds (over stitch welds), and designed drip edges is standard. * **Comprehensive Runoff Management:** The initial staining period may be more pronounced due to higher alloy content. Integrated runoff collection systems or deliberate staining zones are often part of the architectural design. * **Material Compatibility:** Fasteners and connections must use weathering steel or suitably isolated corrosion-resistant alloys to prevent galvanic corrosion. * **Not for Immersion or Constant Wetness:** The patina requires wet/dry cycles to stabilize and protect. Permanently wet or buried sections require alternative protection. * **Higher Initial Cost:** The premium alloy content and processing result in a higher material cost, which must be evaluated against lifecycle savings and project requirements. **In summary, ASTM A782 Class 3 is the pinnacle of commercially available weathering steels, engineered for the most ambitious and exposed structural projects. It delivers 70 ksi minimum yield strength and exceptional atmospheric corrosion resistance, making it ideal for iconic bridges, buildings, and infrastructure in challenging environments. Its successful implementation requires a collaborative approach from the outset, involving materials engineers, fabricators, and architects who understand and respect its sophisticated behavior and detailing requirements.** -:- For detailed product information, please contact sales. -: ASTM A782 Low Alloy Steel, Class 3 Specification Dimensions Size： Diameter 20-1000 mm Length <4539 mm Size:We can customized as required Standard： Per your request or drawing We can customized as required Properties（Theoretical） Chemical Composition -:- For detailed product information, please contact sales. -: ASTM A782 Low Alloy Steel, Class 3 Properties -:- For detailed product information, please contact sales. -:

Applications of ASTM A782 Low Alloy Steel Flange, Class 3 -:- For detailed product information, please contact sales. -: Chemical Identifiers ASTM A782 Low Alloy Steel Flange, Class 3 -:- For detailed product information, please contact sales. -:

Packing of ASTM A782 Low Alloy Steel Flange, Class 3 -:- For detailed product information, please contact sales. -: Standard Packing: -:- For detailed product information, please contact sales. -: Typical bulk packaging includes palletized plastic 5 gallon/25 kg. pails, fiber and Steel Flange drums to 1 ton super sacks in full container (FCL) or truck load (T/L) quantities. Research and sample quantities and hygroscopic, oxidizing or other air sensitive materials may be packaged under argon or vacuum. Solutions are packaged in polypropylene, plastic or glass jars up to palletized 1010 gallon liquid totes Special package is available on request. E FORUs’ is carefully handled to minimize damage during storage and transportation and to preserve the quality of our products in their original condition