ASTM A736 Low Alloy Steel Flange, Grade A, 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 A736 Low Alloy Steel Flange, Grade A, Class 3 Product Information -:- For detailed product information, please contact sales. -: ASTM A736 Low Alloy Steel Flange, Grade A, Class 3 Synonyms -:- For detailed product information, please contact sales. -:

ASTM A736 Low Alloy Steel, Grade A, Class 3 Product Information -:- For detailed product information, please contact sales. -: # **Product Introduction: ASTM A736/A736M Grade A, Class 3 High-Performance Low-Alloy Steel** **ASTM A736/A736M Grade A, Class 3** is the premier grade within the ASTM A736 specification, representing an advanced **precipitation-strengthened, low-carbon alloy steel** engineered for the most demanding pressure vessel and structural applications. This material delivers an exceptional balance of **ultra-high strength, superior toughness, and excellent weldability** through a sophisticated **nickel-copper-chromium-molybdenum-niobium alloy system** combined with optimized **normalizing and tempering or quenching and tempering heat treatments**. Class 3 is distinguished by its enhanced property requirements, typically including **higher minimum yield strength and more stringent impact toughness criteria** than Classes 1 and 2, making it ideal for critical applications in power generation, petrochemical processing, and advanced energy systems. --- ## **International Standard & Key Specifications** * **Primary Standard:** **ASTM A736/A736M** - Standard Specification for Pressure Vessel Plates, Low-Carbon Age-Hardening Nickel-Copper-Chromium-Molybdenum-Columbium Alloy Steel. * **Classification:** Within Grade A, **Class 3 denotes the highest performance tier**, with specific requirements for enhanced toughness, strength, or resistance to temper embrittlement. * **ASME Code Equivalent:** **SA-736/SA-736M** in ASME Boiler and Pressure Vessel Code, Section II, Part A. Mandatory for ASME-stamped pressure equipment. * **Governing Standard:** **ASTM A20/A20M** - Standard Specification for General Requirements for Steel Plates for Pressure Vessels. * **Design Philosophy:** Achieves premium mechanical properties through a combination of ultra-low carbon content and precipitation hardening, enabling lightweight, high-efficiency designs for demanding service conditions. --- ## **Chemical Composition (Weight %, max unless range is specified)** The composition for Class 3 follows the Grade A ranges but is typically produced with tighter controls and optimized balances to achieve the highest performance levels. | Element | Composition Range (%) | Role in Performance for Class 3 | | :--- | :--- | :--- | | **Carbon (C)** | 0.07 max | **Extremely low** – Ensures outstanding weldability and base metal toughness; fundamental to the precipitation-hardening mechanism. | | **Manganese (Mn)** | 0.40 - 0.70 | Solid solution strengthener; typically optimized for best combination of strength and toughness. | | **Phosphorus (P)** | 0.025 max | Impurity – Maintained at minimal levels to prevent temper embrittlement. | | **Sulfur (S)** | 0.025 max | Impurity – Tightly controlled to ensure optimal weldability and ductility. | | **Silicon (Si)** | 0.15 - 0.50 | Deoxidizer; controlled to avoid excessive hardening in the heat-affected zone (HAZ). | | **Nickel (Ni)** | 0.70 - 1.00 | Enhances toughness and hardenability; critical for microstructural stability and low-temperature performance. | | **Chromium (Cr)** | 0.40 - 0.65 | Improves hardenability and provides moderate oxidation resistance. | | **Molybdenum (Mo)** | 0.20 - 0.30 | **Critical element** – Provides solid solution strengthening, improves elevated temperature strength, and significantly reduces susceptibility to temper embrittlement. | | **Copper (Cu)** | 1.00 - 1.30 | **Primary precipitation-hardening element** – Forms fine, coherent Cu-rich precipitates during aging/tempering, providing substantial strength increase. | | **Columbium (Cb/Nb)** | 0.02 - 0.10 | **Key microalloy** – Provides grain refinement through Nb(CN) precipitates and contributes to precipitation strengthening; controls austenite grain growth during heat treatment. | | **Vanadium (V)** | 0.03 - 0.08 | Secondary precipitation strengthener; complements Nb's effect. | | **Aluminum (Al)** | 0.06 max | Grain refining deoxidizer. | --- ## **Typical Physical & Mechanical Properties (Grade A, Class 3)** Class 3 properties represent the peak performance achievable within the Grade A specification, typically requiring quenching and tempering heat treatment. | Property | Value / Description | | :--- | :--- | | **Tensile Strength** | 725 - 895 MPa (105,000 - 130,000 psi) | | **Yield Strength (min)** | **620 MPa (90,000 psi)** | | **Elongation in 2-in (50 mm) (min)** | 18% | | **Reduction of Area (min)** | 50% | | **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:** **-75°F (-60°C)**. **Minimum Avg. for 3 Specimens:** **40 ft·lbf (54 J)**. **Minimum Single Value:** Typically 30 ft·lbf (41 J). | | **Brinell Hardness (typical)** | 240 - 300 HBW | | **Elevated Temperature Yield Strength** | Maintains a high percentage of room temperature strength up to 650°F (345°C), superior to conventional HSLA steels. | --- ## **Product Applications** ASTM A736 Grade A, Class 3 is specified for the most critical applications where the highest levels of strength, toughness, and reliability are required, often in demanding environments. **Primary Industries and Equipment:** 1. **Advanced Power Generation:** * **Components for Supercritical and Ultra-Supercritical Steam Cycles**, such as high-pressure feedwater heaters and steam drums. * **Nuclear Power Plant Components** (where approved by applicable codes and standards). * **Hydrogen Coolers and High-Pressure Casing** in turbine-generator systems. 2. **Petrochemical & Refining:** * **High-Pressure Hydroprocessing Reactors** (hydrocrackers, hydrotreaters) for severe hydrogen service. * **Thick-Walled Pressure Vessels** in ethylene and methanol plants. * **Critical Heat Exchangers** in refining and chemical processes. 3. **Energy Transition Infrastructure:** * **Pressure Vessels for Hydrogen Storage and Transportation** (including tube trailers and stationary storage). * **Components in Carbon Capture, Utilization, and Storage (CCUS) Systems**. * **Geothermal Energy Systems** requiring high strength and corrosion resistance. 4. **High-Performance Engineering:** * **Lightweight Pressure Vessels for Aerospace and Defense Applications**. * **Specialized Equipment for Offshore and Subsea Operations**. --- ## **Advantages and Critical Fabrication Considerations** * **Advantages:** * **Premium Strength-Toughness Combination:** 90 ksi minimum yield strength with excellent impact toughness at low temperatures. * **Excellent Resistance to Temper Embrittlement:** Optimized alloy content, particularly molybdenum, ensures long-term toughness stability. * **Superior Weldability for its Strength Class:** The ultra-low carbon content results in a very low carbon equivalent, minimizing the risk of hydrogen-induced cracking. * **Outstanding Strength-to-Weight Ratio:** Enables significant weight reduction in pressure vessel designs, reducing material and transportation costs. * **Critical Fabrication & Welding Considerations:** * **Precise Heat Treatment Control:** Final properties are highly sensitive to tempering/aging parameters. Any deviation can significantly affect mechanical properties. * **Stringent Welding Requirements:** **Mandatory use of ultra-low hydrogen welding processes** with strict control of heat input. Welding consumables must be carefully selected to match both strength and toughness. * **Comprehensive Procedure Qualification:** Welding Procedure Specifications (WPS) must be rigorously qualified, including extensive mechanical testing (tensile, bend, impact) of weld metal and HAZ. * **Strict Preheat and Interpass Temperature Control:** Typically 250°F-400°F (120°C-205°C) depending on thickness, with continuous monitoring. * **Post-Weld Heat Treatment (PWHT):** Essential for stress relief but must be carefully controlled to avoid over-aging. PWHT parameters should be developed in consultation with material specialists. * **Advanced Non-Destructive Testing (NDT):** Typically requires 100% radiographic (RT) or ultrasonic testing (UT) of all welds, with additional examination of critical areas as specified. **In summary, ASTM A736 Grade A, Class 3 represents the pinnacle of precipitation-hardened low-alloy steels for pressure vessel applications. Its combination of ultra-high strength (90 ksi min yield), superior toughness at low temperatures, and excellent weldability makes it a material of choice for the most demanding applications in the energy and processing industries. However, its successful implementation requires sophisticated metallurgical knowledge, precise heat treatment control, and meticulous fabrication practices throughout the manufacturing process.** -:- For detailed product information, please contact sales. -: ASTM A736 Low Alloy Steel, Grade A, Class 3 Specification Dimensions Size： Diameter 20-1000 mm Length <4529 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 A736 Low Alloy Steel, Grade A, Class 3 Properties -:- For detailed product information, please contact sales. -:

Applications of ASTM A736 Low Alloy Steel Flange, Grade A, Class 3 -:- For detailed product information, please contact sales. -: Chemical Identifiers ASTM A736 Low Alloy Steel Flange, Grade A, Class 3 -:- For detailed product information, please contact sales. -:

Packing of ASTM A736 Low Alloy Steel Flange, Grade A, 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 1000 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