ASTM A736 Low Alloy Steel Flange, Grade A, Class 2

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 2 Product Information -:- For detailed product information, please contact sales. -: ASTM A736 Low Alloy Steel Flange, Grade A, Class 2 Synonyms -:- For detailed product information, please contact sales. -:

ASTM A736 Low Alloy Steel, Grade A, Class 2 Product Information -:- For detailed product information, please contact sales. -: # **Product Introduction: ASTM A736/A736M Grade A, Class 2 Low-Alloy Steel for High-Strength Pressure Vessels** **ASTM A736/A736M Grade A, Class 2** is an advanced **precipitation-strengthened, high-strength low-alloy (HSLA) steel** specifically engineered for **welded pressure vessels requiring exceptional strength and toughness at elevated temperatures**. This grade represents a higher performance tier within the A736 specification, achieving its superior mechanical properties through a sophisticated **nickel-copper-chromium-molybdenum-columbium alloy system combined with precise heat treatment**. Supplied in the **normalized and tempered or quenched and tempered condition**, Class 2 is designed to maintain high yield strength while offering improved notch toughness and enhanced resistance to temper embrittlement compared to Class 1, making it suitable for more demanding service conditions. --- ## **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. * **Key Distinction:** Class 2 typically indicates **specific, more stringent requirements for toughness and/or elevated temperature properties** within Grade A, often achieved through optimized chemistry and heat treatment control. * **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:** Provides one of the highest strength-to-weight ratios among ASME-approved pressure vessel steels while maintaining good fabricability. --- ## **Chemical Composition (Weight %, max unless range is specified)** The chemistry for Class 2 is tightly controlled with optimized alloy balances to achieve enhanced properties. Note that while Grade A composition ranges are specified, Class 2 typically represents material produced to the optimal middle or upper ranges of these limits for superior performance. | Element | Composition Range (%) | Role in Performance for Class 2 | | :--- | :--- | :--- | | **Carbon (C)** | 0.07 max | **Extremely low** - Maximizes weldability and base toughness; essential for the precipitation-hardening mechanism. | | **Manganese (Mn)** | 0.40 - 0.70 | Solid solution strengthener; typically controlled toward the upper end for optimal hardenability. | | **Phosphorus (P)** | 0.025 max | Impurity - kept at absolute minimum to prevent temper embrittlement. | | **Sulfur (S)** | 0.025 max | Impurity - tightly controlled for weldability and ductility. | | **Silicon (Si)** | 0.15 - 0.50 | Deoxidizer; controlled to avoid excessive strength in HAZ. | | **Nickel (Ni)** | 0.70 - 1.00 | Enhances toughness and hardenability; critical for microstructural stability. | | **Chromium (Cr)** | 0.40 - 0.65 | Improves hardenability and provides oxidation resistance; balanced with Ni for optimal properties. | | **Molybdenum (Mo)** | 0.20 - 0.30 | **Key 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 coherent Cu-rich precipitates during aging/tempering; carefully balanced for optimal strengthening. | | **Columbium (Cb/Nb)** | 0.02 - 0.10 | **Critical microalloy** - Provides grain refinement and precipitation strengthening through Nb(CN) particles; essential for controlling the austenite grain size during heat treatment. | | **Vanadium (V)** | 0.03 - 0.08 | Secondary precipitation strengthener; complements Nb's effect. | | **Aluminum (Al)** | 0.06 max | Grain refining deoxidizer; controlled for consistent hardenability. | --- ## **Typical Physical & Mechanical Properties (Grade A, Class 2)** Properties represent material typically supplied in the quenched and tempered condition for optimal performance balance. | Property | Value / Description | Comparison to Class 1 | | :--- | :--- | :--- | | **Tensile Strength** | 690 - 860 MPa (100,000 - 125,000 psi) | Higher strength range | | **Yield Strength (min)** | **585 MPa (85,000 psi)** | **Higher minimum yield** | | **Elongation in 2-in (50 mm) (min)** | 18% | Similar | | **Reduction of Area (min)** | 45% | Typically higher | | **Modulus of Elasticity** | ~200 GPa (29 x 10⁶ psi) | Similar | | **Density** | ~7.85 g/cm³ (0.284 lb/in³) | Similar | | **Charpy V-Notch Impact Toughness** | **Test Temperature:** **-60°F (-50°C)**. **Minimum Avg.:** **35 ft·lbf (47 J)**. | **Higher toughness requirement** | | **Brinell Hardness** | 230 - 280 HBW | Higher due to increased strength | | **Elevated Temperature Yield Strength** | Maintains higher percentage of room temperature strength at 600°F (315°C) compared to conventional steels | **Key advantage over Class 1** | --- ## **Product Applications** ASTM A736 Grade A, Class 2 is specified for the most demanding pressure vessel applications where both exceptional strength and reliability under thermal cycling are critical. **Primary Industries and Equipment:** 1. **Power Generation (Fossil & Nuclear):** * **High-Pressure Feedwater Heaters** (especially for supercritical and ultra-supercritical plants) * **Steam Generators and Moisture Separator Reheaters (MSRs)** * **Nuclear Reactor Coolant System Components** (where approved by code) * **Hydrogen Coolers and High-Pressure Casing** 2. **Oil Refining & Petrochemical:** * **Hydrocracking and Hydrotreating Reactors** (for high-pressure hydrogen service) * **High-Pressure Heat Exchangers** in refinery and chemical processes * **Catalytic Reformer Reactors** 3. **Advanced Energy Systems:** * **Pressure Vessels for Hydrogen Storage and Transportation** * **Components in Carbon Capture and Storage (CCS) Systems** * **Geothermal Energy Systems** 4. **High-Performance Transportation:** * **Lightweight High-Pressure Vessels** for aerospace and defense applications * **Specialized Rail and Road Transport Tanks** for critical commodities --- ## **Advantages and Critical Fabrication Considerations** * **Advantages:** * **Exceptional Strength-Toughness Combination:** 85 ksi minimum yield strength with superior impact energy absorption * **Reduced Temper Embrittlement Susceptibility:** Optimized Mo content provides better resistance to long-term service embrittlement * **Good Elevated Temperature Properties:** Maintains strength better than conventional HSLA steels at moderate temperatures * **Excellent Strength-to-Weight Ratio:** Enables more efficient, thinner-walled designs for significant weight savings * **Critical Fabrication & Welding Considerations:** * **Precise Heat Treatment Control:** Properties are highly sensitive to tempering/aging parameters. Any deviation from specified heat treatment can significantly affect mechanical properties * **Advanced Welding Requirements:** **Mandatory use of ultra-low hydrogen processes** with strict controls on heat input. Welding consumables must be carefully selected to match both strength and toughness * **Comprehensive Procedure Qualification:** WPS qualification must include extensive mechanical testing, including impact tests at multiple locations (weld metal, HAZ, base metal) * **Strict Preheat/Interpass Control:** Typically 250°F-350°F (120°C-175°C) depending on thickness, with precise monitoring * **Post-Weld Heat Treatment (PWHT):** Essential but must be carefully controlled to avoid over-aging. PWHT parameters must be developed in consultation with material specialists * **Advanced NDT Requirements:** Typically requires 100% RT or UT of all welds plus additional examination of critical areas **In summary, ASTM A736 Grade A, Class 2 represents the premium tier of precipitation-hardened pressure vessel steels, offering an exceptional balance of ultra-high strength (85 ksi min yield), superior toughness, and enhanced resistance to service degradation. Its use enables breakthrough designs in weight-sensitive and high-performance applications across the energy sector, though it demands the highest levels of metallurgical expertise and fabrication control throughout the manufacturing process.** -:- For detailed product information, please contact sales. -: ASTM A736 Low Alloy Steel, Grade A, Class 2 Specification Dimensions Size： Diameter 20-1000 mm Length <4528 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 2 Properties -:- For detailed product information, please contact sales. -:

Applications of ASTM A736 Low Alloy Steel Flange, Grade A, Class 2 -:- For detailed product information, please contact sales. -: Chemical Identifiers ASTM A736 Low Alloy Steel Flange, Grade A, Class 2 -:- For detailed product information, please contact sales. -:

Packing of ASTM A736 Low Alloy Steel Flange, Grade A, Class 2 -:- 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 999 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