ASTM A735 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 A735 Low Alloy Steel Flange, Class 3 Product Information -:- For detailed product information, please contact sales. -: ASTM A735 Low Alloy Steel Flange, Class 3 Synonyms -:- For detailed product information, please contact sales. -:

ASTM A735 Low Alloy Steel, Class 3 Product Information -:- For detailed product information, please contact sales. -: # **Product Introduction: ASTM A735/A735M Class 2 Low-Alloy Steel for Cryogenic Pressure Vessels** **ASTM A735/A735M Class 2** is a specialized **low-carbon, nickel-alloy steel** designed for **welded pressure vessels operating at very low temperatures**. This grade is distinguished by its **intermediate nickel content**, which provides a superior balance of cost, strength, and cryogenic toughness. Plates are supplied in the **normalized and tempered (N&T) condition** to achieve a fine-grained microstructure essential for reliable performance in low-temperature environments. Class 2 serves as a critical material for applications demanding robust fracture resistance at temperatures down to **-120°F (-85°C)**, bridging the gap between lower-nickel steels and premium cryogenic alloys. --- ## **International Standard & Key Specifications** * **Primary Standard:** **ASTM A735/A735M** - Standard Specification for Pressure Vessel Plates, Low-Carbon Manganese-Molybdenum-Columbium Alloy Steel, for Moderate and Lower Temperature Service, Normalized and Tempered. * **Clarification:** Despite the title referencing Mn-Mo-Cb steels, this standard explicitly defines **Class 1, 2, and 3** based on their nickel content. Class 2 represents the mid-range nickel grade. * **ASME Code Equivalent:** **SA-735/SA-735M** in ASME Boiler and Pressure Vessel Code, Section II, Part A. This is the mandatory specification for fabricating ASME-stamped pressure equipment. * **Governing Standard:** **ASTM A20/A20M** - Standard Specification for General Requirements for Steel Plates for Pressure Vessels. This governs the common testing, inspection, and delivery requirements. --- ## **Chemical Composition (Weight %, max unless range is specified)** The composition is engineered to ensure excellent weldability and hardenability, with nickel as the primary alloying element for enhancing cryogenic toughness. | Element | Composition (%) | Role in Performance | | :--- | :--- | :--- | | **Carbon (C)** | 0.23 max | Kept low to maximize weldability and toughness. | | **Manganese (Mn)** | 0.80 - 1.40 | Provides solid solution strengthening and aids in grain refinement during normalizing. | | **Phosphorus (P)** | 0.035 max | Impurity, kept low for notch toughness. | | **Sulfur (S)** | 0.040 max | Impurity, controlled for weldability. | | **Silicon (Si)** | 0.15 - 0.50 | Deoxidizer and strengthener. | | **Nickel (Ni)** | **1.07 - 1.62** | **Defining element for Class 2.** Significantly improves low-temperature toughness and strength beyond Class 1 capabilities. | | **Molybdenum (Mo)** | 0.17 max (optional) | May be added to enhance strength and hardenability. | | **Columbium (Cb/Nb)** | 0.05 max (optional) | Powerful grain refiner; inhibits grain growth during normalizing to ensure a fine-grained microstructure. | | **Vanadium (V)** | 0.10 max (optional) | Alternative/complementary microalloy for grain refinement and precipitation strengthening. | **Key Constraint:** The combined total of Cb (Nb), V, and Mo shall not exceed **0.15%**. This controls the microalloying to optimize the normalized and tempered structure. --- ## **Typical Physical & Mechanical Properties** Properties are for normalized and tempered plates. The normalizing process produces a fine, uniform austenitic grain size, which upon tempering yields optimal toughness. | Property | Value / Description | | :--- | :--- | | **Tensile Strength** | 485 - 620 MPa (70,300 - 90,000 psi) | | **Yield Strength (min)** | **345 MPa (50,000 psi)** | | **Elongation in 2-in (50 mm) (min)** | 22% | | **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:** **-120°F (-85°C)**. **Minimum Avg. for 3 Specimens:** **20 ft·lbf (27 J)**. This is the critical performance criterion for cryogenic service. | | **Brinell Hardness (typical)** | 180 - 230 HBW | --- ## **Product Applications** ASTM A735 Class 2 is designed for pressure vessels and critical components that operate at very low temperatures, where notch toughness is paramount to prevent brittle fracture. **Primary Industries and Equipment:** 1. **Cryogenic Storage & Processing:** * **Storage Tanks** for liquefied ethylene (LEG), ethane, and certain lower-temperature refrigerants. * **Process Vessels** in ethylene and olefin production plants. * **Components** in natural gas processing and liquefaction facilities. 2. **Petrochemical Industry:** * **Low-Temperature Separators** and **Cryogenic Heat Exchangers**. * **Vessels** for handling liquefied petroleum gas (LPG) under cold conditions. 3. **Industrial Gases:** * **Storage Vessels** for industrial gases requiring service temperatures between -75°F and -150°F (-60°C to -100°C). * **Inner Casing** of vacuum-insulated containers for gases like argon and oxygen. 4. **Energy & Research:** * **Components** in hydrogen energy infrastructure (e.g., storage for certain hydrogen containment strategies). * **Vessels** for scientific and medical cryogenic applications. --- ## **Advantages and Fabrication Considerations** * **Advantages:** * **Excellent Cryogenic Toughness:** Guaranteed impact properties at -120°F (-85°C) make it suitable for severe low-temperature services. * **Good Strength-to-Cost Ratio:** Provides better low-temperature performance than carbon and lower-nickel steels at a more economical cost than 5% or 9% nickel steels. * **Fine-Grained Structure:** The normalized and tempered condition ensures a uniform, refined microstructure with consistent through-thickness properties and good notch toughness. * **Good Weldability:** The low carbon content and controlled alloying result in a manageable carbon equivalent, allowing for welding with established low-hydrogen procedures. * **Critical Fabrication & Welding Considerations:** * **Welding Requirements:** **Mandatory use of low-hydrogen welding processes** (e.g., SMAW with E7018 or E8018-C1, SAW, GTAW). Welding Procedure Specifications (WPS) must be rigorously qualified. * **Preheat and Interpass Temperature:** Essential to prevent hydrogen-induced cracking. Typical preheat is in the range of **200°F - 350°F (95°C - 175°C)** depending on plate thickness. * **Post-Weld Heat Treatment (PWHT):** Generally required for pressure vessel fabrication to relieve residual stresses. The PWHT temperature must be carefully controlled to remain below the original tempering temperature of the base plate. * **Thermal Cutting:** Preheating is strongly recommended for flame cutting. Machining or plasma cutting is often preferred for critical edges. * **Filler Metal Selection:** Must be compatible with the base metal's chemistry and strength. Nickel-alloyed filler metals (e.g., ENiCrMo-6 for SMAW) are often required to match the low-temperature toughness. **In summary, ASTM A735 Class 2 is a high-performance, nickel-alloyed steel plate supplied in the normalized and tempered condition. It offers a robust combination of strength and exceptional toughness down to -120°F, making it a vital and cost-effective material for pressure vessels in demanding cryogenic services within the petrochemical, industrial gas, and energy sectors.** -:- For detailed product information, please contact sales. -: ASTM A735 Low Alloy Steel, Class 3 Specification Dimensions Size： Diameter 20-1000 mm Length <4525 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 A735 Low Alloy Steel, Class 3 Properties -:- For detailed product information, please contact sales. -:

Applications of ASTM A735 Low Alloy Steel Flange, Class 3 -:- For detailed product information, please contact sales. -: Chemical Identifiers ASTM A735 Low Alloy Steel Flange, Class 3 -:- For detailed product information, please contact sales. -:

Packing of ASTM A735 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 996 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