ASTM A735 Low Alloy Steel Flange, Class 1

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 1 Product Information -:- For detailed product information, please contact sales. -: ASTM A735 Low Alloy Steel Flange, Class 1 Synonyms -:- For detailed product information, please contact sales. -:

ASTM A735 Low Alloy Steel, Class 1 Product Information -:- For detailed product information, please contact sales. -: # **Product Introduction: ASTM A735/A735M Class 1 Low-Alloy Steel for Pressure Vessels** **ASTM A735/A735M Class 1** is a specialized **fine-grained, low-carbon nickel alloy steel** specifically engineered for **welded pressure vessels requiring exceptional toughness at extremely low temperatures**. Its primary application is in cryogenic service, where it provides outstanding resistance to brittle fracture. The steel achieves its superior properties through a combination of **normalizing and tempering heat treatments**, which refine the grain structure and optimize the balance of strength and ductility. Class 1 is characterized by a **moderate nickel content** that significantly enhances low-temperature impact properties, making it a reliable and cost-effective choice for critical containment systems operating well below ambient temperatures. --- ## **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. * **Important Note:** The title of the standard includes "Manganese-Molybdenum-Columbium," but the specification explicitly covers **nickel-alloyed grades (Classes 1, 2, 3)**. Class 1, 2, and 3 are defined by their nickel content. Class 1 contains the lowest nickel level of these grades. * **ASME Code Equivalent:** **SA-735/SA-735M** in ASME Boiler and Pressure Vessel Code, Section II, Part A. This is the mandatory specification for ASME-stamped pressure equipment fabrication. * **Governing Standard:** **ASTM A20/A20M** - Standard Specification for General Requirements for Steel Plates for Pressure Vessels. Governs testing, inspection, and certification procedures. --- ## **Chemical Composition (Weight %, max unless range is specified)** The composition for Class 1 is designed to provide good weldability and the necessary hardenability for normalizing, with nickel as the key alloying element for low-temperature 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)** | **0.40 - 1.06** | **Defining element for Class 1.** Significantly improves low-temperature toughness and strength. | | **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 Distinction:** 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** Plates are supplied in the **normalized and tempered (N&T) condition**. The normalizing process produces a fine, uniform grain size, which is then tempered to achieve the optimal balance of properties. | Property | Value / Description | | :--- | :--- | | **Tensile Strength** | 450 - 585 MPa (65,300 - 84,900 psi) | | **Yield Strength (min)** | **310 MPa (45,000 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:** **-75°F (-60°C)**. **Minimum Avg. for 3 Specimens:** **20 ft·lbf (27 J)**. This is a critical performance criterion for its designated low-temperature service. | | **Brinell Hardness (typical)** | 170 - 220 HBW | --- ## **Product Applications** ASTM A735 Class 1 is designed for pressure vessels and structural components that operate at moderately low to very low temperatures, particularly where notch toughness is a primary design concern. **Primary Industries and Equipment:** 1. **Cryogenic Storage & Processing:** * **Storage Tanks** for liquefied gases such as **carbon dioxide (CO2)**, liquid ammonia, and certain refrigerants. * **Process Vessels** in gas separation and petrochemical plants operating at sub-zero temperatures. 2. **Petrochemical Industry:** * **Separators, Scrubbers, and Knock-Out Drums** in low-temperature gas processing streams. * **Heat Exchanger Shells** for cooling services. 3. **Industrial Gases:** * **Storage Vessels** for industrial gases where temperatures may dip below -50°F (-45°C). * **Cryogenic Equipment Components** not requiring the extreme toughness of higher-nickel grades (like A735 Class 2 or 3). 4. **Power Generation:** * **Feedwater Heaters** and other vessels that may experience low temperatures during startup or upset conditions. --- ## **Advantages and Fabrication Considerations** * **Advantages:** * **Excellent Low-Temperature Toughness:** Guaranteed impact properties at -75°F (-60°C) make it suitable for a wide range of cryogenic applications. * **Good Weldability:** The low carbon content and moderate alloy levels result in a relatively low carbon equivalent (CE), facilitating welding with standard low-hydrogen practices. * **Fine-Grained Structure:** The normalized and tempered condition ensures a uniform, refined microstructure with consistent through-thickness properties. * **Cost-Effectiveness:** Provides better low-temperature performance than carbon steels at a lower cost than high-nickel alloys like 9% nickel steel. * **Critical Fabrication & Welding Considerations:** * **Welding Requirements:** **Use of low-hydrogen welding processes is mandatory** (e.g., SMAW with E7018, SAW, GMAW with appropriate gas shielding). Proper Welding Procedure Specifications (WPS) must be qualified. * **Preheat and Interpass Temperature:** Generally required, especially for thicker sections. Typical preheat is in the range of **150°F - 300°F (65°C - 150°C)** to prevent hydrogen cracking. * **Post-Weld Heat Treatment (PWHT):** Often required for pressure vessel fabrication to relieve residual stresses. The PWHT temperature must be below the original tempering temperature of the base plate to avoid overtempering. * **Thermal Cutting:** Preheating is recommended for flame cutting to prevent localized hardening. **In summary, ASTM A735 Class 1 is a reliable, fine-grained, nickel-alloyed steel plate supplied in the normalized and tempered condition. It offers an excellent combination of strength, weldability, and proven toughness down to -75°F, making it a preferred and economical material for a broad spectrum of low-temperature pressure vessels in the cryogenic, petrochemical, and industrial gas sectors.** -:- For detailed product information, please contact sales. -: ASTM A735 Low Alloy Steel, Class 1 Specification Dimensions Size： Diameter 20-1000 mm Length <4523 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 1 Properties -:- For detailed product information, please contact sales. -:

Applications of ASTM A735 Low Alloy Steel Flange, Class 1 -:- For detailed product information, please contact sales. -: Chemical Identifiers ASTM A735 Low Alloy Steel Flange, Class 1 -:- For detailed product information, please contact sales. -:

Packing of ASTM A735 Low Alloy Steel Flange, Class 1 -:- 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 994 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