ASTM A735 Low Alloy Steel Seamless tube, Class 3

ASTM A735 Low Alloy Steel Seamless tube, Class 3 Product Information -:- For detailed product information, please contact sales. -: ASTM A735 Low Alloy Steel Seamless tube, 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 Seamless tube, Class 3 -:- For detailed product information, please contact sales. -: Chemical Identifiers ASTM A735 Low Alloy Steel Seamless tube, Class 3 -:- For detailed product information, please contact sales. -:

Packing of ASTM A735 Low Alloy Steel Seamless tube, 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 Seamless tube 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