ASTM A735 Low Alloy Steel Capillary, Class 1

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

Packing of ASTM A735 Low Alloy Steel Capillary, 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 Capillary 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