ASTM A387 Alloy Steel Flange, Grade 91

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 A387 Alloy Steel Flange, Grade 91 Product Information -:- For detailed product information, please contact sales. -: ASTM A387 Alloy Steel Flange, Grade 91 Synonyms -:- For detailed product information, please contact sales. -:

ASTM A387 Alloy Steel, Grade 91 Product Information -:- For detailed product information, please contact sales. -: ### **Product Introduction: ASTM A387/A387M Alloy Steel, Grade 91** **1. Overview** ASTM A387 Grade 91 is a high-strength chromium-molybdenum-vanadium alloy steel plate designed for service in welded pressure vessels and other high-temperature applications. It is a creep-strength enhanced ferritic (CSEF) steel, offering significantly superior mechanical properties and creep resistance at elevated temperatures (up to ~600°C / 1112°F) compared to traditional Cr-Mo grades like Grade 22 or Grade 5. Its development allows for the design of thinner-walled, more efficient pressure vessels and components in critical service. **2. Key International Standards** * **Primary Standard:** **ASTM A387/A387M** - Standard Specification for Pressure Vessel Plates, Alloy Steel, Chromium-Molybdenum. * This standard covers the chemical, mechanical, and mandatory heat treatment requirements. * **Dimensional & General Requirements:** * **ASTM A20/A20M** - Standard Specification for General Requirements for Steel Plates for Pressure Vessels. * **Equivalent Standards:** * **EN / DIN:** X10CrMoVNb9-1 (Material No. 1.4903) * **JIS:** SCMV 29 (Not an exact equivalent, but similar application) * **ASME:** SA-387 Gr. 91 (The ASME code case version for boiler and pressure vessel construction). **3. Chemical Composition (Weight %)** The composition of Grade 91 is precisely controlled, with microalloying elements like Vanadium, Niobium, and Nitrogen being critical for its enhanced strength. | Element | Composition (%) | | :--- | :--- | | Carbon (C) | 0.08 - 0.12 | | Manganese (Mn) | 0.30 - 0.60 | | Phosphorus (P), max | 0.020 | | Sulfur (S), max | 0.010 | | Silicon (Si) | 0.20 - 0.50 | | Chromium (Cr) | 8.00 - 9.50 | | Molybdenum (Mo) | 0.85 - 1.05 | | Vanadium (V) | 0.18 - 0.25 | | Niobium (Nb) | 0.06 - 0.10 | | Nitrogen (N) | 0.03 - 0.07 | | Nickel (Ni), max | 0.40 | | **Chromium Equivalent** | **~8.5** | | **Nickel Equivalent** | **~0.5** | *Note: The balance between these elements is crucial for achieving the desired tempered martensite microstructure and precipitation strengthening.* **4. Mechanical & Physical Properties** Grade 91 is **mandatorily supplied in the Normalized and Tempered condition**. The typical normalizing temperature is 1040-1080°C (1904-1976°F) followed by air cooling, and tempering at 730-780°C (1346-1436°F). **Mechanical Properties (at room temperature):** | Property | Value | | :--- | :--- | | Tensile Strength | 585 - 760 MPa (85 - 110 ksi) | | Yield Strength (min) | 415 MPa (60 ksi) | | Elongation in 2 in. (50 mm), (min) | 20% | | **Hardness (typical)** | **~190-250 HB** | **Approximate Physical Properties:** * **Density:** 7.73 g/cm³ (0.279 lb/in³) * **Melting Point:** ~ 1470 - 1510 °C (2678 - 2750 °F) * **Modulus of Elasticity:** 200 GPa (29 x 10⁶ psi) at 20°C * **Thermal Conductivity:** ~ 26.0 W/m·K (at 100°C) * **Coefficient of Thermal Expansion:** ~ 11.5 x 10⁻⁶ /K (20-100°C) * **Poisson's Ratio:** 0.27 - 0.30 *Note: Physical properties, especially modulus of elasticity and thermal conductivity, change significantly with temperature and must be used from validated high-temperature data sheets for design.* **5. Product Applications** ASTM A387 Gr. 91 is used in the most demanding high-temperature and high-pressure applications across the energy sector. Its primary use is where superior creep strength allows for significant weight and wall thickness reduction. * **Power Generation:** Superheater and reheater headers, main steam pipelines, high-temperature turbines, and boilers in ultra-supercritical (USC) power plants. * **Petroleum Refining:** Hydroprocessing reactors (especially in severe service), high-pressure heat exchangers, and transfer lines. * **Chemical & Petrochemical:** High-temperature reactors and vessels where creep deformation is a design-limiting factor. **6. Key Characteristics & Advantages** * **Exceptional Creep Strength:** Offers the highest allowable stress values among Cr-Mo steels at temperatures above 500°C (932°F), enabling more efficient, thinner-walled designs. * **High-Temperature Oxidation Resistance:** The 9% Chromium content provides good resistance to scaling and oxidation in steam and flue gas environments. * **Thermal Fatigue Resistance:** Good resistance to damage from thermal cycling due to its lower thermal expansion coefficient and high thermal conductivity compared to austenitic stainless steels. * **Critical Fabrication Consideration - Weldability:** While weldable, Grade 91 requires strict control. It is essential to use matching filler metals (e.g., ER90S-B9, E9015-B9), mandatory pre-heating (200-300°C), and a strict Post-Weld Heat Treatment (PWHT) at ~760°C to achieve the required tempered martensite structure and avoid premature failure in service. In summary, **ASTM A387 Grade 91** is a premier creep-strength enhanced ferritic steel that is a cornerstone material for modern, high-efficiency power generation and high-pressure petrochemical equipment, offering an optimal balance of high-temperature strength and fabricability. -:- For detailed product information, please contact sales. -: ASTM A387 Alloy Steel, Grade 91 Specification Dimensions Size： Diameter 20-1000 mm Length <4376 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 A387 Alloy Steel, Grade 91 Properties -:- For detailed product information, please contact sales. -:

Applications of ASTM A387 Alloy Steel Flange, Grade 91 -:- For detailed product information, please contact sales. -: Chemical Identifiers ASTM A387 Alloy Steel Flange, Grade 91 -:- For detailed product information, please contact sales. -:

Packing of ASTM A387 Alloy Steel Flange, Grade 91 -:- 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 847 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