ASME B16.47 Blind Flange

1. Standard Overview
ASME B16.47 is a standard issued by the American Society of Mechanical Engineers (ASME), and its full name is "Large Diameter Steel Flanges (NPS 26 to NPS 60)". This standard covers two types of large diameter steel pipe flanges, namely Series A (mainly in English units) and Series B (using metric units), providing the industry with specifications for the design, manufacture and use of flanges in large-diameter pipeline systems. The ASME B16.47 blind flange is a flange product for closing the end of the pipeline produced based on this standard.
2. Structural Features
Appearance: The blind flange is a solid disc with no center hole for fluid to pass through. Its outer diameter is usually consistent with other types of flanges of the same specification (such as butt welding flanges, flat welding flanges, etc.) so that it can be matched with them.
Sealing surface: Common sealing surface forms include raised face (RF), ring joint surface (RTJ), etc. The raised face sealing surface is an annular area that is higher than the plane of the flange body. It needs to be used with a gasket during installation. The gasket is deformed by bolting to achieve sealing; the ring connection surface is specially designed to cooperate with the metal ring gasket, with better sealing performance, suitable for harsh working conditions such as high pressure and high temperature.
Bolt holes: There are several bolt holes evenly distributed on the circumference. The number, diameter and spacing are strictly in accordance with the ASME B16.47 standard to ensure correct connection with the matching flange and ensure sufficient connection strength and sealing.
3. Material selection
Carbon steel: such as ASTM A105, has good strength and toughness, relatively low cost, suitable for general industrial piping systems, and can withstand certain pressures and temperatures.
Alloy steel: Like ASTM A350 LF2, alloy elements are added to make it have better performance in strength and low temperature resistance. It is often used in low temperature environments or piping systems with high strength requirements.
Stainless steel: such as ASTM A182 F304, F316, etc., have excellent corrosion resistance and are widely used in industries such as chemical, food, and pharmaceutical industries that have high requirements for medium purity and corrosion resistance.
4. Pressure-temperature ratings
The ASME B16.47 standard specifies in detail the pressure bearing capacity of blind flanges at different materials and temperatures. For example, for a blind flange of a certain material, it may be allowed to withstand higher pressures at room temperature, but as the temperature rises, its allowable working pressure will decrease accordingly. This is because the mechanical properties of the material will change with temperature, and these ratings must be strictly followed during design and use to ensure the safe operation of the pipeline system.
5. Manufacturing and inspection
Manufacturing process: Generally, flange blanks are produced through forging, rolling and other processes, and then mechanical processing such as turning, drilling, milling, etc. is performed to achieve the dimensional accuracy and surface quality required by the standard.
Inspection items:
Dimensional inspection: Use measuring tools to accurately measure the outer diameter, inner diameter, thickness, bolt hole diameter and spacing of the flange to ensure that it meets the standard tolerance requirements.
Material inspection: Use spectral analysis and other methods to determine whether the chemical composition of the material meets the requirements; perform tensile tests, hardness tests, etc. to test the mechanical properties of the material.
Nondestructive testing: Use ultrasonic testing (UT), magnetic particle testing (MT), radiographic testing (RT) and other methods to check whether there are cracks, pores and other defects inside the flange.
6. Application scenarios
Oil and gas industry: Used for isolation, inspection and maintenance of pipeline systems during oil and gas extraction, transportation and processing. For example, when a section of pipeline is modified or repaired, a blind flange is installed to isolate it from other parts to prevent oil and gas leakage and ensure operational safety.
Chemical industry: In various chemical production devices, it is used to isolate different process units and prevent different media from mixing with each other. For example, a blind flange is installed between the reactor and the pipeline to facilitate cleaning, inspection or replacement of the catalyst of the reactor.
Power industry: In steam pipes, water supply pipes and other systems in power plants, it is used to temporarily or permanently block the ends of pipelines. For example, when a pipeline is subjected to a water pressure test, a blind flange is used to close the pipeline in order to accurately measure the pressure resistance of the pipeline.