In the Middle East, due to the booming development of its oil and gas industry, there are strict and industry-specific requirements for the size and pressure rating of American standard flanges.
1、 Size requirements
Pipeline adaptability
The oil and gas pipeline system in the Middle East is massive in scale. When connecting pipes of different diameters, the outer and inner diameters of American standard flanges must be accurately matched. For example, when connecting large-diameter crude oil pipelines (which may reach a diameter of over 30 inches), the outer diameter of the flange should be strictly manufactured according to ASME B16.5 or ASME B16.47 standards to ensure tight and seamless welding or bolt connections with the pipeline.
For some fine chemical pipelines, the diameter may be smaller (such as 2-6 inches), and higher precision is required for the thickness and aperture size of the flange. Because these pipelines often transport high-value, high-precision chemical products, small deviations in flange size may lead to leaks or unstable connections, affecting the entire process flow.
Layout and quantity of bolt holes
When installing flanges in the Middle East, specific requirements are placed on the layout and quantity of bolt holes, taking into account local environmental conditions such as high temperatures and sandstorms. In order to ensure the firmness of the flange connection, there are a large number of bolt holes on large-diameter flanges (such as those used for natural gas long-distance pipelines), and they are evenly distributed according to the standard circumference. For example, according to the ASME B16.5 standard, larger flanges may have 16-48 bolt holes, with precise specifications for the center circle diameter and spacing of these bolt holes to accommodate the installation of high-strength bolts and ensure that flange connections do not loosen under high pressure environments.
Meanwhile, for some flanges in offshore oil platform facilities, the size accuracy of bolt holes is higher due to the influence of dynamic loads such as waves and sea winds. The diameter tolerance is generally controlled within ± 0.5mm to ensure a tight fit between the bolt and the hole, preventing safety accidents caused by bolt loosening during equipment operation.
Sealing surface size
The size of flange sealing surfaces is crucial in the petroleum and chemical industries of the Middle East. For flanges with flat sealing surfaces (FF), the width of the sealing surface should meet the standard requirements, generally between 3-8mm, in order to ensure sufficient sealing contact area. When using metal gaskets, the flatness requirement for the sealing surface is extremely high, and the flatness error usually does not exceed 0.1mm to prevent medium leakage.
For flanges with raised face seals (RF), there are strict regulations on the height of the raised face. In ASME standards, the height of the protruding surface is generally between 1.6-2.4mm, and the surface roughness of the protruding surface should be controlled within an appropriate range (Ra is generally between 3.2-6.3 μ m) in order to fit well with the gasket and achieve ideal sealing effect, especially when transporting flammable and explosive oil and gas media. The accuracy of the sealing surface size is a key factor in ensuring safety.
2、 Pressure level requirements
Oil extraction field
In the process of oil extraction in the Middle East, the flange pressure rating used for wellhead equipment and downhole equipment is relatively high. For example, in deep well mining, due to the enormous pressure of the underground oil reservoir, which may reach thousands of pounds per square inch (psi), the American standard flange pressure rating used at this time is usually Class 1500 or higher. These flanges should be able to withstand high pressure from underground oil reservoirs, ensuring the safe operation of wellhead equipment and preventing accidents such as oil spills.
For the production facilities of offshore oil platforms, including crude oil separation, processing, and transportation systems, the pressure rating of flanges should also be determined according to specific process requirements. In some high-pressure separation equipment, the flange pressure rating may reach Class 2500, as these devices require effective separation and treatment of crude oil in high-pressure environments, and the flange must have sufficient strength and sealing to cope with high pressure differentials.
Natural gas transportation and processing field
The natural gas pipeline network in the Middle East is crisscrossing. In order to ensure efficient transportation of natural gas over long distances, the pressure inside the pipeline is relatively high. The pressure rating of American standard flanges is generally between Class 900 and Class 1500. For example, on pipelines connecting large natural gas compressor stations, the pressure rating of the flange should be at least Class 1500 in order to withstand the high pressure generated by the compressor during operation and ensure stable transportation of natural gas in the pipeline.
In natural gas liquefaction (LNG) plants, due to the low temperature and high pressure environment involved in the liquefaction process, the pressure rating requirements for flanges are higher. Here, American standard flanges may need to reach a pressure rating of Class 2500 or even higher to adapt to extreme pressure conditions during the production and storage of liquefied natural gas, prevent LNG leaks, and ensure the safety and normal operation of the factory.
