Siku 45°, 90° Siku, and 180° elbow are PIPA FITTING used to change the direction of a piping system. These fittings are widely used in various industries, seperti minyak dan gas, petrokimia, pembangkit listrik, pengolahan air, and many more. This article discusses the differences between these elbow fittings, focusing on long radius (LR) and short radius (SR) siku.
1. Angle of the elbow
The most obvious difference among the three types of elbows is the angle they create:
- 45° Siku: Changes the direction of the pipeline by 45 derajat.
- 90° Siku: Changes the direction of the pipeline by 90 derajat, making a right-angle turn.
- 180° Siku: Changes the direction of the pipeline by 180 derajat, creating a U-turn or complete reversal of flow direction.
2. Long Radius (LR) vs. Radius pendek (SR) siku
Another key distinction between elbow fittings is the radius of curvature, which determines the space required for installation and the pressure drop across the fitting:
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Long Radius (LR) siku: These elbows have a center-to-end distance equal to 1.5 kali ukuran pipa nominal (NPS) or the outside diameter (OD) of the pipe. LR elbows offer less resistance to fluid flow and consequently produce lower pressure drop, making them suitable for low-pressure systems or applications with strict pressure limitations.
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Radius pendek (SR) siku: These elbows have a center-to-end distance equal to the nominal pipe size (NPS) or the outside diameter (OD) of the pipe. SR elbows have a tighter curve compared to LR elbows, resulting in a higher pressure drop. They are typically used in tight spaces or applications where space constraints are critical.
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Siku dibagi menjadi dua kelompok yang mendefinisikan jarak lebih dari yang mereka mengubah arah; garis tengah dari ujung satu ke ujung yang berlawanan wajah. This is known as the center to face distance and is equivalent to the radius through which the elbow is bent.
The center to face distance for a long radius elbow, disingkat LR selalu 1.1/2 x Nominal Pipe Size (NPS) (1.1/2D), while the center to face distance for a short radius elbow, disingkat SR bahkan untuk ukuran pipa nominal.Berikut di bawah ini, Misalnya, anda akan menemukan
pusat untuk wajah jarak NPS 2 siku
(yang A jarak pada gambar)1. 90°-LR.. = 1.1/2 X 2(NPS) X 25.4 A=76,2 mm
2. 180°-LR.. = 2 kali siku 90° LR A=152,4mm
3. 90°-SR.. = 2(NPS) X 25.4 A=50,8 mm
4. 180°-SR.. = 2 kali siku 90° SR A=101,6 mm
3D siku sebagai contoh, are calculated with..
3(D) X 2(NPS) X 25.4
3. Flow characteristics
The angle and radius of an elbow fitting can significantly affect the flow characteristics within a sistem perpipaan:
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45° elbows: These elbows cause the least disturbance to the flow and thus generate the lowest pressure drop among the three types. They are often used for gradual changes in direction or in combination with other elbow fittings to achieve a specific angle.
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90° LR elbows: Offering a smoother flow path than SR elbows, LR elbows cause a lower pressure drop and are preferred in applications where maintaining flow characteristics is important.
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90° SR elbows: Due to their tighter bend, SR elbows generate a higher pressure drop and are more likely to cause turbulent flow, which may lead to increased erosion, vibration, or noise in the piping system.
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180° elbows: These fittings cause the greatest disruption to the flow, as they force the fluid to reverse direction completely. namun, they are essential in specific applications where a complete change in flow direction is required.
4. Aplikasi
Each type of elbow fitting is suited for different applications based on their angle and radius:
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45° elbows: Typically used in applications where a moderate change in direction is needed, such as water and wastewater treatment, Pemrosesan kimia, and power generation.
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90° LR elbows: Commonly used in applications where a right-angle turn is required, and pressure drop is a concern, seperti minyak dan gas, petrokimia, and process industries.
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90° SR elbows: Suitable for space-constrained applications or where a right-angle turn is required, and pressure drop is not a significant concern.
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180° elbows: Often used in applications where a complete reversal in flow direction is necessary, such as process industries, Penukar Panas, and cooling systems.
5. Material and manufacturing
Elbow fittings are made from various materials, termasuk baja karbon, Stainless Steel, Paduan baja, dan banyak lagi, depending on the requirements of the specific application. The manufacturing process for these fittings typically involves forging, casting, atau pengelasan.
6. Standar and specifications
Elbow fittings are manufactured according to various international standards, seperti ASME B16.9 (for factory-made wrought buttwelding fittings), ASME B16.11 (for forged fittings), and ASME B16.28 (for wrought steel buttwelding short radius elbows and returns). These standards define the dimensions, toleransi, penilaian, and material requirements for elbows.
Kesimpulannya, 45°, 90°, and 180° elbows differ in their angle and radius, which affects the flow characteristics, pressure drop, dan space requirements dari sistem perpipaan. These differences make each type of elbow fitting suitable for specific applications, industries, and conditions. It is essential to select the appropriate elbow fitting based on the requirements of the system to ensure optimal performance, keandalan, and safety.
45° Siku
Fungsi siku 45° sama dengan siku 90°, tapi pengukuran dimensi berbeda dengan yang ada pada 90° siku.
Radius 45° siku adalah sama dengan radius dari 90° LR (1.1/2D). namun, pusat untuk wajah dimensi tidak sama dengan jari-jari seperti pada 90° siku LR. Ini diukur dari wajah masing-masing ke titik persimpangan dari garis tengah yang tegak lurus satu sama lain, jarak B pada gambar. Hal ini disebabkan tingkat yang lebih kecil dari tikungan. Short radius 45° siku tidak tersedia.
Wall Thickness of Elbows
The weakest point on an elbow is the inside radius. ASME B16.9 only standardizes the center to face dimensions and some squareness dimensional tolerances. The wall thickness at the weld line location even is standardized, but not through the rest of an elbow. The standard states that the minimum tolerance will be within 12.5% of the minimum ordered wall thickness of the pipe. A maximum tolerance is specified only at the ends of the fitting.
Many providers of buttweld elbows (and tees) provide one schedule greater thickness so that sufficient wall thickness, after forming, remains.
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