Un gomito a 45°, 90° Gomito, and 180° elbow are RACCORDI PER TUBI used to change the direction of a piping system. Questi raccordi sono ampiamente utilizzati in vari settori, come petrolio e gas, petrolchimico, produzione di energia, trattamento delle acque, e molti altri. This article discusses the differences between these elbow fittings, concentrandosi su lungo raggio (LR) and short radius (SR) Gomiti.
1. Angle of the elbow
The most obvious difference among the three types of elbows is the angle they create:
- 45° Gomito: Changes the direction of the pipeline by 45 gradi.
- 90° Gomito: Changes the direction of the pipeline by 90 gradi, making a right-angle turn.
- 180° Gomito: Changes the direction of the pipeline by 180 gradi, creating a U-turn or complete reversal of flow direction.
2. lungo Raggio (LR) vs. corto Raggio (SR) Gomiti
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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lungo Raggio (LR) Gomiti: These elbows have a center-to-end distance equal to 1.5 volte la dimensione nominale del tubo (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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corto Raggio (SR) Gomiti: 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 vincoli di spazio are critical.
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I gomiti sono divisi in due gruppi che definiscono la distanza oltre la quale si cambia direzione; la linea centrale di un'estremità alla faccia opposta. 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, LR abbreviato lo è sempre 1.1/2 x Nominal Pipe Size (NPS) (1.1/2D), while the center to face distance for a short radius elbow, abbreviato SR pari alla dimensione nominale del tubo.Qui sotto, Per esempio, troverai il
distanza da centro a fronte di NPS 2 Gomiti
(Il A distanza sull'immagine)1. 90°-LR.. = 1.1/2 X 2(NPS) X 25.4 A=76,2 mm
2. 180°-LR.. = 2 volte il gomito a 90° LR A= 152,4 mm
3. 90°-SR.. = 2(NPS) X 25.4 A= 50,8 mm
4. 180°-SR.. = 2 volte il gomito SR a 90° A= 101,6 mm
3D gomiti come esempio, 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 sistema di tubazioni:
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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. tuttavia, they are essential in specific applications where a complete change in flow direction is required.
4. applicazioni
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, lavorazione chimica, 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, come petrolio e gas, petrolchimico, 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, scambiatori di calore, and cooling systems.
5. Material and manufacturing
Elbow fittings are made from various materials, compreso l'acciaio al carbonio, IN ACCIAIO INOX, Acciaio legato, e altro ancora, depending on the requirements of the specific application. The manufacturing process for these fittings typically involves forging, casting, or welding.
6. standard and specifications
Elbow fittings are manufactured according to various international standards, come ASME b 16.9 (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, Tolleranze, Marcatura, and material requirements for elbows.
Insomma, 45°, 90°, and 180° elbows differ in their angle and radius, which affects the flow characteristics, pressure drop, e space requirements del sistema di tubazioni. 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, affidabilità, and safety.
45° Gomito
La funzione di un gomito a 45° è la stessa di un gomito a 90°, ma la misurazione delle dimensioni di 90° gomito.
Il raggio di un gomito 45° è lo stesso come il raggio di 90° LR (1.1/2D). tuttavia, il centro per affrontare la dimensione non è l'equivalente del raggio 90° LR gomiti. Questo è misurato da ogni viso il punto di intersezione del centro linee perpendicolari tra loro, distanze B sull'immagine. Questo è dovuto al minore grado di piegare. Breve raggio di 45° gomiti non sono disponibili.
Wall Thickness of Elbows
The weakest point on an elbow is the inside radius. ASME b 16.9 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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