Types of seamless welded pipe fittings

Butt Weld Fitting is a commonly used connecting component in industrial pipeline systems, which is seamlessly connected to pipelines through welding and has the characteristics of high strength and good sealing. The following are common types and uses of butt welded seamless pipe fittings:
1. Bend
-Purpose: Change the direction of the pipeline.
-Common angles:
-90 ° elbow: right angle turning.
-45 ° elbow: angled turning.
-180 ° bend (return bend): completely reversed.
-Category:
-Long radius: large bending radius, low flow resistance.
-Short radius: Used when space is limited.
2. Three connections
-Diverting or merging fluids.
-Type:
-Equal diameter tee: The diameter of the branch pipe is the same as that of the main pipe (such as DN100 × 100).
-Reducing tee: The diameter of the branch pipe is smaller than that of the main pipe (such as DN100 × 50).
-Diagonal tee: Branch pipes are connected to the main pipe at an oblique angle to reduce flow resistance.
3. Reducers
-Purpose: To connect pipes of different diameters.
-Type:
-Concentric reducer: aligned with the centerline, used for vertical pipelines.
-Eccentric reducer: One side is flush and used for horizontal pipelines (to avoid liquid accumulation or bubbles).
4. Cap*
-Purpose: To seal the end of the pipeline and prevent medium leakage.
5. Stub End
-Purpose: Used in conjunction with flanges for pipeline systems that require frequent disassembly (such as Lap Joint Flange).
6. Other special fittings
-Cross: four-way diversion (less commonly used, prone to stress concentration).
-Socket welding to butt welding fittings: used to connect pipes with different welding methods.
Materials and Standards
-Common materials: Carbon steel (ASTM A234), stainless steel (ASTM A403), alloy steel, etc.
-Manufacturing standards:
-International: ASME B16.9 (size), B16.25 (welding groove).
-Domestic: GB/T 12459, HG/T 21635.
selection
1. Match pipeline material and pressure rating.
2. Consider fluid characteristics (corrosiveness, temperature).
3. Prioritize choosing long radius elbows to reduce pressure loss.
4. When selecting reducers, pay attention to the application scenarios of concentricity/eccentricity.
Welded seamless pipe fittings are widely used in industries such as petroleum, chemical, and power, and require strict selection according to engineering design requirements.