MS Pipes & Fittings
Mild Steel (MS) ERW PIpe Fittings
MS ERW Pipe Fittings (Mild Steel Electric Resistance Welded) are essential components used to connect, divert, or terminate pipelines in low-to-medium pressure systems. Like ERW pipes, these fittings are manufactured by cold-forming steel strips and welding the seam using high-frequency electric resistance.
1. Technical Standards & Specifications
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Dimensional Standard: IS 1239 (Part 2) for smaller sizes; ASME B16.9 for larger industrial sizes.
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Material Grades: Fe 330, Fe 410 (most common), or Fe 450.
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Size Range: 15mm (1/2") NB to 600mm (24") NB.
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Thickness Classes: Light (Class A), Medium (Class B), and Heavy (Class C).
2. Common Types of MS ERW Fittings
Fitting Type | Primary Function | Common Angles/Variants | Manual sort |
|---|---|---|---|
Elbows | Changes the direction of the fluid flow. | 45°, 90°, 180° (Long/Short Radius) | 3 |
Tees | Creates a 90° branch from the main line. | Equal Tee, Reducing Tee | 38 |
Reducers | Connects pipes of different diameters. | Concentric (centered), Eccentric (offset) | 3a |
Caps | Seals the end of a pipe. | Hemispherical or Flat | 3c |
Bends | Gradual direction change (less friction). | 3D, 5D, or 10D Radius | 3cg |
Nipples | Short pipe lengths for connections. | Barrel Nipple, Close Nipple | 3g |
3. Dimensional Data (Reference for IS 1239 Part 2)
For ERW fittings, the wall thickness is designed to match the "Class" of the pipe it is being welded to.
Nominal Bore (NB) | Outer Diameter (mm) | Medium (Class B) Wall (mm) | Heavy (Class C) Wall (mm) | Manual sort |
|---|---|---|---|---|
25 mm (1") | 33.7 | 3.25 | 4.05 | 3g |
50 mm (2") | 60.3 | 3.65 | 4.47 | 3o |
80 mm (3") | 88.9 | 4.05 | 4.85 | 3q |
100 mm (4") | 114.3 | 4.50 | 5.40 | 3s |
150 mm (6") | 165.1 | 4.85 | 5.40 | 4 |
4. Mechanical & Chemical Properties
Fittings must match the mechanical integrity of the pipes they serve:
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Tensile Strength: 320 MPa to 410 MPa (for Fe 410 grade).
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Yield Strength: 235 MPa (Min).
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Chemical Composition: Carbon (0.20% max), Manganese (1.30% max), Phosphorus/Sulphur (0.040% max).
5. Surface Finish & End Connections
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Surface: Black (Natural/Oil coated), Galvanized (Zinc coated for rust protection), or Painted/Epoxy coated.
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Ends: * Butt-weld: Beveled ends for permanent, high-strength welding.
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Screwed/Threaded: For low-pressure plumbing (BSP or NPT threads).
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Socket-weld: For smaller, high-pressure utility lines.
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6. Quality Testing
ERW fittings undergo rigorous quality checks to ensure the weld seam is not a point of failure:
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Hydrostatic Testing: Pressure tested to ensure no leaks at the seam.
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Dimensional Inspection: Ensuring precise OD and wall thickness for easy alignment.
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Radiography/Ultrasonic: Used for critical industrial applications to detect internal weld flaws.