MS Pipes & Fittings
Mild Steel (MS) ERW Pipe
MS ERW Pipes (Mild Steel Electric Resistance Welded) are the backbone of many industrial, structural, and utility projects. While "MS" tells you the material (low carbon steel), "ERW" describes how it's made: by cold-forming a steel strip into a cylinder and fusing the longitudinal seam using high-frequency electric current without any filler material.
Technical Specifications (IS 1239 / IS 3589)
In India, these pipes are typically governed by two major standards: IS 1239 (for sizes up to 6" NB) and IS 3589 (for larger diameters).
1. General Parameters
Features | Description | Manual sort |
|---|---|---|
Material Grade | Fe 330, Fe 410, Fe 450 (Mild Steel) | 8 |
Standard | IS 1239 (Part 1), IS 3589, ASTM A53 | 9g |
Size Range | 15mm (1/2") to 508mm (20") NB and above | a |
Length | Single Random (4–7m) or Double Random (up to 12m) | c |
Surface Finish | Black (Natural), Varnished, or Hot-Dip Galvanized (GI) | g |
2. Chemical Composition & Mechanical Properties
Property | Requirement (Typical for Fe 410) | Manual sort |
|---|---|---|
Carbon (C) | 0.20% max | 8 |
Manganese (Mn) | 1.30% max | 9 |
Phosphorus (P) / Sulphur (S) | 0.040% max each | 9g |
Tensile Strength | 320 MPa to 410 MPa (min) | a |
Yield Strength | 235 MPa (min) | c |
Elongation | 18% to 20% (min) | g |
3. Standard Dimensions & Weights (IS 1239)
Commonly referred to by "Class" (Light, Medium, Heavy), which determines the wall thickness.
Nominal Bore (NB) | Outside Dia (mm) | Light (Class A) - mm / kg/m | Medium (Class B) - mm / kg/m | Heavy (Class C) - mm / kg/m |
|---|---|---|---|---|
1/2" (15mm) | 21.43 | 2.00 / 0.95 | 2.65 / 1.22 | 3.25 / 1.45 |
1" (25mm) | 33.80 | 2.60 / 2.00 | 3.25 / 2.44 | 4.05 / 2.97 |
2" (50mm) | 60.30 | 2.90 / 4.11 | 3.65 / 5.10 | 4.47 / 6.17 |
3" (80mm) | 88.90 | 3.25 / 6.81 | 4.05 / 8.47 | 4.85 / 10.10 |
4" (100mm) | 114.30 | 3.65 / 9.89 | 4.50 / 12.60 | 5.40 / 14.40 |
Manufacturing Tests (Quality Assurance)
To ensure the weld is as strong as the parent metal, ERW pipes undergo several mandatory tests:
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Hydrostatic Test: The pipe is filled with water at high pressure (usually 5 MPa) to check for leaks.
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Flattening Test: A sample is flattened between two plates; the weld seam must not crack or open.
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Bend Test: Used for smaller diameters to ensure ductility.
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Eddy Current/Ultrasonic Test: Non-destructive testing (NDT) to find internal flaws in the weld.
Key Advantages of ERW
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Dimensional Accuracy: Highly consistent wall thickness and diameter compared to seamless pipes.
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Smooth Surface: Better for painting or coating (like the epoxy or 3LPE coatings used in industrial gas lines).
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Cost-Effective: Faster and more efficient production makes them cheaper for structural and water applications.
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.
Mild Steel (MS) Seamless Pipe
Mild Steel (MS) Seamless Pipes are high-strength industrial components manufactured without any weld joints or seams. Because they lack a "weak point" (the weld), they are the preferred choice for high-pressure and high-temperature environments.
Here are the technical specifications and standards for MS seamless pipes:
1. General Specifications
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Size Range: Commonly available from 1/8" to 24" NB (Nominal Bore).
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Wall Thickness: Varies by "Schedule" (e.g., SCH 40, 80, 160, XXS). Thicknesses typically range from 1.5 mm to 60 mm.
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Length: Standard lengths are 6 meters (20ft), though "Single Random" (4–7m) and "Double Random" (7–12m) lengths are common.
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Ends: Plain end, Beveled end (for welding), or Threaded/Screwed.
2. Standard Dimensions (Schedule 40 & 80)
The table below shows the most common specifications for standard (SCH 40) and extra-strong (SCH 80) pipes.
Nominal Size (NB) | Outer Diameter (mm) | SCH 40 Wall Thk (mm) | SCH 80 Wall Thk (mm) | Weight (kg/m - SCH 40) |
|---|---|---|---|---|
1/2" | 21.3 | 2.77 | 3.73 | 1.27 |
1" | 33.4 | 3.38 | 4.55 | 2.5 |
2" | 60.3 | 3.91 | 5.54 | 5.44 |
3" | 88.9 | 5.49 | 7.62 | 11.29 |
4" | 114.3 | 6.02 | 8.56 | 16.07 |
6" | 168.3 | 7.11 | 10.97 | 28.26 |
3. Material & Chemical Composition
MS seamless pipes are typically made of low-carbon steel. The most common grade is ASTM A106 Grade B.
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Carbon (C): 0.25% – 0.30% (Max)
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Manganese (Mn): 0.29% – 1.06%
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Silicon (Si): 0.10% (Min)
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Phosphorus & Sulfur: ≤ 0.035% each
4. Mechanical Properties
For the standard ASTM A106 Grade B material:
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Tensile Strength: ≥ 415 MPa (60,000 psi)
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Yield Strength: ≥ 240 MPa (35,000 psi)
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Elongation: Minimum 30%
5. Common Industry Standards
Depending on your application (oil, gas, water, or structural), you will likely look for one of these standards:
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ASTM A106: For high-temperature, high-pressure service.
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ASTM A53: For general-purpose fluid transport and steam.
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API 5L: Specifically for the oil and natural gas industries.
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IS 1239 / IS 3589: Common Indian standards for water, gas, and air lines.
Mild Steel (MS) seamless Pipe Fittings
MS Seamless Pipe Fittings are high-pressure components used to connect seamless pipelines. Unlike ERW (welded) fittings, these are forged from solid steel billets or manufactured from seamless pipes, ensuring there is no "weak link" or weld seam. This makes them the standard choice for critical industrial systems involving steam, oil, and high-pressure fluids.
1. Primary Technical Standards
For seamless mild steel (carbon steel) fittings, two main standards are followed globally and in India:
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ASTM A234 Grade WPB: The most common global standard for wrought carbon steel fittings for moderate and high-temperature service.
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ASME B16.9: Governs the factory-made wrought buttwelding fittings (dimensions and tolerances).
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IS 1239 (Part 2): The Indian standard for mild steel tubulars and other wrought steel fittings (usually up to 6" NB).
2. Common Types of Seamless Fittings
Fitting Type | Functional Detail |
|---|---|
Seamless Elbows | Available in 45°, 90°, and 180° (Long Radius & Short Radius). |
Seamless Tees | Equal Tees (same diameter) and Reducing Tees (branch is smaller). |
Reducers | Concentric (symmetric) and Eccentric (used to prevent air pockets). |
Caps | Used for permanent closure of the pipe end. |
Stub Ends | Used in conjunction with lap joint flanges. |
3. Dimensional Specification (ASTM A234 WPB / ASME B16.9)
Seamless fittings are categorized by "Schedules" to match the wall thickness of the pipe they are welded to.
Nominal Size (NB) | Outer Diameter (mm) | SCH 40 (Standard) Wall (mm) | SCH 80 (Extra Strong) Wall (mm) |
|---|---|---|---|
1/2" (15mm) | 21.3 | 2.77 | 3.73 |
1" (25mm) | 33.4 | 3.38 | 4.55 |
2" (50mm) | 60.3 | 3.91 | 5.54 |
4" (100mm) | 114.3 | 6.02 | 8.56 |
6" (150mm) | 168.3 | 7.11 | 10.97 |
4. Technical Material Properties
For the standard Grade WPB (the "B" refers to the minimum yield strength):
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Chemical Composition:
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Carbon (C): 0.30% Max
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Manganese (Mn): 0.29% – 1.06%
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Silicon (Si): 0.10% Min
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Sulphur/Phosphorus: 0.05% Max each
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Mechanical Properties:
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Tensile Strength: 415 MPa (Min)
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Yield Strength: 240 MPa (Min)
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Elongation: 20% – 30%
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5. Key Advantages over ERW Fittings
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Uniform Strength: Consistent grain structure throughout the body.
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Higher Pressure Rating: Typically rated for 20% more pressure than a welded fitting of the same material.
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Corrosion Resistance: No weld zone means no risk of preferential "weld decay" or intergranular corrosion at the seam.
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Better for Machining: Seamless fittings can be more easily bored or threaded without worrying about a weld line.
Mild Steel (MS) Pipe Flanges
Mild Steel (MS) Pipe Flanges are critical components used to connect pipes, valves, pumps, and other equipment to form a piping system. They provide easy access for cleaning, inspection, or modification. Unlike welded joints, flanged connections are semi-permanent and can be dismantled easily.
1. Primary Technical Standards
MS flanges are manufactured according to various international and national standards depending on the pressure and application:
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ASME/ANSI B16.5: The most common global standard for pipe flanges (1/2" to 24").
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BS 10: British standard (Table D, E, F, H) widely used in older Indian plumbing systems.
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IS 6392: The Indian standard for steel pipe flanges.
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DIN Standards: German standards (e.g., DIN 2576, DIN 2527) common in European machinery.
2. Common Types of MS Flanges
Type | Technical Description | Best For |
|---|---|---|
Slip-On (SORF) | Slides over the pipe and is welded both inside and out. | Low-pressure, easy alignment. |
Blind (BLRF) | A solid disc used to seal the end of a pipeline. | Inspection ports or future expansions. |
Weld Neck (WNRF) | Features a long tapered hub that is butt-welded to the pipe. | High-pressure and extreme temperatures. |
Socket Weld (SWRF) | Pipe is inserted into a socket before welding. | Small diameter, high-pressure lines. |
Lap Joint | Used with a stub end; the flange can rotate freely. | Systems requiring frequent dismantling. |
Threaded | Screwed onto the pipe without welding. | Low pressure; areas where welding is hazardous. |
3. Pressure Ratings (Class)
Under the ASME B16.5 standard, flanges are categorized by their ability to handle pressure at specific temperatures:
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Class 150: Standard utility (Water/Air).
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Class 300: Medium industrial.
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Class 600, 900, 1500, 2500: High-pressure oil, gas, and steam applications.
4. Dimensional Data (Reference: ASME B16.5 Class 150)
Nominal Pipe Size (NB) | Outside Diameter (mm) | Thickness (mm) | No of Bolt Holes | Bolt Circle Dia (mm) |
|---|---|---|---|---|
1/2" (15mm) | 90 | 11.2 | 4 | 60.3 |
1" (25mm) | 110 | 14.3 | 4 | 79.4 |
2" (50mm) | 150 | 19.1 | 4 | 120.7 |
4" (100mm) | 230 | 23.9 | 8 | 190.5 |
6" (150mm) | 280 | 25.4 | 8 | 241.3 |
5. Flange Facing Types
The "Face" determines the gasket surface and the seal quality:
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Flat Face (FF): Used when the mating flange is cast iron (prevents cracking).
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Raised Face (RF): The most common; concentrates more pressure on a smaller gasket area.
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Ring Type Joint (RTJ): A groove is cut for a metal ring gasket; used for very high pressures.
6. Material & Finish
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Material Grade: Commonly ASTM A105 (Forged Carbon Steel) or IS 2062 Gr. B (Mild Steel Plate).
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Surface Coating: * Black: Self-color/Anti-rust oil.
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Galvanized: Hot-dip zinc coating to prevent corrosion.
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Yellow/Blue Primer: For temporary protection during transit.
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