ASTM A106 grade C Seamless Steel Pipes ASME B36.10
ASTM-A106 Grade C is a carbon steel pipe specification for seamless pipe used in high-temperature service, such as refineries, power plants, boilers, and petrochemical plants. It is the highest-strength grade in the ASTM A106 standard (Grades A, B, and C).
ASTM A106 grade C is the starting material to produce ASTM A234 WPC Elbow Pipe fittings.
ASTM A106 Grade C Pipe Specifications:
| Property | Details |
|---|---|
| Standard | ASTM A106 / ASME SA106 |
| Grade | C |
| Type | Seamless (hot or cold drawn) |
| Material | Carbon Steel |
| Manufacturing Process | Hot-finished or cold-drawn |
| Size Range | NPS 1/8” to 48” (DN6 to DN1200) |
| Wall Thickness | SCH 10 to SCH XXS (custom on request) |
| Length | Single Random, Double Random, or Cut-to-Length |
| Ends | Plain End (PE), Beveled End (BE), Threaded End (TE) |
Chemical Composition (ASTM A106 Grade C):
| Element | Content (%) |
|---|---|
| Carbon (C) | ≤ 0.35 |
| Manganese (Mn) | 0.29–1.06 |
| Phosphorus (P) | ≤ 0.035 |
| Sulfur (S) | ≤ 0.035 |
| Silicon (Si) | ≥ 0.10 |
| Property | Value |
|---|---|
| Tensile Strength | ≥ 485 MPa (70,000 psi) |
| Yield Strength | ≥ 275 MPa (40,000 psi) |
| Elongation | 30% (min, in 2″ gauge length) |
| Hardness (optional) | ~179 HB (approximate) |
ASTM A106 Grade C Pipe Outside Diameter Tolerance
| NPS [DN Designator] | Permissible Variations in Outside Diameter – Over (in.) | Permissible Variations in Outside Diameter – Over (mm) | Permissible Variations in Outside Diameter – Under (in.) | Permissible Variations in Outside Diameter – Under (mm) |
| ⅛ to 1½ [6 to 40], incl | ¹⁄₆₄ (0.015) | 0.4 | ¹⁄₆₄ (0.015) | 0.4 |
| Over 1½ to 4 [40 to 100], incl | ¹⁄₃₂ (0.031) | 0.8 | ¹⁄₃₂ (0.031) | 0.8 |
| Over 4 to 8 [100 to 200], incl | ¹⁄₁₆ (0.062) | 1.6 | ¹⁄₃₂ (0.031) | 0.8 |
| Over 8 to 18 [200 to 450], incl | ³⁄₃₂ (0.093) | 2.4 | ¹⁄₃₂ (0.031) | 0.8 |
| Over 18 to 26 [450 to 650], incl | ⅛ (0.125) | 3.2 | ¹⁄₃₂ (0.031) | 0.8 |
| Over 26 to 34 [650 to 850], incl | ⁵⁄₃₂ (0.156) | 4 | ¹⁄₃₂ (0.031) | 0.8 |
| Over 34 to 48 [850 to 1200], incl | ³⁄₁₆ (0.187) | 4.8 | ¹⁄₃₂ (0.031) | 0.8 |
ASTM A106 Grade CTest Requirements:
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Hydrostatic Test
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Nondestructive Electric Test (NDE) – eddy current, ultrasonic, or flux leakage
-
Tensile Test – to determine tensile and yield strength
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Flattening/Bend Test – on smaller diameters
-
Visual and Dimensional Inspection
Documentation & Certification:
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Mill Test Certificate (MTC) to EN 10204 3.1 / 3.2
-
NACE MR0175 / ISO 15156 compliance (if required)
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ASME, ISO, PED, or third-party inspection certificates
Difference between ASTM A106 Grade B and ASTM A106 grace C Seamless pipes
ASTM A106 Grade B vs Grade C Pipes
| Criteria | ASTM A106 Grade B | ASTM A106 Grade C |
|---|---|---|
| Carbon Content | ≤ 0.30% | ≤ 0.35% (higher) |
| Tensile Strength | ≥ 415 MPa (60,000 psi) | ≥ 485 MPa (70,000 psi) (higher) |
| Yield Strength | ≥ 240 MPa (35,000 psi) | ≥ 275 MPa (40,000 psi) (higher) |
| Ductility | Higher ductility | Slightly lower ductility |
| Cost | Generally lower | Slightly higher due to higher strength |
| Common Usage | General pressure and heat applications | Higher-pressure, higher-temperature applications |
| Weldability | Excellent | Still good, but more caution due to higher carbon |
| Heat Treatment Needs | Rarely required | May require PWHT (post-weld heat treatment) in some cases |
Application of Grade B and Grade C
-
Grade B: Most commonly used grade. Preferred for moderate pressure and temperature service. Easier to weld and machine.
-
Grade C: Used in more demanding environments where higher strength and pressure resistance are needed. More suitable for critical services, like steam pipelines, high-pressure boilers, etc.
