| Product Type | Carbon steel seamless pipe | Manufactured without a welded longitudinal seam; commonly produced by hot working and, for some sizes, cold finishing. | Used for pressure piping, process services, steam lines, water lines, and elevated-temperature applications. |
| Primary Material Standard | ASTM A106 / A106M | Seamless carbon steel pipe for high-temperature service. | The purchase order should identify the edition of the standard, grade, size, schedule or wall thickness, length, and inspection requirements. |
| Common Grades | Grade A, Grade B, Grade C | Grade B is widely selected for general industrial pressure piping; Grades A and C are chosen according to the required mechanical properties and design conditions. | Grade selection must be confirmed against the design code, operating temperature, pressure, corrosion conditions, and required weldability. |
| Carbon Content, Maximum | ASTM A106 chemical requirement | Grade A: 0.25%; Grade B: 0.30%; Grade C: 0.35%. | Values are percent by mass and should be verified using the material test certificate. |
| Manganese | ASTM A106 chemical requirement | Grade A: 0.27–0.93%; Grade B: 0.29–1.06%; Grade C: 0.29–1.06%. | The actual heat analysis may vary within the limits specified by the applicable ASTM edition. |
| Silicon | ASTM A106 chemical requirement | Minimum 0.10% for Grades A, B, and C. | Silicon supports deoxidation during steelmaking; certificate values should be checked for each heat. |
| Phosphorus and Sulfur | ASTM A106 chemical limits | Phosphorus: 0.035% maximum; Sulfur: 0.035% maximum. | Lower residual elements can be important for weldability and fracture-related requirements, subject to the project specification. |
| Tensile Strength, Minimum | ASTM A106 mechanical requirement | Grade A: 48 ksi (330 MPa); Grade B: 60 ksi (415 MPa); Grade C: 70 ksi (485 MPa). | Metric conversions are approximate; the governing standard should be used for compliance decisions. |
| Yield Strength, Minimum | ASTM A106 mechanical requirement | Grade A: 30 ksi (205 MPa); Grade B: 35 ksi (240 MPa); Grade C: 40 ksi (275 MPa). | Design allowable stress is not the same as minimum yield strength and must be taken from the applicable design code. |
| Standard Outside-Diameter Range | Nominal pipe size selection | ASTM A106 commonly covers NPS 1/8 through NPS 48, subject to product availability and the applicable dimensional specification. | Large-diameter orders should confirm manufacturing capability, wall-thickness range, length, and inspection scope before purchase. |
| Dimensional Reference | ASME B36.10M | Provides standard outside diameters and nominal wall thicknesses for welded and seamless wrought steel pipe. | ASTM A106 defines material and product requirements; ASME B36.10M is commonly used to identify nominal dimensions. |
| NPS 1/2 Example | Nominal size and schedule | Outside diameter: 0.840 in (21.3 mm); Schedule 40 wall: 0.109 in (2.77 mm); Schedule 80 wall: 0.147 in (3.73 mm); Schedule 160 wall: 0.187 in (4.78 mm). | Actual inside diameter is approximately outside diameter minus twice the nominal wall thickness, before tolerance considerations. |
| NPS 2 Example | Nominal size and schedule | Outside diameter: 2.375 in (60.3 mm); Schedule 40 wall: 0.154 in (3.91 mm); Schedule 80 wall: 0.218 in (5.54 mm); Schedule 160 wall: 0.343 in (8.74 mm). | NPS is a nominal designation; it does not always equal the measured outside diameter in inches. |
| NPS 4 Example | Nominal size and schedule | Outside diameter: 4.500 in (114.3 mm); Schedule 40 wall: 0.237 in (6.02 mm); Schedule 80 wall: 0.337 in (8.56 mm); Schedule 160 wall: 0.531 in (13.49 mm). | Use the project piping class to confirm the required schedule, corrosion allowance, and pressure-temperature rating. |
| NPS 8 Example | Nominal size and schedule | Outside diameter: 8.625 in (219.1 mm); Schedule 40 wall: 0.322 in (8.18 mm); Schedule 80 wall: 0.500 in (12.70 mm); Schedule 160 wall: 0.906 in (23.01 mm). | Heavy-wall pipe may require special handling, beveling, welding procedures, and dimensional checks. |
| NPS 12 Example | Nominal size and schedule | Outside diameter: 12.750 in (323.9 mm); Schedule 40 wall: 0.375 in (9.53 mm); Schedule 80 wall: 0.500 in (12.70 mm); Schedule 160 wall: 1.312 in (33.32 mm). | For large sizes, verify whether the specified wall thickness is standard, special, or project-specific. |
| Length Options | Commercial supply lengths | Random lengths are commonly supplied; exact-length, double-random, and cut-length requirements may be specified by the purchaser. | Length tolerances and end conditions should be stated in the purchase specification. |
| End Finishes | Plain, beveled, or threaded ends | Plain ends are common for fabrication; beveled ends are used for butt welding; threaded ends are used where permitted by the piping design. | End preparation must match the welding procedure, fitting type, or connection standard. |
| Heat Treatment | ASTM A106 processing requirement | Hot-finished pipe is generally supplied without mandatory heat treatment unless required by the specification; cold-drawn pipe is heat treated after the final cold-drawing operation. | Confirm the required delivery condition and any additional post-weld heat-treatment requirements with the design code. |
| Hydrostatic Test | ASTM A106 test requirement | Each length is normally subjected to a hydrostatic test unless an approved nondestructive electric test option is specified. | Test pressure, holding time, and acceptance criteria should be verified against the applicable ASTM edition and purchase order. |
| Inspection Documents | Material Test Report | A typical report includes heat number, chemical analysis, tensile and yield results, elongation, hydrostatic or nondestructive test status, dimensions, and standard compliance. | Traceability markings should remain identifiable during cutting, fabrication, and installation. |
| Selection Checklist | Key information for purchasing | Specify ASTM A106/A106M, grade, NPS or outside diameter, schedule or wall thickness, length, end finish, quantity, testing, coating or preservation, and documentation. | Final acceptance should be based on the latest applicable standard, approved drawings, piping class, and project quality plan. |
