General Description
Specification A106 covers Seamless carbon steel nominal wall pipe for high-temperature service, suitable for bending, flanging and similar forming operations. NPS 1 1/2 and under may be either hot finished or cold drawn. NPS 2 and larger shall be hot finished unless otherwise specified. Surface finish standards are outlined in the specification. Purchaser may specify NDE in lieu of hydrostatic test or neither. Unless otherwise specified, pipe is furnished with plain ends.
Mechanical Properties – Tensile Requirements
| Seamless and ERW | Grade A | Grade B | Grade C |
| Tensile Strengh, min., psi | 48,000 | 60,000 | 70,000 |
| Yield Strength, min., psi | 30,000 | 35,000 | 40,000 |
Chemical Requirements
| Seamless and ERW | Grade A | Grade B | Grade C |
| Carbon, Max. % | 0.25 | 0.30 | 0.35 |
| Manganese % | 0.27 - 0.93 | 0.29 -1.06 | 0.29 - 1.06 |
| Phosphorus, Max. % | 0.035 | 0.035 | 0.035 |
| Sulfer, Max. % | 0.035 | 0.035 | 0.035 |
| Silicon, Min. % | 0.10 | 0.10 | 0.10 |
Testing Requirements
Hydrostatic Testing
Inspection test pressures produce a stress in the pipe wall equal to 60% of specified minimum yield strength (SMYS) at room temperature. Maximum Pressures are not to exceed 2500 psi for NPS 3 and under, and 2800 psi for the larger sizes. Pressure is maintained for not less than 5 seconds.
Mechanical Tests
Tensile Test – NPS 8 and larger – either transverse or longitudinal acceptable.
Flattening Test – NPS 2 and larger.
Bending Test (cold) – NPS 2 and under.
| Degree of Bend | Diameter of Mandrel | |
| For Normal A106 Uses | 90 | 12 X dia. of Pipe |
| For Close Coiling | 180 | 8 X dia. of Pipe |
Number of Tests
Seamless and Electric Resistance Weld – Bending, flattening, tensile on one length of pipe from each lot of 500 lengths, of each pipe size.
| NPS | On one Length From Each Lot of | |
| Tensile | 5 and smaller 6 and larger | 400 or less 200 or less |
| Bending | 2 and smaller | 400 or less |
| Flattening | 2 through 56 and over | 400 or less 200 or less |