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 ERWGrade AGrade BGrade C
Tensile Strengh, min., psi48,00060,00070,000
Yield Strength, min., psi30,00035,00040,000

Chemical Requirements

Seamless and ERWGrade AGrade BGrade C
Carbon, Max. %0.250.300.35
Manganese %0.27 - 0.930.29 -1.060.29 - 1.06
Phosphorus, Max. %0.0350.0350.035
Sulfer, Max. %0.0350.0350.035
Silicon, Min. %

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 BendDiameter of Mandrel
For Normal A106 Uses9012 X dia. of Pipe
For Close Coiling1808 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.

NPSOn one Length From Each Lot of
Tensile5 and smaller 6 and larger400 or less 200 or less
Bending2 and smaller400 or less
Flattening2 through 56 and over400 or less 200 or less