General Description
Specification A53 covers Seamless and Welded, black and hot-dipped galvanized nominal (average) wall pipe for coiling, bending, flanging, and other special purposes and is suitable for welding.
Mechanical Properties – Tensile Requirements
| Seamless and ERW | Grade A | Grade B |
| Tensile Strengh, min., psi | 48,000 | 60,000 |
| Yield Strength, min., psi | 30,000 | 35,000 |
Chemical Requirements
| Seamless and ERW | C max % | Mn Max % | P max % | S max % |
| Grade A | 0.25 | 0.95 | 0.05 | 0.045 |
| Grade B | 0.30 | 1.20 | 0.05 | 0.045 |
Testing Requirements
Hydrostatic Testing
Hydrostatic inspection test pressures for plain end and threaded and coupled pipe are specified. Hydrostatic pressure shall be maintained for not less than 5 seconds for all sizes of Seamless and Electric Resistance Weld Pipe.
Mechanical Tests
Tensile Test – Transverse required on ERW for NPS 8 & lager
Flattening Test – For NPS 2 and larger, STD and XS walls. (Not required for XXS pipe)
Bending Test (cold) – For NPS 2 and under, XS wall and under / For NPS 1 1/4 and under, under XXS wall.
| Degree of Bend | Diameter of Mandrel | |
| For Normal A53 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.
Permissible Variations
Wall Thickness
The minimum wall thickness at any point shall not be more than 12.5% under the nominal thickness specified.
Weights per Foot
Plus or Minus 10%
Outside Diameter
Outside Diameter at any point shall not vary from standard specified more than:
| NPS | Over | Under |
| 1 1/2 and smaller | +1/64 | -1/64 |
| For Close Coiling | +1% | -1% |