ASTM A252 is the standard specification for nominal wall cylindrical steel pipe piles, in which the steel cylinder acts as a permanent load-carrying member or as a shell to form cast-in-place concrete piles. It covers the material requirements, manufacturing methods, tensile properties, minimum elongation values, and common sizes and weights per unit length. The specification is widely used for foundation piling in bridges, docks, and buildings.
Scope of the Specification
The specification covers nominal, or average, wall steel pipe piles of cylindrical shape. The pipe pile can be used as a load-bearing member that carries the structure directly, or as an open or closed-end shell that is filled with concrete after driving to form a composite pile. The values in the specification are stated in inch-pound units, which are to be regarded as standard, with SI values given as mathematical conversions. Notes and footnotes in the text are explanatory and do not contain mandatory requirements.
Manufacturing Processes and Sizes
Each welded pile is made by seamless, electric resistance welding, flash welding, or fusion welding, with seams that can be longitudinal, helical-butt, or helical-lap. This flexibility allows manufacturers to produce piles in the large diameters and wall thicknesses required by foundation designs, and sizes can reach very large diameters for heavy piling work. The specification provides tables of standard sizes and weights per unit length, and the pipe is ordered by outside diameter, wall thickness, and length.
Grades and Mechanical Requirements
The specification defines three grades of piling pipe. Grade 1 requires a minimum yield strength of 30 ksi, about 205 MPa, and a minimum tensile strength of 50 ksi, about 345 MPa. Grade 2 requires a minimum yield strength of 35 ksi, about 240 MPa, and a minimum tensile strength of 60 ksi, about 415 MPa. Grade 3, the most commonly specified grade, requires a minimum yield strength of 45 ksi, about 310 MPa, and a minimum tensile strength of 66 ksi, about 455 MPa. Minimum elongation values are specified for each grade.
Testing and Inspection
The specification includes tensile testing to verify strength and elongation, flattening tests to check the ductility of the pipe wall, and bend tests where applicable. Hydrostatic testing is not a mandatory requirement in the base specification, because the pipe pile is a structural foundation member rather than a pressure boundary. When additional assurance is needed, supplementary tests can be agreed between the purchaser and the manufacturer.
Typical Applications
Foundation piles for bridges, piers, and docks
Deep foundations for high-rise buildings
Marine structures and cofferdams
Earth-retaining structures and slope stabilization
Cast-in-place concrete piles using the pipe as a permanent shell
Frequently Asked Questions
What is ASTM A252? It is the standard specification for welded and seamless steel pipe piles used in structural foundations.
What manufacturing processes are permitted for A252 pipe piles? Seamless, electric resistance welding, flash welding, and fusion welding, with longitudinal or helical seams.
What is the yield strength of A252 Grade 3? The minimum yield strength is 45 ksi, about 310 MPa, and the minimum tensile strength is 66 ksi, about 455 MPa.
Does A252 require hydrostatic testing? Hydrostatic testing is not mandatory in the base specification; additional tests can be agreed when required.
Where are A252 pipe piles used? In bridge, dock, and building foundations, marine structures, and cast-in-place concrete piles.
What does nominal wall mean? It means the wall thickness is the nominal, or average, value specified, within the tolerance allowed by the standard.