ASTM A500 and ASTM A252 are both steel pipe standards, but they are built for different jobs. ASTM A500 is the standard specification for cold-formed welded and seamless carbon steel structural tubing, used where the pipe itself carries structural loads as a column, truss member, or beam. ASTM A252 is the standard specification for welded and seamless steel pipe piles, used in foundations where the pipe is driven into the ground as a permanent load-bearing element or as a shell for cast-in-place concrete piles. Choosing the right standard for a project comes down to the application, and the two should not be used interchangeably.
Application Differences
The most significant difference between the two standards is their intended application. ASTM A500 pipe is specified for welded, riveted, or bolted construction of bridges, buildings, and general structural applications. Round and square hollow structural sections made to A500 are used as columns, bracing, trusses, and space frames, where the strength-to-weight ratio of the hollow section is a key advantage.
ASTM A252 pipe is specified for piling. In a typical pile application, the steel cylinder is driven into the ground and either remains in service as a permanent load-bearing member or acts as a shell that is later filled with concrete. Because the pipe must survive driving stresses and long-term service below grade, the standard focuses on load-carrying capacity and durability rather than the refined surface and shape requirements of structural tubing.
Manufacturing and Welding Methods
Both standards permit seamless and welded pipe, but they differ in the welding methods that are allowed. ASTM A500 permits electric resistance welded pipe with a longitudinal seam, which suits the clean, consistent welds needed for structural tubing. ASTM A252 allows a wider range of processes, including electric resistance welding, flash welding, and fusion welding, and the seams may be longitudinal, helical-butt, or helical-lap.
The wider choice of welding processes in A252 reflects the practical realities of large-diameter pile manufacturing, where helical seam welding is an economical way to build long piles from strip steel. The two standards also differ in their testing requirements: A500 requires supplementary tests such as flattening, flaring, and wedge crush tests in addition to tensile testing, because structural tubing must survive the deformation and crushing loads found in structural joints. A252 does not require these additional tests.
Shapes and Dimensional Rules
ASTM A500 covers round, square, rectangular, and special shapes, which makes it the standard of choice for hollow structural sections in all geometries. The dimensional envelope in the standard includes round sections up to a periphery of about 2235 mm and wall thicknesses up to about 25.4 mm, with square and rectangular sections defined by their outside dimensions and wall thickness.
ASTM A252 covers round pipe only, and the standard does not fix a maximum size, because piles are commonly produced in very large diameters to meet foundation design demands. For piling, the outside diameter, wall thickness, and length are specified to suit the soil conditions and the driving equipment, rather than to fit a table of standard structural sizes.
Chemical Composition Compared
The two standards take different approaches to chemistry. ASTM A500 controls carbon, manganese, phosphorus, sulfur, and copper to support weldability and structural performance. Typical maximum limits include carbon at about 0.30 percent for Grades B and D and about 0.27 percent for Grade C, manganese at about 1.40 percent, phosphorus and sulfur at about 0.045 percent each, and a minimum copper content of about 0.18 percent for the corrosion resistance of structural tubing.
ASTM A252 keeps its chemical requirements relatively simple, since the pipe is used primarily as a load-bearing member or a concrete shell and the emphasis is on strength and durability rather than tight composition control. Phosphorus is limited to a maximum of about 0.050 percent, with the other elements controlled to limits that suit the welding and driving processes used for piles.
Mechanical Properties Compared
Both standards define strength by grade. ASTM A500 has four grades, A, B, C, and D, of which Grade B and Grade C are the most commonly specified. Typical minimum yield strengths are about 315 MPa for Grade B and 345 MPa for Grade C, with corresponding minimum tensile strengths of about 400 MPa and 425 MPa.
ASTM A252 has three grades, 1, 2, and 3. Typical minimum yield strengths are about 205 MPa for Grade 1, 240 MPa for Grade 2, and 310 MPa for Grade 3, with minimum tensile strengths of about 345 MPa, 415 MPa, and 455 MPa respectively. The highest grade of A252 is therefore comparable in strength to the lower grades of A500, but the two standards should still be selected on the basis of application rather than strength alone.
Frequently Asked Questions
Can ASTM A252 pipe be used for structural framing? 252 is designed for piling, not for general structural framing. For columns, trusses, and building frames, ASTM A500 structural tubing is the appropriate specification.
Is ASTM A500 pipe suitable for foundations? 500 is a structural tubing standard and is not intended for driven pile service. Foundation piles should be specified to ASTM A252 or the equivalent piling standard required by the project.
What is the difference between Grade B and Grade C of A500? Grade C has a higher minimum yield strength than Grade B, about 345 MPa compared with 315 MPa, at a slightly lower maximum carbon limit, which makes it a higher-strength option for structural members.
What grades are available in ASTM A252? ASTM A252 defines Grades 1, 2, and 3, with minimum yield strengths of approximately 205 MPa, 240 MPa, and 310 MPa respectively. Grade 3 is the most commonly specified for driven piles.
Does ASTM A252 require flattening or flaring tests? No. A252 does not require the flattening, flaring, and wedge crush tests that are part of A500, because pile pipe is not subject to the same local deformation demands as structural joints.
Can A500 and A252 pipe be welded? Both are weldable. A500 allows electric resistance welding with a longitudinal seam, while A252 permits ERW, flash welding, and fusion welding with longitudinal, helical-butt, or helical-lap seams.
Which standard should I choose for a load-bearing column? For a column carrying axial load in a building or bridge structure, ASTM A500 structural tubing is the correct choice. ASTM A252 should be reserved for foundation pile applications.