What ASTM A252 Grade 2 Piling Pipe Is
ASTM A252 Grade 2 pipe piles are structural tubes driven or vibrated into the ground to carry foundation loads. The pipe is produced to ASTM A252/A252M, most often by the spiral submerged arc welding process, and is supplied with either plain or beveled ends so that sections can be spliced on site to reach the required penetration depth.
The governing requirement is mechanical rather than pressure-related: a minimum yield strength of 240 MPa (35,000 psi) and a minimum tensile strength of 414 MPa (60,000 psi), verified by lot tensile testing. The design intent is to survive repeated driving impacts and then carry compression, bending and occasional tension over the service life of the structure.
Specification Summary
| Item | Typical range |
|---|---|
| Standard | ASTM A252/A252M, Grade 2 |
| Nominal outside diameter | 219 mm to 3,620 mm (8 in to 144 in) |
| Wall thickness | Selected from design load and driving stress |
| Length | About 6 m to 24 m, or cut to order |
| Manufacturing route | SSAW, LSAW or EFW welded pipe |
| Ends | Plain or beveled, square cut |
| Minimum yield strength | 240 MPa (35,000 psi) |
| Minimum tensile strength | 414 MPa (60,000 psi) |
| Acceptance testing | Lot tensile test, dimensional inspection, visual weld examination |
Why the Spiral Seam Suits Piling Work
In the spiral process a continuous strip is fed through forming rolls that bend it into a helix, and the edges are welded inside and outside by submerged arc welding. The resulting seam runs around the circumference rather than along the pile axis, which has two practical consequences.
Large diameters are produced from relatively narrow strip, so heavy sections and long lengths are easier to supply.
The helical seam spreads driving stress around the circumference instead of concentrating it in one longitudinal line.
Where a project prefers a longitudinal seam, LSAW pipe formed from plate and welded inside and outside delivers equivalent mechanical performance to the same grade.
Applications
Building and industrial plant foundations on soft or filled ground.
Bridge piers, abutments and approach structures.
Wharf, jetty and marine structures, usually with a protective coating system.
Retaining walls, cofferdams and temporary works supports.
Transmission tower bases and solar or wind plant foundations.
Selection, Coating and Handling
Wall thickness should be fixed by the pile design, checking both the geotechnical capacity and the driving stress against the hammer selected. Because Grade 2 is not a pressure specification, thickness is not chosen from a pipe schedule.
For buried or marine service, specify an external coating such as fusion bonded epoxy, three layer polyethylene or a bituminous system, and consider a corrosion allowance for the design life.
Splice welds must be made to a qualified procedure with the correct bevel preparation and alignment.
Lift piles with slings or purpose-made clamps, never by the pipe ends alone.
Store clear of the ground on timber supports so that moisture and standing water do not attack the surface.
FAQ
Q: What grade and standard is a spiral welded piling pipe certified to?
ASTM A252/A252M Grade 2 is the common callout, with the grade and the dimensions quoted on the mill certificate together with the results of the lot tensile test.
Q: Can A252 Grade 2 pipe be welded on site?
Yes. Splices are normally made by shielded metal arc, flux cored or submerged arc welding using a qualified procedure and low-hydrogen consumables.
Q: Is Grade 2 strong enough for bridge foundations?
It frequently is, provided the section is sized for the design load and driving stress. Where driving conditions are severe, Grade 3 with a higher yield strength may be specified instead.
Q: What coating is used for marine piles?
Fusion bonded epoxy or a multi-layer polyolefin system applied over a prepared and blast cleaned surface is common, with the splash zone often given additional protection.
Q: How should piles be stored before driving?
On dry timber supports, clear of soil and standing water, with end caps or covers in place to stop water and debris entering the bore.
Q: Which documents should accompany a shipment?
The mill test certificate for the grade and heat, dimensional inspection records and, where specified, non-destructive examination reports for the seam.
