ASTM A252 covers the manufacturing standards of pile pipes, either seamless or welded. This specification includes nominal wall steel pipes with cylindrical shapes- to be used as permanent piles or casing for concrete piling. These pipes are available in Grades 1, 2, and 3, with the last one getting mainly in piling to help provide base stability and support to buildings and other construction projects.
For most standard construction jobs, ASTM A252 pipes of Grades 1 and 2, 3 should work just fine. Among these ASTM Grade-3, pipe piles are the preferred variety because they have a tensile strength of 60000 psi and yield strength of 45,000 psi. This specification covers only cylindrical-shaped pipes and excludes all rectangular steel pipes.
Length Requirements for ASTM A252 Pipes
The length specs for ASTM A252 pipes are as follows
- Single Random Length (SRL)- 16 to 15 feet
- Double Random Length (DRL)- Average 35 ft, with a minimum length of 25 feet.
- Uniform lengths under ASTM A252 should be as specified with an available variation of +/- 1 inch.
Chemical Specifications for ASTM A252 Pipes
As for its mechanical properties, under ASTM A52 Specs, the maximum phosphorus content in piling pipes should not exceed 0.50%. This limit is necessary because this substance can make the steel brittle while adversely affecting the steel's welding capabilities. The other elements used in a pile should be administered according to the general requirements of carbon steel pipes.
Tensile Measurements for ASTM A252 Grade 3 Pipes
|Grade||Yield Point||Min. Elongation at 2°||Tensile Strength||Min. Elongation at 8°|
|3||45000 psi||20%||66000 psi||…|
Calculated Minimum Elongation Values of ASTM A252 Grade 3 Pipes
|Nominal Wall Thickness in Inches||Minimum Elongation % in 2 Inches for ASTM A252 Grade 3|
|5/16 or 0.312 inch||20.00|
|9/32 or 0.281 inch||19.00|
|¼ or 0.250 inch||18.00|
|7/32 or 0.219 inch||17.00|
|3/16 or 0.188 inch||16.00|
|11/64 or 0.172 inch||16.00|
|5/32 or 0.156 inch||15.00|
|9/64 or 0.141 inch||14.00|
|1/8 or 0.125 inch||14.00|
|7/64 or 0.109 inch||13.50|
Types of Pipe Ends Permissible According to ASTM A252 Specifications
According to these standards, all pipes should have a standard plain end unless otherwise specified. Steel pipe piles should either possess machine-cut or flame-cut ends. Manufacturers must also remove the burrs at the ends of these pipes.
In cases where beveled edges are permissible, certain specifications must be maintained. According to ASTM A252 standards, all beveled-ended pipe piles must have an angle of 30 degrees +5, -0 degrees. These edges must be obtained by drawing a perpendicular line from the axis of the pipe pile.
Characteristic Features of ASTM A252 Pipes
- Steel piles made according to ASTM A252 specifications can be seamless, electric resistance welded, flash or fusion welded, longitudinal submerged arc welded (LSAW), and submerged helical arc welded (HSAW), or SSAW.
- The seams of ASTM A252 welded piles should be helical-butt, helical-cap, or longitudinal.
- ASTM A252 pipes get made using hot rolling, cold drawing, open-hearth, basic-oxygen, or electric furnace processes.
- Grade 3 pipes made according to this specification have a higher tensile and yield strength of 455 Mpa and 310 MPa, respectively. This enhanced strength makes them a great fit for piling projects as they can weather the harsh driving force exerted by pile drivers onto the steel pipe piles.
- When used in piling, ASTM pipe piles can be open or closed-ended, depending on the soil requirements.
- Unlike other specifications, a hydrostatic test is not required in ASTM A252 pipes. Since these pipes provide stability to project foundations, they often get filled with concrete instead of being used to transport liquids. This factor makes the test unnecessary in these steel pipe piles.
- However, these pipes must pass through a heat analysis and tests for tensile requirements and overall product quality before being considered fit for sale.
Reference Standards for ASTM A252 Grade 3 Pipe Pile Production
- ASTM A941 provides the terminology for different types of steel used in STM A252 pipe pile production, including stainless steel, alloy, and carbon steel.
- ASTM A751 provides the basis for the test for the chemical analysis of steel pipe piles
- ASTM A370 provides the inspection guides and terminology for the mechanical analysis of steel pipe piles.
- E29 helps confirm the specification conformity of the steel pipe piles to ASTM A252 Grade B standards. It provides practice for digits to be used in the conformance test results.
Available Variations in Weights and Dimensions According to ASTM A252 Standards
Permissible Variations in Weight- 5 % to 15 %
According to ASTM A252 standards, each steel pipe pile should be weighted separately to ensure that they fall under the above limit on weight variation. According to this specification, the pile weight should not be more than 15% nor less than 5% of its theoretical weight.
To generate the theoretical weight, the length and weight of the pipe pile are to be calculated per unit length using the following formula, where
W= weight per unit length, i.e., pound per foot
D= Specified Outside Diameter (OD) in inches
t= Specified Nominal Wall Thickness in inches
Permissible Variations in Outside Diameter (OD)
According to ASTM A252 specs, the outside diameter should not vary by more or less than 1% of the specified OD.
Permissible Variations in Wall Thickness
ASTM A252 specs state that steel piles' wall thickness should not exceed or be less than 12.5% of the specified nominal wall thickness.
Uses of ASTM A252 Grade 3 Steel Pipes in Piling
In piling, pre-made, heavy-duty tubing gets driven into the ground at specific angles and spots based on the recommendations of the geotechnical engineer. Pipes made under ASTM A252 Grade 3 are particularly well adapted for this purpose due to their enhanced tensile properties. This extra strength is necessary because vehicles like piles drivers and hydraulic hammers pound these piles into the soil with extreme force. The piles must be strong enough to withstand the onslaught of force.
This step is necessary because driven piles usually provide more support than drilled piles because they get inserted without drilling a hole in the ground first. These pipes displace the soil on entering, and the friction and pressure result in a more compact and secure foundation.