AASHTO T 249:03(2020) Standard Method of Test for Helical Lock Seam Corrugated Pipe

AASHTO T 249:03(2020) Standard Method of Test for Helical Lock Seam Corrugated Pipe.
APPARATUS
A standard calibrated tensile testing machine.
TEST SPECIMEN
Cut a sample from the end of a fabricated pipe by sawing or burning, with dimensions at least 100 mm parallel to the lock scam and 150 mm perpendicular to the lock seam. If the ends of the pipe have been rerolled to form annular corrugations, take the sample from an area that has not been rerolled unless it is specifically intended to test for the seam strength after rerolling.
4.2. Trim the edges of the sample by sawing to provide a test specimen 25 mm wide (measured parallel to the lock seam), with the edges parallel (see Figure 4).
4.3. Flatten the ends of the specimen for gripping in the testing machine, using a vise or similar tool. Insert one end at a time into the vise to 13 mm from the lock seam. As the vise flattens the corrugations, the unrestrained end will rotate. Realign the lock seam with the flattened ends by use of a crescent wrench (or similar) tightened over the lock seam to prevent distortion of the seam itself while bending the strip back into line.
PROCEDURE
Measure the width of the specimen at the lock seam to the nearest 0.2 mm. Measure the thickness of the sheet to the nearest 0.02 mm to determine the nominal sheet thickness.
5.2. Insert the specimen in the testing machine and apply a tensile load until the specimen separates at the lock seam. Record the maximum load.
CALCULATION AND REPORT
Determine thc lock seam tcnsilc strength by dividing the maximum load by the width of the specimen. Report the results as kilonewtons per meter (kN/m), and indicate whether the specimen is from an area where the corrugations have been rerolled.
KEYWORDS
Calibrated tensile testing machine; corrugated pipe; helical lock seam: lock seam tensile strength.AASHTO T 249 pdf download.