Major investment to safely harvest and refine our natural resources throughout the world has caused the marketplace to focus more broadly on the quality of steel pipe for oil casing and pipeline transportation systems. ISO 6892-1, ASTM A370, API5L, and ISO 3183 specifications contain tensile testing procedures which can present a variety of challenges based on the shape of the pipe, the wall thickness, and the radius.

The challenges of tension testing of pipe and tube to these standards:

  • Gripping full section pipe/tube
  • Obtaining suitable strain measurements

Instron's solution:

  • The desire to test full section pipe is understood on the part of both the pipe manufacturer and Instron to ease the burden of specimen preparation. However, the pipe must be plugged at each end to avoid crushing the ends during the tensile test. When the full section pipe is too large to be gripped by the test frame, longitudinal strip specimens are cut from the tubular product as described in the standards. Instron can provide a range of end plug sizes designed with a "lip" for easy removal.
  • For strain measurement, the methods require a gauge length of 2” (50mm). Clip-on or automatic extensometry can be used, and in the case of full size material, we offer an industrial style clip on extensometer (up to 89 mm in diameter). For longitudinal strip specimens, a smaller frame clip-on instrument is available that fits snugly against the ID, and OD of the strip specimen to prevent slippage on the irregular shape to ensure accuracy.

For tensile testing of pipe and tube products our most popular system is the Industrial Series 1000HDX. We recommend the fully open hydraulic gripping configuration for ease of use, enhanced safety, and secure gripping of the material without slippage. When testing pipe and tube, we recommend our comprehensive Bluehill® software which provides pre-built standard test methods to meet the requirements of ISO 6892-1, ASTM A370, API5L, and ISO 3183.

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