ASME B31G Original/Modified and RSTRENG Overview

ASME B31.G Original and Modified (0.85) are Level 1 assessment along with most other metal loss calculations that are limited to pits and short lengths of pitting clusters.

• These calculations require only two measurements

  • Maximum length

  • Maximum depth or minimum remaining wall thickness

• These calculations are considered conservative based on the limitation of two measurements

RSTRENG is a Level 2 metal loss calculation; however, it is not limited just to pits, but most lengths of pitting i.e., 2500 mm (100 inches) using interaction rules that is not uncommon on some pipelines.

• These calculations require multiple measurements

  • Increment lengths i.e., 10, 20, 25 mm (1/4”, ½” and 1 inch) are typical examples.

  • Maximum depth in each increment that is measured longitudinal along the axis of the pipe.

RSTRENG+ allows the user to determine where there may be multiple effective lengths of long length corrosion versus other programs that do not do this calculation.

• In addition, if you have the Zero Out Method, this will assist in making the appropriate repairs on effective lengths of multiple corrosion areas.

Limitations of all metal loss corrosion programs

• Weldable pipeline steels

• Crack-like defects

• Combined corrosion and crack-like defects

• Combined corrosion and mechanical damage

• Metal loss defects due to mechanical damage (e.g., gouges)

• Metal loss in fittings

• Pipelines that operate at temperatures outside their original design envelope or operating at temperatures in the creep range.