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.