API 579 Part 4 and Part 5 – General and Local Metal Loss

Metal loss is one of the most common flaws encountered in service.  INSPECT addresses metal loss with its rigorous API 579-1 general and local metal loss assessments and detailed reports.  INSPECT’s 3D models take the guess work out of verifying that the metal loss has been correctly entered.  Since other flaws such as pitting are often present within metal loss regions, INSPECT detects pitting overlaid onto the metal loss and factors this in accordingly.  INSPECT covers:

  • Level 1 and 2 assessments for both Part 4 and Part 5.

  • Local metal loss assessments for nozzles.  These Level 2 assessments follow the rules of  API 579, Part 4 (  INSPECT’s 3D modeling capabilities simplify this process providing concise nozzle assessments quickly.

  • Supplemental loads due to wind, seismic, weight, liquid contents, lateral forces and vertical loads.  These are automatically considered for Part 4, Level 2 assessments.

  • Integration with Olympus Data loggers (read/write capabilities) for enhanced productivity.

Part 5 – Groove-like Flaws

API 579 Part 5 groove-like flaw assessments can be utilized in INSPECT to perform “What if” scenarios for possible remedies to flawed areas.  For example, would the flaw pass assessment if the crack or metal loss was ground into a groove-like flaw?  Groove-like flaws may be combined with pitting damage (Part 6) as well.

An INSPECT API 579 Part 5 Local Metal Loss Map

Create Detailed Part 4 and Part 5 Reports

INSPECT quickly generates metal loss assessment reports.  INSPECT reports contain a full audit trail of all API 579 calculations performed including equations and tables referenced.  Other engineering highlights include:

  • PTR (point thickness reading) and CTP (critical thickness profile) assessments.

  • CTP values may be entered manually or input via a measurement grid.  Grids calculate the CTP values automatically.

  • Scaled grids are shown on the 3D model to represent areas of metal loss.

  • Visual representations of CTP profiles are given in the report and dialog.

  • Calculations from API 579 Annex A along with ASME Section VIII Division 1 are used to evaluate the flaw.  ASME Section VIII Division 2 equations can be used.

  • Part 5 metal loss reports with plots of the remaining strength factor (RSF) and interpolated tensile strength factor (TSF) for each flaw.

  • Joint efficiencies may be defined for each flaw’s location.

How to Perform Part 5 Local Metal Loss Assessments in INSPECT

More Information on Metal Loss Can be Found at:

INSPECT Featured Capabilities