An Advanced Approach to Fitness-For-Service (FFS) and Corrosion ...

DOT 49CFR195 High Consequence Area Requirements
Immediate Repair
• Calculation of the remaining strength of the pipe (using ASME/ANSI B31G;
RSTRENG) shows a predicted burst pressure less than the established maximum
operating pressure at the location of the anomaly.
• In addition any metal loss greater than 80% wt is also considered to be an
immediate repair regardless of the feature dimensions.
180 – Day Conditions
• Calculation of the remaining strength of the pipe shows an operating pressure
that is less than the current established maximum operating pressure at the
location of the anomaly. For this pipeline this has been calculated by assuming
that the pipeline is operating at 72% SMYS resulting in a safety factor of 1.39.
• An area of general corrosion with a predicted metal loss greater than 50% wt.
• Predicted metal loss greater than 50% of nominal wall that is located at a
crossing of another pipeline, is in an area with widespread circumferential
corrosion, or is in an area than could affect a girth weld.
• Corrosion of, or along a longitudinal seam weld.
To maintain safety prior to any immediate repairs an operator must temporarily
reduce the operating pressure or shut down the pipeline until the operator
completes these repairs.
On the basis of the above, 1 external feature requires immediate repair and 12
external features require remediation within 180 days of the date of discovery.