Hard Spots

Gas Pipeline Inspection: Putting Hard Spot history in context

This in-line inspection case study explores how ENTEGRA's UHR system gave one operator clarity.

Hard spots in gas pipelines can lead to significant integrity threats. Detecting hard spots and characterizing those that might pose the most immediate concern is critical. The harder the hard spot, the more important it is to understand. Localized quenching—caused during the manufacturing process—results in the most problematic hard spots. Hard spots from welding and cold working tend to be less concerning. In a typical ILI inspection, the differences among these types of hard spots can be difficult to detect and discern. It becomes even more challenging when those hard spots appear among metal loss, expander marks and an array of expected features throughout a pipeline. When ENTEGRA® does a pipeline inspection with our true Ultra-High Resolution (UHR) ILI technology, we are capable of not only distinguishing, characterizing and sizing hard spot anomalies, but evaluating them for a hardness value, allowing operators to prioritize repair needs. Here’s how the process worked for one gas pipeline operator in Texas.

Characterizing multiple anomaly types

ENTEGRA was tasked with inspecting a 93.5-mile gas pipeline with a complex configuration that included multiple 1.5D bends. The entire line was mapped in a single run using our 30” UHR MFL/CAL/IMU combo tool. The inspection revealed numerous anomalies, including:

  • Large restrictive dents
  • Metal loss with significant depths (>70%) and lengths
  • Metal loss interacting with the seam (long seam and spiral pipe)
  • Hard spots

The hard spots received special attention from the gas pipeline operator, since a prior survey had identified more than 350 hard spots. The operator asked ENTEGRA to correlate the new data gathered with this historical information.

Oil and Gas Pipeline Hard Spots chart describing the key performance spec for sizing and determining hardness.

Better correlation and classification

Utilizing a combination of advanced automated data analysis technology and interpretation by our experienced Level III data analyst staff, ENTEGRA correlated all of the historic hard spots but also provided more precise classification of the features. The ENTEGRA analysis differentiated between quenched hard spots and expander marks, a more moderate form of hard spot that poses a lesser threat. The ENTEGRA analysis also included more accurate POD and POI information for various metal loss anomalies. With ENTEGRA’s pipeline inspection report, the operator could distinguish between gouges, manufacturing anomalies and corrosion to better prioritize repairs. ENTEGRA data also included information on wall thickness changes and pipe grade classification across the entire line.

With a single ILI run, ENTEGRA UHR technology captured comprehensive data which was reported out in actionable insights for the operator. With better information, the operator could more effectively manage challenges across their entire pipeline and map the right course for maintenance and repair.