101 Mile Pipeline Integrity Assessment & Cleaning

A major midstream gas transmission company required stress corrosion cracking (SCC) integrity assessment services by hydrotesting to remain compliant with regulatory specifications. The project consisted of a single 101.9 mile pipeline with both 24 inch and 26 inch diameter pipe. Significant environmental hazards were encountered from pipeline contaminants. Additionally, unknown to the pipeline operator, the pipeline contained a significant amount of debris.

Location: Texas


Diameter: 24 inch & 26 inch

Length: 101.9 miles broken into 11 segments with the longest being 12.47 miles

Scope of Work

Complete pressure test and dewatering of pipeline containing contaminants and debris.


  • High economic impact for an extended outage


  • Working near energized pipelines and facilities

  • Mercury elements required competent decontamination and cleaning procedure

  • Debris in the line created pig movement challenges

Plan of Execution

  1. Project Pre-planning

    1. Multiple site surveys

    2. Stakeholder planning meetings

    3. Creation of technical procedures

  2. Pipeline Filling

    1. Utilized water already in the pipe to ensure proper water column integrity.

    2. Utilization of appropriate back pressure to mitigate the risk of “air lock”.

  3. Hydrostatic Pressure Testing

    1. 24-hour stabilization period.

    2. Pre-planned controlled pressurization and depressurization process.

    3. Multiple data points to monitor pressure and temperature along each testsection.

  4. Pipeline Dewatering

    1. Utilization of carbon and particulate filtration to remove mercury and arsenic.

    2. Utilized frac tanks to drop high level of solids prior to filtration.

    3. Controlled release to maintain back pressure to prevent air lock.

  5. Pipeline Cleaning

    1. Developed progressive pigging program.

    2. Utilized surfactant chemistryand mechanical pigs.

  6. Caliper

    1. Ran a caliper tool on selected sections to determine pipeline geometry.

  7. Pipeline Drying

    1. Achieved customer approved dew point and penetration.

Technical Achievements & Benefits

  • Multiple integrity tests with no ruptures.

  • Developed procedures to address mercury and arsenic contamination.

  • Successful caliper tool run.

  • Successful integration with end user and general contractor management,consultants, and field personnel. Frequent communication, multiple planning sessions, and highly competent field personnel were key to executing this project.

  • Project completed with zero incidents and no environmental impact.