United States
Summary
A natural gas pipeline operator observed external corrosion during inspection of a 24” carbon-steel pipe. The asset owner delivers natural gas to power generation, industrial and utility customers throughout the southeastern United States. To maintain reliable service, a quick, proven repair was required. CSNRI was called on to design a permanent repair that would allow the pipeline to remain operational, while providing external corrosion remediation. A+ Wrap was selected based on ease of installation and compatibility with condensating and underwater pipe.
Benefits
- Easy installation
- Restores structural integrity
- Extends the life of the pipe
- Prevents future external corrosion
- Factory-saturated for time-saving application on site
- No pipe cutting or welding
- Permanent repair with no disruption to pipeline operation during installation
- Can be applied to thin wall pipe, allowing installation in areas where Type B sleeves cannot be welded
- Can install, re-coat, and backfill on the same day, saving time and money
- Easily applied on condensating pipelines and underwater
- Customized engineering design package supports regulatory compliance requirements
Challenge
The damaged pipe was located in a creek crossing in a deep “V” at the bottom of two hills. To prepare for the repair process, an inflatable dam was put in place in a semi-circle from bank to bank. Water was then pumped to the lower side of the dam to create a dry space for the crew to work. A plywood platform was put in place to provide safe footing, allowing the crew the access necessary to apply the A+ Wrap composite system in a safe, dry environment. While technically an above-ground pipe, at times it becomes submerged, requiring a repair that could withstand the variations in environment.
Solution
Based on a long-standing relationship with a contact on the asset owner’s team, CSNRI was called on to create a customized solution for this tricky repair. The asset owner was familiar with composite systems, but had never before used the A+ Wrap product, which is designed to work in both wet and dry environments. The design team developed a solution in accordance with both ASME PCC-2 and ISO 24817 to restore pipe integrity while protecting it from future corrosion.
Application
Wall loss to corrosion was estimated at 34.6%. A system was designed to include 19 layers of 12-inch A+ Wrap applied in an offset manner over the 168-inch repair zone. CSNRI trained a four-person contractor crew to execute the repair. The corroded pipe exterior was media-blasted prior to application of the system. EPN-242 was used as a load-transfer material. The high-strength, high-compression epoxy filler material is used with CSNRI’s non-metallic composite repair systems as a critical component to their success and effectiveness. EPN-242 is used to smooth transitional geometries to facilitate wrapping pipes with the composite system.
The pipe was then coated with PPR-290 adhesive primer prior to the application of A+ Wrap. The fully saturated fabric was then wrapped with compression film and allowed to cure to an average Shore D hardness of 75. Although the repair took place during December, temperatures were above the minimum required for curing and no heat blankets were required.
Results
A+ Wrap is engineered to perform in both wet and dry environments, making it an ideal choice for the challenging location of this repair. Corrosion was quickly remediated and structural integrity was restored to the pipeline as a permanent repair. The ease of application of the system allowed the crew to complete the repair in less than a day. There was no disruption to operation during the repair process.
