Gas Pipe Corrosion Protection & Reinforcement Repair Kits Keep California Safe
California is full of movers and shakers. Unfortunately, California itself moves and shakes. A state known as much for its high seismic activity, as for its Hollywood stars; it isn’t surprising that when it comes to gas pipe, California does not take any chances.
When the owners of a 36-inch OD carbon steel, natural gas pipeline (operating at 500 psi / 34.5 bar) discovered a small dent and multiple hairline surface cracks at the Heat Affected Zone of one of the pipe’s critical welds, they knew that they had a problem. Given that the defective section of pipe was located in a populated area, state, and federal pipeline repair codes mandated that they conduct an emergency repair – immediately – for safety.
There were several considerations that went into choosing the right product for the repair. The pipe provided service to tens of thousands of customers. Disrupting service was not an option – the repair had to be accomplished while the pipe was in operation. From a design standpoint, because the defect was located on an elbow joint, any repair system had to be flexible in order to effectively accommodate the bend. Lastly, the repair had to be strong enough to withstand the seismic activity that comes with the territory — the repair solution had to withstand not only the pipe’s cumbersome geometry, but also the location’s strange geology.
The owners turned to Neptune Research Inc. (NRI), the innovators in the field of carbon fiber composite technology, for a solution.
NRI’s engineers visited the site, assessed the situation, and wrote a custom-designed specification for corrosion protection and pipeline reinforcement based around epoxy and carbon-fiber-reinforced technology. They recommended NRI’s Viper-Skin™ system.
Viper-Skin™ is the first bi-axial, hybrid carbon and glass fiber polyurethane pre-impregnated system that blends the unsurpassed strength and stiffness of carbon with the ease of use of a moisture-cured, pre-impregnated cloth. This operator-qualified, engineered system was designed to conform to and is recognized by ASME PCC-2, ASME B31, ISO TS24817, DOT, API, and CSA Z662 standards for nonmetallic reinforcing solutions, thus ensuring product application integrity. As a result of the micro-controlled, wet-out process, nearly perfect resin content and maximum, repeatable strength properties are attainable. The time and cost associated with in-field saturation of the composite is removed from the equation altogether, thus eliminating the nonconformity caused by human variability. The moisture-curing properties of Viper-Skin™ are also ideal for subsea and wet environment applications. The Viper-Skin™ solution conforms to all shapes, welds, and irregular geometries, and one size can be used on a variety of pipe diameters.
Application Over Before You Know It — Just Like A Quake
The job began with proper surface preparation, cleaning the steel surface to the NACE No. 2 / SSPC-SP10 standard for Near-White Blast Cleaning. This removed any contamination, including rust, paint, and other foreign matter.
Next, the surface cracks were ground out to stop any future crack growth. Then the dent and the cracks were filled with Syntho-Poxy™ HC, a high-compression-strength, 18,000 psi, load transferring filler epoxy. Syntho-Poxy™ HC is a two-part epoxy compound that cures quickly. Its high compressive strength and superior bond strength make it very suitable for repairing pitted metal and steel surfaces that are subjected to high pressure. When fully cured, the material provides a high-compressive-strength filler material that is capable of providing the load transfer required to fill anomalies and profile inconsistent geometries.
Once the Syntho-Poxy™ HC, had been applied, it was time to apply the corrosion-inhibiting epoxy primer. Syntho-Subsea™ LV is a unique blend of liquid epoxy, polymer, and aliphatic polyamine curing agents that is able to displace water from wet surfaces in order to maintain a mechanical bond.The formulation is solvent-free to ensure safety and maximum technical performance. Kevlar® fibers are incorporated for reinforcement and viscosity management to achieve high-application rates – even subsea. Providing long-term protection even under the most adverse conditions, the formula is uniquely field-friendly and uses advanced, low-toxicity ingredients in a high-build brushable / rollable product. This versatile epoxy system can achieve high-performance characteristics, excellent adhesion, resistance to high pressures, resistance to high and low temperature extremes, as well as outstanding resistance to petroleum products and chemicals. Specified for use for above-grade and below-grade applications, Syntho-Subsea™ LV Epoxy can even be shipped non-regulated by USDOT, IATA, and IMO.
For this above-grade application, the crew applied 30 mils of Syntho-Subsea™ LV epoxy over the entire affected area in order to provide corrosion protection and to effectively lock out any atmospheric conditions.
Then, while the Syntho-Subsea™ LV was still wet, it was time for the Viper-Skin™ carbon fiber composite application. The Viper-Skin™ system was applied at the calculated number of layers over the calculated length, using calculations supplied by NRI’s engineers. When fully protected with the Viper-Skin™ system, the pipeline was restored to its original integrity.
The Viper-Skin™ composite repair system eliminated the need to immediately replace the defective section of pipe, or to even shut down the pipe for the repair. And the entire repair was completed in one afternoon. Talk about Moving and Shaking!
Contact NRI and learn how our efficient, effective repairs and kits can provide corrosion protection and reinforcement for your pipeline.