When it comes to maintaining, repairing, or proactively protecting high-voltage pipe-type power transmission cables, reliability, safety, and continuity of service are of the utmost importance. Composite repairs for these pipe-type cables come with their own set of key challenges not always encountered in other industries.
High-pressure, fluid-filled (HPFF) transmission lines often face substantial threats. Their repairs can be equally complicated, as many of these lines are located in crowded, urban areas, making repairs difficult. Let’s talk about the key challenges of composite repair in power transmission pipelines, how to overcome them, and an inside-look into a project spotlight.
Key Challenge #1: Age of high-pressure fluid-filled pipe-type cables and applied coatings
According to the Electric Power Research Institute, there are more than 4,000 miles of HPFF pipe-types cables in the United States that were installed over the past 80+ years. Many of those miles of cables were installed from 1950-1970. Because of their age, these pipe-type cables may have asbestos or lead-containing material in their coating, which poses a challenge for repairs due to the necessary safety precautions during coating abatement/removal activities.
Composite repairs that require minimal surface preparation work well in this situation. Advanced FRP Systems’ composite repair solution for transmission systems uses an “adhesion zone” concept, where the structurally independent composite repair only adheres to 3 ft. sections of the pipe approximately every 100 linear feet. Only the areas identified as “adhesion zones” require full abatement of the existing coating, which reduces required surface preparation by over 90%.
Figure: Older pipelines may have lead, asbestos, or other toxic materials in the coatings, making the coating abatement process more dangerous and complicated.
Key Challenge #2: Stray currents interfering with cathodic protection
Cathodic protection prevents corrosion. In high-pressure, pipe-type cables, interference from stray currents can overwhelm the cathodic protection and actually accelerate corrosion rates.
In a recent project, Advanced FRP Systems worked with an operator who was dealing with this kind of interference on its pipe-type cables. A strong stray current interfered with its impressed current cathodic protection, and it accelerated the degradation to the point that the operator saw
Key Challenge #3: Indirect application challenges, including labor fatigue, training, and setting restrictions
There are a number of factors, such as labor challenges or environmental restrictions, that can affect the successful repair of pipe-type power transmission cables.
First, comprehensive, However, managing labor fatigue and the potential for human error during the application remains a key challenge for properly installing the composite repair. For example, labor fatigue was a key challenge when Advanced FRP Systems assisted a utility provider with repairing 16,000 linear feet of pipe over the course of 8 months. In that case, selecting a repair system with efficient installation in mind was paramount.
In addition, the environment can be challenging, such as being in a high-population urban environment, next to high-speed vehicle traffic (i.e. next to a highway), or obstacles in the repair space (i.e. overlapping utility pipe). These heavily populated environments may also come with stipulations that restrict when the work can be performed.
To overcome these challenges, a user-friendly composite system with comprehensive high-quality training can make a big difference. It can be applied much more efficiently and cut down on exposure to dangerous working conditions.
Figure: Properly trained workers and ease of repair can make repairs more efficient and mitigate safety risks.
Key Challenge #4: Keeping assets online
For HPFF cables, keeping assets online is key because they are a vital part of the power transmission infrastructure. Repairs on these types of systems need to be compatible with keeping the assets in service. HPFF pipe-type cables are particularly challenging assets to work with because they have the dangers associated with pressurized fluids and electrification.
Project Highlight: Composite repair for massive system of HPFF pipe-type cables in urban environment
A major utility provider needed a proactive solution to refurbish its HPFF pipe-type cables in an urban environment. The provider owned and operated 680 circuit-miles of underground pipe-type cables that experienced multiple dielectric fluid leaks per month. Many of the HPFF cables were over 50 years old, and were susceptible to stray current interference, leaking water and sewer lines, and highly-corrosive soil.
Figure: Composite repair being applied to HPFF pipe-type cable
Key Challenges for Composite Repairs for Power Transmission Pipe-Type Cables and How to Overcome Them
When it comes to maintaining, repairing, or proactively protecting high-voltage pipe-type power transmission cables, reliability, safety, and continuity of service are of the utmost importance. Composite repairs for these pipe-type cables come with their own set of key challenges not always encountered in other industries.
High-pressure, fluid-filled (HPFF) transmission lines often face substantial threats. Their repairs can be equally complicated, as many of these lines are located in crowded, urban areas, making repairs difficult. Let’s talk about the key challenges of composite repair in power transmission pipelines, how to overcome them, and an inside-look into a project spotlight.
Key Challenge #1: Age of high-pressure fluid-filled pipe-type cables and applied coatings
According to the Electric Power Research Institute, there are more than 4,000 miles of HPFF pipe-types cables in the United States that were installed over the past 80+ years. Many of those miles of cables were installed from 1950-1970. Because of their age, these pipe-type cables may have asbestos or lead-containing material in their coating, which poses a challenge for repairs due to the necessary safety precautions during coating abatement/removal activities.
Composite repairs that require minimal surface preparation work well in this situation. Advanced FRP Systems’ composite repair solution for transmission systems uses an “adhesion zone” concept, where the structurally independent composite repair only adheres to 3 ft. sections of the pipe approximately every 100 linear feet. Only the areas identified as “adhesion zones” require full abatement of the existing coating, which reduces required surface preparation by over 90%.
Figure: Older pipelines may have lead, asbestos, or other toxic materials in the coatings, making the coating abatement process more dangerous and complicated.
Key Challenge #2: Stray currents interfering with cathodic protection
Cathodic protection prevents corrosion. In high-pressure, pipe-type cables, interference from stray currents can overwhelm the cathodic protection and actually accelerate corrosion rates.
In a recent project, Advanced FRP Systems worked with an operator who was dealing with this kind of interference on its pipe-type cables. A strong stray current interfered with its impressed current cathodic protection, and it accelerated the degradation to the point that the operator saw
Key Challenge #3: Indirect application challenges, including labor fatigue, training, and setting restrictions
There are a number of factors, such as labor challenges or environmental restrictions, that can affect the successful repair of pipe-type power transmission cables.
First, comprehensive, However, managing labor fatigue and the potential for human error during the application remains a key challenge for properly installing the composite repair. For example, labor fatigue was a key challenge when Advanced FRP Systems assisted a utility provider with repairing 16,000 linear feet of pipe over the course of 8 months. In that case, selecting a repair system with efficient installation in mind was paramount.
In addition, the environment can be challenging, such as being in a high-population urban environment, next to high-speed vehicle traffic (i.e. next to a highway), or obstacles in the repair space (i.e. overlapping utility pipe). These heavily populated environments may also come with stipulations that restrict when the work can be performed.
To overcome these challenges, a user-friendly composite system with comprehensive high-quality training can make a big difference. It can be applied much more efficiently and cut down on exposure to dangerous working conditions.
Figure: Properly trained workers and ease of repair can make repairs more efficient and mitigate safety risks.
Key Challenge #4: Keeping assets online
For HPFF cables, keeping assets online is key because they are a vital part of the power transmission infrastructure. Repairs on these types of systems need to be compatible with keeping the assets in service. HPFF pipe-type cables are particularly challenging assets to work with because they have the dangers associated with pressurized fluids and electrification.
Project Highlight: Composite repair for massive system of HPFF pipe-type cables in urban environment
A major utility provider needed a proactive solution to refurbish its HPFF pipe-type cables in an urban environment. The provider owned and operated 680 circuit-miles of underground pipe-type cables that experienced multiple dielectric fluid leaks per month. Many of the HPFF cables were over 50 years old, and were susceptible to stray current interference, leaking water and sewer lines, and highly-corrosive soil.
Figure: Composite repair being applied to HPFF pipe-type cable
Advanced FRP Systems’ composite repair solution promised the provider:
To learn more about the factors that you should consider for repairs of power transmission, pipe-type cables, contact us for a free consultation.