A 7-ft (84-in.) diameter, 5,742-ft cast-in-place concrete pipeline was losing as much as 20% of its flow to leaks. About 150,000 sq ft of QuakeWrap® glass FRP liner was installed in 15 days.
"El Encanto" pipeline, hydropower generating plant
LOCATION
Sardinal, Costa Rica
STRUCTURE
Cast-in-place reinforced concrete low pressure pipeline, 7 ft x 5,742 ft
COMPLETED
July 2009
QUAKEWRAP® SYSTEM
Bidirectional glass FRP liner with epoxy top coat
FRP SYSTEM AND MATERIALS
QuakeWrap, Inc., Tucson, Arizona
FRP INSTALLATION
FRP Construction in cooperation with Ghella S.p.A.
GENERAL CONTRACTOR
Ghella S.p.A., San José, Costa Rica
01 · THE CHALLENGE
Up to 20% of the Flow Lost to Leaks
The low pressure pipeline at the "El Encanto" power plant showed significant longitudinal cracking during a pressurized test run, and as much as 20% of the flow was lost to leaks.
The pipeline was drained and all visible cracks were sealed. But most crack sealing materials are rigid, so they could not move with the concrete. The seals broke and the leaks returned.
02 · THE SOLUTION
One Layer of Glass FRP, Inside the Pipe
The pipeline was pressure washed with 7,000 psi machines to remove scour, sediment, curing compounds and anything else that could weaken the bond.
The FRP liner is one layer of bidirectional glass fabric that acts as a humidity barrier, controls cracking and adds hoop strength to make up for significant loss of hoop steel to corrosion. A concrete-gray epoxy top coat adds abrasion resistance against river sediment and seals remaining pinholes. Because the liner is light green, any missed spot in the gray top coat is easy to see.
Epoxy top coatConcrete gray, abrasion resistant
Bidirectional glass FRP1 layer
Cast-in-place concrete pipeHost
03 · THE RESULT
The Largest Reported FRP Pipeline Retrofit at the Time
Each installation station averaged 2,500 sq ft of FRP liner in an 8-hour day. Working seven days a week, crews completed about 150,000 sq ft of liner in 15 days.
When it was completed in July 2009, it was the largest reported FRP pipeline retrofit job.
per station per 8-hour day
2,500 sq ft
a week
7 days
FRP liner
150,000 sq ft
to complete
15 days
What the Project Team Said
PENSTOCK“
QuakeWrap provided an innovative, multi-purpose FRP liner design that not only targeted the leak problems, but also provided additional structural strengthening to account for steel reinforcement loss due to future corrosion damage, as well as an efficient crack control system, which increased the life cycle of the penstock.
