CASE STUDY

120-in. Riveted Steel Penstock Rehabilitation at Lake Lure Dam

A nearly century-old riveted steel penstock at the Lake Lure hydroelectric dam had lost up to 80% of its wall to corrosion. A fully structural carbon FRP liner with QuakeWrap® materials was installed in two weeks.

PRODUCT: WET LAYUP CFRP
APPLICATION: PENSTOCK
INDUSTRY: HYDROPOWER

GET A PIPE REPAIR CONSULTATION ALL PROJECTS

Finished carbon FRP liner with a gray top coat inside the 120-in. Lake Lure penstock reducer and branch

80% wall loss found by nondestructive testing

main line diameter: 120 in.
wall loss from corrosion: Up to 80%
hydrostatic head: 100 ft
installation: 2 weeks

Project Details

OWNER: Town of Lake Lure, North Carolina
LOCATION: Lake Lure, North Carolina
STRUCTURE: Riveted steel penstock, 72-in. and 120-in. sections
PROJECT ENGINEER: SDG Engineering
QUAKEWRAP® SYSTEM: Carbon + glass FRP liner (QW B20C, QW B2610G), wet layup
MATERIALS: QuakeWrap, Inc.
FRP INSTALLER: FRP Construction

01 · THE CHALLENGE

A Century-Old Penstock With Up to 80% Wall Loss

The penstock at the Lake Lure hydroelectric power dam was built nearly a century ago with riveted steel. Nondestructive testing by others found up to 80% wall loss from corrosion.

The project engineer, SDG Engineering, recommended a fully structural lining system for the internal pressure from 100 ft of hydrostatic head.

120-in. main line reduced to 96 in., then to a 48-in. pipe with a butterfly valve
A 72-in. branch off the 96-in. pipe, ending in a butterfly valve

Crew in protective suits preparing the corroded riveted steel wall inside the Lake Lure penstock

02 · THE SOLUTION

A Fully Structural Carbon FRP Liner

QuakeWrap® (materials) and FRP Construction (installation) were selected for a design-build solution. A fully structural carbon FRP liner retrofits the 67-ft penstock between the valves at the upstream and downstream ends.

A dual-layer glass fabric laminate went on first for impermeability, a dielectric barrier between the steel and the carbon, and added strength in the hoop and longitudinal directions. End terminations used dual steel band EPDM compression seals, pressure tested on installation.

Abrasion-resistant epoxy top coat40 mil
Carbon + glass FRP (QW B20C, QW B2610G)2 layers
Epoxy tack coatHigh-adhesion bond
Riveted steel penstockHost

03 · THE RESULT

Back in Service in Time for Spring

FRP Construction completed the installation in two weeks using the wet layup method. That met the owner's schedule to refill the reservoir to normal levels for the annual recreational season in the spring.

penstock lined between valves: 67 ft
installation: 2 weeks
hydrostatic head: 100 ft
abrasion-resistant top coat: 40 mil