PIPES & UNDERGROUND
Utility Vault Repair With FRP
The same FRP systems that repair pipes rehabilitate below-ground structures such as manholes, tanks and vaults.
MATCHING PRODUCTS
QuakeWrap® Systems for Utility Vaults
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PipeMedic®
Structural FRP repair for pipes 4 in. to 180+ in.
Explore PipeMedic® -
Wet & Dry Layup FRP
Carbon and glass fabric systems for beams, columns, slabs and walls.
Explore Wet & Dry Layup FRP
Not sure which system fits?
Tell us about the structure and conditions. Our team will recommend the right QuakeWrap® system.
WHY VAULTS DETERIORATE
Why Utility Vaults and Pull Boxes Deteriorate
Vaults and pull boxes, often the size of a small room, are buried below streets so electrical, telephone and fiber optic cables can be connected.
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Trapped moisture
Moisture gets trapped inside and corrodes the side walls and the ceiling slab.
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Traffic overhead
A deteriorated ceiling slab is unsafe for the vehicles that drive over the vault.
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Manhole-only access
Entry through a street-level manhole makes repairs with steel and concrete difficult.
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Heavier new equipment
New switchgear or transformers mean the vault must be checked for the added loads, including the effect of openings in its top slab.
How a Vault Is Repaired Through the Manhole
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Protect the cables
Cables inside the vault are protected before work starts.
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Patch the concrete
Any major concrete spalls are patched first.
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Saturate at street level
Carbon fabric is saturated with resin outside, at street level.
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Pass through & apply
Crews inside apply the sheets to the ceiling and walls, restoring capacity and sealing out moisture.
ADVANTAGES
Advantages of FRP for Vault Repair
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Thin
Typically about ¼ in. (5 mm) added to the member.
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Fast
Repairs are often completed in 1 to 2 days.
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Spot repair
Ideal for repairing only the damaged areas.
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Moisture barrier
Protects the walls and ceiling against future corrosion.
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Hardly visible
The finished installation can be painted.
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Strength restored
Reestablishes capacity lost to corroded reinforcement.
Vault ceiling corroding?
Tell us about the vault, its access and the damage. Our team will recommend the right QuakeWrap® system and provide specifications for your engineer of record.
CASE STUDY
Tucson Electric Power Pull Boxes: Repaired in a Day, Sound After 5 Years
Several underground pull boxes owned by Tucson Electric Power had severe corrosion in the top slab. The damage compromised the structural integrity of the boxes and the power cables serving important industrial facilities, so TEP needed a long-term repair that could be done quickly with minimal power downtime.
After the concrete was repaired, one layer of QuakeWrap® biaxial carbon fabric was installed. It restored the strength of the ceiling and side walls lost to the deteriorated steel and formed an airtight membrane against future corrosion. A three-person crew repaired each pull box within a day, starting in May 2007.
In February 2012, TEP and QuakeWrap® engineers inspected several of the boxes. All the FRP installations were in excellent shape. The humid air had left some mildew on the surface, but no structural degradation of the FRP was observed after 5 years in service.
- One layer of biaxial carbon fabric
- Three-person crew, one day per box
- No structural degradation after 5 years
PROVEN RESULTS
Vault and Pull Box Projects
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Tucson Electric Power, Tucson, Arizona
Corroded top slabs and walls of underground pull boxes restored with biaxial carbon fabric, one box per day.
Project sheet (PDF) -
Arizona State Hospital, Phoenix
Severely corroded reinforcing steel in a pull box on the hospital grounds; carbon fabric passed through a small manhole strengthened the walls and ceiling.
Project sheet (PDF)
Utility Vaults FAQs
Can you provide specifications and design details for our engineer?
Yes. Our team will recommend the right QuakeWrap® system and provide product data sheets, specifications and sample design details for your engineer of record.
How long does a vault repair take?
Repairs are often completed in 1 to 2 days. For Tucson Electric Power, a three-person crew repaired each pull box within a day.
Do the cables have to be removed or de-energized for long?
The cables are protected in place while the FRP is applied, and the work is fast, so downtime is minimal.
How has FRP held up in buried vaults?
When TEP and QuakeWrap® engineers inspected pull boxes in 2012, the FRP was in excellent shape after 5 years, with some surface mildew but no structural degradation.
Will the FRP keep water out?
Yes. The impervious FRP prevents moisture penetration and protects the concrete against future corrosion.
Related FRP Repair Applications
Have a Project That Needs Repair?
Tell us about your structure. Our team will recommend the right QuakeWrap® system and provide specifications for your engineer.