1.1 Problems with Aging Pipes
After pipes are buried or installed, they experience the following problems over time:
- Corrosion: Pipes are continuously exposed to water, gas, chemicals, and wastewater internally, and to soil moisture, seawater, and humidity externally. Metal pipes oxidize and corrode, while concrete pipes undergo chemical erosion.
- Leakage/Spillage: Fine gaps form due to corrosion or joint defects. Internal fluids leak out through these gaps. The risk increases for pipes with high pressure or those transporting chemicals.
- Cracks: Physical stress accumulates from ground subsidence, vibration, load changes, and repeated freezing and thawing. As this stress builds up, cracks occur in the pipe walls.
- Structural Damage: As corrosion and cracks accumulate, the structural integrity of the pipe degrades. This can lead to collapse if the pipe cannot support overhead loads such as roads, vehicles, or buildings.
Pipe aging is not merely a facility malfunction. It can escalate into secondary damage in two directions.
First, water leaking from aging water and sewer pipes erodes the surrounding soil. This creates and expands underground voids, which can lead to sinkholes where roads or the ground collapse if they can no longer support the overhead load.
Second, leaks from chemical or gas pipelines can lead to fires, explosions, and major industrial accidents.
For pipe problems, prevention is more advantageous than reactive measures. Repairing and reinforcing pipes proactively, before corrosion progresses or at a minor stage, is beneficial for both safety and cost.
1.2 Limitations of Excavation-Based Pipe Replacement
When a pipe problem occurs, the most fundamental solution is to replace it with a new pipe. However, the traditional method of digging up the ground, removing the existing pipe, and burying a new one—known as excavation-based replacement—has the following structural limitations:
| Category | Limitations of Excavation-Based Pipe Replacement |
|---|---|
| Cost | Total construction costs significantly increase compared to simple pipe material costs, including excavation, backfilling, and road/pavement restoration. |
| Construction Period | The construction period is long as excavation, pipe replacement, backfilling, and pavement restoration must proceed sequentially. |
| Traffic Control | If pipes are buried under roads, road closures and detours in the excavated sections are unavoidable. |
| Noise/Dust | Noise, vibration, and dust are generated from the use of excavation equipment such as breakers and excavators. |
| Construction Waste | A large amount of construction waste is generated, including removed old pipes, concrete, and asphalt debris. |
| Construction Constraints | Excavation itself is difficult or involves structural damage for pipes buried in building walls or floors, or pipes inside high-rise buildings. |
Specifically, in the following situations, excavation-based replacement is virtually difficult or incurs very high social costs:
- Pipes buried deep under roads or in the ground.
- Pipes buried in internal building walls or floors, where removal causes structural damage.
- Pipes submerged in seawater or difficult to access.
- Pipes in ultra-high-rise buildings that pass through residents' living spaces.
- Urban water and sewer lines where traffic control causes significant social inconvenience.
Due to these limitations, there is increasing demand for trenchless methods that restore existing pipes from within without removal.
1.3 What is Trenchless Rehabilitation?
Trenchless rehabilitation refers to construction technologies that repair, restore, or replace underground pipes with minimal or no excavation of the ground surface, typically only for access points.
A representative method involves forming a new layer, or lining, inside the existing pipe instead of removing it, thereby restoring the original pipe's waterproofing and structural performance. This offers the following advantages:
- Minimizes road and ground excavation, reducing traffic control, noise, and construction waste.
- Shortens construction period and costs by eliminating backfilling and pavement restoration processes.
- Allows for internal pipe repair without damaging building walls or structures.
- Enables continuous construction over sections ranging from tens to hundreds of meters once an access point is secured.
Trenchless methods are broadly divided into two approaches based on how they are applied. One is the internal pipe lining method, which forms a new layer inside the existing pipe without installing a new pipe. The other is the pipe insertion/replacement method, which involves burying or inserting a new pipe alongside or within the existing one.
HIGHCOATIC's polyurea-based methods fall under the internal pipe lining approach. This means we restore the pipe itself by forming a lining inside the existing pipe without removing it.
1.4 Overview of Trenchless Pipe Rehabilitation Methods
Trenchless rehabilitation methods that form a lining inside existing pipes are broadly categorized into three types based on how the material is applied inside the pipe.
1.4.1 CIPP — Cured-In-Place Pipe
CIPP, or Cured-In-Place Pipe, is a method where a resin-impregnated liner is inserted into an existing pipe and then cured in place to form a new pipe.
The construction principle proceeds in the following sequence:
- Insert the liner into the pipe.
- Adhere the liner closely to the inner wall of the pipe.
- Cure it in place using heat, UV light, chemical reactions, etc.
- A seamless new pipe is formed inside the existing pipe.
CIPP is applied to relatively large pipes and can create a seamless, continuous pipe regardless of the pipe's shape, making it primarily used for large-diameter water and sewage pipelines.
1.4.2 SIPP — Spray-In-Place Type
SIPP stands for Spray-In-Place Pipe, a method that forms a coating and structural layer in place by directly spraying lining material inside the pipe without inserting a separate liner.
The construction principle proceeds in the following order:
- Insert a rotating nozzle or spray device into the pipe.
- Spray the material onto the pipe wall at high pressure.
- It cures in a short time, forming a lining that adheres closely to the inner wall of the pipe.
SIPP is easy to apply to relatively small pipes or irregularly shaped pipes with bends, as it does not require a liner insertion process.
HIGHCOATIC applies polyurea high-pressure spray lining technology to this SIPP method and has adopted it as its primary method, utilizing remote and unmanned construction through 360 Ringtech robotics.
1.4.3 PVC Lining — Sheet Adhesion Type
PVC lining is a method that involves attaching and adhering a sheet-type liner made of PVC or similar materials to the inner wall of a pipe.
The construction principle proceeds in the following order:
- Insert a sheet, cut and processed to match the pipe's shape, into the pipe.
- Attach it to the inner wall of the pipe with a dedicated adhesive and primer.
- Protect the pipe with the sheet's inherent chemical resistance and waterproofing properties.
PVC lining uses a solid sheet material, which has the advantage of producing less debris during construction. However, for irregularly shaped areas such as inside tanks or complex structures, manual construction is required, which can relatively reduce constructability. Additionally, joints may occur, and if the joint treatment is incomplete, there is a possibility of leakage at those points.
1.4.4 Comparison of Methods and Application Standards
① Basic Comparison of SIPP and CIPP
| Category | SIPP | CIPP |
|---|---|---|
| Basic Principle | Directly sprays lining material inside the pipe to form a coating in place | Inserts a liner into the pipe and cures it in place |
| Main Applicable Pipe Diameter | Relatively small pipes | Relatively large pipes |
| Joints | None | None |
| HIGHCOATIC Application Method | Remote construction of polyurea high-pressure spray lining with 360 Ringtech robotics | Introduced as one of the applicable methods, targeting large-diameter pipes |
② Comparison of Three Methods
| Category | SIPP, Spray-In-Place Type | CIPP, Cured-In-Place Type | PVC Lining, Sheet Adhesion Type |
|---|---|---|---|
| Material Application Method | Direct spray application | Insertion of impregnated liner, then curing | Sheet attachment and adhesion |
| Suitable Pipe Diameter | Small to medium diameters, complex shapes including irregular and curved pipes | Medium to large diameters | Applicable to various diameters, but complex structures require manual work |
| Occurrence of Joints | None | None | Possible at connection points |
| Response to Deterioration/Damage | Applicable to pipes with corrosion and abrasion, as well as structural reinforcement through thickness adjustment | Used for rehabilitation of pipes with structural damage | Suitable for surface protection for waterproofing and corrosion prevention purposes |
| Construction Method | Unmanned construction possible with remote spraying using robots | Requires liner insertion and curing equipment | High proportion of manual work, such as sheet cutting and attachment |
HIGHCOATIC introduces itself as capable of handling all three methods: SIPP, CIPP, and PVC lining. Among these, it has adopted SIPP, the polyurea high-pressure spray method, as its primary technique, offering unmanned and remote construction through 360 Ringtech robotics. In actual field applications, the method is selected based on the pipe's diameter, degree of deterioration and damage, type of transported material, and facility purpose.
PART 1 Summary
- Aging pipes suffer from corrosion, leaks, cracks, and structural damage, which can lead to sinkholes or major accidents if left unaddressed.
- Excavation-based pipe replacement has clear limitations in terms of cost, construction period, traffic control, noise, and construction waste.
- Trenchless methods restore pipes by forming a lining inside them without removing the existing pipes.
- Trenchless pipe rehabilitation is categorized into three methods: CIPP, SIPP, and PVC lining. HIGHCOATIC specializes in SIPP-method polyurea high-pressure spray lining.
On-site Diagnosis Checklist
- Are there signs of leaks or seepage from the pipe?
- Are there signs of ground or road subsidence around the pipe?
- Is the pipe located in a difficult-to-excavate area, such as under a road, within a building wall, or in seawater?
- What substance does the pipe transport: drinking water, chemicals, or wastewater?
- Have the pipe's diameter and degree of aging/damage been assessed?