Facility Maintenance Division of Kukje Chemical & Construction Co., Ltd.
Method for recycling of large diameter pipe
Countless number of pipes, called ‘lifeline’, are buried under the ground to support our daily lives and can be compared to the blood vessels in human body. As those pipes have their own lifetime, many pipes are showing a gradual decline in their performance due to cracks, corrosion, and disconnection proportionally to the quantity of pipes buried. However, it is hazardous to carry out works for improvement of facilities with excavation on the roads where cars are travelling fast, and furthermore, tremendous loss in social overhead capital, such as transportation and everyday life, etc., is caused unavoidably. The strip lining method, which enables quick construction without need for excavation of large diameter pipe, is a breakthrough method developed to resolve aforesaid problems.
The strip, made from rigid polyvinyl chloride, is cut into a helical form, using the joiner, while closely adhering the strip to the inside of existing pipe. High-strength mortar, which has excellent workability, is injected into the gap between the strip pipe, made by aforesaid process, and existing pipe to form a complex pipe integrating the 3 units, such as existing pipe, filling mortar, and strip pipe, into a single unit, which minimizes the reduction of inner cross section of pipe and increases the strength of pipe.
| Type | Name | Size | Scope of Application | Features | Materials Used |
|---|---|---|---|---|---|
| Case1 | SL-R | Repair | When it is required to improve the performance and durability of existing pipes | The reduction of water-passing cross section can be minimized. | Material for SL Method |
| Case2 | SL-R | Repair and reinforcement | Repair and reinforcement of pipes necessary for structural reinforcement due to defect in concrete and cross section of rebar | By processing the spacer according to the state of damage in the pipeline, it has an effect of placing the 10mm rebar by 150mm apart from each other. | Material for SL Method * |
| Case3 | SL-RE | Rehabilitation | It is applied when severe structural problem occurred past the appropriate timing for repair and reinforcement. | Rebar placement and covering are determined in accordance with the structural calculation, and the recycled pipe can provide the load-bearing capacity same as that of new pipe. | Material for SL Method + rebar |
| Partial installation | All applicable | It is applied to the pipes that are in overall good condition and have only partial problems. | As it is installed partially, economical design is allowed. | All applicable | |
* In most cases, sufficient reinforcement can be achieved, using the spacer. However, rebar reinforcement is sometimes needed when the cross section of rebar is severely defective.
It can be installed even when there is a difference, curvature, bending, or gap in the existing pipes.
The recycled pipe, made from destroyed hume pipe, has the strength equal to or exceeding that of new pipe.
| Type of pipe | Size of pipe(mm) | Load(kN/m) | Comparison | |||
|---|---|---|---|---|---|---|
| Breaking load standard - KS Standard | Breaking load test data of new pipe | Breaking load test data of recycled pipe | 3/1 | 3/2 | ||
| Circular pipe type A (repair) | Ø 1,200 | 71.7 | - | 156.8 | 2.19 | - |
| Circular pipe type A (reinforcement) | Ø 1,200 | 71.7 | - | 164.8 | 2.30 | - |
| Circular pipe type B (repair) | Ø 1,500 | 134 | 131.8 | 137.2 | 1.02 | 1.04 |
| Circular pipe type B (reinforcement) | Ø 1,500 | 134 | 133.1 | 199.92 | 1.49 | 1.50 |
| PC BOX (repair) | 1,500 X 1,500 | - | 294.25 | 455.7 | - | 1.55 |
| PC BOX (reinforcement) | 1,500 X 1,500 | - | 294.49 | 485.1 | - | 1.65 |
Recycled pipes increase the flow rate and flow volume more than exiting pipes. The results of hydraulic characteristics test showed that the flow rate increased. despite the reduction in inner diameter of pipe due to the decline in the coefficient of friction, and that the roughness coefficient was 0.010 or less(in the case of ordinary concrete pipe).
Recycled pipe did not show any leakage even under the internal and external water pressure of 1kgf/㎠, the underground water pressure at a depth of 10m under the ground.
Recycled pipe has excellent chemical resistance, wear resistance and durability. Strip pipe is highly resistant to acid and alkali and has greater wear resistance as compared to rigid polyvinyl chloride pipe. In addition, the strip joint and pipe finish part is not affected even by water jet cleaning.
It increases efficiency of construction as it requires shorter construction period and is more cost-effective, compared to excavation method.
The section for installation should be cleaned by water jet.
The spacer for injection of filling materials and the rebar should be installed on the front of pipe in the installation section.
Strip should be placed in existing pipe and closely adhered inside the pipe, and should be made into a helical form.
High-strength mortar is filled in the gap between existing pipe and strip pipe by using the space of spacer, installed before canning, as the passageway of injection hose.
