Trenchless Pipeline Rehabilitation Technology - Close-fit Short Pipe Lining Method
1. Introduction to Close-Fit Liner Technology
Close-Fit Liner technology represents a significant advancement in trenchless pipeline rehabilitation, offering engineers a reliable and efficient method for renewing aging municipal drainage systems without extensive excavation (1). This technique involves installing a new liner inside an existing pipeline that is either temporarily deformed prior to insertion and then allowed to revert to its original shape to create a tight fit, or designed to expand and conform closely to the host pipe's inner surface (31). The result is a structurally robust, seamless pipe within a pipe that can extend the service life of the pipeline by at least 50 years (18).
The Close-Fit Liner method has gained substantial traction in both the United States and Europe over the past two decades as a preferred solution for rehabilitating gravity flow pipes such as sanitary sewers, storm sewers, and culverts (2). Unlike traditional open-cut methods that disrupt traffic, damage landscapes, and cause significant environmental disturbance, this trenchless approach minimizes disruption while providing a cost-effective alternative for pipeline renewal (45).
2. Technical Principles and Operation Process
2.1 Basic Mechanism and Material Science
Close-Fit Liner technology operates on the principle of utilizing the inherent memory properties of certain polymeric materials, primarily polyethylene (PE) and polyvinyl chloride (PVC) (31). These materials can be temporarily deformed for insertion into the host pipe and then 恢复 to their original shape once in place, creating a tight seal against the existing pipe wall . The liners are typically manufactured from high-density polyethylene (HDPE) or PVC, chosen for their exceptional chemical resistance, durability, and long-term performance in buried environments (45).
Recent technological advancements have introduced reinforced liners with various high-tensile fibers that enhance the overall strength and structural integrity of the finished product (1). These advanced materials allow the liner to withstand higher internal and external pressures while maintaining flexibility during installation . The development of heat-shrinkable liners and fold-and-form techniques has further expanded the application range of Close-Fit Liner technology (31).
2.2 Detailed Installation Process
The installation process for Close-Fit Liners typically follows these systematic steps:
- Pre-inspection and preparation:
- Thoroughly inspect the existing pipeline using CCTV to assess its condition and identify any potential obstacles or areas requiring special attention (4).
- Clean the pipe thoroughly to remove debris, scale, and loose materials that could interfere with the liner installation or reduce the bond between the liner and the host pipe (4).
- Liner preparation:
- For swaged liners: The HDPE or PVC pipe is passed through a die to temporarily reduce its diameter, allowing it to be inserted into the host pipe (45).
- For fold-and-form liners: The pipe is folded into a "U" or "C" shape, significantly reducing its cross-sectional area for easier insertion (31).
- For heat-shrinkable liners: The liner is manufactured with a pre-stretched diameter that allows it to shrink back to its original size when heated after installation (31).
- Insertion:
- The prepared liner is pulled or pushed through the existing pipeline from one access point to another (45). This can be done using winches, rods, or other specialized insertion equipment (4).
- Care must be taken to ensure the liner does not become damaged during insertion, especially when navigating bends or fittings (45).
- Re-expansion and sealing:
- Swaged liners: After insertion, the liner is pressurized to restore it to its original diameter, creating a tight fit against the host pipe (45).
- Fold-and-form liners: Heat and/or pressure are applied to reshape the liner back into a circular cross-section (31).
- Heat-shrinkable liners: Hot air or steam is used to activate the shrinking process, causing the liner to conform tightly to the host pipe (31).
- Joint and end sealing:
- Post-installation inspection:
2.3 Key Advantages of Close-Fit Liner Technology
The Close-Fit Liner method offers several distinct advantages over traditional rehabilitation techniques:
- Minimal disruption: As a trenchless method, it significantly reduces surface excavation, minimizing traffic disruption, environmental impact, and restoration costs (18).
- Structural integrity: The tight fit between the liner and the host pipe creates a composite structure that can carry both internal and external loads, extending the pipeline's service life by at least 50 years (18).
- Versatility: Suitable for a wide range of pipe materials, diameters (typically DN 150-DN 1400), and configurations, including pipelines with bends (14).
- Improved hydraulic performance: The smooth interior surface of the liner reduces friction and increases flow capacity, often restoring the pipe to near-original hydraulic efficiency .
- Cost-effectiveness: While initial material costs may be higher than some alternatives, the overall lifecycle cost is typically lower due to reduced excavation, labor, and restoration expenses (45).
- Environmental benefits: Reduced excavation means less waste generation and lower carbon footprint compared to open-cut methods (45).
3. American and European Case Studies
3.1 American Case Studies
3.1.1 North McKinney Interceptor Main Rehabilitation Project, Texas
The North McKinney Interceptor Main in Texas, constructed in 1992, is a critical wastewater conveyance system for the North Texas Municipal Water District (NTMWD). The system consists of approximately 44,200 feet of reinforced concrete pipe and rubber gasketed ASTM C-76 pipe (62). In the second phase of its rehabilitation, 22,540 linear feet of 24-inch to 36-inch diameter sanitary sewer lines were evaluated for trenchless rehabilitation options (62).
The project team used CCTV inspection and condition assessment based on ASTM F1216 standards, classifying the pipelines as being in a "partially deteriorated condition" (62). After evaluating four rehabilitation alternatives—conventional open-cut, cured-in-place pipe (CIPP), sliplining, and spray-applied pipe lining—the project selected CIPP as the most reliable and cost-effective solution for most sections, with some segments receiving close-fit liners where appropriate (62).
This project demonstrated the successful application of ASTM F1216 guidelines in assessing pipeline conditions and selecting appropriate rehabilitation methods, highlighting the role of close-fit technologies in modern sewer infrastructure renewal (62).
3.1.2 Pilot Test Bed for HDPE Liner Restoration Rate Study
A significant research project conducted in the United States involved the development of a 50-meter steel-framed pilot test bed to study the restoration behavior of modified cross-section close-fit HDPE liners (45). The project team tested 450 mm (approximately 18 inches) and 630 mm (approximately 24 inches) outside diameter HDPE pipes through different swage die sizes to verify the magnitude of cross-section profile reduction between 6.7% and 17.14% (45).
The tests were conducted without artificial heating or steaming sources to increase flexibility, using a conventional static pipe bursting hydraulic rig rated at 60 bars (21 metric tons) to pull the HDPE pipe through the swage dies (45). The research focused on two key performance factors: restoration rate and time, which are critical for ensuring constructability and quality control during field applications (45).
The study produced valuable data on the time-dependent deformation restoration behavior of close-fit liners, resulting in a prediction model that provides engineers with a better understanding of this trenchless rehabilitation technology (45). This research has informed the development of design guidelines and quality control protocols for close-fit liner installations across the United States.
3.2 European Case Studies
3.2.1 Attersee Lake Sewer Rehabilitation, Austria
One notable European case study took place in September 2012 at Attersee Lake in the Austrian 度假 region of Salzkammergut (18). The project involved the rapid rehabilitation of 150 meters of a DN300 wastewater pipeline located directly beside the shore of this popular recreational lake (18).
SPR Europe provided a Close-Fit Liner solution that was specifically chosen for its ability to deliver a fast, cost-effective, and minimally disruptive rehabilitation (18). The technology selected allowed the pipeline to be rehabilitated in place without extensive excavation, preserving the lakeshore environment and minimizing disruption to tourism activities in the area (18).
The project demonstrated how close-fit liner technology can be successfully applied in sensitive environmental and recreational areas where traditional open-cut methods would be impractical or environmentally damaging (18). The solution provided by SPR Europe extended the service life of the pipeline by at least 50 years while maintaining the aesthetic and functional integrity of the lakeshore area (18).
3.2.2 Asbestos Cement Pipe Rehabilitation with NordiTube Systems
In Europe, thousands of kilometers of aging asbestos cement (AC) pipes continue to pose significant challenges for water and wastewater utilities (14). Similar to Australia, the rehabilitation solutions for this aging material have historically been limited (14).
NordiTube, a leading provider of trenchless rehabilitation solutions, has developed two liner systems specifically designed for AC pipe rehabilitation: the NordiFlow fully structural lining technology and the R-tec Close-Fit Liner system (14). The NordiFlow system (Class A) is completely independent of the AC pipe and can carry all internal loads (pressure and vacuum) as well as external loads including soil, groundwater, surge, and traffic loads for pipes ranging from DN 150 to DN 1400 (14).
The R-tec Close-Fit Liner system consists of pre-folded PE pipes that are factory-made Class A systems capable of carrying all loads for pipes from DN 150 to DN 400 (14). These systems have been successfully deployed across Europe to rehabilitate aging AC pipelines while minimizing disruption and ensuring long-term performance (14).
This case study illustrates how close-fit liner technology has been adapted to address the specific challenges posed by aging infrastructure materials like asbestos cement, providing European utilities with viable alternatives to costly and disruptive replacement projects (14).
4. International Standards and Regulatory Compliance
4.1 American Standards and Guidelines
In the United States, the design and installation of close-fit liners for municipal wastewater pipelines are governed by several key standards and guidelines:
4.1.1 ASTM F1216 Standard Practice
ASTM F1216, "Standard Practice for Rehabilitation of Existing Pipelines and Conduits by the Inversion and Curing of a Resin-Impregnated Tube," provides comprehensive guidance for the design and installation of close-fit liners (38). Although originally developed for cured-in-place pipe (CIPP) technology, many aspects of this standard are also applicable to other close-fit liner systems (38).
Key provisions of ASTM F1216 include:
- Specifications for materials used in liner construction, including resins, reinforcements, and other components (39).
- Requirements for the design of liners to ensure they can withstand the anticipated internal and external loads (39).
- Guidelines for the installation process, including inversion, curing, and quality control measures (39).
- Performance criteria for the finished liner, including structural integrity, leak tightness, and chemical resistance (39).
ASTM F1216 has been widely adopted across North America as the primary standard for evaluating the condition of existing pipelines and designing appropriate rehabilitation strategies (57). The standard specifies procedures for the reconstruction of pipelines and conduits with diameters ranging from 4 to 96 inches through the installation of a resin-impregnated, flexible tube that is inverted into the existing conduit using hydrostatic head or air pressure (39).
4.1.2 ASCE Manual of Practice No. 145
The American Society of Civil Engineers (ASCE) has published Manual of Practice No. 145 (MOP 145), titled "Design of Close-Fit Liners for the Rehabilitation of Gravity Pipes," which provides a comprehensive source of information on the design of flexible, close-fit linings for gravity flow pipes such as sanitary sewers, culverts, and storm sewers (2).
This peer-reviewed industry resource offers guidance for the robust design of both circular and non-circular shaped flexible liners installed in gravity pipe sewers and culverts (35). The manual covers various types of close-fit liners, including CIPP (both non-reinforced and GRP-reinforced) and fold-and-form liners (50).
Key features of MOP 145 include:
- Design methodologies for different types of close-fit liners under various loading conditions (35).
- Guidance on material selection and properties, including consideration of long-term performance and environmental factors (35).
- Procedures for evaluating existing pipeline conditions and determining appropriate liner thickness and configuration (35).
- Case studies and examples demonstrating practical application of the design principles (35).
MOP 145 has been widely adopted by consulting engineers across the United States as the go-to resource for designing close-fit liners in gravity pipe rehabilitation projects (50).
4.1.3 Proposed ASTM WK 29237 Standard
Recognizing the need for updated design calculations specific to close-fit liners for plastic pipes, ASTM International is developing a new standard, ASTM WK 29237, titled "Practice for Design Calculations of Close-Fit Liners" (30).
This proposed standard responds to innovations in equations and analytical tools that engineers have developed for designing close-fit liners (43). The new standard will provide specific guidance on:
- Structural design methodologies for close-fit liners in various soil and loading conditions (43).
- Consideration of material properties, including creep and long-term performance (43).
- Methods for calculating liner thickness and determining appropriate safety factors (43).
- Design considerations for different types of close-fit liners, including swaged, folded, and heat-shrinkable systems (43).
Once published, ASTM WK 29237 is expected to become an important reference for engineers designing close-fit liner systems in North America (43).
4.2 European Standards and Guidelines
In Europe, the design and installation of close-fit liners are governed by a different set of standards and guidelines:
4.2.1 EN ISO 11296 Series
The EN ISO 11296 series of standards, titled "Plastic piping systems for renovation of underground non-pressure drainage and sewerage networks," provides comprehensive guidance for the design, materials, and installation of close-fit liners in Europe (60).
Key parts of this series include:
- EN ISO 11296-3: "Plastic piping systems for renovation of underground non-pressure drainage and sewerage networks - Part 3: Lining with close-fit pipes" (7).
- EN ISO 11296-4: "Plastic piping systems for renovation of underground non-pressure drainage and sewerage networks - Part 4: In-situ cured-in-place piping (CIPP) lining" (60).
EN ISO 11296-3 specifies requirements for close-fit pipe lining systems, including materials, dimensions, performance characteristics, and installation procedures (7). It covers both polyethylene (PE) and unplasticized polyvinyl chloride (PVC-U) materials for liners used in the rehabilitation of underground non-pressure drainage and sewerage networks (8).
EN ISO 11296-4 focuses specifically on CIPP lining systems but shares many general principles with other close-fit liner technologies (60). This standard has played an important role in the standardization of CIPP liners and has contributed to the development of intensive quality assurance systems, particularly in Germany (60).
4.2.2 German ATV Standards
In Germany, the ATV (Arbeitsgemeinschaft für Technik und Wasserwirtschaft) standards provide detailed technical guidance for various aspects of water and wastewater engineering, including pipeline rehabilitation .
Key ATV standards related to close-fit liners include:
- ATV A127: This standard provides guidelines for the evaluation of the structural condition of existing sewer systems, which is an important precursor to selecting appropriate rehabilitation methods including close-fit liners .
- ATV DWA-M 149: This guideline addresses the design and installation of close-fit liners for sewer rehabilitation, providing detailed technical requirements and recommendations .
Research has shown that pipelines rehabilitated with close-fit liners according to ATV standards, even those initially classified as being in the third technical condition (significantly deteriorated), are capable of withstanding external loads and extending the service life of the pipeline .
4.2.3 Other European National Standards
Several European countries have developed their own national standards and guidelines for close-fit liner technology:
- French standards: The French standard for the design of liners for gravity pipe applications offers a fully analytical approach for the design of circular and non-circular liners under groundwater pressure (11). This method has been widely adopted in France and other parts of Europe.
- British standards: The United Kingdom has developed comprehensive guidance on close-fit lining as part of its suite of trenchless technology standards, which are published by the Water Research Centre (WRc) and other organizations (31).
These national standards often incorporate principles from the EN ISO 11296 series while adding specific requirements tailored to local conditions and practices (31).
4.3 International Harmonization of Standards
There has been significant progress toward harmonizing close-fit liner standards internationally:
The development of the ISO 11296 series represents an important step toward international standardization of close-fit liner technology (7). This series has been adopted as national standards in many countries, including China, which has published GB/T 41666.3-2022 based on ISO 11296-3:2018 (7).
Similarly, the principles outlined in ASTM F1216 and ASCE MOP 145 are increasingly being recognized and incorporated into standards and practices in other parts of the world (57). This international harmonization is facilitating the transfer of technology and best practices across borders, benefiting both manufacturers and end-users of close-fit liner systems (57).
5. Comparison with Other Trenchless Rehabilitation Technologies
5.1 Cured-in-Place Pipe (CIPP) Technology
Cured-in-Place Pipe (CIPP) is another widely used trenchless rehabilitation technology that shares some similarities with close-fit liners but differs in several key aspects (49).
Technical principles:
- CIPP involves inserting a resin-impregnated tube into the existing pipeline, which is then inflated and cured in place to form a new pipe within the old one (1).
- The resin can be cured using various methods including hot water, steam, or ultraviolet (UV) light (1).
- Unlike close-fit liners, CIPP does not rely on mechanical deformation and recovery but rather on chemical curing of the resin matrix (1).
Advantages of CIPP:
- Can be installed in continuous lengths of over 2,500 linear feet, making it suitable for long pipeline segments (49).
- Forms a seamless, structural lining with excellent hydraulic characteristics (1).
- Can conform to complex pipe geometries and fittings (1).
- The cured liner has high structural strength and can span voids or gaps in the host pipe .
Limitations of CIPP:
- Higher material costs compared to some other trenchless methods (62).
- Longer installation times due to curing requirements (62).
- More complex material handling and safety considerations due to the use of resins and chemicals (62).
- The resin curing process requires careful temperature and time control to ensure proper performance (1).
Application scenarios:
- CIPP is particularly well-suited for pipelines with complex configurations, multiple bends, or varying diameters (62).
- It is often the preferred choice for structural rehabilitation of large-diameter pipelines in critical infrastructure applications (62).
- UV-cured CIPP is increasingly popular for its faster curing times and reduced energy consumption (1).
5.2 Spiral Wound Trenchless Pipeline Renewal
Spiral wound trenchless pipeline renewal is another alternative to close-fit liners, with its own distinct characteristics (49).
Technical principles:
- This technology involves installing a new pipe inside the existing one by spirally winding a specially formed strip of material (usually PVC or steel) to create a continuous, watertight lining (49).
- The strip is typically interlocked as it is wound, creating a structural pipe that conforms to the shape of the host pipe (49).
Advantages of spiral wound technology:
- Specifically designed for and used primarily in large-diameter pipelines, typically worker-entry size (49).
- Can provide a customized structural solution to aging pipelines, with varying wall thicknesses and configurations possible (49).
- The spiral winding process allows the liner to adapt to irregularities in the host pipe (49).
- No need for temporary deformation and recovery like close-fit liners (49).
Limitations of spiral wound technology:
- Generally limited to larger diameter pipes (typically 36 inches and above) (49).
- Higher equipment and labor costs compared to some other trenchless methods (62).
- The spiral joint may be more susceptible to certain types of damage compared to seamless liners (62).
- Not as suitable for pipelines with tight bends or complex configurations (62).
Application scenarios:
- Spiral wound renewal is particularly well-suited for large-diameter gravity sewers, storm drains, and culverts (49).
- It is often used in situations where the existing pipe has significant structural deterioration but remains mostly intact (49).
- This technology is commonly employed in municipal wastewater systems where large flow capacities must be maintained (49).
5.3 Spray-Applied Pipe Lining
Spray-applied pipe lining represents another alternative to close-fit liners, with its own unique characteristics and applications (62).
Technical principles:
- This method involves spraying a layer of protective or structural material directly onto the interior surface of the existing pipeline (62).
- Common materials include cementitious coatings, epoxy resins, and polyurethane compounds (62).
- The sprayed material adheres to the host pipe surface, forming a protective barrier or structural lining (62).
Advantages of spray-applied lining:
- Can be applied without inserting a full-length liner, potentially reducing installation time and complexity (62).
- Provides excellent coverage of complex geometries, fittings, and transitions (62).
- Thickness can be varied to address different levels of deterioration or performance requirements (62).
- Lower material costs compared to some other trenchless methods in certain applications (62).
Limitations of spray-applied lining:
- Generally provides less structural support compared to close-fit liners or CIPP (62).
- Thinner coatings may be more susceptible to damage during installation or service (62).
- Requires specialized spraying equipment and skilled operators (62).
- Cure times can be affected by environmental conditions such as temperature and humidity (62).
Application scenarios:
- Spray-applied lining is well-suited for non-structural rehabilitation where the primary goal is to provide corrosion resistance or leak control (62).
- It is often used for smaller diameter pipes, service connections, and areas with complex geometry (62).
- This technology is commonly employed in situations where the existing pipe has minor to moderate deterioration but remains structurally sound (62).
5.4 Short Tube Replacement and Other Methods
Several other trenchless rehabilitation methods should also be considered when evaluating alternatives to close-fit liners:
Short tube replacement:
- Involves replacing short sections of deteriorated pipe with new sections, typically using specialized couplings or fittings (4).
- Advantages include simplicity, low cost for small repairs, and the ability to precisely target damaged areas (4).
- Limitations include the need for multiple excavation points and the potential for creating joints that may leak over time (4).
- Best suited for localized damage in otherwise sound pipelines (4).
Point repair methods:
- Include technologies such as packers, grouting, and mechanical seals used to repair specific leaks or defects in the pipeline (4).
- Advantages include minimal disruption, targeted repair, and lower cost for small defects (4).
- Limitations include the inability to address widespread deterioration and the potential for multiple interventions over time (4).
- Best suited for pipelines with isolated defects or leaks (4).
Bursting and sliplining:
- Pipe bursting involves fracturing the existing pipe and simultaneously pulling in a new pipe of equal or larger diameter (45).
- Sliplining involves inserting a new, smaller diameter pipe inside the existing one, often with a grout filling the annulus (45).
- Advantages include the ability to increase pipe diameter (bursting) or provide a smooth interior surface (sliplining) (45).
- Limitations include the need for excavation at both ends of the pipeline segment and potential challenges with bends and fittings (45).
- Best suited for situations where the existing pipe is severely deteriorated or when increased capacity is desired (45).
5.5 Comparative Analysis of Rehabilitation Methods
The following table provides a comparative analysis of close-fit liners and other major trenchless rehabilitation technologies across several key criteria:
Criteria | Close-Fit Liners | CIPP | Spiral Wound | Spray-Applied |
Structural Capacity | High - can carry all internal and external loads (14) | Very high - forms a structural pipe within a pipe (1) | High - customizable structural solution (49) | Moderate - primarily for corrosion protection and minor structural support (62) |
Diameter Range | DN 150-DN 1400 (14) | DN 100-DN 2400+ (1) | Primarily large-diameter (worker-entry) (49) | DN 100-DN 2000+ (62) |
Installation Speed | Fast - typically 1-2 days per 100 meters (18) | Moderate - depends on curing method (hours to days) (1) | Moderate - depends on diameter and length (49) | Fast - can be applied in a single day for many applications (62) |
Suitability for Bends | Good - can navigate standard bends (31) | Excellent - can conform to complex geometries (1) | Limited - best for straight runs (49) | Excellent - can coat around fittings and bends (62) |
Flow Capacity Reduction | Moderate - typically 10-20% depending on liner thickness | Moderate - typically 15-25% (1) | Minimal - can maintain or increase diameter (49) | Minimal - thin coating does not significantly reduce diameter (62) |
Typical Service Life | 50+ years (18) | 50+ years (1) | 40-50 years (49) | 20-30 years (62) |
Cost (per linear meter) | Medium - $100-300 (4) | High - $200-500 (62) | High - $250-600+ (49) | Low - $50-200 (62) |
Environmental Impact | Low - minimal excavation and waste (18) | Moderate - some chemical waste from resin systems (1) | Moderate - requires specialized equipment and materials (49) | Low to moderate - depends on coating material (62) |
Based on this comparison, close-fit liners offer an attractive balance between structural performance, cost, and installation speed for many municipal drainage applications (18). They are particularly well-suited for situations where maintaining flow capacity is important but not critical, and where moderate structural support is needed (18).
6. Technical Advantages and Application Scenarios
6.1 Key Technical Advantages of Close-Fit Liners
Close-Fit Liner technology offers several significant technical advantages that make it a compelling choice for many pipeline rehabilitation projects:
Superior hydraulic performance:
- The tight fit between the liner and the host pipe creates a smooth interior surface that minimizes friction and turbulence .
- Studies have shown that close-fit HDPE liners can reduce the relative roughness of the pipe, improving flow efficiency compared to both new steel pipes and deteriorated original pipes .
- While there is some reduction in cross-sectional area (typically 10-20%), the improved surface characteristics often result in better overall hydraulic performance than the original deteriorated pipe .
Structural integrity and durability:
- The tight contact between the liner and the host pipe allows for load sharing, creating a composite structural system that can withstand significant external pressures (57).
- Modern close-fit liners are designed using advanced materials and reinforcement techniques that provide excellent resistance to chemical corrosion, abrasion, and biological degradation (1).
- The continuous nature of the liner eliminates joints and potential leak points, improving long-term performance and reducing maintenance needs (31).
Installation efficiency and reliability:
- The installation process is generally faster and less complex compared to CIPP, with fewer variables to control (18).
- The mechanical deformation and recovery process is less dependent on environmental conditions (temperature, humidity) compared to resin-based systems (45).
- The use of prefabricated liners ensures consistent quality and performance, with less variability compared to 现场 - applied systems (45).
Material versatility and adaptability:
- Close-fit liners can be manufactured from a variety of materials (HDPE, PVC, etc.) to suit different environmental conditions and performance requirements (45).
- The technology can be adapted to a wide range of pipe diameters, configurations, and conditions (31).
- Specialized liners can be developed for specific applications, such as high-temperature environments, aggressive chemical exposures, or high-pressure conditions (31).
6.2 Optimal Application Scenarios
Based on the technical characteristics and advantages of close-fit liners, they are particularly well-suited for the following application scenarios:
Rehabilitation of gravity sewer systems:
- Close-fit liners are ideally suited for rehabilitating sanitary sewers and storm drains where maintaining structural integrity while preserving flow capacity is important (2).
- They are particularly valuable for pipelines that are experiencing moderate deterioration but are not yet structurally compromised (2).
- The tight fit helps prevent infiltration and exfiltration, improving system performance and reducing the risk of groundwater contamination (2).
Rehabilitation of asbestos cement pipes:
- As demonstrated in European case studies, close-fit liners provide a safe and effective solution for rehabilitating aging asbestos cement pipes without the need for hazardous material removal (14).
- The R-tec Close-Fit Liner system from NordiTube has been specifically developed for this application, providing a Class A structural solution for pipes from DN 150 to DN 400 (14).
- This application is particularly important in regions where large numbers of aging asbestos cement pipes are still in service (14).
Sensitive environmental and urban areas:
- The minimal excavation required for close-fit liner installation makes it ideal for use in environmentally sensitive areas, historic districts, or heavily trafficked urban locations (18).
- Projects near water bodies, parks, or other sensitive ecosystems benefit from the reduced environmental impact of trenchless methods (18).
- In urban settings, the reduced disruption translates to lower traffic management costs, less business interruption, and improved public safety (18).
Pipeline segments with moderate structural deterioration:
- Close-fit liners are particularly effective for pipelines that are in a "partially deteriorated condition" as defined by ASTM F1216 (62).
- They provide sufficient structural support to extend the service life of the pipeline while addressing issues such as corrosion, scaling, and minor leaks (62).
- For pipelines that are more severely deteriorated, close-fit liners can still be used in combination with other methods or as part of a comprehensive rehabilitation strategy (62).
Applications requiring chemical resistance:
- The use of HDPE or PVC materials provides excellent resistance to a wide range of chemicals commonly found in wastewater systems (45).
- Specialized liners can be developed for environments with particularly aggressive chemical conditions (45).
- This chemical resistance ensures long-term performance and reduces the need for frequent maintenance or replacement (45).
6.3 Limitations and Considerations
While close-fit liners offer many advantages, there are also certain limitations and considerations that should be taken into account:
Flow capacity reduction:
- The installation of a close-fit liner reduces the internal diameter of the pipeline, which can result in a 10-20% reduction in flow capacity .
- This reduction should be carefully evaluated during the design phase to ensure the rehabilitated pipeline will meet future capacity requirements .
- In some cases, it may be necessary to consider alternative methods such as pipe bursting or spiral wound lining that can maintain or increase flow capacity (45).
Suitability for severely deteriorated pipes:
- Close-fit liners are most effective when applied to pipes that are still structurally sound but have deteriorated internally (62).
- In cases where the host pipe is severely cracked, collapsed, or otherwise structurally compromised, alternative methods such as CIPP or full pipe replacement may be more appropriate (62).
- For pipes with significant structural damage, a structural assessment should be conducted to determine the most appropriate rehabilitation method (62).
Installation challenges:
- Installing a close-fit liner requires careful planning and execution to ensure the liner is properly inserted and expanded (45).
- Navigating bends, fittings, and transitions can be challenging and may require specialized equipment or techniques (45).
- The success of the installation can be affected by factors such as pipe alignment, debris in the host pipe, and variations in pipe diameter (45).
Temperature and environmental limitations:
- Some close-fit liner materials may be sensitive to extreme temperatures, which can affect installation and long-term performance (45).
- Special considerations may be needed for installations in areas with high groundwater levels, extreme soil conditions, or other challenging environmental factors (45).
- In some cases, additional measures such as grouting or external coatings may be needed to protect the liner and ensure optimal performance (45).
7. Future Developments and Trends
7.1 Technological Advancements
Close-Fit Liner technology continues to evolve, with several promising advancements on the horizon:
Advanced materials:
- Development of new polymer formulations with enhanced mechanical properties, chemical resistance, and thermal stability (1).
- Introduction of nanocomposite materials that can provide improved strength-to-weight ratios and durability (1).
- Integration of self-healing properties into liner materials to address minor damage and extend service life (1).
Intelligent liners:
- Development of liners embedded with sensors to monitor structural performance, temperature, pressure, and other parameters in real-time (58).
- Integration of RFID tags or other tracking technologies to facilitate inventory management and maintenance planning (58).
- Creation of liners with built-in diagnostic capabilities that can detect leaks, blockages, or other issues and transmit data to monitoring systems (58).
Improved installation techniques:
- Development of more efficient methods for deforming and inserting liners, reducing installation time and cost (45).
- Introduction of robotic systems for precise placement and expansion of liners, particularly in complex or hard-to-reach locations (45).
- Integration of advanced imaging and navigation technologies to improve the accuracy and reliability of the installation process (45).
Enhanced structural performance:
- Development of hybrid liner systems that combine the advantages of different materials and technologies (1).
- Introduction of liners with variable thickness and reinforcement patterns tailored to specific loading conditions (1).
- Improvement of joint and sealing technologies to enhance the overall integrity and performance of the liner system (48).
7.2 Standardization and Regulatory Trends
The standardization and regulation of close-fit liner technology are also evolving:
International standardization:
- Continued development and harmonization of international standards such as ISO 11296 to facilitate global adoption and application of close-fit liner technology (7).
- Integration of lessons learned from various national standards and practices into international guidelines (7).
- Development of specialized standards for emerging applications and new materials (7).
Performance-based standards:
- Shift toward performance-based standards that focus on desired outcomes rather than prescriptive methods (43).
- Development of comprehensive performance testing protocols that simulate real-world conditions and evaluate long-term performance (43).
- Integration of reliability-based design approaches into standards and guidelines .
Sustainability considerations:
- Development of standards and guidelines that incorporate sustainability criteria such as embodied energy, carbon footprint, and recyclability (43).
- Increased emphasis on lifecycle assessment and whole-life costing in the selection of rehabilitation methods (43).
- Development of environmental performance standards for liner materials and installation processes (43).
7.3 Market and Industry Trends
The market for close-fit liners and related technologies is experiencing several notable trends:
Growing market demand:
- The global plastic liner market is projected to grow from USD 5,201.7 million in 2025 to USD 7,774.1 million by 2035, with a compound annual growth rate (CAGR) of 4.1% (27).
- Increasing focus on infrastructure renewal and sustainability is driving demand for trenchless technologies like close-fit liners (27).
- Urbanization and population growth are creating increased demand for wastewater infrastructure rehabilitation (27).
Expansion of application areas:
- Growing interest in applying close-fit liners for pressure pipelines, such as water mains and gas distribution systems (31).
- Increased use of close-fit liners in industrial applications, including chemical process piping and stormwater systems (31).
- Development of specialized liners for challenging environments such as offshore applications, high-temperature systems, and radioactive waste disposal (31).
Industry consolidation and innovation:
- Mergers and acquisitions among trenchless technology providers are creating larger, more capable companies with broader service offerings (27).
- Increased collaboration between manufacturers, contractors, and research institutions is driving innovation and technological advancement (27).
- Growing emphasis on training and certification programs to ensure consistent quality and performance across the industry (27).
8. Implementation Considerations for Engineering Projects
8.1 Project Planning and Design
Successful implementation of close-fit liner projects requires careful planning and design:
Pre-project assessment:
- Conduct a thorough condition assessment of the existing pipeline using CCTV inspection, structural evaluation, and other appropriate methods (62).
- Evaluate the hydraulic capacity of the existing pipeline and determine if the expected reduction from a close-fit liner will impact system performance (62).
- Consider the surrounding environment, access points, and potential constraints that may affect the installation process (62).
Design considerations:
- Select the appropriate liner material and configuration based on the specific conditions and requirements of the project (45).
- Determine the required liner thickness and structural properties to ensure the rehabilitated pipeline will meet performance expectations (45).
- Design appropriate connections to manholes, fittings, and other appurtenances to ensure a watertight and structurally sound system (48).
- Consider the long-term performance and maintenance requirements of the liner system (45).
Design tools and resources:
- Utilize the latest design standards and guidelines, including ASTM F1216, ASCE MOP 145, and EN ISO 11296 (38).
- Take advantage of specialized software tools developed to facilitate close-fit liner design, such as those based on MOP 145 principles (50).
- Consult with experienced trenchless technology engineers and manufacturers to ensure the design is appropriate for the specific project conditions (50).
8.2 Material Selection and Quality Control
Selecting the right materials and ensuring quality control are critical to the success of close-fit liner projects:
Material selection criteria:
- Consider the chemical composition of the wastewater and potential environmental exposures when selecting liner materials (45).
- Evaluate the mechanical properties of candidate materials, including strength, stiffness, toughness, and creep resistance (45).
- Assess the compatibility of the liner material with the host pipe material and any grouts or other materials that will come into contact with it (45).
- Consider the temperature range the liner will be exposed to during both installation and service (45).
Material testing:
- Conduct appropriate testing of candidate materials to verify they meet the required performance specifications (36).
- Three-point flexural tests (ASTM D790, ISO 178) can be used to measure the force required to bend a beam under three-point loading conditions, providing valuable data on material properties (36).
- For reinforced materials, test specimens should be prepared in both the hoop and longitudinal directions to account for anisotropic properties (36).
- Conduct long-term performance testing to evaluate creep, environmental stress cracking, and other time-dependent phenomena (36).
Quality control measures:
- Implement a comprehensive quality control program that includes material testing, installation monitoring, and post-installation inspection (60).
- Follow established standards and guidelines for material handling, storage, and installation (60).
- Conduct regular inspections and testing during the installation process to identify and address any issues promptly (60).
- Implement a documentation and traceability system to track materials, installation parameters, and test results (60).
8.3 Construction and Installation Best Practices
Successful installation of close-fit liners requires adherence to best practices:
Pre-installation preparation:
- Thoroughly clean the existing pipeline to remove debris, scale, and other materials that could interfere with liner installation or performance (4).
- Repair any significant defects or obstructions in the pipeline that could prevent proper liner insertion or seating (4).
- Prepare access points and staging areas to facilitate liner insertion and equipment setup (4).
- Develop a detailed installation plan that addresses potential challenges and includes contingency measures (4).
Installation techniques:
- Follow the manufacturer's recommendations for liner deformation, insertion, and expansion (45).
- Use appropriate equipment and techniques to ensure the liner is inserted smoothly and without damage (45).
- Monitor the insertion process closely to detect any 异常 or resistance that could indicate a problem (45).
- Control the expansion process carefully to ensure the liner achieves full contact with the host pipe and maintains the required dimensions (45).
Post-installation inspection and testing:
- Conduct a post-installation CCTV inspection to verify the liner's condition and ensure proper installation (4).
- Perform appropriate pressure or vacuum tests to confirm the liner's integrity and watertightness (4).
- Inspect connections to manholes, fittings, and other appurtenances to ensure they are properly sealed (4).
- Document the results of all inspections and tests for future reference (4).
Safety considerations:
- Implement appropriate safety measures for all personnel involved in the installation process (4).
- Follow all applicable regulations and standards for working in confined spaces, handling materials, and operating equipment (4).
- Provide adequate training and personal protective equipment for all workers (4).
- Develop and implement an emergency response plan for potential incidents (4).
8.4 Maintenance and Long-Term Performance
Proper maintenance is essential to ensure the long-term performance of close-fit liners:
Routine inspection and monitoring:
- Establish a regular inspection schedule based on the liner's expected service life and the conditions to which it is exposed (45).
- Use CCTV inspection and other appropriate techniques to evaluate the liner's condition over time (45).
- Monitor flow rates, pressure, and other operational parameters to detect any changes that could indicate liner degradation or blockage (45).
Preventive maintenance:
- Implement a preventive maintenance program that includes regular cleaning and inspection (45).
- Address minor issues promptly to prevent them from developing into more significant problems (45).
- Develop and follow a maintenance plan that is tailored to the specific characteristics of the liner and the operating conditions (45).
Repair and rehabilitation strategies:
- Develop strategies for repairing or rehabilitating close-fit liners that have been damaged or degraded over time (45).
- Consider the use of localized repair techniques for minor damage, while reserving full liner replacement for more severe issues (45).
- Evaluate the feasibility of combining close-fit liners with other rehabilitation methods for comprehensive solutions (45).
Lifecycle management:
- Develop a comprehensive lifecycle management plan that considers initial costs, maintenance requirements, and replacement intervals (45).
- Consider the environmental impact and sustainability of the liner system throughout its lifecycle (45).
- Update the lifecycle plan regularly based on actual performance data and changing conditions (45).
9. Conclusion
Close-Fit Liner technology represents a valuable addition to the engineer's toolkit for municipal drainage pipe rehabilitation. This comprehensive guide has explored the technical principles, application scenarios, case studies, standards, and comparative advantages of this trenchless rehabilitation method.
Key takeaways include:
- Technical superiority: Close-fit liners offer excellent structural performance, hydraulic efficiency, and durability when properly designed and installed (18).
- Application versatility: The technology can be applied to a wide range of pipe materials, diameters, and conditions, making it suitable for many municipal drainage applications (31).
- Proven track record: Successful implementations in both the United States and Europe demonstrate the reliability and long-term performance of close-fit liners (18).
- Standardization and regulation: A growing body of standards and guidelines provides a solid foundation for the design, installation, and quality control of close-fit liner systems (38).
- Cost-effectiveness: While initial costs may be higher than some alternatives, the overall lifecycle cost of close-fit liners is often competitive when considering reduced disruption, maintenance, and replacement needs (45).
As municipalities worldwide face increasing challenges with aging infrastructure and limited budgets, close-fit liner technology offers a compelling solution for extending the service life of drainage systems while minimizing disruption and environmental impact. By leveraging the latest advancements in materials, design, and installation techniques, engineers can effectively address the rehabilitation needs of municipal drainage systems and ensure their continued reliable performance for decades to come.
The future of close-fit liner technology looks promising, with ongoing developments in materials science, intelligent liners, and installation techniques poised to further enhance the capabilities and applications of this important trenchless rehabilitation method. As these advancements are incorporated into standards, guidelines, and industry practices, close-fit liners will continue to play a vital role in the sustainable renewal of municipal infrastructure.
参考资料
[1] Close-Fit Liner: Technical Guide to Variations of Close-Fit Liners for Mainline Pipe | Underground Construction https://undergroundinfrastructure.com/magazine/2022/november-2022-vol-77-no-11/features/close-fit-liner-technical-guide-to-variations-of-close-fit-liners-for-mainline-pipe
[2] Design of Close-Fit Liners for the Rehabilitation of Gravity Pipes | Books https://ascelibrary.org/doi/10.1061/9780784415801
[3] DB(pdf) https://swj.wuhan.gov.cn/xxgk/new_qtzdgknr/new_jcygg/202301/P020230105613019242933.pdf
[4] 短管内衬 局部内衬修复处理 施工操作规范 收费透明合理 视频 https://m.11467.com/product/d36310807.htm
[5] 【图朴解决方案】雨污混接改造采用哪些施工方法?|内壁|内衬|型材|塑料|混接改造|砂浆|软管|雨污_手机网易网 http://m.163.com/dy/article/JR69MFFA0538EZRW.html
[6] 地下供水管网非开挖修复用塑料管道系统 第11部分:软管穿插内衬法(pdf) https://m.book118.com/try_down/415302211200012111.pdf
[7] GBT 41666.3-2022 地下无压排水管网非开挖修复用塑料管道系统 第3部分:紧密贴合内衬法.docx - 人人文库 https://m.renrendoc.com/paper/337195585.html
[8] GB∕T 41666.3-2022 地下无压排水管网非开挖修复用塑料管道系统 第3部分:紧密贴合内衬法-20240308090910.pdf-原创力文档 https://m.book118.com/html/2024/0308/7163056110006050.shtm
[9] 内衬速格垫混凝土和钢筋混凝土管道 工程技术规程(pdf) https://www.china-cas.org/u/cms/www/202007/271355177ukx.pdf
[10] LINER LONG-TERM PERFORMANCE LIFE PREDICTION USING CRITICAL BUCKLING STRAIN https://www.semanticscholar.org/paper/LINER-LONG-TERM-PERFORMANCE-LIFE-PREDICTION-USING-Wei-Grant/8aa429b5adadba1fc5be0da44de6714cff17cfbf
[11] Structural Design of Close-Fit Liners in Fractured Rigid Circular or Non-Circular Gravity Pipes https://www.semanticscholar.org/paper/Structural-Design-of-Close-Fit-Liners-in-Fractured-Th%C3%A9pot/a7ae79eaaaf65ba8e3ed0f6faec4ea2370947915
[12] Design of Close-Fit Liners for the Rehabilitation of Gravity Pipes https://www.semanticscholar.org/paper/Design-of-Close-Fit-Liners-for-the-Rehabilitation/bac2954c137bcb40809e8c7e2cf866aa3c28fb10
[13] Update on the ASTM International Standard Test Method for Respirator Fit Capability. https://www.semanticscholar.org/paper/Update-on-the-ASTM-International-Standard-Test-for-Coffey-Miller/7489ca441154dcf881307221d73c3db656582d6f
[14] NordiTube offers safe solutions for asbestos cement water pipes https://m.zhangqiaokeyan.com/journal-foreign-detail/0704034572927.html
[15] Duct Liner Specification Improvement https://www.ingentaconnect.com/contentone/ince/incecp/2020/00000262/00000001/art00068
[16] Close-Fit-Liner——Verfahrensbedingte BeeinflussungWerkstoffeigenschaften和Rohrlangzeitverhaltens 展开▼
展开▼ https://m.zhangqiaokeyan.com/journal-foreign-detail/0704031684298.html
[17] Automated Composite Pipe Cutting Machine for ASTM Standard Testing Specimen Preparation https://discovery.researcher.life/article/automated-composite-pipe-cutting-machine-for-astm-standard-testing-specimen-preparation/c8aa2406e2a2345ab85e562f8c94155d
[18] 数十年来,运河再次合体在奥地利阿特湖上进行修身改造 https://m.zhangqiaokeyan.com/academic-journal-foreign_gwf_thesis/020416010735.html
[19] 美国材料与试验协会(ASTM)标准题录(上) https://m.zhangqiaokeyan.com/academic-journal-cn_standard-living_thesis/02012149891407.html
[20] [Standard and special liner in primary hip arthroplasty : Current study and survey results from the German Arthroplasty Registry (EPRD)] https://pubmed.ncbi.nlm.nih.gov/36635446/
[21] The impact of using an ASTM standard. https://www.semanticscholar.org/paper/The-impact-of-using-an-ASTM-standard.-Seeger/18fb7e3ad680e964d8a8e2e3e574adc3f2386567
[22] Close-fit pipes lining system of trenchless technology having means for preventing deformation by changes of temperature and apparatus thereby https://www.semanticscholar.org/paper/Close-fit-pipes-lining-system-of-trenchless-having-%EA%B9%80%EC%98%81%ED%83%9D-%EC%86%A1%ED%98%B8%EB%A9%B4/b3205c47c749d4bbbdaf398377e8aa42bbdcefad
[23] 美国材料与试验协会(ASTM)标准题录(中)(2003年版) https://m.zhangqiaokeyan.com/academic-journal-cn_world-standard-information_thesis/020123814190.html
[24] No difference in range of motion in reverse total shoulder arthroplasty using standard or constrained liners: a matched cohort study https://pubmed.ncbi.nlm.nih.gov/36353430/
[25] Compilation of ASTM Standard Definitions https://www.semanticscholar.org/paper/Compilation-of-ASTM-Standard-Definitions-Townshend/73681cd873f912f716d940834dd62b14822deb1d
[26] Development and use of ASTM standards for wear testing https://www.semanticscholar.org/paper/Development-and-use-of-ASTM-standards-for-wear-Blau-Budinski/6451d3d898f33a9b67e1db86efd7c3310adb2cfd
[27] Plastic Liner Market Size & Trends 2025-2035 https://www.futuremarketinsights.com/reports/plastic-liners-market
[28] Prosthetic Liner Market Trends & Forecast Analysis to 2031 https://www.factmr.com/report/prosthetic-liners-market
[29] Container Liner Market Trends, Outlook 2025 to 2035 https://www.futuremarketinsights.com/reports/container-liner-market
[30] Close-Fit Liners | ASTM Standardization News https://sn.astm.org/update/close-fit-liners-nd10.html
[31] Close-Fit Lining - ASTT https://www.yumpu.com/en/document/view/42132311/close-fit-lining-astt
[32] Web-Based Database on Renewal Technologies https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=P100PHAK.txt
[33] ASTM Standards 2023 | Expert Guide to ASTM Safety Shoes https://larnmernwork.com/blogs/news/astm-standards-2023-expert-guide-to-astm-safety-shoes
[34] Interim Report 2 : Synthetic Cap and Liner Systems https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=91022OGE.txt
[35] ASCE Manual of Practice for Design of Close-Fit Liners for the Rehabilitation of Gravity Pipes Is Here https://trenchlesstechnology.com/asces-manual-of-practice-for-design-of-close-fit-liners-for-gravity-pipe-rehab-is-here/
[36] Studying the Properties of Close-fit Liners | Trenchless Technology https://trenchlesstechnology.com/studying-the-properties-of-close-fit-liners/
[37] Cushion Case Liner Market 2025-2034 | Size,Share, Growth https://markwideresearch.com/cushion-case-liner-market/
[38] F1216 Standard Practice for Rehabilitation of Existing Pipelines and Conduits by the Inversion and Curing of a Resin-Impregnated Tube https://www.astm.org/f1216-22.html
[39] ASTM-F1216 | Standard Practice for Rehabilitation of Existing Pipelines and Conduits by the Inversion and Curing of a Resin-Impregnated Tube | Document Center, Inc. https://www.document-center.com/standards/show/ASTM-F1216
[40] ASTM F1216-98 https://www.techstreet.com/standards/astm-f1216-98?product_id=13457
[41] ASTM-F1216, 2016 - MADCAD.com https://www.madcad.com/store/subscription/ASTM-F1216-16?landing=1
[42] Glass Standards and Ceramic Standards - Standards Products - Standards & Publications - Products & Services https://www.astm.org/products-services/standards-and-publications/standards/glass-standards-and-ceramic-standards.html
[43] Proposed New ASTM Plastic Piping System Standard to Focus on Design Calculations | NEWSROOM https://newsroom.astm.org/proposed-new-astm-plastic-piping-system-standard-focus-design-calculations
[44] Fine Abrasive Liner (ASTM & AATCC) (Pack of 50) | Test Material Products | SDL Atlas https://sdlatlas.com/test-materials/abradents/fine-abrasive-liner-astm-aatcc-pack-of-50
[45] Restoration Data Collection and Modeling for a Modified Cross-Section Close Fit Lining Trenchless Technology Application | Proceedings | Vol , No https://ascelibrary.org/doi/10.1061/9780784484272.007
[46] Medium Abrasive Liner (ASTM & AATCC) (Pack of 50) | Test Material Products | SDL Atlas https://sdlatlas.com/test-materials/abradents/medium-abrasive-liner-astm-aatcc-pack-of-50
[47] Design of Close-Fit Liners for the Rehabilitation of Gravity Pipes https://sp360.asce.org/PersonifyEbusiness/Merchandise/Product-Details/productId/275088835
[48] Close-fit Lining - HDPE pipe systems (plastic & polyethylene pipe) - PE100+ association https://www.pe100plus.com/PE-Pipes/Technical-guidance/Trenchless/Methods/Pipe-Rehabilitation/Close-fit-Lining-i4010.html
[49] Technical guide to variations of close-fit liners for mainline pipe | Underground Construction https://undergroundinfrastructure.com/magazine/2023/april-2023-vol-78-no-4/rehab-technology/technical-guide-to-variations-of-close-fit-liners-for-mainline-pipe
[50] New Software Simplifies, Facilitates Use of ASCE MOP 145 for Close-Fit Liners | Underground Construction https://undergroundinfrastructure.com/magazine/2022/april-2022-vol-77-no-4/rehab-first-look/new-software-simplifies-facilitates-use-of-asce-mop-145-for-close-fit-liners
[51] Liner Shipping in 2025 https://www.porttechnology.org/technical-papers/liner_shipping_in_2025/
[52] Release Liners Market Size, Share & Forecast | Report, 2032 https://www.marketresearchfuture.com/reports/release-liner-market-6241
[53] EPE Liner Market Size, Trends, Share & Forecast 2025-2035 https://www.futuremarketinsights.com/reports/epe-liner-market
[54] Technology – 6D Helmets https://www.6dhelmets.com/pages/technology
[55] Design, Construction, and Evaluation of Clay Liners for Waste Management Facilities https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=100018BV.TXT
[56] The Best Gas Mask Buyers' Guide for 2025 | MIRA Safety https://www.mirasafety.com/blogs/news/the-best-gas-mask-buyers-guide
[57] Liner Buckling Design Using Critical Buckling Strain https://www.semanticscholar.org/paper/Liner-Buckling-Design-Using-Critical-Buckling-Whittle/1d7876b07662a89761e096cadbe94898dd4c7bb1
[58] A personalised prosthetic liner with embedded sensor technology: a case study https://pubmed.ncbi.nlm.nih.gov/32928238/
[59] Buckling Behavior of Loosely Fitted Formed-In-Place Pipe Liner in Circular Host Pipe under External Pressure https://www.semanticscholar.org/paper/Buckling-Behavior-of-Loosely-Fitted-Formed-In-Place-Zeng-Yan/a8f956df799cad7c014f6651691b4c59a774c0eb
[60] Quality Assurance of CIPP Liners According EN ISO 11296-4 https://www.semanticscholar.org/paper/Quality-Assurance-of-CIPP-Liners-According-EN-ISO-Cigler-Kube%C4%8Dka/f7fc295f649e853565084417fbd999620ae35b3f
[61] New Approach to Design of Circular Liner Pipe to Resist External Hydrostatic Pressure https://www.semanticscholar.org/paper/New-Approach-to-Design-of-Circular-Liner-Pipe-to-Gumbel/732d73f18f06aad96fba23d604c44a7af7bbf7fa
[62] Case Study from Trenchless Rehabilitation Evaluation of North McKinney Interceptor Main for North Texas Municipal Water District https://ascelibrary.org/doi/10.1061/9780784483626.008
[63] Assessment of polyethylene wear in dual mobility implant for Asians on various head-to-liner ratios: A finite-element analysis https://journals.sagepub.com/doi/abs/10.1177/13506501241240021
[64] Accuracy and precision of the measurement of liner orientation of dual mobility cup total hip arthroplasty using ultrasound imaging https://pubmed.ncbi.nlm.nih.gov/36195356/
[65] A study of the compression molding method for manufacturing a UHMWPE liner https://www.semanticscholar.org/paper/A-study-of-the-compression-molding-method-for-a-Wicaksono-Ismail/071607ba5ad33de6dbf06e7c487e1bf5e0baf5ba
[66] Techniques for Assessing Case Liner-Bond Integrity in Solid Propellant Rocket Motors https://www.semanticscholar.org/paper/Techniques-for-Assessing-Case-Liner-Bond-Integrity-Anderson-Oavelka/d13c5619fc957df6fa0044ef289b7e830cbce8b9
[67] Parametric Study for Buckling of Liners: Effect of Liner Geometry and Imperfections https://www.semanticscholar.org/paper/Parametric-Study-for-Buckling-of-Liners:-Effect-of-El-Sawy-Moore/cdf918159c1ab998eca0d86ddd01952031167a77
[68] Cementation of a polyethylene liner into a metal acetabular shell: a biomechanical study https://pubmed.ncbi.nlm.nih.gov/18701253/
[69] Structural Performance of Additively Manufactured Cylinder Liner—A Numerical Study https://www.semanticscholar.org/paper/Structural-Performance-of-Additively-Manufactured-Alshwawra-Swerih/b8f48557927164c67428188098acd0c10f385fc6
[70] Reliability of the liner system using the response surface method https://www.semanticscholar.org/paper/Reliability-of-the-liner-system-using-the-response-Santhosh-Babu/9640665f8ca94f92574cd2c6168875cb4a07d7d2