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Plastic Pipe and Fitting Failure Analysis: Understanding the Causes and Solutions


By PPN Editor | 26th October 2023


Plastic pipes and fittings have become an integral part of modern infrastructure, offering versatility and cost-effectiveness in various applications. However, like any other material, plastic pipes and fittings can experience failures, leading to significant consequences. In this article, we will delve into the various aspects of plastic pipe system failures, including their root causes and potential solutions.

Performance Characteristics

Plastic pipe systems are made from a variety of materials such as UPVC, CPVC, PE, PEX, PP, ABS, Polybutylene (PB), PVDF, and GRP, each offering distinct performance characteristics tailored to specific applications. These materials are used to create extruded pipes of varying diameters, complemented by injection-molded fittings, including tees, elbows, adapters, and sleeves. The proper functioning of a thermoplastic pipe system is influenced by factors like time, temperature, and applied stress, which can impact the material’s long-term behavior and product life. Therefore, careful consideration of material properties during the design stage is crucial for ensuring the reliability of the installation over its lifecycle.

Installation Variables

The success of a plastic pipe system depends on the installation process. During installation, several variables must be taken into account to ensure the system’s longevity. Common installation issues include poor-quality heat welding or solvent cement jointing, inadequate provisions for thermal expansion, and insufficient fixed supports. These issues can create stress on the system and affect its performance, potentially leading to failures.

Types of Failures

Failures in plastic pipe systems can be classified into four main categories:

  1. Manufacturing: These failures stem from faults in the original pipe or fittings.
  2. Workmanship: Faulty installation or engineering practices can lead to failures.
  3. Environmental: Factors such as chlorine oxidation, extreme temperatures, pressure fluctuations, contamination, or solvent cement effects can affect the system’s performance.
  4. Operational: When a system operates outside its design criteria, whether during storage or post-installation, it can lead to failures.

In cases of plastic pipe failures, litigation often ensues, resulting in a blame game between installers, end-users and pipe manufacturers. End-users blame the manufacturer, while manufacturers point to issues with installation, operation, or maintenance.  This scenario, known as the IOM (Installation-Operation-Maintenance) defence, has become all too common in plastic pipe failure litigation.

Performance Testing

Performance testing is essential for assessing plastic pipe systems. It involves evaluating various factors such as appearance, dimensions, resistance to internal pressure, impact resistance, tensile strength, Vicat softening temperature, longitudinal reversion, and thermal stability. Rigorous analytical testing ensures that the pipes and fittings meet the required standards and specifications.

ExcelPlas: Your Partner in Failure Analysis

ExcelPlas specializes in investigating plastic pipe system failures and provides comprehensive root cause diagnosis. Our team of polymer experts possesses a deep understanding of polymer behaviour, failure modes, design, and processing. We offer a range of services related to plastic pipes, fittings, and seals, from concept to end-of-life, including polymer characterization and product testing.

Our extensive microscopy, analytical, material, and product testing laboratories allow us to fully characterize polymer composition and mechanical performance, enabling us to identify the causes of product or material failure. We provide recommendations for remedial or corrective actions to mitigate the risk of further failures.


Understanding the causes of plastic pipe and fitting failures is essential for ensuring the reliability and longevity of these systems. Whether it’s issues with manufacturing, workmanship, environmental factors, or operational challenges, ExcelPlas is your trusted partner in conducting a thorough failure analysis. By addressing the root causes of failures, we help pipe manufacturers and service installation sectors enhance the performance and safety of plastic pipe systems, ultimately benefiting end-users and minimizing risks.

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