Assessment of the Service Life of Polyethylene Pipes with Controlled Defects Using Internal Pressure Test

Area of Science:

• Materials Science
• Mechanical Engineering
• Civil Engineering

Background:

• API 579-1/ASME FFS-1, Part 9 guidelines define crack-type defects.
• HDPE pipes (PE100, SDR 17) are crucial for water distribution systems.
• Understanding defect impact is vital for infrastructure safety and longevity.

Purpose of the Study:

• To evaluate the influence of controlled, crack-type defects on the strength of HDPE water pipes.
• To determine critical pressure, time, and defect depth for pipe failure.
• To estimate the remaining service life of pipes with different defect orientations.

Main Methods:

• Controlled internal pressure testing of HDPE pipes with induced defects.
• Numerical simulations to analyze stress and failure mechanisms.
• Application of API 579-1/ASME FFS-1 standards for defect assessment.

Main Results:

• Identified critical pressure (Pcr), critical time (tcr), and critical defect depth (acr).
• Circumferentially oriented defects resulted in a remaining service life of approximately 83 years.
• Longitudinally oriented defects resulted in a remaining service life of approximately 69 years.

Conclusions:

• Controlled defects significantly reduce the service life of HDPE water pipes.
• Defect orientation plays a critical role in determining the remaining structural integrity.
• The study provides valuable data for assessing the safety and maintenance of aging HDPE pipelines.