High Density Polyethylene (HDPE) pipe is one type of nonmetallic piping material used for a wide range of applications and services, such as fire water, oil and gas. HDPE pipes provide many advantages, including corrosion resistance, lightweight, flexible, and cost effective. Appropriate HDPE construction methods should be developed and followed to mitigate any risk of failure in the piping, fittings or joints. This paper illustrates the challenges faced during the construction of a new project. Furthermore, HDPE field fabricated joints — that failed hydrotesting due to air entrapment — will be showcased. Although the total number of failed joints was insignificant compared with the total joints completed; a thorough review was carried out to prevent any similar failures during operations. The review identified the root cause, the best practices and recommendations wherein the main is to ensure proper venting and to allow for more time to stabilize the pressure during hydrotesting. Sharing these real-life challenges will help avoid recurrence of these failures and their associated cost, and impact on safety and operations.
High-density polyethylene (HDPE) is a thermoplastic polymer that with the application of heat and pressure can form desirable shapes. HDPE is defined as a polyethylene containing very few short-chain branches (< 4 per 1,000 carbon atoms), having a density greater than 0.940 g/cm3 [1]. HDPE pipes have been used around the world in different fields, such as fire water, potable water, seawater, waste water, oil, and gas services. The performance of HDPE depends on three key parameters: density, molecular weight and molecular weight distribution. These parameters play a crucial role in designing the HDPE pipe to suit the intended service [2].
As the use of HDPE in fire water service is considered relatively new, this technical paper provides information related to utilization of HDPE in Fire Water Service, including advantages and disadvantages when compared to RTR, common challenges that are faced when installing HDPE pipes in new projects such as NDT applicability, poor workmanship, and installers qualification, quality control recommendations and a case study of HDPE field fabricated joints that failed hydrotesting due to air entrapment. Figures 1 and 2 show installed HDPE pipe and an HDPE joint undergoing welding.
