FRP wrapping: an inexpensive, reliable repair solution

July 21, 2023
Before and after images of a portion of a piping system repaired with FRP wrap in a sewer system wet well.
Before and after images of an FRP wrap repair on steel piping in a wet well at a wastewater facility.

FRP wraps are increasingly used to repair pipes, pipeline systems and other infrastructure for oil and gas, municipal water and sewage, district heating systems and other industry applications.

Adding layers of FRP to reinforce damaged piping and pressure vessels is a proven fast, inexpensive and safe alternative to traditional repair methods that require removing and replacing damaged sections of pipe, encasing it with a steel sleeve, or welding a patch onto the pipe. The process of dismantling defective sections of pipe can cause even more damage and typically requires a partial or temporary shutdown of operations.

FRP wrap repair on a wastewater piping system
FRP wrap repair on wastewater piping

FRP wrap advantages

FRP composite materials have a longer lifespan and greater ability to withstand corrosive environments than other materials. Hand-wrapping layers of FRP over the damaged area allows for quick, effective repairs that save time and money with minimal downtime. FRP wraps also enable infrastructure managers to delay major repairs until their next scheduled maintenance period – in fact, a well designed and installed wrap will often give owners years of service without concern.

Note that the wrap must be bonded, especially along the edges, so that any leaks that develop through the substrate (e.g., steel, concrete, wood) are contained by the wrap, which is designed for this purpose. Until the substrate starts to fail, the wrap is simply “waiting” to be called into action.

Inspecting FRP wraps

As FRP wrapping is done by hand, the quality of repairs using this method is variable and highly dependent on individual workmanship. In general, companies that use FRP wrap reinforcement to extend the life of their equipment must inspect and monitor the repair to answer these two questions:

  1. Is the FRP overwrap in good condition?
  2. Is the FRP properly bonded / attached to the steel? (Bonding along the edges can change in service due to different thermal expansion of the substrate and the wrap material.)

While it’s impossible to predict the remaining lifespan of the overwrap until the material encased by the FRP begins to fail, UltraAnalytix NDT inspection quickly and reliably answers both these questions by: 

  • accurately measuring the thickness of the FRP wrap, and 
  • assessing the quality of the bond (the contact factor)

Done properly and inspected regularly, FRP wrapping provides additional structural reinforcement and leak protection that will likely outlast the pipe itself. 

Note that UltraAnalytix inspection does not measure the thickness of the underlying steel, but this can be done using other non-destructive testing methods in concert with the UltraAnalytix NDT system.

Read our case study of an FRP wrap inspection at a petrochemical facility in Saudi Arabia: