Test Method for Measurement of Peel Strength of Multilayer Polyolefin Coating Systems

This test method describes a reliable methodology for determining the peel strength of polyolefin-based multilayer pipeline coating systems, generally for coating thickness less than 12 mm (0.47 in). This standard provides a method to measure the peel strength of polyolefin-based multilayer coating systems, such as 2-layer polyethylene coating (2LPE), 3-layer polyethylene (3LPE), 3-layer polypropylene (3LPP), and heat shrink sleeve (HSS) field joint coating. It provides essential information on the quality of the applied coating. This is particularly important for field-applied coatings, of which the application process is significantly impacted by the environmental conditions and the skill set of the field applicators.

There have been several efforts in the past to develop a reliable field peel strength test method for coating systems. Current practice and standards allow the use of different methods to measure peel strength, leading to inconsistent results. Examples include a method that uses a hand-held, spring-loaded gauge without control of the peeling speed and angle; and a hanging weight test method where the peeling angle varies with pipe size and position at the point of peeling. There are types of equipment capable of providing consistent peel test results as noted in ISO 21809-1 and ISO 21809-3; however, that equipment is often complicated, heavy, more practical for in-house use, but inconvenient to operate in the field.