Wedge Impact Tests on FRP laminates used in Jet Bubbling Reactors

Flue gases emitted by coal fired power plants use large vessels called Jet Bubbling Reactor (JBR) also known as scrubber units to put air pollution measures in place. The environment in these air pollution control systems is highly corrosive to metals (e.g. stainless steel). As a result fiberglass reinforced plastic (FRP) composites with epoxy vinyl ester resins have proven to be an effective material for construction of these pollution control JBR's.

FRP composites with dual laminate technology can improve life span of the structure. Inner corrosion resistant liners in these dual laminates are reinforced with an outer layer of fiberglass resulting in a strong and light weight structure.Typically, hand-lay-up is the best suited lamination technique for construction of these scrubbers in which case, human error can be a significant factor. Regional environmental conditions can also affect curing of the resin which in turn affects bonding of various layers in the laminate. Therefore, quality checks are widely performed on the bond strength of these dual laminates from time to time.

We used the wedge impact fixture on a CEAST 9350 to test the bond strength of a 40% glass/epoxy laminate. This composite laminate with random fiber orientation was hand-laid-up & cured at 32ºC. Coupon specimens were prepared to ISO 11343 and were impacted with a special striker used for adhesive bonds in conjunction with a symmetric wedge.

In contrast to an in-field manual peel test, using this wedge impact fixture is a good way to create reproducible & reliable data on the bond strength of laminates from different parts of the JBR, for example, the gas cooling duct, the mist eliminator & the reaction zone at base of the JBR for quality control purposes.