Failure analysis of the adhesive metal joint bonded on anticorrosion plastic alloy composite pipe

The break off of adhesive metal joint from the anticorrosion plastic alloy composite pipe has caused serious burst. Investigations are performed to identify the most probable causes of the break off. The development of the composite pipe, the inner liner and outer GRP layer, glass transition temperature (Tg) and bonding strength of the adhesive resin are investigated in detail to understand the reasons of failure. Results have revealed that a fully break off of the adhesive metal joint from the composite pipe causes the burst of the pipeline. The average Tg value of the cured adhesive resin suggests that it is suitable for transporting the media with a temperature lower than 60 °C. Moreover, the shear strength of adhesive resin reaches maximum at room temperature and decreases with either increased or decreased temperature. The continuous higher working temperature of the whole pipeline causes gradual decrease of the bonding strength of adhesive resin and results in final break off of the adhesive metal joint.