FAILURE OF POLYPROPYLENE LINED PIPE IN SULFURIC ACID - A CASE HISTORY

摘要

Polypropylene (PP) and PVDF lined pipe experienced frequent failures in spent (60-78 percent) sulfuric acid after about seven to ten years in service. The failures were due to exceeding the design temperature when mixing 98 percent acid where high temperature is generated which then created thermal stress in the liner and bolted flared joints and developed cracks and product leaks. The PP was replaced by Polytetrafluoroethylene (PTFE) lined pipe using proper bolting torque. PTFE has been in service for more than 7 years without any failure.