Chemical Degradation of High-Density Polyethylene
Specimen: High-density Polyethylene Sulfuric Acid Storage Tank (mining industry)
Material: High-density Polyethylene
Background: The plastic sulfuric acid storage tank had been in service for approximately 15 years. An inspection of the tank was performed to determine if it was still suitable for further service.
Service Life: Approximately 15 years.
Findings: Examination of the interior of the tank revealed the interior surface was riddled with surface cracking - caused by chemical attack of the sulfuric acid on the HDPE. A cross-section through the tank wall revealed the presence of micro-cracking. Based upon the condition of the tank, it was deemed unfit for further service and it was recommended that the tanks be replaced immediately.
Interior surface of the HDPE sulfuric acid tank which had clearly suffered chemical attack during the 15 years of service, b) A cross-section through the tank wall revealed the presence of micro-cracks.