Case Histories » Mining

Chemical Degradation of High-Density Polyethylene

Chemical degradation of the interior of a polyethylene sulfuric acid tank
Interior surface of the HDPE sulfuric acid tank which had clearly suffered chemical attack during the 15 years of service
Cracking within wall thickness of an HDPE sulfuric acid tank
A cross-section through the tank wall revealed the presence of micro-cracks.

Specimen

High-density polyethylene sulfuric acid storage tank.

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 service.

Service Life

Approximately 15 years.

Findings

Examination of the interior of the tank revealed a surface riddled with surface cracking caused by chemical attack of the sulfuric acid on the HDPE. A cross-section of the tank wall revealed the presence of micro-cracking. Based on the condition of the tank, it was deemed unfit for further service. It was also recommended that the tank be replaced immediately.