(54e) Mechanical Integrity Best Practice for Sulphuric Acid Plants

In applying the principles of process safety management to a sulphuric acid plant, Mechanical Integrity is probably the most important element. The harsh operating environments that exist throughout an acid plant result in the need for careful attention especially to reliability engineering, materials selection, good operating principals and good maintenance regimes.

Extensive downtime for sulphuric acid plants is really not an option for any company operating one. In most pyrometallurgical smelter complexes, loss of the acid plant would immediately necessitate shut down of the entire plant due to pollution concerns. Where acid is used as a raw material (e.g. fertiliser industry, hydrometallurgical metals production) or regenerated in the chemical process industry, the interruption of raw materials would have an immediate effect on downstream processes. Of particular note, in the metallurgical processing industry, there is a noticeable shift from acid producers (pyrometallurgical processes) to acid users (hydrometallurgical processes). This is resulting in a reduction of available and relatively cheap smelter acid. In turn there has been a large increase the value of sulphuric acid.

Because of the issues noted, the drive to improve plant availability and especially avert catastrophes that could result in long term plant outage is of paramount importance to the industry. Although some industries (such as the Florida fertilizer industry) have gone a long way to developing best practice, there is a need to consolidate these best practices across all industries, especially new hydrometallurgical plant operators now operating large sulphur burning plants.

This paper looks at the best practice maintenance and operating procedures for sulphuric acid plants within the scope of mechanical integrity. More specifically breaks down the analysis into six key equipment factors: Environment, Safety Devices, Contingency Planning, Age/History, Maintenance, Operator Training, and Operating Conditions. The overall goal is to define a good general best practice for the industry.