Oversight and elimination of refinery

During the period from 1968 until 2012, I was directly involved in the non-destructive testing (NDT) activities at the Chevron Richmond Refinery. During that period, the refinery had several significant material failures. The NDT programme was largely very effective and prevented several mishaps.

A refinery is an ongoing opportunity for material failure and potentially significant fire and/or explosion. The following is a description of a relatively recent example of the dangers inherent in oil refineries. I count my blessings that during the period in which I was intimately involved in ‘on-stream’ NDT examinations, I was never a victim of an explosion, despite some close calls.

The Chevron Richmond Refinery experienced a catastrophic pipe rupture at its process plant on 6 August 2012. During the incident, there was 10,800 barrels per day of light gas oil flowing through the pipeline. The plant operated at 338°C and a pressure of 55 PSIG at the incident location. The flammable hydrocarbon was released to the air through the ruptured pipe and then vapourised into a massive, opaque vapour cloud.
18 employees escaped from the cloud before the ignition, while one employee, a firefighter, was caught within the fire but emerged safely because he was protected by firefighting equipment.

The technical cause of the pipe rupture was due to the sulphidation corrosion. It was discovered that the pipe had experienced intense thinning and the average wall thickness close to the rupture area was around 40% thinner than the thinnest American coin. The 52" piping had an initial thickness of 0.322" in 1976, but in 2012 it was reported that the pipe had lost 90% of its original thickness due to the corrosion.

It was reported that, before the incident, the small group of employees who were experts in sulphidation corrosion provided a recommendation regarding the problems, but the recommendations were not employed and the piping continued in service until it failed.

There was no high-level manager assigned to guarantee that the recommendations were included in the turnaround scope. The 4-sidecut piping was proposed to have 100% component inspection or to upgrade the material of construction, but the recommendations were excluded by the turnaround planning group.

The Chevron refinery had made the calculation to determine the date to replace the thinned pipe. Based on the calculation, it was predicted that the piping could still be operated until the next turnaround. Guidelines from API RP 574 already stated the minimum thickness for the piping but, during the detailed calculation, the specification from API RP 574 was not used.

The safety issues were also one of the ethical points related to the Chevron incident. Based on the report, the Chevron refinery continued to run regardless of the harmful leaks. There was another leak that occurred in 2010, where they continued operation despite the flammable process fluid released in an active unit.

>Secondly, it was found that the employees were disinclined to use the Stop Work Authority. This was proven by the safety culture surveys that showed that the employees had become less willing to use their Stop Work Authority between the years 2008 and 2010. Thus, as a result, people thought that they were doing the job or task correctly as they were following the culture.

>The reaction between sulphur and iron at certain temperatures can lead to corrosion. For the Chevron refinery, it was found that the piping material constructed was made up of carbon steel, which can corrode faster when reacting with the sulphur element. Basically, the typical material used to avoid sulphidation corrosion is higher chromium containing steel.

It was found that the 4-sidecut piping in the Chevron refinery did not fulfil the requirements from ASTM A53B for carbon steel to have the minimum content of silicon. This was proven by the post-incident investigation of the carbon steel piping. From that investigation, there were 12 samples taken and it was found that six of the samples had a silicon content less than 0.1 wt%. The pipe component that ruptured and failed during the incident had a silicon content of only 0.01 wt%.

Suggestions to solve the problem
High-level management need to understand their roles and responsibilities and become role models to the employees. The management need to show ethical behaviour and decision-making in their actions. They need to provide guidelines and remind the employees on the rules and regulations. Besides that, management have to be alert to any response from the employees.

The best suggestion for the problem related to the safety culture is enforcement of safety awareness. All employees need to be educated in safety awareness or information related to their process plant. Safety awareness among the employees can be carried out through lessons learned from previous incidents. It is important for employees to identify and understand the hazards and develop an effective safety culture.

Conclusion
In conclusion, an incident is less likely to occur when all levels of people in the workplace take part in effectively fulfilling their responsibilities. Study cases from the Chevron refinery show that a little ignorance or lack of responsibility to the problem can lead to major disaster. Both the management and employees need to work together hand in hand to ensure that the plant operates safely. The culture within the organisation should be developed with rules and regulations, as well as ethics.

Information for this article has been extracted from an article published in an ‘Inspection Connection’ blog dated 6 August 2022.