Process Safety Moments
This page contains brief descriptions of situations that have occurred at process facilities which can teach important lessons. Questions are posed to help focus on the key points.
New moments are added regularly so check back periodically.
Human Factors in the HMI
On investigating an incident involving high temperature heat transfer fluid at a facility, it was discovered that from approximately 2:00 to 4:00 in the afternoon, the operators could not see the control panel due to glare from the fall sun.
Do your human factors reviews recognize and correct deficiencies in the human-machine interface (HMI)? Do you have a system in place to respond effectively to operators' concerns about their working conditions?
At a solvent spun synthetic fibers facility, operators did not recognize for over 36 hours that a 60" duct carrying solvent laden air at 70% LEL had physically blown an end off and was releasing the mixture to the environment. Relying on detection and correction of an abnormal situation solely by operating personnel is a weak safeguard.
Are your operators well enough trained to recognize and respond to unusual process upsets in a timely manner? Does refresher training reflect lessons learned in recent incidents?
Expecting the Unexpected
A batch nitroglycerin process at a Government Owned – Contractor Operated (GOCO) facility exploded after having been operated without incident for forty-six years, proving once again that, “we have never seen anything like that,” is not a sufficient criterion for ruling a scenario out in a PHA.
Do your PHA teams understand that their charge is to identify the potential incidents that haven't happened but might? Are your risk tolerance criteria, and your culture, sufficiently rigorous to deal with rare events?
A series of PHA studies identified the possibility of the nitrogen blanket on flammable storage tanks being turned off so that the tanks might collapse during pump-out. Each scenario was judged to be acceptably safe individually. About 4 years later, one of the events occurred, and the company questioned the validity of the PHA. On review, they found that the tank collapse should have been expected based on the aggregate risk from all the tanks. They had no system to look at the aggregate risk and determine if they still met their safety criteria.
Does your company look at aggregate risk from similar scenarios that occur in multiple PHAs? If not, does management have a false sense of security?
Confined Space Created by a Tarpaulin
A work crew used a tarpaulin to provide protection from the weather while performing work on process piping. Inadvertently, they created a confined space but did not follow the company’s confined space procedure. One fatality occurred.
How will your employees know if they have created a confined space? Are they able to recognize when they encounter a confined space?