09 September 2007

Explotion Incident

Safety Incident Topic: Explotion Incident
Location of Incident: Texas, USA
Date of Incident: Unknown

Brief Account Of Incident
A trailer being towed by a forklift snagged and pulled a small drain valve out of a strainer in a liquid propylene system. Escaping propylene rapidly vaporized, forming a large flammable vapor cloud. Two minutes after the released the vapor ignited creating an explosion. The explosion knocked down several and burned two (one seriously) operators exiting the unit. Flames from the fire reached more than 500 feet in the air .Because of the size of the fire, Formosa initiated a site-wide evacuation. Fourteen workers sustained minor injuries including
scrapes and smoke inhalation. The extensive damage shut down Olefins II unit for 5 months

Incident Analysis

1. Vehicle Impact Protection
The polypropylene involved in this incident protruded into an open space, yet had no impact protection. Formosa has administrative safeguards for vehicle operation in the unit but not specifically address the operating safe area. The plant design drawing are also not marked in the unit. Guidance about protecting control pipelines is stated that protective measure should be in place to prevent impact.

2. Structual Steel Fire Protection
During the fire , part of a stucture suppoting the relief valves and emergency piping to flare header collapsed. Passive fire protection was installed only on three of four support column rows and the column supported the pressure relief valves and emergency vent pipe had no firefroofing. The API “Fire froofing Practices In Petroleum And Petrochemical Processing Plants” publication was issued after Kellogs was contracted for the early design. If had the steel been firefroof as API recommend. The consequences of this incident would likely have been less severe.

3. Remote Equipment Isolation
A check valve and remote isolation valve located downstream of the leak prevented the backflow of propylene from storage product. Operator were unable to reach the manual valve to isolate the leak as well as local control station to turn off pump supplying propylene. Kellogg specified the remote operation of islotaion valves and equipment only at the local.

4. Flame Resistance Clothing
Neither of the two operators burned in this incident were wearing FRC. Had they been heir injury wolud likely have been less severe. Formosa point comfort evaluated requiring FRC following two incident where static electricity was suspected og igniting hydrocarbon releases but decided not require FRC for operator in the Olefin II Unit except for those involved in emergency response.

Lesson Learned

Hazard Reviews
While Formosa conducted a preliminary hazard analysis, a process hazard analysis, a siting analysis, and a PSSR prior to operating the Olefins II unit, these reviews did not fully address protection of specific process equipment from vehicle impact or the use of remotely actuated valves to control a catastrophic release.When performing a hazard analysis, facility siting analysis, or pre-startup safety review, vehicle impact and remote isolation of catastrophic releases should be investigated.

Flame resistant clothing
Formosa had prior incidents of flash fires from hydrocarbon leaks and evaluated the use of FRC. However, Formosa did not require FRC for operators working within the unit, even though the large flammable liquid and gas inventory may put operators at risk of injury from flash fires.In process plants with large flammable liquid and/or gas inventories, mechanical failures can result in flash fires that endanger workers. The use of FRC may limit the severity of injury to employees who work in plants with large inventories of flammable gases and liquids.

Use of Current Standards
The the plant design used at Formosa multiple times between the mid-1980s and 2000. However, the design was not updated to incorporate improved recommended practices with respect to fireproofing structural steel that supports critical safety systems.
Evaluate the applicability and use of current consensus safety standards when designing and constructing a chemical or petrochemical process plant. This should include reviewing and updating earlier designs used for new facilities.

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