Process safety: Remote control

In an ideal world, the design and layout of any facility handling or processing hazardous materials should take into account not only normal operating conditions but also what could happen in the event of a major accident. Sadly, this is not always the case – despite there being a long history of events that escalated into fatal incidents because of the loss of control over plant operations.

This is something that the US Chemical Safety and Hazard Investigation Board (CSB) has attempted to address over several years. Its investigation of the November 2019 fire and explosions at the TPC Group’s chemical plant in Port Neches, Texas, CSB’s report highlighted the inability to isolate the release of highly flammable or toxic materials and concluded that improved requirements in both industry guidance documents and federal regulations are necessary to prevent the recurrence of such highly destructive and dangerous events.

Following that investigation, CSB set about conducting further analysis of incidents that have involved a lack of remote isolation capability, so that it could determine the appropriate recommendations to industry groups and regulatory agencies. It initiated a Safety Study, now published as Remote Isolation of Process Equipment (No 2024-01-H), to review previous incidents and address gaps and deficiencies in industry guidance and federal regulations.

HISTORY REPEATING

CSB’s study looks in detail at six events, beginning with the August 1975 disaster at the Gulf Oil refinery in Philadelphia. A 75,000-bbl tank overfilled and ignited; firefighters worked all day to control the fire, eventually standing in a mixture of oil, fire water and foam. The level of flammable liquid rose throughout the day, eventually finding an ignition source. The sudden fire engulfed several firefighters, eight of whom died; 11 others were injured and the damage to the refinery was more than $10m.

During the incident, a damaged naphtha storage tank was feeding the fire by releasing between 500 and 600 gallons of liquid naphtha every minute. Because the tank was not equipped with a remote isolation valve, firefighters had to take extreme efforts to access and close the valve on the tank manually. Press reports at the time referred to firefighters having to push a rowboat through a tank dike that was flooded with hot crude oil, foam, and water as the fire burned around them in order to reach the tank so that they could manually close the valve. Had a remotely operated emergency isolation valve been installed on the naphtha storage tank, it could have been closed much sooner and likely would have helped limit the spread of the fire, from a much safer distance, without requiring firefighters to unnecessarily risk their lives.

Shockingly, CSB was called to the same site, now called the Philadelphia Energy Solutions (PES) Refinery, in June 2019 after a pipe elbow in the hydrofluoric acid (HF) alkylation unit ruptured, and a large vapour cloud – composed of roughly 95 per cent propane, 2.5 per cent HF, and other hydrocarbons – engulfed part of the unit. The vapour cloud ignited two minutes after the start of the release, causing a large fire and subsequent explosions. Property damage was put at $750m, making this, according to Marsh JLT Specialty, the third largest refinery loss worldwide since 1974.

CSB found that there were no remotely operated emergency isolation valves installed in the HF alkylation unit that could have stopped the release. It concluded that, had this safety equipment been available, the release of hydrocarbons from the pipe elbow would have been minimised and the subsequent explosions could have been prevented.

CSB’s study notes: “The fact that two loss-of-containment incidents at the same facility more than 40 years apart could not be safely isolated and as a result drastically escalated, highlights the key concern.”

In addition to the three incidents mentioned above, CSB’s study also looks at the release of propylene at the Formosa Plastics complex in Point Comfort, Texas in October 2005, when 16 workers were injured; the propane fire at the Valero McKee Refinery in Sunray, Texas in February 2007, which injured four workers; the large tank fire at the Intercontinental Terminals Company (ITC) storage facility in Deer Park, Texas in March 2019; and the fatal isobutylene vapour explosion at the KMCO facility in Crosby, Texas in April 2019.

In each case, CSB determined that the inability to isolate releases by the use of remotely operated isolation valves was a critical factor, and it made recommendations for change, which it is now reinforcing.

OTHER SOURCES

CSB’s study reviews other agency activities, noting for instance that the Pipeline and Hazardous Materials Safety Administration (PHMSA) responded to a recommendation from the National Transportation Safety Board (NTSB) to require automatic shutoff valves or remote-control valves on pipelines, following a major fire on the PG&E gas transmission line in San Bruno, California in September 2010.

The UK Health & Safety Executive (HSE) has also issued regulatory guidance to assist facilities in assessing whether there is a need for remotely operated shutoff valves; this was published in 2004 following HSE’s investigations into incidents at the Associated Octel plant in Ellesmere Port in February 1994 and BP’s Grangemouth refinery in June 2000. Within that guidance, HSE stated: “As part of their comprehensive risk assessments, companies in control of chemical process plants at major hazards sites should critically review the provision of remotely operated shut off valves at both storage and process vessels in which significant inventories of dangerous substances are held.”

CSB notes the recommended practices published by the American Petroleum Institute (API) apply only to petroleum refineries, so do not cover all facilities at risk; furthermore, API RP 553 and RP 2001 do not establish criteria for when remote isolation is needed. The Center for Chemical Process Safety (CCPS), a group within the American Institute of Chemical Engineers (AIChE), on the other hand, produced relevant guidance in its 2003 book Guidelines for Fire Protection in Chemical, Petrochemical and Hydrocarbon Processing Facilities. CSB itself has used these guidelines in recent investigations.

ACTION REQUIRED

As several major incidents investigated by CSB have demonstrated, many chemical facilities are not protected with remote isolation equipment that can help mitigate loss-of-containment incidents. This is despite copious evidence of the value of such equipment in mitigating the effects of product releases. Its study ends with three specific recommendations:

1. API should develop a new publication or revise an existing publication that should be applicable to various facility types such as refineries, chemical and petrochemical facilities, terminals, etc. with major process equipment and atmospheric storage tanks, that details conditions that necessitate the installation of remote isolation devices [use “shall” instead of “should” language] that may be automatically activated or remotely activated from a safe location, particularly during an emergency. This should reflect the guidance published by CCPS.
2. The US Environmental Protection Agency (EPA) should update the Risk Management Program (RMP) rule to include an evaluation of the need for remote isolation devices for major process equipment that can be remotely activated from a safe location or automatically activated during a release. The evaluation should be included in hazard assessments, hazard reviews, and process hazard analyses.
3. The Occupational Safety and Health Administration (OSHA) should update the Process Safety Management (PSM) standard to include an evaluation of the need for remote isolation devices for major process equipment that can be remotely activated from a safe location or automatically activated during a release.

source: https://hcblive.com/process-safety-remote-control/