Finding The Cause - Accidents can happen anytime and anywhere. Dr. Prof. Franz Schmalz at the Swiss Federal Institute of Technology at Zurich has indentified four categories as the main cause of workplace-related incidents.

Incidents occur because the concerned organization or person did not know the hazard; knew the hazard, but did not consider it; considered it, but made a wrong assessment; or made the right assessment, but did not implement or maintain precautions. In practice for any given incident, the failure is on a different level for different organizations or persons involved.

Of course these four categories cannot cover each and every element in the hundreds and thousands of event chains that ultimately lead to an incident.

Hot Work Incidents

In the last 20 years, the U.S. Chemical Safety Board (CSB) has identified over 60 fatalities due to explosions and fires from hot work activities on tanks. In 2010, CSB issued a bulletin with key lessons to prevent worker deaths during hot work in and around tanks.

Eleven Incidents were analyzed and lessons were derived. Regarding the categories above, it is obvious that the scientific facts related to the ignition risks during hot work in presence of flammable vapors are well established, and the respective framework of legal requirements exists.
In all the other cases missing hot work permit procedures and - related to that - lack of risk analysis were identified as the major cause on company level.

Operators were therefore often not appropriately informed and instructed, but often lacked also the qualification to ask for the necessary information. In one case, bad maintenance was an important contributing factor and only in one case existing safety rules were not observed by the operator.

Dust Explosions

A special investigation of dust explosions states very clearly: "The CSB found that industry and safety professionals often lacked awareness of combustible dust hazards. Neither the OSHA (Occupational Safety and Health Administration) hazard communication standards nor the ANSI [American National Standards Institute] guidance ... provide clear requirements or instructions for including and warning about combustible dust explosion hazards (in MSDS).

The facilities failed to follow the widely recognized standards of good engineering practice ... . As a result, facilities did not implement appropriate engineering controls, adequate maintenance and housekeeping, and other measures that could have prevented the explosions."

Obviously, the root cause is a lack of knowledge both on the organization and the operator level, resulting subsequently in deficiencies in the implementation safety concepts. Again, the necessary information and know-how was clearly available in the public domain.

Regulation And Standardization Authorities

Almost any major accident in the process industries has resulted in new rules and regulation: The release of a reaction mass containing tetrachlorodibenzodioxin (TCDD) in Seveso, Italy, resulted in the European Directive on the control of major accidents, still known today as Seveso II Directive.

The big warehouse fire in Schweizerhalle, Switzerland, after which contaminated fire water severely polluted the Rhine river, led to numerous new national standards on chemical warehouses.

Two years after the 2001 fertilizer factory explosion at a Toulouse chemical plant, the French regulation on risk management was updated. After a 2005 BP refinery explosion in Texas City, numerous measures were initiated based on the Baker Report, for example new standards on reporting of process safety incidents.

CSB also systematically analyses the legal situation related to incidents. In almost all incidents analyzed by CSB, gaps and lack of clear requirements were identified and respective recommendations were made. In about one third of the cases considered here, the gaps were significant.
Below the legal level, industry standards play an important role. The following examples show potential deficiencies on this level, which contributed to process safety incidents:

Two explosions were examined by CSB, which occurred when natural gas piping were cleaned using the "gas blow" method, whereby natural gas is forced through the piping at a high pressure and volume to remove debris. The natural gas and debris are subsequently released directly to the atmosphere. In its analysis, the CSB recommended National Fire Protection Association revise the National Fuel Gas Code (NFPA 54) and address the explosion risks of this practice.

These facts might indicate that legislation and standardization are always behind the industrial development and the associated risks, in other words, they are reactive instead of proactive. Whether or not this should be changed is a matter of political discussion and the mutual agreement between industry and the public.

Basically, the legal (and standardization) framework should set only the very general rules, leaving the detailed technical issues to the direct responsibility of the industry. Too detailed and strict rules cause excessive costs and sometimes even hinder innovation. On the other hand, such a liberal agreement requires good citizenship practices and reliable accountability on the industry side.

In the above example, this would mean that the explosion risk related to the release of natural gas is carefully considered based on long existing common knowledge and also existing standards (NFPA 497) which clearly addresses a physically comparable situation without waiting for a revision of the specific standard (NFPA 54).

Lack of Scientific and Technical Foundation

In the cases considered above, the scientific foundation for preventive measures was clearly available. The following two examples show, that - albeit rarely - there are incidents which can only be explained based on new scientific findings.

The first example is related to three tanker explosions, which occurred in 1969 when cleaning empty dirty cargo tanks with high pressure water jets. It turned out the explosions were caused by static discharges between charged water slacks falling over internal steel structures in the tanks and the tank wall.

Another is the explosion of a polyethylene powder silo in the 1970s that could - after extensive research work attributed to cone discharges. Since then this type of ignition sources is routinely considered in explosions risk analysis and has become common knowledge.

From published incidents analyses it can be concluded that lack of scientific and technical foundation is clearly not the missing link.
Does this mean that we can stop research in the area of process safety?

If the motivation was reduction of incidents the answer would be yes. The focus should be more on knowledge transfer and knowledge management if the most frequent gaps are to be closed.

Nevertheless, safety research is necessary. First of all, there may still be hidden potentials. Second, we have to make sure that the scientific and technical foundation for safe processes is also available for new technologies (e.g. new material, processes under very high pressure, at high temperatures and under very reactive atmospheres, e.g. pure oxygen).

And finally, to design more economic processes: If more fundamental details on a process are known, the safety concept can be tailored more specifically, which often means that safety margins (introduced to compensate missing information) can be reduced and production costs lowered.

Knowledge Transfer

The missing link is the transfer of the scientific and technical foundation for designing and running pro¬cesses safely to plant managers, plant safety professionals and operators. To close the gap is by no means simple.

• Plant managers, plant safety professionals: Surveys by EFCE and EPSC have shown that many curricula for engineers do no comprise an adequate number of lectures in process safety. Thus process safety is often left either to post graduate courses or to training on the job. More¬over, outsourcing of engineering activities has led to a reduction of internal safety professionals. Although high quality safety know-how can be bought from excellent consultants today, an experienced internal counterpart is important for effective buying-in of know-how.
• The modern trend of job hopping is a great hindrance on the way to build-up a good and sustainable internal safety know-how. It has been shown that the increased frequency of changing the job is not associated with an increased frequency to change the employer; thus it is a company-internal phenomenon. Ways must be found, how competent safety professionals can make a remunerative career, without changing their field of activity every five years.
• Operators: It is evident that awareness for certain hazards and the knowledge on the respective preventive measures must be available at the front, i.e. where the processes are carried out and the work is physically done.

The reach the concerned persons is by no means a simple task:

• Plant design and construction is inherently complex and many different companies are involved, each company having its own schedule for their individual workers and a characteristic fluctuation pattern of personnel.
• Recently the situation has become similar in the field of operation and maintenance: Many tasks are out-sourced and performed by contractors and subcontractors.
• This complex situation is further made worse by a continuous acceleration of processes and an increase on the frequency of changes and modification.

Acceptance of these facts as a problem for plant and process safety may be the first step in solving the problem. To improve the situation, more emphasis must be put on

• Specification of know-how required for a given task
• Regular training on safety related topics including performance review
• Use of e-learning, to overcome the problem of scheduling courses
• Certification of contractors for specific tasks