Modifications hazards

This incident, as well as a number of other problems with plant modifications, has been published by Trevor Kletz under the title Some Loss Prevention Case Histories. [8] It is now also available as part of a training kit with 35mm slides, presenters guides, and booklets. The kit is entitled Hazards of Plant Modifications—Hazard Workshop Module 02 and can be purchased from the Institution of Chemical Engineers, Warwickshire, England. I highly recommend it for in-plant training. 

Kletz, Trevor A., A Three-Pronged Approach to Plant Modifications, Loss Prevention 10, 1976 pp. 91—98. This material is also available as Hazards of Plant Modifications—Hazard... 

Kletz T.A. A three-pronged approach to plant modifications. Loss Prevention 1976 10 91-8. Previously available as Hazards of Plant Modifications - Hazard Workshop Module 002 as a training kit with shdes, booklets, guides, etc., by the Institution of Chemical Engineers, Rugby, England). 

Chapter 4, General Topics, deals with safety topics not directly related to specific operations. Principal subjects include the inspection and maintenance of equipment, spare parts handling, storage and warehousing, plant modifications, hazardous work, and worker protection. 

Control of Plant and Process Modifications Many accidents have occurred because plant or process modifications had unforeseen and unsafe side effects (Sanders, Management of Change in Chemical Plants Learning from Ca.se Histories, Butterworth-Heinemann, 1993). No such modifications shoiild therefore be made until they have been authorized by a professionally quahfied person who has made a systematic attempt to identify and assess the consequences of the proposal, by hazard and operability study or a similar technique. When the modification is complete, the person who authorized it... 

Management Operating policies and procedures Training for vapor release prevention and control Audits and inspections Equipment testing Maintenance program Management of modifications and changes to prevent new hazards Security... 

Piping Modifications One resiilt of the inspec tion of the sample locations is a list of sample locations that will require modifications. The mechanical department will be required to make these modifications before the unit test is run. It is likely that the locations that are not typically used will be plugged with debris. The plugs will have to be drilled out before the test begins. Drilling out plugs presents a safety hazard, and those involved must be aware of this and follow the plant safety protocols. 

A PHA has heen performed for new facilities. The management of change documentation packages and referenced documents should indicate when a process hazard analysis was performed for the modification or new facility. The PSSR Team should verify all of the PHA recommendations have been implemented or otherwise resolved before the toll process can be judged ready to operate. 

The tolling team has analyzed the hazards, addressed the risks and modifications using a management of change system, revised and written procedures, trained the workers, performed a PSSR, and completed any required test runs. The pre-startup phase is complete at this point. 

Hazard analysis (HAZAN) is a quantitative way of assessing the likelihood of failure. Other names associated with this technique are risk analysis, quantitative risk assessment (QRA), and probability risk assessment (PRA). Keltz [44] expressed the view that HAZAN is a selective technique while HAZOP can be readily applied to new design and major modification. Some limitations of HAZOP are its inability to detect every weakness in design such as in plant layout, or miss hazards due to leaks on lines that pass through or close to a unit but cany material that is not used on that unit. In any case, hazards should... 

The safety status of the process should be periodically reviewed against the guiding principles for the original design. Monitoring of add-ons can detect potentially dangerous modifications. Process hazards analysis or process safety audits are useful tools for this review. Documentation of inherently safer principles is critical to ensure that future changes don t nullify the positive features of the initial installation. 

We put a lot of effort into improving safety by adding protective equipment onto our plants, new and old gas detectors, emergency isolation valves, interlocks, steam curtains, fire insulation, catchment pits for LPG storage tanks, and so on. We also introduced new procedures, such as hazard and operability studies and modification control, or persuaded people to follow old ones, such as permits-to-work and audits. 

A vvhat-if analysis identifies hazards, hazardous situations, and accident events with undesirable consequences (CCPS, 1992). What-if analysis considers deviations from the design, construction, modification, or operating intent of a process or facility. It is applicable at any litc stage of a process. 

Occasionally, however, it may be impossible to be certain that a piece of equipment is spotlessly clean, especially if it has contained a residual oil or a material that polymerizes. If this is the case, or if there is some doubt about its cleanliness, then the hazards and the necessary precautions should be made known to the workshop or the other company. This can be done by attaching a certificate to the equipment. This certificate is not a work permit. It does not authorize any work but describes the state of the equipment and gives the other company sufficient information to enable it to carry out the repair or modification safely. Before issuing the certificate, the engineer in charge should discuss with the other company the methods it proposes to use. If the problems are complex, a member of the plant staff may have to visit the other company. The following incidents show the need for these precautions. 

Modifications made to improve the environment have sometimes produced unforeseen hazards [16J. We should, of course, try to improve the environment, but before making any changes we should try to foresee their results, as described in Section 2.12. 

The managers and engineers who authorize modifications cannot be expected to stare at a drawing and hope that the consequences will show up. They must be provided with an aid, such as a list of questions to be answ ered. Such an aid is shown in References 1 and 2. Large or complex modifications should be subjected to a hazard and operability study (see Chapter 18). 

The incident shows once again how a simple modification, in this case adding liquid to the bottom of a tank instead of the top, can produce an unforeseen hazard. In the oil and chemical industries we are taught to add liquid to the bottom of a tank, not the top, to prevent splashing, the production of mist, and the generation of static electricity (see Section 5.4.1). No rule is universal. 

On chemical plants and oil refineries, steam, nitrogen, compressed air. lubricating oil, and other utility systems are responsible for a disproportionately large number of accidents. Flammable oils are recognized as a hazard, but services are given less attention. If the modification to the lubricating system had been systematically studied before it was made, as recommended in Chapter 2, a larger vent could have been installed, or a pipe-break and funnel could have been installed at the inlet to the sump. 

The first and third incidents are examples of hazards introduced by simple modifications (see Chapter 2). Many dust explosions caused by other sources of ignition are reviewed in Reference 10. 

Each PSM system can then be examined to determine what system modifications (if any) are needed to address the new issues. For example, the process hazard assessment system might be modified to include participation by industrial hygienists to identify potential sources of exposure. Some process safety management systems (e.g., process documentation) may require no modification to support a wider scope. 

The first perspective is the traditional safety engineering approach (Section 2.4). This stresses the individual factors that give rise to accidents and hence emphasizes selection, together with motivational and disciplinary approaches to accident and error reduction. The main emphasis here is on behavior modification, through persuasion (motivational campaigns) or pimishment. The main area of application of this approach has been to occupational safety, which focuses on hazards that affect the individual worker, rather than process safety, which emphasizes major systems failures that could cause major plant losses and impact to the environment as well as individual injury. 

The successes of the traditional approach have largely been obtained in the area of occupational safety, where statistical evidence is readily available concerning the incidence of injuries to individuals in areas such as tripping and falling accidents. Such accidents are amenable to behavior modification approaches because the behaviors that give rise to the accident are under the direct control of the individual and are easily predictable. In addition, the nature of the hazard is also usually predictable and hence the behavior required to avoid accidents can be specified explicitly. For example, entry to enclosed spaces, breaking-open process lines, and lifting heavy objects are known to be potentially hazardous activities for which safe methods of work... 

The Chemical Process Industry (CPI) uses various quantitative and qualitative techniques to assess the reliability and risk of process equipment, process systems, and chemical manufacturing operations. These techniques identify the interactions of equipment, systems, and persons that have potentially undesirable consequences. In the case of reliability analyses, the undesirable consequences (e.g., plant shutdown, excessive downtime, or production of off-specification product) are those incidents which reduce system profitability through loss of production and increased maintenance costs. In the case of risk analyses, the primary concerns are human injuries, environmental impacts, and system damage caused by occurrence of fires, explosions, toxic material releases, and related hazards. Quantification of risk in terms of the severity of the consequences and the likelihood of occurrence provides the manager of the system with an important decisionmaking tool. By using the results of a quantitative risk analysis, we are better able to answer such questions as, Which of several candidate systems poses the least risk Are risk reduction modifications necessary and What modifications would be most effective in reducing risk ... 

Other inspection services available include the examination of steel structures (new and existing), electrical wiring installations, containers (to meet Statutory Instm-ment No. 1890), dangerous substances (carriage by road in road tankers or tank containers) to meet Statutory Instmment No. 1059, examination of second-hand plant prior to purchase, plant undergoing repair or modification, the Control of Industrial Major Accident Hazard Regulations (CIMAH) Statutory Instmment No. 1902 and Control of Substances Hazardous to Health (COSHH) and Pressure Systems Regulations. 

Nitronium tetrafluoroborate has been prepared by interaction of nitric acid, hydrogen fluoride, and boron fluoride in nitromethane.5 However, mixtures of nitric acid and nitromethane are extremely explosive.6,7 The present modification of the procedure, in which the medium is methylene chloride instead of nitromethane, was developed to avoid this hazard. It has not been published before. 

There is no induced radioactivity [30,44] with EB irradiation (unlike 7- or neutron irradiation) and hence EB-induced modification of materials is less hazardous compared to neutron or 7-ray-induced modifications. 

The ventilation system must be able to carry away hazardous fumes that may form during normal work. Monitoring the laboratory atmosphere for such fumes while work is in progress is not only advisable, but may even be required by law. Monitoring must be repeated whenever new fume-producing procedures are introduced or any time modifications are made to the ventilation system. Local health authorities should be contacted about... 

Familiarization with plant hazards, rules and safety practices, security Clear delineation of work, responsibilities and handover (See also maintenance, permit-to-work systems, personal protection, site restrictions, access, modifications, personal hygiene etc.)... 

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