‘LESSONS LEARNT – LACK OF PREVENTIVE MAINTENANCE AND INCORRECT INSTALLATION CAN LEAD TO FAILURES AND SHUT DOWNS’

摘要

Hazardous incidents and operational failures jeopardize health and safety of workers at work. They influence the most sensitive nerve of a process controlled plant and create shut downs and end up in cost. Preventive measures for plant maintenance are regular and frequent inspection and servicing. Safety-relevant equipment and protective systems must be serviced by trained experts. Most important for the risk assessment procedure are the many small defects when commissioning the processing units and the insufficient servicing of safety relevant equipment during processing. “Small defects – large effects” this principle must be considered at the stage of installing the devices to exclude or minimize risks. Following this idea the international Loss Prevention Seminars of the chemical and petrochemical industry together with the Health and Safety Executives are offering the “Lessons learnt” to show practical examples of possible and impossible failures. Not everything can be foreseen by the manufacture and printed in the manual as a warning, although he is obliged to highlight all possible failures and malfunction during operation. The daily work is showing the many false uses during installation, process and maintenance. The device may be inappropriate due to the false requisition of the operating conditions and it may be installed in a physically wrong way against all minds. Further description of unsufficient servicing in the end shall wake you up. Wrong design: Although the manufacturer of the equipment or protective system must check all relevant datas for the design of the device the operator – the employer – is responsible in the end for the correct use of the device. He must control before installation and putting into use. All defects at delivery may have an influence on the safe use of the device. Protective systems are marked with regard to the intended use. Wrong installation: Weight-loaded safety valves are to be installed that the weight is operating vertically and not against the physics horizontally. The non trained staff sometimes is not in a position to evaluate the function of the device by itself without studying the manual, if written in the appropriate language and readable by the staff. This in particular if the installation is executed based on isometrics. Transportation lockers must be removed before commissioning. They are protective devices for the sensitive parts of the safety valves. To ignore this will create the hazard of implosion of a tank because the vacuum braker is blocked in case of required inbreathing. Insulation of valves must leave free space for breathing. Follow the recommendations of the manufacturer and don’t block the relief-opening of the pressure and vacuum valve. Wrong servicing: Maintenance, Inspection, Repair must guarantee the technical function of the device to guarantee minimum life cycle cost of the installed devices and of the total plant. Based on an example of the wrong repair of a fusible element the vision of an accident can be realized. Wrong maintenance: Proper maintenance requirement is part of the guarantee of the manufacturer. The frequency is determined by the process and its parameters and must be fixed by the employer when experiencing the commissioning stage. Examples of delayed maintenance will show the need for regular and accurately timed maintenance. Corrective maintenance presumes qualified actions with original parts declared by the manufacturer. These are measures to reconstruct the original order or to keep the device in good repair. Training and local servicing by the manufacturer assure competent advice and long life time. The responsibility of the employer and plant operator incorporates that safety devices shall be serviced and repaired by trained experts.