Thursday, June 10, 2010

Evaluation of reactivity hazards often involves interpretation of reactive chemicals test data from techniques as Accelerating Rate Calorimetry (ARC), Reactive System Screening Tool (RSST), or Vent Sizing Package (VSP).  Endothermic reactions represent a potential hazard if gaseous or highly volatile products are generated.  Exothermic reactions have the potential for a runaway reaction leading to a dramatic increase in temperature, pressure and reaction rate.  Incorporation of pressure and pressure rate data, in addition to temperature rate data, provides key information to better understand the potential for runaway reaction and/or gas evolution.  Simple models may be used to better estimate temperature of no return, time to maximum rate, heat and gas evolution rate at relief device set pressure, or similar hazard screening criteria.  In some cases, autocatalysis or an overall mechanism involving consecutive reactions may be distinguished from simple Arrhenius kinetics where pressure rate and temperature rate does not appropriately match.  Screening for potential autocatalytic behavior may help identify runaway reactions which may occur at lower temperature than expected following prolonged exposure at process conditions.

API Recommended Practice RP-752, "Management of Hazard Associated with Process Plant Building" has undergone extensive revision for the 3rd Edition, which was published in December, 2009. The recommended practice has gone from a technical document to a management document, focusing on the process of conducting a facility siting evaluation. Major changes will be highlighted in the discussion, including occupancy criteria, levels of analysis, performance criteria, scenario selection, siting evaluation study execution, and risk management.

Thermal loads on buildings produced by process unit fires can be significant, and the temperature rise inside nearby occupied buildings is of concern for occupant safety. This presentation will cover the determination of thermal loading from a process unit fire, calculation of the rise in temperature inside a nearby building, and correlation of heat inside the building to occupant vulnerability.  The thermal analysis and occupant vulnerability models provide approaches by which facilities can conform with the revised requirements for API RP752.

Worker fatigue has proven to be a major contributor to many major accidents. API recently completed an ANSI standard that outlines the recommended practice for minimizing worker fatigue. This paper discusses the benefits of a fatigue program and presents challenges you will face in implementing such a program.

One of the main issues of concern when managing MOC is the quality of the MOCs as much as the quantity of those that have not been completed. The reason is that people tend to concentrate on the mechanics of MOC rather than the content because of limited resources and the need to be in compliance. We can assure quality by recognizing the elements that are crucial to make a good MOC and by using a database to accomplish the mechanics, thus freeing personnel to concentrate on the important requirements.

It will be proposed that a good MOC requires three main elements to be very well executed: the technical description of the change, the safety analysis (which includes its review) and the Pre-Startup Safety Review. Having achieved quality it is important to manage the process efficiently and this can be done with the help of a database that automatically provides the necessary metrics. The requirements of high-quality MOCs and of an efficient process will be discussed.