Materials selection prioritization

Materials Selection, Testing, and Design Considerations 445 11.3.3 Prioritization... 

Introduction Theprevious sections dealt with techniques for the identification of hazards and methods for calculating the effects of accidental releases of hazardous materials. This section addresses the methodologies available to analyze and estimate risk, which is a function of both the consequences of an incident and its frequency. The apphcation of these methodologies in most instances is not trivial. A significant allocation of resources is necessary. Therefore, a selection process or risk prioritization process is advised before considering a risk analysis study. 

In Superfund s Section 105 requirement for a Revised NCP, Congress mandated a scheme for responding to releases of hazardous materials. For old dump sites response starts with a survey and prioritization of sites based on risk assessment. After prioritization the focus turns to selection of cost-effective remedies which will adequately protect the public health and welfare and the environment. In revising the NCP, EPA is engaged in a pioneering effort to develop a practical and effective site assessment model. After prioritization additional assessment will often... 

The 1996 Amendments further require EPA to establish a mechanism to identify and select new contaminants, as well as specific efforts to establish criteria for arsenic, sulfates, radon, and disinfection by-products. The SDWA required EPA to establish a list of contaminants every five years that are known or anticipated to occur in public water systems and may require further investigation and possible regulation under SDWA. The list is divided into those materials that are candidates for additional research, those that need additional occurrence data, and those that are priorities for consideration in rulemaking. The EPA then must prioritize the critical substances in each category and develop a plan of action for making regulatory decision for the most appropriate candidates. 

Traditionally, the first step in natural product lead discovery is the selection of source material. The search for novel organisms, and their associated novel chemistries, has taken many forms that include collection from unique locales and microclimates as well as the use of ethnobotany and traditional medicine. Once collected, several methods have been developed to prioritize these library candidates for further study. One of the more traditional methods applied to this process is chemical hngerprinting [7-10]. 

Topics covered include life cycle analysis, identifying and prioritizing pollutants for industrial sites, selecting environmentally compatible materials, design of unit operations for waste minimization, and pollution prevention economics. 

To prioritize maintenance and refurbishment and to select the most suitable materials of construction, the aggressivity of the environment must be established. Passive corrosion tests are the most economical way of mapping large areas accurately. The CLIMAX test [//] and a test [13] comprising of zinc cans and aluminum wire twisted around steel bolts are used most frequently. 

A major component of this framework is the use of nondestructive evaluation technicjues to provide information about the condition of the pijjeline. All pip>es will eventually fail, but the rate of failure will dejjend on both the pipe material and the actual exposure to environmental and ojjerational conditions. The most important feature of the framework relates to the cyclical nature of pipeline management. Each pipe in the system must be examined periodically, and its condition reassessed in order to determine what action should be taken to maintain or upgrade its condition. The entry point to the cycle is the pipe selection area labeled as "Prioritize Pipes for Analysis" in Fig. 8.3. 

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