by Lew Gordon, Invensy plc
The objective of a study effort is to provide a useful basis for making decisions about future control systems design, application, and pharmaceutical operations. This basis takes the form of the insights, information, and recommendations that are presented in the final study report. Study efforts generally fall into either one of two broad categories - control studies or economic benefits studies. These two types of studies are not totally exclusive - there will be overlap in their scopes. However, the emphasis is different. Control studies focus on the issues relating to control system design and performance expressed in operational terms and units. By contrast, economic benefits studies focus on the economic value to be gained from improved control with little emphasis on how a system designed to achieve these goals would be implemented. The quality of the recommendations that will be presented in the final study report depends on the quality of the information gathered during the plant study visit, and the availability of key personnel during the study. In general, three kinds of information need to be collected during the study visit, according to the focus of the study. These include current control strategy information to support control design recommendations, current economic performance information to support potential benefits analysis, and current regulatory information to support regulatory requirements and manage risk.
For a control study, the information that will support analyzing current control systems and recommending potential improvements in control system design may include, as appropriate:
For an economic benefits study, the information that will support identifying and estimating the potential economic benefits which might be obtained from applying improved controls may include, as appropriate:
The biologics industry is investing significant capitol in switching from 316L SS to more costly corrosion resistant metal alloys such as I625, C276, and AL6XN. While this investment is reducing their corrosion and metal extractables problems, it is not eliminating the contamination. Stainless steel requires expensive passivation and electropolishing steps to meet validation. Electropolishing smooths the surface by reducing the height of asperities, but does not remove the crannies at the base of these peaks and can even create pits that lead to increase biofilm adhesion.2 In contrast, the metal contamination from the Teflon® PFA coupon is so low that it is analytically non-detectable. PFA also has greatly reduced biofilm adhesion relative to conventional electropolished 316L SS.2 These qualities should translate into reduced CIP operations, reduced maintenance costs, reduced time to validation, and improved product yields.
In order to support regulatory requirements, the information about quality systems and other specific company or global regulatory requirements will need to be identified to make performance improvements while managing risk. In any specific study, not all of this information will be necessary, appropriate, or even available. However, the more complete the information package is, the better the quality of the analysis results will be. When key information is missing, the study results can be seriously compromised. If a data collection effort is to be successful and efficient, the customer must be involved in facilitating the process of obtaining information. As much as possible, this information should be assembled prior to the site visit. This will save time and allow the plant time to be focused on understanding and interpreting the data. During the plant visit, it will be necessary to discuss this information with experienced, key personnel who are familiar with the plant operations - personnel who can provide missing information, and who can clarify the information which has been collected. Typically, the positions that can provide this input include:
Finally, if possible, the study engineer will need a suitable workspace for gathering and reviewing the information collected during the study. A thorough and efficient data collection effort will make it possible for engineers to reach a complete and insightful understanding of the process characteristics and performance under study. With such an understanding in place, a report may be generated which will fulfill its role as a sound basis for informed management decisions, and make recommendations for potential performance improvements.