Control of modifications

How can we prevent modifications from producing unforeseen and undesirable side effects References I and 2 propose a three-pronged approach  

To paraphrase an old fable, Midas asked the gods that everything he touched might be turned to gold. His request was granted. His food turned to gold the moment he touched it, and he had to ask the gods to take their favor back. 

Loss Prevention in the Process Industries, 2nd edition, But-tenvorth-Heinemann, Oxford, UK, 1996, Chapter 21. 

The Flixborough Cyclohexane Disaster, Her Majesty s Stationery Office, London, 1975. 

Guide Notes on the Safe Use of Stainless Steel. Institution of Chemical Engineers, Rugby, UK, 1978. 

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Control of Modifications to Plants, Processes, and Organization Many accidents have occurred when such modifications had... 

Key Performance Indicators Preparation for maintenance, the control of modifications, and the testing of protective equipment are examples of key performance indicators i.e., taken together, they indicate uie quality of the plant s and company s process safety. If they are below standard, the plant is at risk. The usual measure of safety, the lost-time accident (LTA) rate, does not measure process safety. Many companies that had a low LTA rate and assumed that their process safety was therefore under control have experienced serious fires and explosions. 

Procedures (Control of modifications and of maintenance activities can reduce CCF)... 

Control of modifications is an important aspect and requires that all change request documents specifically identify changes as safety related or NOT safety related. The change request document will contain a safety related/not safety related option, a space to record the impact of the change. This judgment must be ratified by the Safety Authority. 

During many years in Scientific Research Institutes of Nuclear Physics and Introscopy at Tomsk Polytechnical University (TPU) researches into induction electron accelerators and their uses for non-destructive radiation quality control of materials and articles have been conducted. Control sensitivity and efficiency detection experimental researches have been conducted with the high-current stereo-betatron modifications [1], and KBC-25 M and BC-50 high-current betatrons [2,3] in range of 11 MeV and 25-50 MeV radiation energy. 

A good compilation of the functions of fats in various food products is available (26). Some functions are quite subtle, eg, fats lend sheen, color, color development, and crystallinity. One of the principal roles is that of texture modification which includes viscosity, tenderness (shortening), control of ice crystals, elasticity, and flakiness, as in puff pastry. Fats also contribute to moisture retention, flavor in cultured dairy products, and heat transfer in deep fried foods. For the new technology of microwave cooking, fats assist in the distribution of the heating patterns of microwave cooking. 

Numerous modifications of chromium-based catalysts have been made through the introduction of various additives, the most effective of which are titanium alkoxides (38,39). These additives apparentiy reduce surface silyl chromate moieties to chromium titanates, which are then oxidized to titanyl chromates. These catalysts offer a better control of the resin molecular weight (39). 

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... 

Control of stationary sources of air pollution requires the application of either the control concepts mentioned in Chapter 28 of the control devices mentioned in Chapter 29. In some cases, more than one system or device must be used to achieve satisfactory control. The three general methods of control are (1) process change to a less polluting process or to a lowered emission from the existing process through modification of the operation,... 

Control of diesel-powered vehicles is parhally accomplished by fuel modification to obtain reduced sulfur content and cleaner burning and by proper tuning of the engine using restricted fuel settings to prevent overfueling. 

Detailed modifications in the polymerisation procedure have led to continuing developments in the materials available. For example in the 1990s greater understanding of the crystalline nature of isotactic polymers gave rise to developments of enhanced flexural modulus (up to 2300 MPa). Greater control of molecular weight distribution has led to broad MWD polymers produced by use of twin-reactors, and very narrow MWD polymers by use of metallocenes (see below). There is current interest in the production of polymers with a bimodal MWD (for explanations see the Appendix to Chapter 4). 

Safe systems of work to control plant modifications etc... 

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