Proceedings of the Institution of Mechanical Engineers,Part E: Journal of Process Mechanical Engineering

The topic of oil pollution of the sea by the offshore industry is topical in view of public reaction to the Exxon Valdez accident. The facts are examined to show whether the offshore industry's record is acceptable. Without such a rational examination and presentation of the facts and a global perspective, public pressure may lead governments, regulatory authorities and oil companies to act in such a way that the risk of oil pollution is increased. Oil-spills are examined on a global basis and several specific oil-spill cases are detailed. An outline of oil industry blow-outs shows that very little of the oil spilled into the oceans is derived from this source. Data on oil from drill cuttings and produced water is presented. The paper brings the various aspects together in a comparative analysis. Costs are also discussed. The conclusion is drawn that increasing the level of domestic exploratory drilling together with piping it to shore would in turn reduce the amount of imported oil in many countries. The reduced need for tankers would reduce the amount of oil spilled. Facts are also presented which show that both tankers and offshore drilling are less than 5 per cent of the source of oil in our oceans.

This paper investigates the thrust exerted on a vessel as a result of axial rupture, which has not previously been examined theoretically or practically. A simple model is developed to predict the peak thrust when the breach is large, that is when the fracture is propagating with constant velocity and the maximum rate of separation of the free edges downstream of the fracture tip has been achieved. The model assumes that the depressurization process within the breach zone is dominated by the transverse rarefaction wave initiated by the arrival of the breach as it advances along the vessel.

The prediction is compared with a measurement made during a burst test on a large air-pressurized steel vessel. A novel measurement technique employed an inverse Brinell hardness test, in which the indentation size was used to calculate back to the force that produced it. This was interpreted with the help of a finite element computer simulation of the indentation process.

The integrity of large storage tanks features significantly in the budget of maintenance and inspection departments within the petroleum and petrochemical industries. The unpredicted failure of a storage tank will not only seriously affect the operating flexibility within a company, but may lead to punitive action being taken by the authorities against the company for any pollution that may occur.

A great deal of effort, as well as expense, is expended in the monitoring and inspection of storage tanks to ensure their integrity. Techniques used in predicting and assessing the condition of storage tanks are improving steadily and this paper provides an insight into techniques that are currently being used and methods that are being developed. The paper also proposes areas of research which need to be undertaken if economies are to be realized in this expensive process.

A control system has been designed and implemented to provide more effective energy management of low-pressure gas distribution networks. The key to this is the provision of a control scheme that maintains low pressures across a network.

The work was approached from first principles and a modelling technique has been developed which provides reduced order models that adequately describe the characteristics of multi-feed gas networks. The models were then used for the control system design, which in this case also included the selection of the optimal measurement points for most effective control.

Following extensive design studies a relatively straightforward control scheme resulted which has been implemented and proved to be effective.

Computer-integrated design techniques have been applied to the design and analysis of stirred tank bioreactors, and in particular their agitation systems. Bespoke software has been written for problem specification and preliminary design, with particular attention paid to data presentation and the user interface. The data generated can be passed to a large range of existing analysis, database and graphics software to enable detail design of each component. The result is a powerful design aid that in particular reduces the need for user speciality. This concept can be applied to any process or product that currently employs unrelated software in its design.

There appears to be an increasing awareness that organizational and managerial factors play a critical role in ensuring plant safety. A detailed study is presented of one branch of industrial management, viz. maintenance management. It has highlighted the nature of some of the links between managerial practices and the reliability of plant equipment and personnel.

The causes of several major accidents are analysed using a systems approach, with the aim of understanding how the maintenance function was involved. A key conclusion is that, prior to major accidents, there is often a lack of detailed safety objectives and long-term safety control. Without these it becomes very difficult to assess the adequacy or otherwise of other maintenance management elements such as maintenance strategy, resources or administrative structure.

In the absence of tight safety and reliability control and consequent corrective actions a mismatch can develop between the perceptions of management and the actual condition of the plant.

The chemical and petrochemical industries have decades of experience in specifying metallic piping lined with non-metals as a cost effective alternative to high-priced alloy materials of construction for piping in corrosive service. Early on, application of plastic piping was essentially limited to atmospheric chemical sewage service and to above-ground vents and drains. However, applications and usage of plastic piping continue to increase as engineers become more confident in specifying plastic materials and mechanical contractors gain experience with their installation. Non-metallic materials are being developed that are not only corrosion resistant but also have increasingly higher pressure and temperature capabilities. Plastic double-containment piping has experienced tremendous growth for handling hazards and toxic fluids. In the United States, recent dramatic growth of plastic double-containment piping applications has been, to a large extent, for compliance with the Environmental Protection Agency (EPA) regulations of the 1976 Resource Conservation and Recovery Act (RCRA). Related EPA regulatory efforts were accelerated in 1988 by more stringent amendments to this legislation. Industry in the United States must comply with these EPA regulations by December 1998.

Plastic piping and metallic piping lined with non-metals have been covered to some extent by the ASME B31.3 Chemical Plant and Petroleum Refinery Piping Code for several years. The distinctive requirements of non-metallic piping and piping lined with non-metals were incorporated into the 1980 edition as a separate Chapter VII, which is dedicated to this growing area of interest in piping.

This paper provides an overview of the present coverage of non-metallic piping lined with non-metals in the ASME B31.3 Chemical Plant and Petroleum Refinery Piping Code (1). Some topics that warrant further investigation are presented as well.