This paper focuses on design optimization of brick-lined autoclaves to reduce wall thickness without compromising autoclave integrity. The use of acid resistant, brick lined, horizontal, autoclaves is common for hydrometallurgical processing within the mining industry. To prevent corrosion of the carbon steel pressure boundary, autoclaves are often lined with an acid proof flexible membrane and high nickel alloy overlay localized at nozzle areas. A brick lining protects the membrane against high temperature and abrasive damage that would result in corrosion of the carbon steel pressure boundary. Because of stringent out-of-roundness and deflection requirements, autoclave designers are faced with the challenge of choosing the proper thickness and layout of the autoclaves. Common practice for satisfying stringent requirements is to design much thicker autoclave than what is required to satisfy pressure and temperature conditions. This paper provides a methodology for the design that utilizes stiffening rings for controlling out-of-roundness that results in thinner and lighter autoclaves.

Depending on plant/site location, it may be advantageous to dress a vertical vessel, in horizontal position, prior to erection. Dressing refers to the installation of items attached to the vessel such as internals, insulation, piping, ladders, platforms, electrical cable trays, lighting, etc. The decision to dress a vessel may be due to safety, schedule or economic reasons. Dressing a vessel results in higher lifting loads. Vessel Codes address loadings to be considered when designing a vessel in its operating position and not necessarily for lifting. Since the Codes do not address erection loadings, engineering judgment must be used in their consideration and analysis in order to avoid overstressing the vessel. In some cases, erection loads govern the design thickness of the vessel. Lifting analysis in the context of this paper is the evaluation of stresses in the vessel when it is initially picked up from the horizontal position. This paper discusses the compressive stresses which usually govern in the lifting analysis of thin-walled vessels. Different methods used in literature and industry are presented in the paper. Some Owners/Users, engineering firms, and fabricators use the Factor B in ASME Section II, Part D, Subpart 3 as the limiting criterion for compressive stresses. In some cases, this criterion is too conservative. This paper presents the application of alternative buckling criteria for lifting analysis.

It is a common challenge for pressure vessel and foundation engineers to determine the effects of piping loads on the foundation and vessel support design and to find out the appropriate design method to be used. Pressure Vessel Codes specify loadings to be considered in the vessel design but limited guidance is provided on the application of piping loads when designing vessel supports. Consideration of piping loads in the design of vessel supports and foundation is left to the engineer’s judgment. Vessel supports are typically designed to withstand the operating weight of the vessel, seismic and wind loading. Pressure vessel literatures provide well-established methodologies in considering these loads in the design of vessel supports. Civil engineering literature, such as the American Society of Civil Engineers (ASCE) Wind Loads for Petrochemical and Other Industrial Facilities [11] or the ASCE Guidelines for Seismic Evaluation and Design of Petrochemical Facilities [17], provide well documented procedures and guidelines for evaluating wind and seismic loads. However, there is limited literature on how to account for external loads from attached piping. Typical major project schedules have vessels and their supports/foundations designed well before the development of the piping design that provides calculated actual nozzle and piping loads on the vessel. This paper reviews the type of piping loads, how the piping loads are translated to the vessel support/foundation and provides a proposal for simplified approach analysis on how to apply these piping loads in the design of the vessel support/foundation. There might be cases where the piping loads will cancel out, but that may not always be the case. Ignoring and not considering nozzle loads in the support design/foundation may not be appropriate for all vessels. The intent of this paper is to also make the Vessel Engineer aware of ways to reduce these loads and to encourage communication with Stress Engineers in regards to flexibilities and other factors used to calculate nozzle/piping loads. In most cases, the vessel shell and nozzles are considered as rigid anchors in the piping stress analysis. By using the proper flexibility at nozzle junctions and the global vessel flexibility, the effect of piping loads in the design of the vessel support can be reduced. There is little or no industry guideline on how to include loads due to the thermal expansion or contraction of piping. Since the thermal loads and calculation of flexibility are the least understood part of the analysis, this paper provides background including examples of how these loads and flexibilities can be calculated. In short, the intent of the paper is to provide a better understanding of how piping loads are translated to the vessel support and to provide some design guidelines that are not readily available in current literature and are not clearly specified in the industry codes or standards.