ASME boiler and pressure vessel codeの許容応力の改訂

Unfired pressure vessels

Determination of design and operation parameters of a surface condenser using an adaptive neuro-fuzzy inference system

Failure cause analysis of an expansion bellow of integrated turbine unit

Fixed-tube-sheet shell-and-tube heat exchangers (FTHEs) are widely used in process plants to enhance energy efficiency and to control temperature levels of unit operations. Even moderate temperature differences between shell and tube bundle of FTHEs can lead to failure mechanisms induced by thermal stress. To avoid equipment failure, design codes require an analysis of the transient response of an FTHE during special operating conditions. This work presents a modular-hierarchical approach for the dynamic simulation of FTHEs, which is applied to special operating scenarios such as a loss of tube-side flow, a shell-side steaming-out (cleaning procedure to remove hydrocarbon residues with steam) and a reactor trip (sudden stop of exothermic reaction). 

Hazard Analysis of Fixed‐Tube‐Sheet Shell‐and‐Tube Heat Exchangers

\n Differential longitudinal thermal expansion between the shell and the tube bundle is a well-known problem in fixed tubesheet heat exchanger design. An expansion bellows provide flexibility for thermal expansion and also function as a pressure retaining part. In this paper, guidelines for design of flanged and flued type (thick wall) expansion bellows available in international codes and standards including ASME VIII-1 and 2, EN-13445, and TEMA and EJMA codes are presented. These codes and standards are compared in terms of information available for thick wall expansion bellows design with regard to condition of applicability of design formula, spring rate determination, parameter to define the initial geometry, stress determination, and fatigue evaluation. Inherent limitations of these codes with respect to expansion bellows design, research gape, and recommendations for effective design are also presented in this paper. Brief history and information provided in various codes and standards related to unreinforced thin wall expansion bellows (bellows expansion joints) are also presented to understand evaluation of expansion bellows design.

Study of Various International Codes and Standards for Flanged and Flued Type Expansion Bellows Design

Flanged and flued type expansion joint (thick wall expansion bellow) used as an integral part of many shell and tube heat exchanger where process conditions produce differential expansion between shell and tubes. It provides flexibility for thermal expansion and also functions as a pressure retaining part. Design of expansion joints is usually based on trial and error method in which initial geometry must be assumed, and accordingly maximum stresses and spring rate are be calculated. Inadequate selection of geometry leads to higher tubesheet and bellow thickness, which increases cost of equipment. This paper presents standardization and optimum design approach of flange and flued expansion bellow fulfilling ASME VIII-1 and TEMA standard requirement. Methodology to define expansion bellow geometry is developed, and geometry dimensions are tabulated for expansion bellow diameter from 300 to 2000 mm and thickness from 6 to 30 mm. Each defined geometry is analyzed using finite element method, and maximum von Mises stresses are calculated for bellow axial displacement from 0.5 to 1.5 mm and internal pressure from 0.1 to 6.5 MPa. Spring rate is also calculated for each defined geometry for consideration in tubesheet calculation. Accordingly, optimum design methodology is developed, tested, and compared with existing design. Results depicted that proposed standardization approach and design methodology will optimize expansion bellow and tubesheet thickness and will also save considerable time in finalization of heat exchanger design.

Optimization and Standardization of Flanged and Flued Expansion Joint Design


 Capital costs of static equipment including pressure vessels, heat exchangers and process columns contribute approx. 20 to 40% of cost of total plant. Static equipment is being designed and manufactured based on international codes, standards and statutory legal requirements. Selection of appropriate equipment construction code fulfilling ambient conditions, equipment design temperatures and country specific regulations has significant implications on cost effectiveness and required safety of process plant. This paper presents basic criteria for selection of ASME Sec. VIII or EN-13445 for equipment design and construction based on design temperature, ambient conditions and country specific legal requirements like PED 2014/68/EU and TRCU 032/2013. Effect of change of elevated temperature and material on weight of equipment is also demonstrated by example. Material selection based on corrosion aspects is not included in this paper.

Kamlesh M. Chikhaliya

Papers

Study of Various International Codes and Standards for Flanged and Flued Type Expansion Bellows Design

Optimization and Standardization of Flanged and Flued Expansion Joint Design

Criteria for Specifying Static Equipment Construction Code for Process Plant