Pressure vessels ASME code developments

If the plant safety shutdown is not rapid enough and an overpressure situation develops, then the pressure relief system is activated. Pressure vessel design codes such as the ASME Boiler and Pressure Vessel Code require relief devices to be fitted on all pressure vessels (see Section 13.17). If the relief system has been properly designed and maintained, then in the event of an overpressure incident, the plant contents will be vented via relief valves or bursting disks into the relief system, where liquids are recovered for treatment and vapors are sent to flare stacks or discharged to the atmosphere if it is safe to do so. The pressure relief system should allow the plant to be relieved of any source of overpressure before damage to process equipment (leaks, bursting, or explosion) can occur. 

Mraz GJ. Development of design criteria for a high pressure vessel construction code. ASME Journal of Pressure Vessel Technology 1987 Vol. 109 256-9. 

The American Society of Mechanical Engineers (ASME), was asked by the government to formulate a design code, and developed the famous Boiler and Pressure Vessel Code between 1911 and 1914 as a set of safety mles to address the serious problem of boiler explosions in the United States. Average steam pressure in those days had reached only about 300 PSI (20 bar). Europe and other parts of the world used the code as a basis for their own safety mles. 

Construction Codes Rules for Construction of Pressure Vessels, Division 1, which is part of Section VIII of the ASME Boiler and Pressure Vessel Code (American Society of Mechanical Engineers), serves as a construction code by providing minimum standards. New editions of the code are usually issued every 3 years. Interim revisions are made semiannually in the form of addenda. Compliance with ASME Code requirements is mandatory in much of the United States and Canada. Originally these rules were not prepared for heat exchangers. However, the welded joint between tube sheet and shell of the fixed-tube-sheet heat exchanger is now included. A nonmandatory appendix on tube-to-tube-sheet joints is also included. Additional rules for heat exchangers are being developed. 

Designers incorporate a suitable safety factor with tensile and yield point/yield strength values to develop maximum allowable stress data. For example, in the ASME Boiler and Pressure Vessel Code, maximum allowable stresses are based on one quarter of the tensile strength divided by 3.5, or two thirds of the yield stress/yield point, whichever is lower. 

Most localities mandate compliance with national engineering codes such as the ASME (American Society of Mechanical Engineers) Boiler Pressure Vessel Code [1]. These codes govern mechanical design and provide the maximum allowable stresses and required low-temperature toughness, as a function of temperature, for approved materials. The codes also define requirements for fabrication procedures such as PWHT. All codes contain rules that ensure the selected material of construction will not be susceptible to brittle fracture at the minimum design temperature. Users of the codes must develop a familiarity with these rules. Eor example, code rules help avoid specifying materials at temperatures for which they are not permitted. 

In 1955, recognizing the large volume of new information developed by the PVRC and other organizations, the ASME Boiler and Pressure Vessel Committee organized its Special Committee to Review Code Stress Basis. The committee was... 

Standard calculation forms can save considerable time in pressure vessel design. These forms also systematize the mechanical design procedure to insure that nothing is omitted. Most engineering contractors have developed their own vessel calculation forms. Basically, all are alike in that they correlate, in easy-to-use fashion, the design rules set forth in Section VIII of the ASME Boiler and Pressure Vessel Code for Unfired Pressure Vessels. They also include design considerations not covered by the code, such as wind loading for tall vessels. (Text continues on p. 139.)... 

For AS ME Code vessels the allowable compressive stress is Factor B. The ASME Code, factor B. considers radius and length but does not consider length unless external pressure is involved. This procedure illustrates other methods of defining critical stress and the allowable buckling stress for vessels during transport and erection as well as equipment not designed to the ASME Code. For example, shell compressive stresses are developed in tall silos and bins due to the side wall friction of the contents on the bin wall. 

The plant duty cycle establishes the plant design events, their frequency of occurrence, and the ASME Boiler and Pressure Vessel Code Service Level for operation of a Standard MHTGR. The plant duty cycle is developed based on a plant operating life of 40 calendar years from the start of operation at 80% capacity factor. Both base load and load following operation are accommodated as well as occurrences which result from unplanned component failures or protective trips. The weekly load following cycle shown in Figure 3.9-1 is used when the plant is operated in a load following mode. 

An in-service test program will be developed that includes preservice (baseline) testing and a periodic inservice test program to insure that all "safety-related" valves will be in a state of operational readiness to perform their principal radionuclide control function throughout the life of the plant. The test program will be based on the ASME Boiler and Pressure Vessel Code, Section XI, Division 2, Subsection IGV (primarily IGV-1000). 

Materials for nuclear RPVs developed to meet the advances in RPV technology and attain the safety and reliability are discussed in this section. The designation of the materials has been standardized in the pressure vessel codes and regulations of many countries. The evolution of the ASME Code is described as a typical example. 

Because the Ki, and Ki curves in the ASME Code are normalized to REndt, potential application of the Master Curve procedure within the ASME Code structure is not straightforward. Figure 10.7 from Sokolov and Nanstad (1999) shows the relationship between REndt and the Master Curve Eo for the steels used to construct the A curve shown in Fig. 10.2. To overcome the lack of correlation between Eo and REndt, the Pressure Vessel Research Council and the Electric Power Research Institute (EPRI) in the USA developed a separate reference temperature based on Eo (Server et al, 1998 Van Der Sluys et al., 2000, 2001a, b). This reference temperature, RTj, was developed by determination of a temperature offset to Eo that would bound the fracture toughness data similar to that of the Ric curve in the ASME Code and has been incorporated into the ASME Code by Code Cases N-629 (ASME, 2013b) and N-631 (ASME, 2013c). Thus, in this scheme, Eq. 10.11 is contained in both Code Cases ... 

Many professional societies have developed standards on matters related to their fields. Some organizations sponsor ANSI and ASTM International standards. Others professional societies maintain and publish their own standards. For example, the American Society of Mechanical Engineers (ASME) has published its boiler and pressure vessel code since 1914, along with other standards. Also, SAE International, formerly the Society of Automotive Engineers, publishes many standards related to automobiles, trucks, and other vehicles. Table 5-2 is an incomplete list of professional societies and organizations that produce standards related to safety and health. 

P-T Limits for in-service inspection and hydrostatic test are developed in the same manner as for the reactor vessel beltline described in D.l above. The exception is that a safety factor of 1.5 is applied to the stress intensity factor foi>membrane stress due to pressure,, rather than 2, as allowed by G-2400 in Appendix G to SecrPon III of the ASME Code. 

V. In the US the primary code is that developed, published, and supported by the American Society of Mechanical Engineers known as the ASME Boiler and Pressure Vessel Code, Section VIII, Division 1. Within states and regions of the US various jurisdictions have modified the means by which local operators are allowed to implement the national ASME code. The national code, which is more complicated than the naming system for fluorinated chemicals (Ref. 3, Appendix 2), can be purchased together with a training course for its use at http // www.asme.org/products/courses/boiler-and-pressure-vessel-code-section-8-division. 

The rules for design, fabrication and inspection of pressure vessels are provided by codes that have been developed by industry and govermnent in various countries and are indicated in Table 1.1. The design and construction codes all have established rules of safety governing design, fabrication and inspection of boilers, pressure vessels and nuclear components. These codes are intended to provide reasonable protection of life and property and also provide for margin for deterioration in service. Table 1.1 also includes the ASME Boiler and Pressure Vessel Code. Some of the significant features of the latest version of the ASME Code Section 111 are ... 

Lnited States and Canada (227). Regaihil of the method of design, pressure vessels within the liu ts of tihe ASME code specifications are usually checked against th specifications. Before discussing the code it kt of interest to briefly review the antecedents of the code and its develop-mmt. A. M. Greene, Jr. has published an extensive history of tte ASME boBer code (177-184). 

ASME then convened its ASME Boiler Code Committee, formed in 1911. This committee led to the creation of the first edition of the ASME Boiler Code - Rules for the Construction of Stationary Boilers and for the Allowable Working Pressures, which was issued in 1914 and published in 1915. This first 1914 edition was later incorporated into laws throughout most of the United States and Canada. The ASME Boiler Code has continued to be developed over time into the ASME Boiler and Pressure Vessel code, and its use worldwide has spread. Today, there are over 92,000 copies in use, in over 100 countries around the world. 

American Society of Mechanical Engineers (ASME) http //www.asme.org (accessed June 22, 2010). Eounded in 1880, the ASME focuses on technical, educational, and research issues related to the field of mechanical engineering. It is responsible for the development of the International Boiler and Pressure Vessel Code that establishes rules of safety governing the design, fabrication, and inspection of boilers and pressure vessels. 

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