ASME PTB-3-2013 pdf download

ASME PTB-3-2013 pdf download.Section VIII – Division 2 Example Problem Manual.
2.1 General Example problems are provided for the following parts of the document; · Part 3 – Materials Requirements · Part 4 – Design By Rule Requirements · Part 5 – Design By Analysis Requirements · Part 6 – Fabrication Requirements · Part 7 – Examination Requirements · Part 8 – Pressure Testing Requirements A summary of the example problems provided is contained in the Table of Contents. 2.2 Example Problem Format In all of the example problems, with the exception of tubesheet design rules in paragraph 4.18, the code equations are shown with symbols and with substituted numerical values to fully illustrate the use of the code rules. Because of the complexity of the tubesheet rules, only the results for each step in the calculation producer is shown. 2.3 Calculation Precision The calculation precision used in the example problems is intended for demonstration proposes only; an intended precision is not implied. In general, the calculation precision should be equivalent to that obtained by computer implementation, rounding of calculations should only be done on the final results.
Per paragraph 3.11.2.3 for Carbon and Low Alloy Steel Except Bolting. a) Since the vessel has been PWHT, Figure 3.8 (or Table 3.15) shall be used to establish impact testing exemptions based on the impact test exemption curve for the subject material specification, MDMT, and governing thickness of a welded part. b) As noted in Figure 3.8, from the Material Assignment Table, a material specification of 516, 70, . SA Grade Norm – is designated a Curve D material. c) The governing thickness g t of a welded part is determined from the criteria of paragraph 3.11.2.3.b. For a butt joint in a cylindrical shell, g t is equal to the nominal thickness of the thickest weld joint, see Figure 3.9 Sketch (a). 1.8125 g t in = d) If an MDMT and thickness combination for the subject material is on or above the applicable impact test exemption curve, then impact testing is not required for base metal. Requirements for weld metal and heat affected zones are provided in paragraph 3.11.8. Interpreting the value of MDMT from Figure 3.8 is performed as follows. Enter the figure along the abscissa with a nominal governing thickness of 1.8125 g t in = and project upward until an intersection with the Curve D material is achieved. Project this point left to the ordinate and interpret the MDMT. This results in an approximate value of 19.0 MDMT F = – ° . A more accurate value for MDMT can be achieved by using the tabular values found in Table 3.15. Linear interpolation between thicknesses for a 1.8125 g t in = and a Curve D material results in the following value for MDMT.
4.1 General Requirements 4.1.1 Example E4.1.1 – Review of General Requirements for a Vessel Design a) General Requirements An engineer is tasked with developing a design specification for a new pressure vessel that is to be constructed in accordance with ASME B&PV Code, Section VIII, Division 2 (VIII-2). The VIII- 2 Code is being considered because the vessel in question is to be constructed of carbon steel with a specified corrosion allowance and a design pressure and temperature of 1650 psig at 200°F. As part of developing the design specification, the following items need to be evaluated. b) Scope 1) The vessel may be designed using the design-by-rule procedures of Part 4, using the design-by-analysis rules of Part 5, or a combination of both Parts 4 and 5. Some limitations may apply to either design method. 2) The user of the vessel is responsible for defining all applicable loads and operating conditions that the vessel will be subject to. All loads and conditions must be specified on the User’s Design Specification, see Part 2 paragraph 2.2. 3) A fatigue screening shall be applied to all vessel part designed in accordance with this Division to determine if a formal fatigue analysis is required, see Part 5 paragraph 5.5.2. c) Minimum Thickness Requirements Based on product form and process service, the parts of the vessel must meet the minimum thickness requirements presented in Part 4, paragraph 4.1.2. d) Material Thickness Requirements Fabrication tolerances must be considered in the design of the vessel components, based on forming, heat treatment and product form. e) Corrosion Allowance in Design Equations The equations used in a design-by-rule procedure of Part 4 or the thicknesses used in a design- by-analysis of Part 5 must be performed in a corroded condition. The term corrosion allowance is representative of loss of metal due to corrosion, erosion, mechanical abrasion, or other environmental effects. The corrosion allowance must be documented in the User’s Design Specification. f) Design Basis 1) The pressure used in the design of a vessel component together with the coincident design metal temperature must be specified. Where applicable, the pressure resulting from static head and other static or dynamic loads shall be included in addition to the specified design pressure. The typical loads that need to be considered in the design of a vessel are shown in Part 5, Table 5.1. 2) The specified design temperature shall not be less than the mean metal temperature expected coincidentally with the corresponding maximum pressure.