ASME PTB-13-2021 pdf download

ASME PTB-13-2021 pdf download.Criteria for Pressure Retaining Metallic Components Using Additive Manufacturing.
6 ADDITIVE MANUFACTURING DESIGN REQUIREMENTS
(a) In addition to the design requirements of the ASME Construction Code or Standard, the design requirements in 6(b) through 6(g) apply for components produced using the powder bed fusion AM process.
(h) Any material produced during the AM build that is specified as cosmetic material shall not he credited as load bearing material in the stress analysis.
(c) Fatigue-critical surfaces shall be designed to be accessible for liquid penetrant examination.
(d) Surfaces interfacing with sacrificial supports shall he fully accessible for removal of supports and for liquid penetrant examination.
(e) The effect of any support that will not be removed following the AM build shall be included in the stress analysis.
(0 Supports that are credited as load hearing in the stress analysis shall meet all relevant criteria identified in this document.
(g) A design report is required for all additively manufactured components.
6.1 Commentary
The design requirements for AM components follow the requirements in the applicable ASME Construction Code or Standard. The criteria require that each component has a design report. ASME BPV Code Section III and Section VIII, Division 2 have requirements for the content of a design report and can be applied for nuclear and non-nuclear applications, respectively. When the governing Construction Code or Standard applicable to the AM component does not have specific requirements for a design report the requirement in Section VIII, Division 2 are recommended for design. The Section VIII, Division 2 rules in Part 4 and Part 5 are acceptable for design as applicable. Since many of the AM components will have a significantly complex geometry, the rules of Section VIII Division 2, Part 5 are the most applicable for AM design for non-nuclear applications. The detailed stress analysis requirement in Section V III, Division 2, Part 5 also allows for identilication of the areas of high stress and fatigue critical areas in a component necessary for use in determining the location of required test specimens specified in Section 9 and direct NDE.
The AM build process requires that support structures be integrated into the build to provide support for overhanging sections of the component that occur above the build plate. The integral supports also serve to restrain the geometry against deflections caused by residual stresses that are generated during the build. These supports can he either sacrificial or permanent. Component surfaces interfacing with sacrificial supports need to be fully accessible for removal of supports and for liquid penetrant examination. The examination of these locations ensure that an unevaluated stress riser does not affect the structural integrity of the component. The effect of possible stress risers from any support that will not be removed following the AM build is required to be evaluated during the component stress analysis. Any material in a permanent support that is credited as load bearing in the stress analysis shall meet all relevant AM criteria provided in this report.
The surfaces of an AM component can be constructed with machine parameters to optimize dimensional tolerances and surface finish. These surfaces are defined as cosmetic material. Specifically, cosmetic material is material produced by process parameters that are not represented by qualification or witness specimen test results. When performing a stress analysis for an AM component, cosmetic material is not credited as load hearing material in the stress analysis. The cosmetic layer is addressed in the same manner as for material added for corrosion or mechanical allowance in the ASME construction code.
7ADDITIVE MANUFACTURING PROCEDURE
(a) The Additive Manufacturer shall prepare an Additive Manufacturing Procedure.
(b) The AM Procedure shall address applicable process variables shown in Table 7-1 and include any required tolerance limits for process variables. The Additive Manufacturer may include additionalprocess variables.