SOW.pdf

NASGRO Development Phase 9 - Statement of Work (SOW) April 24, 2023

Summary: Provide Phase 10 professional development services to implement features in NASGRO that will enable the performance of fitness-for-service (FFS) and fatigue crack growth (FCG) analyses consistent with the approaches outlined in API 579. The objectives of these tasks are to simplify the NASGRO inputs such that it is easier for the user to follow the API 579 approaches and use API 579 materials data. While prior tasks have used API-579 – 2016 as the baseline, current and future efforts shall reference the now-available 2021 edition.

Short title:

NASGRO Phase 10 development, tasks 5, 8 (cont.), 12 – 15 for pressure vessel applications.

Background NASA’s Office of Safety and Mission Assurance (OSMA) and NASA Ames Research Center’s Pressure Systems Manager (PSM) on behalf of all NASA Centers require the ability to evaluate the fitness for service and remaining safe life of ground-based pressure vessels and pressurized systems that experience cyclic pressure, mechanical and thermal loadings during operation that causes fatigue / fracture damage and crack growth. Commercially available software that offers this capability does not adequately address NASA’s technical requirements for layered vessels, is very expensive, and requires per-user seat license procurement and annual maintenance contracts for upgrades and security patching. Therefore, NASA desires to use the NASGRO fracture mechanics analysis software since the Agency has unlimited free use rights through the Space Act Agreement signed with Southwest Research Institute (SwRI), who is the legal copyright holder for the software. However, significant further development is required for its desired application to NASA’s fleet of pressure vessels and systems, and this phased development effort is NASA’s investment to develop and mature the software for such use by all Centers.

NASGRO was initially developed in the 1980s by Lockheed Martin Services (LMS) under contract to NASA to meet space flight program fracture control requirements, but the features required for current assessment of institutional ground-based pressure vessels and systems were generally not included in that development. In 2000, a Space Act Agreement (SAA) was signed with SwRI for the collaborative development and commercialization of NASGRO to ensure its ongoing availability and support through the establishment of a fee-based industry consortium with SwRI serving as the managing partner and principal developer. At the same time, the NASGRO copyright was reassigned and transferred from LMS to SwRI, who retains it to the present. Under the terms of the SAA, NASA retains a perpetual royalty-free license for use of NASGRO for NASA programs and projects. NASA is not a consortium member, however, and any NASA-specific development tasks must be funded by NASA. NASA JSC continues funding the development of space flight related fracture control features and improvements, while NASA’s Office of Safety and Mission Assurance (OSMA) has provided incremental funding of tasks related to ground-based pressure vessels and systems since 2014 with Phase 1 of this effort. It is anticipated that additional development phases will be undertaken in the future as funds become available.

NASGRO Phase 10 development

NASA’s policy in NPR 8715.1B (chapter 7) and pressure system safety requirements in NASA STD- 8719.17C and NASA STD 8719.26 require that each NASA Center demonstrate the safety, fitness for service, and remaining safe life of potentially hazardous ground-based pressure vessels and systems.

NASA has many such systems that are both vital to NASA’s mission and present significant potential hazards to staff. Most vessels are subjected to cyclic service loadings, and many were fabricated from undocumented, non-Code materials and processes. Standard ASME Code rule-based techniques are often inadequate for addressing the in-service conditions and features of these vessels without excessive conservatisms, and the specialized capabilities of fracture mechanics and cyclic crack growth software is needed to provide remaining safe life assessments of such legacy equipment. In addition, industry codes and standards mandated by OSHA (e.g., ASME Boiler & Pressure Vessel Code, and ASME FFS-1 / API-579 Fitness for Service) require the application of the failure assessment diagram (FAD) approach and its underlying analytical methodologies in these assessments. NASGRO did not originally address the ASME/API FAD approach because the consortium members and JSC interests were in aerospace rather than ground-based vessels, but this has been included in the completed tasks of this phased work. NASGRO requires ongoing targeted engineering and software development to fully incorporate the ASME/API stress intensify factor (SIF) models and weight function methodologies and to provide options for consistency with API-579 – 2021 outputs. An updated plan of development tasks was agreed upon with NASA in 2018 and the current task reference numbers reflect the updated plan and tasks 12 – 15 which new in the current effort.

This document is the Phase 10 development SOW. The subtasks listed below require fracture mechanics engineering, software coding, verification and validation testing, reporting, and project management in accordance with SwRI standards. The successful completion of this work will benefit NASA and industry through improved safety assessments with the incorporation of the desired capabilities in future commercial releases of NASGRO.

1. Objective

The bidder shall perform Phase 10 engineering and software development including graphical user interface (GUI) tasks as a follow-on to Phase 1 - 9 work to incorporate prior development and enhance NASGRO’s API-579 capabilities and compatibility as related to assessment of NASA’s institutional ground-based pressure vessels and systems. This work requires completing development tasks, documentation of progress and functionality reports, and publishing NASGRO updates for user community assessment. This work must proceed as a single source procurement to SwRI, the sole legal copyright and SAA holder, based on the sole source justification provided separately.

2. Scope & Specifications

Perform Phase 10 NASGRO development by completing the six tasks listed below. All work shall be based on the current release of API-579, the 2021 edition.

Task 5: Alternative Criteria for Surface & Embedded Crack Transitions

The crack transition criteria in NASGRO differ from those contained in the API 579 "recategorization" guidelines. For example, the API guidelines require transition to a through crack at an a/t of 0.80 whereas the NASGRO weight function surface crack models transition to a through crack at an a/t of

0.95 (e.g., SC30 & 31). The objective of this task shall be to implement an option within NASGRO to allow the user to optionally choose crack transition criteria based on the API flaw recategorization guidelines for surface and embedded cracks in Section 9.3.6.6 of API 579. It is anticipated that this transition criteria option would be implemented in NASFLA via the "Options" menu item on the NASFLA main menu.

Task 8: Investigate Compatibility of NASGRO SIF models with API 579 solutions

Comparisons of NASGRO SIF solutions with corresponding SIF solutions from API 579 have been an ongoing effort in Phase 9 (and earlier) and will continue in Task 10 with a focus on documenting the comparisons and results. The results of this task shall feed into the construction of the Task 15 report. However, results from this task will be presented as they become available in the progress reports throughout the year. Recommendations for future development and/or comparisons will be provided.

Task 12: Implement API 579 Polynomial Weld Residual Stress (WRS) Distributions

Previously, in Phase 5 (2018) the capability to specify a residual stress distribution in polynomial form was implemented in NASGRO to enable easier use of commonly used equations for weld residual stresses (e.g., API 579 equations) without having to program them into a spreadsheet and then cut and paste the stresses into the NASGRO graphical user interfaces (GUIs). This new Task 12 shall further simplify this process by providing the user the capability to choose from a menu of API 579 weld residual stress (WRS) equations (from Annex 9D) and not have to manually enter polynomial coefficients into the GUI. It is anticipated that a button would be added to the Geometry screen that would activate a pop-up menu for the user to select the desired API 579 WRS description (component, weld type, direction, etc.) and equation number from Annex 9D. The GUI will provide the capability to plot the selected WRS distribution.

Task 13: Provide Capability to Use API 579 Lower Bound Fracture Toughness This task shall provide the capability for a user to calculate a lower bound fracture toughness (K1c) in accordance with API 579 – 2021 section 9F.3.5 for ASME Sect. VIII Div. 1 & 2 fracture toughness (eqn. 9F.42 and 9F.43) and API-579 -2021 section 9F.4.2 for ASME Section XI fracture toughness when no data are available (eqns. 9F.44 and 9F.45). The user would supply the ASME Exemption Curve designation (A, B, C, or D), the Minimum Specified Yield Strength (MYS), and the operating temperature. The reference temperature will be determined using API 579 Table 9.2 and the lower bound fracture toughness computed using the above referenced equations. This new feature would be implemented as an option on the NASGRO material screens for NASFLA and NASFAD.

Task 14: Provide Capability to Simply Use the Paris Equation in NASFLA It is currently possible to specify a Paris equation in NASFLA via the NASGRO equation by making specific choices for various parameters in the NASGRO equation. The new approach for this task shall allow the user to specify only the simple Paris parameters in the GUI and/or access them from a NASGRO or user material database file. This option shall present as new choices for "Data Source" and "Data Format" in the material selection process. The Paris data would be stored in the NASGRO or user database as Paris data, not as NASGRO equation data, so some new fields and tags would need to be introduced in the XML database. These tags would allow the user to choose from a list of the AP1 579 – 2021 Paris equations (from Sections 9F.5.2) and provide the flexibility for the addition of other Paris equation parameters in the future.

While the Paris equation is "simple" in form, this task involves many interrelated factors that will complicate its implementation and consequently, the effort proposed for Phase 10 will focus on developing a detailed design plan for the implementation of a Paris equation capability in NASGRO.

Factors that will need to be addressed include the database structure for the API 579 Paris equation parameters, material chooser modifications in the GUI that reflect the choices of the API 579 plan for the Paris equation implementation will be submitted as an attachment to a progress report.

Implementation of the design plan will begin as time permits but is not expected to be completed in Phase 10.

Task 15: Provide a Report Documenting the Use of NASGRO for API 579 Analyses The objective of this task is to produce a report summarizing and demonstrating the use of NASGRO to perform FFS assessments and fatigue crack growth evaluations of representative pressure vessel examples in accordance with API 579 - 2021 procedures. The report is planned to include (at a minimum):

• Comparison of NASGRO and API 579 SIF solutions

• Overview of key NASGRO SIF models for pressure vessel (PV) analyses

• Specification of material properties (strength, fracture toughness, FCG rates)

• Specification of weld residual stress distributions

• Overview of Failure Assessment Diagram (FAD) failure criteria

• NASGRO FAD options

• Using NASFAD for FFS assessment

• Using NASFLA for fatigue crack growth analyses

• Examples for different PV geometries, crack orientations, and shapes

Since the content of the above items will depend strongly on the completion of the other tasks in Phase 10, the Phase 10 objective for Task 15 shall be to develop a detailed outline of this report.

Writing of some portions of the report will begin as time permits but the full report is not expected to be completed in Phase 10.

Program Management

Bi-monthly progress reports shall be written to track technical progress and expenditures. The new NASGRO features developed in this effort shall be documented in the NASGRO Reference Manual with excerpts submitted as attachments to the final progress report.

4. Period of Performance

Work to begin as soon as possible which is assumed to be no later than May 31, 2023 and will extend through May 31, 2023.

5. Technical Point of Contact / Deliver to:

NASA ARC Pressure Systems Manager / Code QS Building N-237, room 213 Moffett Field, CA 94035-0001