SATPC0038451 TAB 04 4 SOW.pdf

NASGRO Development Phase 12 - Statement of Work (SOW) May 13, 2025

Summary: Provide Phase 12 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 / ASME FFS-1 - 2021. The general objectives of these tasks are to implement through-wall crack transitions for circumferential cracks in cylindrical and spherical weight function SIF solutions consistent with API-579 transition criteria that are fully FAD enabled and to implement FAD capability for selected univariant weight function through-thickness SIF models. These will enable NASA engineers to evaluate additional fitness for service crack scenarios in full compliance with the applicable National Consensus Standard API-579 without having to resort to expensive outside consulting services or procurement of very expensive third-party commercial software (NASGRO is free us for all government employees and contractors performing NASA work).

Short title:

NASGRO Phase 12 development, tasks 15 (continued), 17 and 18 for pressure vessel and piping 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 (SAA) signed with Southwest Research Institute (SwRI), who is the legal copyright holder for the software. However, further development is required for its desired application to NASA’s fleet of pressure vessels and piping 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 piping systems were generally not included in that development. In 2000, an SAA was signed with SwRI for the collaborative development and commercialization of NASGRO to ensure its ongoing availability and support through the

NASGRO Phase 12 development 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.

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 new tasks 17 and 18 based on identified requirements to fully support API-579 assessment requirements as applied to NASA systems.

This document is the Phase 12 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 12 engineering and software development including graphical user interface (GUI) tasks as described in tasks 15, 17 and 18 below to add to NASGRO’s API-579 assessment 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 NASA’s assessment. Execution of this work requires 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 12 NASGRO development by completing the three tasks listed below. All work shall be based on the current release of API-579, 2021 edition.

Task 15 (cont’d): Provide a Report Documenting the Use NASGRO for API 579 Analyses

The objective of this task was 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 procedures. This report is being written in Phase 11, and this Phase 12 task is planned to address any updates that may be needed following the submittal of the report at the end of Phase 11. Additionally, the review and approval process with NASA for this report will begin with the goal of eventually issuing it as an official NASA Technical Memorandum (TM) report.

Task 17 (new): Implement Through-wall Crack Transitions for Circumferential Surface Cracks in a Cylinder (SC34) and a Sphere (SC36)

The weight function (WF) solutions for an external circumferential surface crack in a cylinder (SC34) and an internal or external surface crack in a sphere (SC36) were developed and implemented in previous phases. However, these solutions do not currently have the capability to transition to a through-crack solution. Therefore, the objective of this new task would be to implement two new through-wall crack models for these geometries. Because of the nature of the WF formulations for SC34 and SC36 and the complex surface crack geometry near transition, the development of a post-transition WF formulation would be very involved and potentially intractable. Therefore, as an expedient, SwRI will implement the existing API 579 solutions for the post-transition through cracks (KCTCC2 for the cylinder and KSTC for the sphere). This approach will require linearization of through-wall nonlinear stress gradients into membrane tension and linear bending components and will conservatively consider straight through-wall cracks. These two new models (tentatively named TC51 and TC52) will also be available in NASGRO to be run separately. They will be implemented for use with the failure assessment diagram (FAD) failure criteria using the corresponding API 579 reference stress solutions (RCTCC2 and RSTC). The new models will be available in NASFLA, NASSIF, NASCCS and NASFAD.

Task 18 (new): Implement FAD Capability for Two Univariant WF Through-thickness Models (TC29 and TC47)

The existing offset curved through crack in a plate solution (TC29) and the curved through crack at the edge of a plate (TC47) solution are not currently FAD enabled in any of the NASGRO modules.

This creates a problem, for example, when performing a crack growth calculation using the FAD failure criterion and SC30 because if a transition to a through crack is predicted, the calculation must stop because a post-transition curved through crack model using FAD does not exist. Therefore, the objective of this new task is to derive and implement limit load solutions for both TC29 and TC47 to enable SC30, SC31 and other models to continue the analysis utilizing the FAD failure criterion. The FAD capability for each of these models would be implemented in NASFLA and NASFAD.

Program Management

Bi-monthly progress reports will be written to track technical progress and expenditures. The new NASGRO features developed in this effort will be documented in the NASGRO Reference Manual with excerpts submitted as attachments to the progress reports. Access to the evaluation versions (12.0 alpha and beta) will be provided to NASA pressure vessel engineers as needed to enable them to review the new features.

San Antonio, TX 78238

4. Period of Performance

Work to begin as soon as possible during June 2025, and will extend through July 31, 2026.