P45200_SOW_Hull_Structure_Corrosion_Statistics_7-18-2017.docx

Statement of Work Probabilistic Life Prediction of Hull Structure Corrosion in U. S. Coast Guard Cutters

CONTENTS

1.0 Introduction

2.0 Reference Materials

3.0 Scope of Work

4.0 Deliverables and Schedule

5.0 Quality Assurance

6.0 Security Clearance

7.0 Use of Government Furnished Material

8.0 Notes

1. INTRODUCTION

The U.S. Coast Guard (USCG) SFLC has been involved in a number of special studies to assess the remaining life of structures of USCG Cutters. These efforts required the use of risk assessment and management methods to support engineering, operational and maintenance decisions. The assessment of life expectancy of structures should include as a core set of failure modes the ultimate hull girder collapse initiated by the failure of a stiffened panel, and fatigue and fracture. Variability of corrosion experienced on USCG Cutters is a specific example of factors effecting structural integrity requiring evaluation using a probabilistic risk based evaluation approach. Factors affecting structural integrity such as operational environment and structural response are probabilistic based and require a probabilistic based approach to evaluate statistics based risk associated with various alternatives being considered for design criteria, maintenance and repair.

Corrosion in USCG cutters is a primary degradation mode that accounts for a significant portion of depot budgets and the unavailability of these cutters. Corrosion exhibits great variability spatially and temporally. Although, the "average" corrosion rates in USCG cutters are manageable under current maintenance procedures, a small amount, although unknown percentage, of corrosion, both spatially and temporally, goes undetected and becomes more severe and damaging resulting in increased repair costs and loss of availability.

This project will empirically characterize the underlying stochastic processes to better understand these outliers in corrosion that are viewed as problematic. Several questions will be examined. For example, can we explain the problematic or the aggressive corrosion as resulting from variability in the sample average of corrosion? Would an extreme value model better fit the data representing the aggressive corrosion? Is there a need for a different statistical model for these outliers? What are the relationships and synergies between pitting and general corrosion? What the affects of coating and other protection methods?

The objective of this effort is to investigate the spatial and temporal statistics of corrosion rates on USCG Cutters for the purpose of predictive model development.

2.0 REFERENCE MATERIALS

The Tasks of this project require information about an existing cutter and their performance in ocean waves. Specific references are as follows:

· Structural loading calculations and strength assessments

· Other related engineering reports as needed

3.0 SCOPE OF WORK

To achieve the objective, the following tasks shall be performed:

Task 1 – Review corrosion data, such as ultrasonic scans and visual observations, and historical data for two cutter classes provided by the USCG.

Task 2 – Review literature on corrosion rates in structures in other industries, such as commercial nuclear power plants, petrochemical plants, other industrial facilities, offshore facilities, etc., for the purpose of identifying suitable models.

Task 3 – Evaluate statistics-based spatial and temporal models for corrosion in USCG cutters that would be suitable for prediction. The models that would be examined include statistical methods, extreme value models, Markov Process models. This task will be compatible with the Structural Life of Ship Hulls (SLASH) and also use data captured in and MAESTRO-Corrosion Database that is being used by the USCG to evaluate structural reliability models. The ongoing reliability evaluation by the USCG is not specifically part of this task. The contractor shall meet with the USCG to discuss the interim progress on this task.

Task 4 – Recommend approaches for monitoring the corrosion based on prediction modeling. The appropriateness of using Bayesian methods will be examined. Other methods will also be explored. Illustrative examples will be developed for prediction and use in corrosion inspection planning although the illustrations will not include the economics associated with the planning but they would be compatible with inspection planning and lifecycle economics.

Task 5 – The contractor shall document the results of Tasks 1-4 in a final report. The contractor shall present the findings from the project at the USCG SFLC in Baltimore MD any other location in the Washington Metropolitan area as defined by the U.S. Coast Guard.

4.0 DELIVERABLES AND SCHEDULE

4.1 DELIVERABLES – The Contractor shall include in the report deliverable of Tasks 1 through 4 to SFLC-ESD-NAME-NAV ARCH all photographs, illustrations, charts, graphs, tables, calculations, text, analyses, algorithms, conclusions and recommendations developed completely and exclusively as a part of this project. After receiving SFLC-ESD-NAME-NAV ARCH comments, the Contractor shall produce the updated deliverable within four weeks. Each deliverable, both draft and final, shall be transmitted to the SFLC-ESD-NAME-NAV ARCH with a documenting cover letter and a copy of the cover letter shall be provided directly to the Contracting Officer.

4.2 Modifications to contractor submittals required by the government reviewers, if judged by the contractor to be outside the scope of this Statement of Work, shall be discussed at a meeting of the government technical and contracting personnel with contractor representatives.

4.3 SCHEDULE – The following schedule of events shall be followed by both the U.S. Coast Guard and the Contractor in carrying out the provisions of this Statement of Work. When either party becomes aware of their inability to conform to this schedule, they shall so advise the other party, in writing, propose an alternate schedule, and provide justification. Period of Performance is 52 weeks after contract award.

5.0 QUALITY ASSURANCE

5.1 The government reserves the right to witness the validation procedures and validation processes of any part of the project development at whatever site such action is taking place.

5.2 The government will review the contents and format of the deliverables in their entirety prior to issuing approval.

6.0 SECURITY CLEARANCE

6.1 This work is not classified. No security clearance is required.

6.2 Foreign nationals may be used on the project as long as USCG data are not shared with them.

7.0 USE OF GOVERNMENT FURNISHED MATERIAL

7.1 Government furnished material shall be used for the delivery order only and shall not be used or disseminated for any other purpose.

8.0 NOTES

8.1 DELIVERY DESTINATION – All items to be delivered under this work statement shall be delivered to the SFLC-ESD-NAME-NAS technical point of contact, Mr. Karl Stambaugh, with a documenting cover letter at the following address:

For each deliverable a copy of the cover letter shall be provided directly to the Contracting Officer at the following address:

8.2 RIGHTS IN DATA – All data produced exclusively and completely based on this effort, regardless of form or medium, are considered to be solely the property of the U.S. Coast Guard and shall not be released without the written consent of the U.S. Coast Guard.