High Temperature

Advanced Methodologies for Remaining Life Assessment

High and normal operating temperatures can degrade metallurgical properties and produce damage not seen at lower temperatures. The design codes for components in this temperature range only provide basic design requirements, but actual component behavior is strongly dependent on the existing operating conditions and service environment. To prevent both under-utilization and failure of equipment, the challenge for owner-users is to accurately predict remaining life, prevent unnecessary repairs or replacements, and extend equipment life and availability.

Equity has in-depth experience in evaluating the suitability for service of components operating in the high temperature range and subject to a variety of damage mechanisms. Our membership and support of joint industry programs sponsored by the Materials Properties Council (MPC) Project Omega for creep damage evaluation and MolyHy for assessment of High Temperature Hydrogen Attack (HTHA) gives us special expertise in state-of-the-art technologies for equipment assessment.

Equity’s David Osage and Gerrit Buchheim are recognized high temperature experts:

Drafted creep life assessment rules for Part 10 in API 579-1/ASME FFS-1
Authored Appendix F of API 579-1/ASME FFS-1
Active members of MPC Project Omega since its inception in 1984
Created VCESage remaining life assessment module
Active members of MPC MolyHy program

We can help you understand – and deal with – the various ways high temperatures can impact your equipment and the interactions between mechanical, metallurgical, and environmental causes of high temperature damage mechanisms.

Practical Advice for a Complicated Problem

Equity's close working relationship with MPC provides us access to extensive materials property information, and insight into innovative analytic methodologies. MPC's Project Omega methodology can be used to accurately determine the remaining life of aging equipment not only by providing materials properties that are the best in the industry, but also through a procedure for conducting creep strain rate tests from the assessment day forward, thereby avoiding the need for a precise past pressure and temperature operating history. The methodology has been validated through experience and is published in API 579. Most of the major integrated oil companies are using this technology with great success.

Equity uses a phased approach to help you mitigate and manage the damage mechanisms that most often cause costly failure: creep, High Temperature Hydrogen Attack, metallurgical embrittlement, and thermal stresses/fatigue. This approach saves time and money by giving you the ability to stop applying technology as soon as the essential need is satisfied.

Phase 1 – Preliminary calculations based on previous industry inspections and nominal operating conditions
Phase 2 – More sophisticated stress analysis and better understanding of the materials involved; possibly some chemical analysis
Phase 3 – Creep testing through one of the most respected labs in the country
Phase 4 – Remaining life calculations
Phase 5 – Probabilistic assessments

This working process assures that you won't get caught in a consulting quagmire of doing unnecessary work that yields marginal value. Our goal is to give you practical advice.

Creep

Equity uses the MPC Project Omega approach to identify vulnerable equipment long before inspectors can find advanced damage. We have applied this method to many fired heater tube assessments and have found that, in most cases, the predicted life is much longer than using standard industry guidelines such as API 530. The Omega method enables us to optimize heater throughput and tube life based on the accuracy of our assessments.

We use our proprietary VCESage software program to perform remaining life calculations. The heater tube creep module in our VCESage program contains both the API 530 and the API 579 Omega equations, materials data, and also considers tube wall thinning.

We have also applied the Omega approach and properties to other equipment operating in the creep regime with similar results (hot wall reactors, piping, valves, etc. See section “Beyond Heater Tubes”)

High Temperature Hydrogen Attack (HTHA)

HTHA, particularly of C-0.5Mo steels, is a continuing industry challenge in high temperature / hydrogen environments. This issue is relevant now that many refineries are converting existing equipment as part of low sulfur fuels projects.

Equity engineers have been involved with API 941 for over 35 years, and we are members of the MPC JIP Moly-Hy, which has developed innovative technology to better characterize incipient damage and assistance with remaining life/FFS issues. We can help your facility identify potential HTHA issues with Risk-Based Inspection (RBI) methods, and then with inspection and assessment planning. We can also help you manage replacement versus maintenance decisions.

Our Buckeye II Sampler™ cuts small samples without the need for weld repair. Samples are analyzed for methane content and voids.

We are the only engineering consulting company in the MPC Moly-Hy Joint Industry Program.

Metallurgical Embrittlement

There are number of changes that occur with certain alloys due to high temperature exposure:

Sigma Phase Embrittlement of austenitic stainless steel
Carbide Precipitation in many alloys
885F(430C) Embrittlement in ferritic stainless steel
Temper Embrittlement of 2.25Cr alloys
Reheat Cracking of 1.25Cr steel

These changes can be subtle, but can lead to big failures. Our materials experience can guide you as to when, where and how to look for these changes.

Beyond Heater Tubes: Help with Other At-Risk Components

Equity has performed hundreds of heater tube assessments, using VCESage software plus the API 530 design code for heaters and the API 579-1/ASME FFS-1 FFS Standard. However, many components require more sophisticated analysis, including vessels, piping, and other heater components.

Equity performs finite element stress analysis to simulate temperature and structural response of complex components and loading conditions. We are one of the few firms to commonly employ advanced stress analysis techniques in conjunction with the MPC material models (that is, advanced non-linear inelastic stress analysis combined with an understanding of metallurgical properties) to simulate high temperature response and characterize creep damage.

This multifaceted approach can be beneficial in assessing high temperature damage in the following:

Process heaters (coke heaters, cat reformers, steam/ammonia reformer heaters
Heater components (tube sheets, hangers, ducts, headers)
Hot piping and valves
FCCU reactor and regenerator components
Reactor health/remaining life
Thermal diffusion calculations for start-up and shutdown; safe envelopes
PWHT simulations to advise on difficult applications
Hot-tap analysis

Equity performs these state-of-the-art assessments quickly, to help you make informed decisions in a timely manner.

Featured Experts

David Osage
P.E.

Mr. Osage has over 30 years of experience in the refining and petrochemical industry both as an owner-user and consultant. He is responsible for engineering consulting services for pressure containing....

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David Osage, P.E.

Osage Mr. Osage has over 30 years of experience in the refining and petrochemical industry both as an owner-user and consultant. He is responsible for engineering consulting services for pressure containing systems including pressure vessels, piping, and tankage. His responsibilities include stress and thermal analysis of pressure vessels, piping and tankage; development and maintenance of CAE systems for plant engineering; advanced finite element methods; Fitness-For-Service analysis of in-service equipment; high temperature design and remaining life assessment; fracture mechanics; failure analysis and resolution of lessons-learned; development and maintenance of engineering standards; implementation of design changes and problem solving at shut-downs; and troubleshooting and recommendations for repairs to damaged equipment.

Mr. Osage is internationally recognized as an industry expert and leader in the development and use of FFS technology. As the architect and principal author of API 579 Fitness-For-Service, he developed many of the assessment methodologies and supporting technical information. Mr. Osage was the recipient of a Certificate of Appreciation from API for his work on API 579. Mr. Osage is the chairperson for the API/ASME Joint Committee on Fitness-For-Service and was instrumental in completing the update to API 579 entitled API 579-1/ASME FFS-1 Fitness-For-Service. For his efforts on API 579-1/ASME FFS-1 and API 579-2/ASME FFS-2 Fitness-For-Service Example Problem Manual, Mr. Osage received a Resolution of Appreciation from API and Certificates of Acclamation from ASME.

Mr. Osage also has considerable expertise in the design of new equipment. As the lead investigator and principal author of the new ASME, Section VIII, Division 2 Pressure Vessel Code, he developed a new organization and writing style for this code and was responsible for introducing the latest developments in materials, design, fabrication, and inspection technologies. These technologies include a new brittle fracture evaluation method, new design-by-analysis procedures including the introduction of elastic-plastic analysis methods, and a new fatigue method for welded joints. Mr. Osage serves on the ASME Section VIII main Committee and the Subgroup Design.

Mr. Osage was the lead investigator in an effort to revamp the API Risk-Based Inspection (RBI) technology and software. The main focus of this effort is a clean-sheet rewrite of API 581 Risk-Based Inspection and the development of a new version of the API RBI software. Mr. Osage is also currently working on the next generation of RBI technology where Fitness-For-Service assessment procedures will be used to compute the probability of failure for Risk-Based Inspection.

Mr. Osage provides engineering consulting for all levels of refinery capital projects including, preparation of design specifications, coordination of design reviews, development of engineering standards for refinery equipment, and QA/QC procedures for project administration. He also has extensive experience in preparation and delivery of training courses to practicing engineers in industry-related technologies such as Fitness-For-Service. As an Adjunct Visiting Assistant Professor at Steven Institute of Technology, Mr. Osage taught graduate level courses in strength of materials and elasticity, structural analysis and finite element methods, and structural optimization.