HTHA/High Temp Damage Mechanisms Track

DetaClad Characterization for High Temp and High Pressure Hydrogen Service
Olivier Sarrat, NobelClad
When it comes to considering high temperature damage mechanisms, one of the most challenging examples is related to heavy wall pressure vessels that operate at high pressure with hydrogen containing fluids. Thick wall pressure vessels often have an austenitic stainless-steel lining to protect the inner side from corrosion or exposure to hydrogen at high temperature and pressure that could result in stress corrosion cracking. In addition to the embrittlement of the carbon steel due to Hydrogen propagation in
grain boundaries generating cracks, dis-bonding on the cladder interface can occur after reactors cool down when operating at these stringent conditions. Whether end users must address corrosion cracking or cladding disbanding, the cost of down-time or maintenance work on these pressure vessels is costly and restricts total output. The purpose of this presentation is to present finding from a study around characterizing the DetaClad Explosion bonded interface while in under these extreme operating conditions. This presentation will cover various test protocols such as mechanical and dis-bonding tests that were conducted. The tests from this study, benefit the most common reactor designs for various post weld heat treatment and welding internal supports.

Determining Inspection Intervals for Equipment at Risk of High Temperature Attack
Nathaniel Sutton, The Equity Engineering Group

High Temperature Hydrogen Attack (HTHA) has been a recent area of focus for numerous industries, including fertilizer, petrochemical, refining, and others. Guidance regarding non-destructive examination (NDE) for HTHA has recently been updated in API RP 941, 8th Ed., Addendum 1 (2020). Ongoing work by MTI seeks to further optimize these techniques. Many owner-operator companies are inspecting equipment flagged as at-risk for HTHA. If the inspection demonstrates that no significant HTHA is present in the equipment, mechanical integrity professionals must then identify the interval until the next inspection. Considering the time-dependent progression of HTHA damage, this may prove challenging. This presentation will focus on the method applied by E2G to establish inspection/reinspection intervals for equipment in HTHA service. The processes for (1) identifying equipment to be inspected, (2) determining the appropriate coverage and sensitivity needed for inspection, and finally (3) determining frequency of inspection will be demonstrated on example equipment. It will be shown that a quantitative approach can be used to set intervals, which considers both volumetric HTHA as well as the growth of crack-like-flaws due to HTHA. Application of this methodology is intended to allow users to balance the costs of repeat inspections with the risk of failure or loss-of-containment due to HTHA.

High Temperature Oxidation Performance of Sanicro 25

Luiza Esteves, Sandvik
Sanicro 25 (UNS S31035) is an austenitic 22Cr25NiWCoCu stainless steel material with excellent high temperature properties that can be applied in supercritical carbon dioxide (sCO2), supercritical water as well in superheater and steam boilers employing different fuel types. The material has been specifically developed for applications up to around 700°C (1300° F) and has high creep strength, good steam oxidation resistance, good flue gas corrosion resistance, structural stability, good fabricability, and weldability. The aim of this work is to compare the corrosion performance of the main alloys used in sCO2 and steam oxidation with Sanicro 25 as an interesting option in higher pressure/temperature applications

Insights from Creep Testing of Service Exposed Components
Arun Sreeranganathan, Ph.D., P.E., Stress Engineering Services, Inc
Creep is one of the most common damage mechanisms of concern at elevated temperatures. Creep testing of service-exposed material is a valuable tool in extending the service lives of high temperature components. Often, sample removal and creep testing are carried out in the event of operational upsets or anomalies leading to the component being exposed to temperatures far in excess of typical operating conditions, raising concerns about significant creep damage accumulation in the material. This presentation will focus on degradation in the creep properties of various alloys from long-term service under normal operating conditions as well as short-term exposure to higher temperatures due to operational upsets. Results from metallurgical assessment and creep testing of virgin and service-exposed materials will be used to try to correlate microstructural changes with the creep properties.

New Insights on the High Temperature Resistance of UNS N08800, S30815 and S31009 Alloys
Sandra LE MANCHET, Industeel – ArcelorMittal
This presentation will provide new results on the high temperature corrosion resistance of several heat resistant stainless steels. The materials investigated in this study are UNS N08800 (800H), S30815 and S31009 (310S). The high temperature tests were conducted in gaseous environments representative of industrial applications, such as waste incineration, fuel combustion and chemical reactors / furnaces. A first series of trials was performed in 20% oxygen and 80% nitrogen gas mixture at 1000°C (1830°F), both in isothermal and cyclic conditions. A second series was conducted in a gas mixture of oxygen, carbon dioxide and water, containing hydrochloric gas and sulfur dioxide contamination in the temperature range between 500°C (930°F) and 800°C (1470°F). Special attention will be paid to the formation and adherence of the protective layer formed at the surface of the steels, and to the influence of the alloying elements on the heat resistance, particularly silicon, aluminum, titanium and rare earth elements. Scanning electron microscope observations linked to X-ray diffraction analyses will be provided to support the results.

Thermal Mix Points – Developing Criteria for Using Sleeved Mixing Tees
Cathleen Shargay, Fluor; Jeremy Nelson, Koch; Garry Jacobs, Fluor
Past references have highlighted that process mixing points with “delta temperature (ΔT)” exceeding certain thresholds will have risk of fatigue cracking which is typically avoided by installing a sleeved thermal mixing tee. In reality, the risk of cracking is influenced by numerous additional variables, particularly the fluid or vapor properties, the relative flow rates, and any mechanical pulsations in the flow of the parent streams, as well as the piping materials of construction and layout. Research into predicting delta T limits for thermal fatigue and thermal shock mitigation considering the additional variables, has progressed in both the nuclear and refining/petrochemical industries, but firm guidelines are still not available. This presentation will briefly summarize key literature references from these industries, and show examples of failures due to both mechanical and thermal fatigue in order to advance industry awareness of the issues. Typical sleeved mixing tee design features are also described, and the benefits of adding a static mixer within the sleeve for the most severe delta T’s are highlighted, along with examples of unit designs with these conditions.