Managing the Risks Associated With Operating a Hydrotreater Reactor With Possible High-Temperature Hydrogen Attack Damage

2019 ◽  
Author(s):  
Phillip E. Prueter ◽  
Ryan Jones ◽  
Jacki Hess ◽  
Joel DeLuca
Keyword(s):  
High Temperature ◽  
Management Strategies ◽  
Damage Mechanism ◽  
Operating Conditions ◽  
Hydrogen Attack ◽  
Material Defects ◽  
Start Up ◽  
Load Carrying ◽  
Risk Management Strategies ◽  
Non Destructive

Abstract High-temperature hydrogen attack (HTHA) is a damage mechanism that can detrimentally affect the service life of carbon steel and low-chrome pressure equipment in the petroleum refining and related industries. HTHA involves the diffusion of hydrogen into steel, where it chemically reacts with free carbon at high temperatures to produce methane. This methane then gets trapped inside small cavities and other material defects. Over time, the rising methane pressure in these cavities can cause damage at the material grain boundaries. To this end, long-term exposure to high-temperature hydrogen environments can lead to volumetric damage that can diminish the load carrying capability of pressure equipment and accelerate the propagation of crack-like flaws. There have been several known industry failures attributed to HTHA damage as well. This paper summarizes a case study of a detailed analytical evaluation of potential HTHA damage in a vintage C-0.5Mo hydrotreater reactor. The goal of this study is to quantify the severity of HTHA damage using methods developed as part of an ongoing, multi-year Joint Industry Project (JIP) to justify continued operation of the reactor until the earliest practical replacement opportunity. HTHA damage and crack growth predictions are carried out based on documented historical operating conditions. Additionally, sensitivity in predicted remaining life to anticipated future operating temperatures is considered. Furthermore, based on state-of-the-art non-destructive examination (NDE) methods, fracture mechanics-based minimum pressurization temperature (MPT) envelopes are generated to help guide start-up and shut-down procedures that mitigate the risk for brittle fracture. Practical recommendations are also provided to facilitate the interpretation of NDE findings and to implement on-going failure mitigation and risk management strategies, including the development of Integrity Operating Windows (IOWs), for the reactor until planned replacement.

Effect of Carbide Content on Temper Embrittlement of 2.25Cr1Mo Steel

2016 ◽  
Author(s):  
Yian Wang ◽  
Guoshan Xie ◽  
Zheng Zhang ◽  
Xiaolong Qian ◽  
Yufeng Zhou ◽  
...  
Keyword(s):  
High Temperature ◽  
Pressure Vessel ◽  
High Stress ◽  
Temper Embrittlement ◽  
Damage Mechanism ◽  
Pressure Vessels ◽  
Nondestructive Method ◽  
Operating Conditions ◽  
Low Alloy Steels ◽  
Carbide Content

Temper embrittlement is a common damage mechanism of pressure vessels in the chemical and petrochemical industry serviced in high temperature, which results in the reduction of roughness due to metallurgical change in some low alloy steels. Pressure vessels that are temper embrittled may be susceptible to brittle fracture under certain operating conditions which cause high stress by thermal gradients, e.g., during start-up and shutdown. 2.25Cr1-Mo steel is widely used to make hydrogenation reactor due to its superior combination of high mechanical strength, good weldability, excellent high temperature hydrogen attack (HTHA) and oxidation-resistance. However, 2.25Cr-1Mo steel is particularly susceptible to temper embrittlement. In this paper, the effect of carbide on temper embrittlement of 2.25Cr-1Mo steel was investigated. Mechanical properties and the ductile-brittle transition temperature (DBTT) of 2.25Cr-1Mo steel were measured by tensile test and impact test. The tests were performed at two positions (base metal and weld metal) and three states (original, step cooling treated and in-service for a hundred thousand hours). The content and distribution of carbides were analyzed by scanning electron microscope (SEM). The content of Cr and Mo elements in carbide was measured by energy dispersive X-ray analysis (EDS). The results showed that the embrittlement could increase the strength and reduce the plasticity. Higher carbide contents appear to be responsible for the higher DBTT. The in-service 2.25Cr-1Mo steel showed the highest DBTT and carbide content, followed by step cooling treated 2.25Cr-1Mo steel, while the as-received 2.25Cr-1Mo steel has the minimum DBTT and carbide content. At the same time, the Cr and Mo contents in carbide increased with the increasing of DBTT. It is well known that the specimen analyzed by SEM is very small in size, sampling SEM specimen is convenient and nondestructive to pressure vessel. Therefore, the relationship between DBTT and the content of carbide offers a feasible nondestructive method for quantitative measuring the temper embrittlement of 2.25Cr-1Mo steel pressure vessel.

A Qualitative Risk-Based Assessment Procedure for High Temperature Hydrogen Attack of C-1/2Mo Steel

2007 ◽  
Author(s):  
James E. McLaughlin
Keyword(s):  
High Temperature ◽  
Partial Pressure ◽  
Elevated Temperatures ◽  
Probability Of Failure ◽  
Hydrogen Partial Pressure ◽  
Operating Conditions ◽  
Assessment Procedure ◽  
Hydrogen Attack ◽  
Relative Dependence ◽  
Petroleum Refineries

A qualitative risk-based assessment procedure was developed to determine the relative probability of failure for high temperature hydrogen attack (HTHA) of C-1/2Mo steel. It is well documented that C-1/2Mo possesses a variable resistance to HTHA. Over the years, the Nelson curve limits, as published in API RP 941, Steels for Hydrogen Service at Elevated Temperatures and Pressures in Petroleum Refineries and Petrochemical Plants, have been significantly reduced since originally published. This has created a need for an assessment procedure to evaluate C-1/2 Mo equipment that was designed many years ago when the Nelson curve was at much higher operating conditions than today. This assessment procedure is based on the current ExxonMobil assignment of C-1/2Mo resistance to HTHA on the Nelson curve and the relative dependence of HTHA on temperature, hydrogen partial pressure and time. We use the Pv relationship that appears in literature to define the relative dependence of HTHA on temperature, hydrogen partial pressure and time. This qualitative assignment of probability levels for HTHA was validated against actual HTHA failures of C-1/2Mo in high temperature hydrogen service that have been reported to the API and other internal Company incidents not reported to API. This assessment procedure is used to qualitatively define the probability of failure consistent with the probability levels defined in the ExxonMobil risk matrix which is used to manage all risk based decisions in the Corporation.

High Temperature Hydrogen Attack: New NDE Advanced Capabilities — Development and Feedback

2019 ◽  
Author(s):  
Charles Le Nevé ◽  
Sophie Loyan ◽  
Léonard Le Jeune ◽  
Steve Mahaut ◽  
Serge Demonte ◽  
...  
Keyword(s):  
High Temperature ◽  
Early Stage ◽  
Degradation Mechanism ◽  
Petroleum Industry ◽  
Hydrogen Attack ◽  
Ultrasonic Methods ◽  
Capability Of Detection ◽  
Ultrasonic Techniques ◽  
Ultrasonic Backscatter ◽  
Non Destructive

Abstract In petroleum industry, hydrogen is used in many assets. With temperature and pressure, hydrogen can damage materials. This damage is called High Temperature Hydrogen Attack (HTHA) and is a time dependent degradation mechanism that can affect the integrity of steels used for pressure containment operating above about 400°F (204°C). HTHA has caused major accidents in Petroleum Industry. API RP 941 [1] currently provides guidance for steel selection (and so susceptibility to attack) in relation to temperature and ppH2 via Nelson curves. In the last edition, 4 stages of degradation for both base metal and weld metal are described. In the past, only stage III was detectable by the combination of different Ultrasonic methods which were known as AUBT – Advanced Ultrasonic Backscatter Technique. But, capability of detection was limited to defects above 500–1000μm, correspondent to small fissures. So, it was impossible to detect early stage of degradation as steel grain size (around 50μm). For several years, performances of non-destructive techniques have rapidly increased and new advanced ultrasonic technologies are available such as: - Phased Array Ultrasonic Techniques (PAUT) - Time Of Flight Diffraction (TOFD) - Total Focusing Method (TFM) This paper describes latest techniques and results obtained by Total and French Welding Institute in laboratory, and discuss the efficiency of the methods, over real HTHA degradation blocks. An overview of TFM is also proposed by CEA who work on innovating development to increase the performance of this technique.

The management of risk in a dryland environment

2011 ◽  
pp. 13-21
Author(s):  
D.I. Gray ◽  
J.I. Reid ◽  
D.J. Horne
Keyword(s):  
Risk Management ◽  
Service Providers ◽  
Management Strategies ◽  
Subterranean Clover ◽  
Farming Systems ◽  
Market Risk ◽  
Farm Size ◽  
Forage Crops ◽  
Risk Management Strategies ◽  
Upside Risk

A group of 24 Hawke's Bay hill country farmers are working with service providers to improve the resilience of their farming systems. An important step in the process was to undertake an inventory of their risk management strategies. Farmers were interviewed about their farming systems and risk management strategies and the data was analysed using descriptive statistics. There was considerable variation in the strategies adopted by the farmers to cope with a dryland environment. Importantly, these strategies had to cope with three types of drought and also upside risk (better than expected conditions), and so flexibility was critical. Infra-structure was important in managing a dryland environment. Farmers chose between increased scale (increasing farm size) and geographic dispersion (owning a second property in another location) through to intensification (investing in subdivision, drainage, capital fertiliser, new pasture species). The study identified that there may be scope for further investment in infra-structural elements such as drainage, deeper rooting alternative pasture species and water harvesting, along with improved management of subterranean clover to improve flexibility. Many of the farmers used forage crops and idling capacity (reduced stocking rate) to improve flexibility; others argued that maintaining pasture quality and managing upside risk was a better strategy in a dryland environment. Supplementary feed was an important strategy for some farmers, but its use was limited by contour and machinery constraints. A surprisingly large proportion of farmers run breeding cows, a policy that is much less flexible than trading stock. However, several farmers had improved their flexibility by running a high proportion of trading cattle and buffer mobs of ewe hoggets and trade lambs. To manage market risk, the majority of farmers are selling a large proportion of their lambs prime. Similarly, cattle are either sold prime or store onto the grass market when prices are at a premium. However, market risk associated with the purchase of supplements and grazing was poorly managed.

Trends in the development of flexible thermal protection systems for modern aircraft

2020 ◽  
pp. 10-21
Author(s):  
V. G. Babashov ◽  
◽  
N. M. Varrik ◽  
Keyword(s):  
High Temperature ◽  
Thermal Protection ◽  
Heat Removal ◽  
Operating Conditions ◽  
Passive Protection ◽  
Thermal Protection Systems ◽  
Heat Protection ◽  
Protection Systems ◽  
Protected Surface ◽  
Flexible Panels

The emergence of new types of space and aviation technology necessitates the development of new types of thermal protection systems capable of operating at high temperature and long operating times. There are several types of thermal protection systems for different operating conditions: active thermal protection systems using forced supply of coolant to the protected surface, passive thermal protection systems using materials with low thermal conductivity without additional heat removal, high-temperature systems, which are simultaneously elements of the bearing structure and provide thermal protection, ablation materials. Heat protection systems in the form of rigid tiles and flexible panels, felt and mats are most common kind of heat protecting systems. This article examines the trends of development of flexible reusable heat protection systems intended for passive protection of aircraft structural structures from overheating.

UNITEMP HX

Alloy Digest ◽  
1964 ◽  
Vol 13 (5) ◽  
Keyword(s):  
Fracture Toughness ◽  
Corrosion Resistance ◽  
High Temperature ◽  
Physical Properties ◽  
Base Material ◽  
Heat Treating ◽  
Operating Conditions ◽  
High Temperature Strength ◽  
Temperature Performance ◽  
Nickel Base

Abstract Unitemp-HX is a nickel-base material recommended for high temperature applications. It has outstanding oxidation resistance at high temperatures under most operating conditions, and good high-temperature strength. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness and creep. It also includes information on low and high temperature performance, and corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: Ni-91. Producer or source: Universal Cyclops Steel Corporation.

HASTELLOY ALLOY X

Alloy Digest ◽  
1954 ◽  
Vol 3 (12) ◽  
Keyword(s):  
High Temperature ◽  
Physical Properties ◽  
Tensile Properties ◽  
Oxidation Resistance ◽  
High Temperatures ◽  
Heat Treating ◽  
Operating Conditions ◽  
Molybdenum Alloy ◽  
High Temperature Strength ◽  
Nickel Chromium

Abstract HASTELLOY Alloy X is a nickel-chromium-iron-molybdenum alloy recommended for high-temperature applications. It has outstanding oxidation resistance at high temperatures under most operating conditions, and good high-temperature strength. This datasheet provides information on composition, physical properties, and tensile properties as well as creep. It also includes information on forming, heat treating, and machining. Filing Code: Ni-14. Producer or source: Haynes Stellite Company.

REMANIT 4306

Alloy Digest ◽  
1997 ◽  
Vol 46 (4) ◽  
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
High Temperature ◽  
Austenitic Stainless Steel ◽  
Cold Working ◽  
Heat Treating ◽  
Operating Conditions ◽  
Low Carbon ◽  
Corrosion Resistant ◽  
Temperature Performance

Abstract Remanit 4306 is a low-carbon chromium nickel austenitic stainless steel that is superior in corrosion resistance to type 302 (see Alloy Digest SS-99, revised September 1998). Due to its low carbon content, Remanit 4306 is intergranular corrosion resistant under continuous operating conditions up to 350 C (652 F). This grade is particular suitable for high degrees of cold working and for sequential drawing. This datasheet provides information on composition, physical properties, elasticity, and tensile properties. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, and joining. Filing Code: SS-679. Producer or source: Thyssen Stahl AG.

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