Assessment of Residual Stress and Suitability for Subsea Service of a Welded Superduplex Stainless Steel Flange Joint

2016 ◽  
Author(s):  
M. Dodge ◽  
S. D. Smith ◽  
T. London ◽  
K. Sotoudeh ◽  
R. Morana ◽  
...  
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Duplex Stainless Steel ◽  
Oil And Gas ◽  
High Stress ◽  
High Strength ◽  
Gas Production ◽  
Successful Operation ◽  
Oil And Gas Production ◽  
Superduplex Stainless Steel

Ferritic-austenitic (duplex) stainless steel components are used for oil and gas production duties due to their high strength and corrosion resistance. The material is routinely used for short flowlines, as well as for welded hubs and flanges. Cathodic protection (CP) is employed, via sacrificial aluminium based anodes, which protects ferritic steel parts from seawater corrosion. Whilst CP has proven successful in preventing corrosion, failures have occurred due to the ingress of electrolytically evolved hydrogen. Duplex stainless steel joints become susceptible to environmental cracking under a combination of high stress, hydrogen content, and susceptible microstructures; critical combinations of which may result in hydrogen induced stress cracking (HISC). Successful operation of duplex equipment, in avoidance of HISC, necessitates a good understanding of the total in-service stresses (including from loading applied in service and from residual stresses from manufacture, fabrication, installation and commissioning). One of the key components of understanding the in-service stress at welds is knowledge of the residual stress distribution, following welding. The focus of this paper is to provide an overview of the typical residual stress levels in a welded superduplex stainless steel (SDSS) subsea joint, using neutron diffraction and finite element modelling. The results are presented in the context of current recommended practice, for example DNV RP-F112.

SANICRO 41

Alloy Digest ◽  
1995 ◽  
Vol 44 (1) ◽  
Keyword(s):  
Corrosion Resistance ◽  
Physical Properties ◽  
Oil And Gas ◽  
High Strength ◽  
Heat Treating ◽  
Gas Production ◽  
Oil And Gas Production ◽  
Corrosion Resistant ◽  
Corrosion Resistant Alloy ◽  
Nickel Base

Abstract SANDVIK SANICRO 41 is a nickel-base corrosion resistant alloy with a composition balanced to resist both oxidizing and reducing environments. A high-strength version (110) is available for oil and gas production. This datasheet provides information on composition, physical properties, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, and joining. Filing Code: Ni-475. Producer or source: Sandvik.

Alloying Concept for High-Strength Seamless Heavy-Wall Line Pipe Suitable for Sour Service Applications

2004 ◽  
Author(s):  
K. Biermann ◽  
C. Kaucke ◽  
M. Probst-Hein ◽  
B. Koschlig
Keyword(s):  
Heat Treatment ◽  
Wall Thickness ◽  
Oil And Gas ◽  
High Strength ◽  
Gas Production ◽  
Pipe Material ◽  
Low Carbon ◽  
Line Pipe ◽  
Oil And Gas Production ◽  
Sour Service

Offshore oil and gas production worldwide is conducted in increasingly deep waters, leading to more and more stringent demands on line pipes. Higher grades and heavier wall thicknesses in combination with deep temperature toughness properties, good weldability and suitability for sour service applications are among the characteristics called for. It is necessary that pipe manufacturers develop materials to meet these at times conflicting requirements. An alloying concept based on steel with very low carbon content is presented. This type of material provides excellent toughness properties at deep temperatures in line pipe with a wall thickness of up to 70 mm, produced by hot rolling followed by QT heat treatment. Pipes from industrial production of identical chemical composition and heat treatment achieved grades X65 to X80, depending on wall thickness. The properties of the steel used in pipes are presented. The resistance of the pipe material to the influence of sour gas was assessed by standard tests. To demonstrate weldability, test welds were performed and examined.

scholarly journals Corrosion Behavior of AISI 316L Stainless Steel Used as Inner Lining of Bimetallic Pipe in a Seawater Environment

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1539
Author(s):  
Daquan Li ◽  
Qingjian Liu ◽  
Wenlong Wang ◽  
Lei Jin ◽  
Huaping Xiao
Keyword(s):  
High Pressure ◽  
Stainless Steel ◽  
High Temperature ◽  
316L Stainless Steel ◽  
Oil And Gas ◽  
Gas Production ◽  
Atmospheric Conditions ◽  
Oil And Gas Production ◽  
Corrosion Rates ◽  
Seawater Environment

Seawater leakage commonly leads to corrosion in the inner lining of submarine bimetallic pipes, with significant financial implications for the offshore oil and gas production industry. This study aims to improve understanding of the performance of bimetallic pipes by investigating the corrosion behaviors of mechanically bonded 316L stainless steel. Immersion experiments were conducted in a seawater environment, under both atmospheric conditions and high temperature and high pressure conditions, and corroded surfaces were examined using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) to reveal micromorphology and elementary compositions. The results demonstrated that the corrosion rates of the bonded 316L specimen were between 5% and 20% higher than those of specimens without bonding under atmospheric conditions. This is attributed to the stress cracking that occurs during corrosion. Under high temperature and high pressure conditions, the corrosion rates were remarkably increased (91% to 135%) and the corrosion process took longer to reach equilibrium. This may be attributed, firstly, to the products becoming increasingly porous and weak, and also to the fluid stress caused by stirring in these experiments to simulate seawater movement.

scholarly journals Materials and Corrosion Trends in Offshore and Subsea Oil and Gas Production

2017 ◽  
Author(s):  
Mariano Iannuzzi ◽  
Afrooz Barnoush ◽  
Roy Johnsen
Keyword(s):  
Energy Demand ◽  
Oil And Gas ◽  
Extreme Environments ◽  
High Strength ◽  
Advanced Characterization ◽  
Gas Production ◽  
Oil And Gas Production ◽  
Environmentally Assisted Cracking ◽  
Engineering Alloys ◽  
Cantilever Bending

The ever-growing energy demand requires the exploration and the safe, profitable exploitation of unconventional reserves. The extreme environments of some of these unique prospects challenge the boundaries of traditional engineering alloys as well as our understanding of the underlying degradation mechanisms that could lead to a failure. Despite their complexity, high-pressure and high-temperature, deep- and ultra-deep, pre-salt, and Arctic reservoirs represent the most important source of innovation regarding materials technology, design methodologies, and corrosion control strategies.This paper provides an overview of trends in materials and corrosion research and development, with focus on subsea production but applicable to the entire industry. Emphasis is given to environmentally assisted cracking of high strength alloys and advanced characterization techniques based on in situ electrochemical nanoindentation and cantilever bending testing for the study of microstructure-environment interactions.

Characterization of Corrosion Scales on Fe-13Cr Stainless Steel

1998 ◽  
Vol 4 (S2) ◽  
pp. 542-543
Author(s):  
S. Subramanian ◽  
S. Ling ◽  
T. A. Ramanarayanan
Keyword(s):  
Stainless Steel ◽  
Oil And Gas ◽  
Gas Production ◽  
Oil And Gas Production ◽  
Rock Formation ◽  
Partial Pressures ◽  
Production Environments ◽  
Corrosion Resistant Alloy ◽  
Increase Productivity ◽  
Corrosion Scales

Fe-13Cr stainless steel is a corrosion resistant alloy (CRA) that is widely used in oil and gas production for equipment such as tubes in wells. The high temperature, high CO2 and H2S partial pressures of typical production environments and the significant amounts of Cl- containing water that is produced along with the hydrocarbons affects the corrosion processes. Fe-13Cr is used for tubes since it exhibits passivity and low corrosion rates in production environments. But, during production operations, it is often necessary to pump strong acids into the underground rock formation through the tubes to stimulate the field and increase productivity. This is done in order to dissolve deposits that clog pores in the rock formation, thus improving permeability and facilitating the flow of hydrocarbons. This is expected to significantly degrade the passivity and lead to increased corrosion. Therefore, there is a concern about the corrosion rate during the operation and the rate at which the alloy repassivates when production is resumed.

Influence of pH on Hydrogen Absorption in Duplex Stainless Steel

2013 ◽  
Vol 794 ◽  
pp. 592-597
Author(s):  
V. Viswanathan ◽  
Nage Deepashri
Keyword(s):  
Stainless Steel ◽  
Hydrogen Embrittlement ◽  
Duplex Stainless Steel ◽  
Cathodic Protection ◽  
Oil And Gas ◽  
Current System ◽  
High Strength ◽  
Oil And Gas Exploration ◽  
Production Of Hydrogen ◽  
Critical Ph

With rising demands, oil and gas exploration of high-pressure high-temperature (HPHT) wells are increasing worldwide. Due to aggressiveness of HPHT environments, piping and equipments are constructed with high-strength corrosion resistant alloys (CRAs). Duplex stainless steel is one of the candidate alloys that offer high strength along with corrosion resistance. It possesses the advantages of both austenitic and ferritic stainless steels and hence, the name duplex or dual phase stainless steel. In order to control corrosion, cathodic protection is commonly being employed on the structures and equipment. Cathodic protection is accomplished by applying a direct current to the structure which causes the structure potential to change from the natural corrosion potential (Ecorr). The required cathodic protection current is supplied by sacrificial anode materials or by an impressed current system. Hydrogen embrittlement (HE) is an associated phenomenon, which results in the production of hydrogen ions, leading to its absorption in the protected metal and subsequent hydrogen embrittlement of metals and welds. To prevent this embrittlement, cathodic protection is closely studied in terms of finding the critical potential, pH, temperature etc. that does not cause hydrogen embrittlement. This paper describes the study carried out to find the role of pH on the absorption of hydrogen in Duplex Stainless steel. It has been observed that at a critical pH, hydrogen intake in the sample is very high, as compared to the pH below and above the critical pH. Critical pH observed for duplex stainless steel is a trade of between hydrogen evolution and absorption for given duplex structure.

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