Effects of Microstructure and Hydrogen Charging on Fatigue Performance of Duplex and Superduplex Stainless Steels

2011 ◽  
Author(s):  
Amir Bahrami ◽  
Yanhui Zhang ◽  
Peter Tubby
Keyword(s):  
Cathodic Protection ◽  
Stainless Steels ◽  
Fatigue Loading ◽  
Stress Cracking ◽  
Viable Solution ◽  
Material Environment ◽  
Steel Catenary Risers ◽  
Girth Welds ◽  
Sour Service ◽  
Fatigue Endurance

Steel Catenary Risers (SCRs) are a viable solution for production and export of offshore hydrocarbons in many deepwater developments. In addition to exposure to seawater from the outside, the pipes and their girth welds in an SCR are often exposed to aggressive environments on the inside surfaces due to the produced fluids. The fatigue life of pipe girth welds in aggressive environments is dependent on the material-environment interactions. Duplex and superduplex stainless steels are particularly good candidate materials for construction of corrosion resistant steel centenary risers. However, these steels have shown susceptibility to hydrogen induced stress cracking (HISC) when in seawater and under cathodic protection (CP). In addition there is very little published knowledge related to their sour service performance under fatigue loading. This paper provides new fatigue endurance data for superduplex riser girth welds tested in air, seawater with CP and sour environment. It further compares the fatigue crack growth rate (FCGR) in the same welded material in air and sour environment. Finally preliminary results of investigations made on the effect of frequency, microstructure and grain coarseness on FCGR in parent superduplex and duplex materials in seawater and under cathodic protection are presented.

Resistance Toward Hydrogen-Induced Stress Cracking of Hot Isostatically Pressed Duplex Stainless Steels Under Cathodic Protection

CORROSION ◽  
2010 ◽  
Vol 66 (11) ◽  
pp. 115004-115004-13 ◽  
Author(s):  
GØ Lauvstad ◽  
R. Johnsen ◽  
I. Asbjørnsen ◽  
M. Bjurström ◽  
C.-G. Hjorth
Keyword(s):  
Cathodic Protection ◽  
Stainless Steels ◽  
Duplex Stainless Steels ◽  
Stress Cracking ◽  
Induced Stress

Hydrogen Induced Stress Cracking (HISC) of Stainless Steels Under Cathodic Protection in Seawater: Presentation of a New Test Method

2009 ◽  
Author(s):  
Roy Johnsen ◽  
Ba˚rd Nyhus ◽  
Stig Wa¨stberg
Keyword(s):  
Stainless Steel ◽  
Carbon Steel ◽  
Cathodic Protection ◽  
Stainless Steels ◽  
Production Systems ◽  
Oil Industry ◽  
Test Method ◽  
Stress Cracking ◽  
Induced Stress ◽  
Subsea Pipelines

There has been an increasing trend in the use of stainless steel alloys instead of carbon steel for subsea flowlines and production systems during the last 15 years in the oil industry. Even if this normally is a more robust solution compared to the use of carbon steel insofar as internal corrosion problems are concerned, the use of stainless steels has led to leakage, production shutdown and expensive repair work. The reported failures were associated with hydrogen entrapment resulting from welding and/or external cathodic protection (CP), combined with a certain stress/strain level. Atomic hydrogen entering the alloy can weaken the mechanical strength of the alloy, cause cracks and destroy the integrity of equipment or a system. Such failures attributed to hydrogen induced stress cracking (HISC) are clearly not acceptable from the perspective of safety, environmental hazard and cost. Leading oil and engineering companies and supplier industry have pointed out HISC as one of the major obstacles against safe operation of stainless steel subsea pipelines and production systems. It is important for the oil industry to have design guidelines and reliable test method(s) for qualification and safe utilization of subsea pipelines and components made from the actual stainless steels. This paper describes a test method that has been developed through a Joint Industry Project (JIP) executed by SINTEF and Det Norske Veritas (DNV) with support from leading oil companies and material suppliers. The method has been qualified for use on 13% Cr super martensitic (SMSS) and 22% Cr / 25% Cr duplex stainless steels (DSS/SDSS). The link to DNV-RP-F112 [1] will also be described.

Avoiding Hydrogen Embrittlement Stress Cracking of Ferritic Austenitic Stainless Steels Under Cathodic Protection

2004 ◽  
Author(s):  
P. Woollin ◽  
A. Gregori
Keyword(s):  
Hydrogen Embrittlement ◽  
Cathodic Protection ◽  
Stainless Steels ◽  
Large Scale ◽  
Austenitic Stainless Steels ◽  
Austenitic Steels ◽  
Stress Cracking ◽  
Initiation And Propagation ◽  
Phase Balance ◽  
Large Scale Tests

The paper presents the results of a programme designed to define the material, stress and environmental factors controlling sensitivity of ferritic-austenitic stainless steels to hydrogen embrittlement stress cracking when exposed to cathodic protection. Factors examined in small and large-scale tests include microstructural coarseness, phase balance and hardness of a range of parent steels and welds. The results are presented in terms of threshold strain and normalised stress to develop hydrogen embrittlement stress cracks. The effects of microstructure and applied potential on crack initiation and propagation are described. Recommendations are made with respect to the strain/normalised stress levels for ferritic-austenitic steels under cathodic protection.

Hydrogen Induced Stress Cracking (HISC) in Duplex Stainless Steels: DNV-RP-F112, Design of Duplex Stainless Steel Subsea Equipment Exposed to Cathodic Protection

2009 ◽  
Author(s):  
Stig Wa¨stberg ◽  
Morten Solno̸rdal ◽  
Gustav Heiberg ◽  
Rikard To¨rnqvist ◽  
Pedro M. Vargas
Keyword(s):  
Stainless Steel ◽  
Duplex Stainless Steel ◽  
Cathodic Protection ◽  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
Design Guideline ◽  
Oil Companies ◽  
Stress Cracking ◽  
Induced Stress ◽  
Offshore Industry

Both 22Cr and 25Cr duplex (ferritic-austenitic) stainless steels have been extensively used for subsea equipment. In general the experience is good but some significant failures have occurred where Hydrogen Induced Stress Cracking (HISC) have been identified as a contributing factor. Because of these failures there was identified a need within the offshore industry for a design guideline treating HISC as a failure mode and reflecting best practice based on today’s knowledge, experience from in-service failures and recent research. The paper starts with a brief review of some of the failures and the main results from the comprehensive test program in the HISC JIP conducted in cooperation between Sintef and DNV. The JIP is supported by several major oil companies, subsea contractors and material suppliers and constitute the main scientific background for the recently issued Recommended Practice, DNV-RP-F112, Design of Duplex Stainless Steel Subsea Equipment Exposed to Cathodic Protection (October 2008).

Hydrogen Induced Stress Cracking of Superduplex Steels: Effect of Operation Temperature

2018 ◽  
Author(s):  
Lars M. Haldorsen ◽  
Bård Nyhus ◽  
Gisle Rørvik
Keyword(s):  
Cathodic Protection ◽  
Life Time ◽  
Oil Companies ◽  
Stress Cracking ◽  
Operation Temperature ◽  
Induced Stress ◽  
Duplex Steel ◽  
Future Revision ◽  
Cathodic Protection System ◽  
Guidelines And Recommendations

Duplex stainless steel has been used on subsea facilities since the mid 80-ties. The experiences with these materials have been relative good and only a few failures have been reported. However, BP and Shell experience some serious cracking of duplex steel in the mid 90-ties and in beginning of the century. The root cause of these failures was identified to be Hydrogen Induced Stress Cracking, HISC, where the hydrogen source was the cathodic protection system of the subsea facility. These and other similar failures resulted establishment of Joint Industry Projects, JIPs with financial and technical contribution from leading oil companies, contractors, material suppliers and research institutions as TWI, SINTEF and DNVGL. The objective of the JIPs was to establish practical usage limits for duplex stainless steels. The JIPs resulted in a recommended practice “DNV-RP-F112 - Design of duplex stainless subsea equipment exposed to cathodic protection.” This document minimized the failure rate of duplex steel components used subsea. However, since duplex steels components have been used on subsea facilities long before the guidelines and recommendations were issued, there are lot of components presently in use that may be overloaded compared to guidelines and recommendations. As a part of life time extension of one of Statoil’s long time producing fields, a HISC re-calculation of spools connecting SPSs to infield pipelines showed that many of the spools were exposed to stresses above the recommended stresses given in DNV-RP-F112. Since these recommendations were primarily based on testing at ambient seabed temperature (4°C), Statoil, together with SINTEF, started in 2016 a project where the aim was to evaluate the resistance against HISC as an effect of the operation temperature. The results of this project show that the critical net section stress/AYS (HISC resistance) increases with increasing temperature. Based on this, the before mentioned spools can be considered safe even though the spools are exposed to stresses above the recommendations in DNV-RP-F112. Further, the investigations show that the guidelines and recommendations given in DNV-RP-F112 may be conservative for temperatures above 4°C. It is therefore recommended to perform more testing to confirm and incorporate the findings from the present investigation in future revision of DNV-RP-F112.

scholarly journals Comparison of 2507 Duplex and 28 % Cr- Austenitic Stainless Steel Corrosion Behavior for High Pressure and High Temperature (HPHT) in Sour Service Condition with C-ring Experiment

2021 ◽  
Author(s):  
Harris Prabowo ◽  
Badrul Munir ◽  
Yudha Pratesa ◽  
Johny W. Soedarsono
Keyword(s):  
High Pressure ◽  
Stainless Steel ◽  
High Temperature ◽  
Austenitic Stainless Steel ◽  
Corrosion Behavior ◽  
Material Selection ◽  
Stress Cracking ◽  
Sulfide Stress ◽  
Sulfide Stress Cracking ◽  
Sour Service

The scarcity of oil and gas resources made High Pressure and High Temperature (HPHT) reservoir attractive to be developed. The sour service environment gives an additional factor in material selection for HPHT reservoir. Austenitic 28 Cr and super duplex stainless steel 2507 (SS 2507) are proposed to be a potential materials candidate for such conditions. C-ring tests were performed to investigate their corrosion behavior, specifically sulfide stress cracking (SSC) and sulfide stress cracking susceptibility. The C-ring tests were done under 2.55 % H2S (31.48 psia) and 50 % CO2 (617.25 psia). The testing was done in static environment conditions. Regardless of good SSC resistance for both materials, different pitting resistance is seen in both materials. The pitting resistance did not follow the general Pitting Resistance Equivalent Number (PREN), since SS 2507 super duplex (PREN > 40) has more pitting density than 28 Cr austenitic stainless steel (PREN < 40). SS 2507 super duplex pit shape tends to be larger but shallower than 28 Cr austenitic stainless steel. 28 Cr austenitic stainless steel has a smaller pit density, yet deeper and isolated.

Fit For Service Qualification for Sour Service High Strength Production Casing For High Temperature

2021 ◽  
Author(s):  
Luciana I. L Lima ◽  
Christelle Gomes ◽  
Carine Landier ◽  
Marilia Lima ◽  
Kevin Schleiss ◽  
...  
Keyword(s):  
Carbon Steel ◽  
Yield Strength ◽  
High Strength ◽  
Materials Selection ◽  
Well Production ◽  
Stress Cracking ◽  
Sulfide Stress ◽  
Sulfide Stress Cracking ◽  
Sour Service ◽  
Minimum Yield

Abstract In recent years the application of high strength carbon steel with 125ksi specified minimum yield strength as a production casing in deepwater and high-pressure reservoirs has increased. Sulfide stress cracking (SSC) can develop when high strength carbon steel is exposed to a sour environment. The H2S partial pressure in these sour reservoirs is above the 0.03 bar limit for this material at room temperature. Materials SSC performance evaluation requires an accurate simulation of field conditions in the laboratory. To evaluate the production casing SSC behavior, some fit for service (FFS) tests were carried out considering the well geothermic temperature profile for the materials selection. This paper presents a fit for service qualification carried out on Casing 125 ksi SMYS (Specified Minimum Yield Strength) materials. Two products with 125ksi SMYS were considered: one that has existed for several years and one developed more recently with a better SSC resistance – above the pH2S limit considered for the standard 125ksi SMYS material. The results obtained in this test program allowed casing 125 ksi SMYS materials selection for temperature above 65°C and environment more severe in terms of pH2S than the domain previously established for this grade. This allowed a new well production design, which saves one casing phase and avoids the necessity to use intermediate liners to prevent collapse.

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