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.

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.

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.

Stress Based Design Guidelines for Hydrogen Induced Stress Cracking (HISC) Avoidance in Duplex Materials

2009 ◽  
Author(s):  
Pedro M. Vargas ◽  
Stig Wa¨stberg ◽  
Paul Woollin
Keyword(s):  
Stainless Steels ◽  
Design Guidelines ◽  
Design Criteria ◽  
Strain Measurements ◽  
Stress Cracking ◽  
Steel Making ◽  
Induced Stress ◽  
Duplex Steel ◽  
Cathodic Protection System ◽  
Design Guidance

Following the failure of several subsea components made of duplex steel, two JIPs were formed, one by TWI and another by DNV and Sintef to address the failure mechanism and to formulate design guidance for the industry. (TWI: The Effects of Notches and Welds on Hydrogen Embrittlement Stress Cracking of Duplex Stainless Steels, Sintef/DNV: HISC) Hydrogen charging from the cathodic protection system in the presence of creep strains embrittles the duplex steel, making the duplex susceptible to cracking (hydrogen-induced-stress-cracking, HISC). Creep effects focused on strain measurements in the test specimens from early work at TWI, favoring a strain based approach in the development of early versions of the design guidance for the industry. This paper summarizes the relevant content from the two JIPs to formulate a stress based design criteria, and provides new FEA assessment of the Foinhaven Hubs to better quantify the effect of residual stresses. The basis for the stress-based design guidelines in DNV-RP-F112 is presented that promises to be easier to apply and equally robust as the strain-based approach.

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.

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