Improving Reliability of Carbon Steel Girth Welds in Sour Environment

2020 ◽  
Author(s):  
Harpreet Sidhar ◽  
Neerav Verma ◽  
Chih-Hsiang Kuo ◽  
Michael Belota ◽  
Andrew J. Wasson
Keyword(s):  
Carbon Steel ◽  
Base Material ◽  
Oil And Gas Industry ◽  
Critical Parameters ◽  
Welding Parameters ◽  
Pipe Material ◽  
Line Pipe ◽  
Weld Root ◽  
Girth Welds ◽  
Sour Service

Abstract The oil and gas industry has seen unexpected failures of sour service carbon steel pipelines in the recent past. Below par performance of girth welds and line pipe material have been identified as the root causes of such failures. Although mechanized welding can achieve good consistency, the weld region is more heterogeneous as compared to base material, which can lead to inconsistencies and poor weld performance. Overall, the effects of welding parameters on performance of carbon steel pipeline girth welds for sour service are not well understood. Furthermore, industry is moving towards more challenging environments, such as production of hydrocarbons from ultra-deepwater, which further necessitates the need to improve welding practices for additional high criticality applications. Many of the critical parameters for sour service performance will also improve general weld performance for ultra-deepwater. So, there is a clear need to understand the effects of various welding parameters on weld properties and performance. This effort aims at assessing the effects of key welding parameters on performance of girth welds to develop improved welding practice guidelines for sour service pipeline applications. In this study, several API X65 grade line pipe girth welds were made using commercially available welding consumables. The effects on weld root performance of preheat, wire consumable chemistry, hot pass tempering, single vs. dual torch, copper backing, root pass heat input, metal transfer mode, pipe fit-up (root gap, misalignment) were studied. Generally, carbon steel welds with hardness 250HV or below are considered acceptable for sour service. So, detailed microhardness mapping and microstructural characterization were conducted to evaluate the performance and reliability of welds. It was evident that the welding parameters studied have a significant impact on root performance. Preheat and pipe fit-up showed the most significant impact on weld root performance. Based on the results and understanding developed with this study, recommendations for industry are provided through this paper to improve reliability of pipeline girth welds in sour service application.

Evaluation of Welding Practices on Sour Service Performance of Carbon Steel Pipeline Girth Welds

2021 ◽  
Author(s):  
Harpreet Sidhar ◽  
Neerav Verma ◽  
Chih-Hsiang Kuo ◽  
Michael Belota ◽  
Andrew J. Wasson
Keyword(s):  
Carbon Steel ◽  
Oil And Gas ◽  
Pipeline Steel ◽  
Oil And Gas Industry ◽  
Welding Parameters ◽  
Line Pipe ◽  
Steel Pipeline ◽  
Weld Root ◽  
Girth Welds ◽  
Sour Service

Abstract In recent past, there have been unforeseen sour service pipeline failures in the oil and gas industry. Sub-optimal microstructure resulting in high hardness (above 250 HV10) in pipeline steel is one of the root causes of such failures. Poor girth weld quality is another leading cause which adversely affects pipeline integrity and safe operations in sour environments. While advancements in welding technologies have led to consistency in production girth welds, effects of welding parameters on performance of carbon steel pipeline girth welds for sour service are not well understood. So, a systematic study is needed to understand the effects of various welding parameters on weld properties and performance. This paper aims at evaluating the effects of various welding parameters on performance of girth welds to provide welding practice guidelines for sour service pipeline applications. In this effort, several welds on X65 grade line pipe girth welds using commercially available welding consumables were made to study the effects of preheat, hot pass tempering, copper backing, root pass heat input, wire consumable chemistry, single vs. dual torch, metal transfer mode, pipe fit-up (root gap, misalignment), on weld root performance. Detailed microhardness mapping and microstructural characterization were conducted. It was evident that the welding parameters studied have a significant impact on root performance. While preheat and pipe fit-up showed most significant impact on weld root performance, other parameters also affected the root performance by varying degree. Based on these results, recommendations for industry are provided to improve reliability of pipeline girth welds in sour service application.

Carbon Steel X65QS Pipeline Qualification for Extreme Sour Service a Global Approach: Line Pipe, Welding, Eca Methodology and Diyab Pipeline Case Study

2021 ◽  
Author(s):  
Lam-Thanh Luc ◽  
Hamdi Saad ◽  
Matta Tanios ◽  
Dr. Al Bannay Aamer ◽  
Meer Mumtaz Ali Imtiaz Sirsimth ◽  
...  
Keyword(s):  
Carbon Steel ◽  
Large Diameter ◽  
Base Material ◽  
Global Approach ◽  
Production Environment ◽  
Destructive Testing ◽  
Line Pipe ◽  
Steel Material ◽  
Pipe Welding ◽  
Sour Service

Abstract In the wake of failures of large diameter pipelines made from plates using the Thermo-Mechanically Controlled Process (TMCP), the suitability of carbon steel material for sour environments where the H2S partial pressure is largely over 1 bar has been questioned. Understanding that seamless quench and tempered material are not prone to the same phenomenon as large diameter TMCP pipes, it has been decided to ensure the integrity of the DIYAB pipeline by qualification using the actual production environment pH=3.5 at 24°C and 6.84 bar H2S plus 6.84 bar CO2. The global approach includes the qualification to sour service resistance under 6.84bar H2S of the base material and the welds without post weld heat treatment. Fracture toughness tests under 6.84bar H2S were also conducted, and the results fed into an Engineering Criticality Assessment (ECA) to define the Non-Destructive Testing (NDT) acceptance criteria. The NDT tools were selected for their ability to detect the critical flaws and validated. The global approach methodology and results are presented.

Effect of Strain Ageing on Mechanical Properties of Pipeline Girth Welds

2011 ◽  
Author(s):  
Badri K. Narayanan ◽  
Jon Ogborn
Keyword(s):  
Yield Strength ◽  
Weld Metal ◽  
Base Material ◽  
Dynamic Strain ◽  
Pipe Material ◽  
Cored Wire ◽  
Line Pipe ◽  
Strain Ageing ◽  
Girth Welds ◽  
Welding Processes

Pipeline girth welds for on-shore and off-shore pipelines use a variety of arc welding processes. The trend towards strain based designs for line pipe installation and the effect of coatings for off-shore pipelines have resulted in evaluation and testing of pipe material subjected to strain ageing. However, very little work has been done to systematically study the effect on ferritic weld metal. This work details some initial work done on evaluating the effect of strain ageing on ferritic weld metal deposited with a 1.2 mm diameter flux cored wire under 75% Ar −25% CO2 shielding gas. Pipeline girth welds were welded on API Grade X-70 pipe and tested to get all weld metal tensile and Charpy V-Notch properties. The weld metal strength overmatched the base material by 7–9%. The ductile to brittle transition temperature for the weld metal was −40°C. The effect of strain ageing on weld metal properties was evaluated. All weld metal tensile samples were subjected to varying levels of pre-strain and ageing treatments to evaluate the effect on yield strength and post-yield behavior. An increase in yield strength after straining and ageing as well as the re-appearance of yield point is observed. Increase in pre-strain decreases elongation. Increase in ageing temperature delays the appearance of dynamic strain ageing. The activation energy for the increase in strength after strain ageing has been measured by assuming a diffusion controlled mechanism. Charpy V-Notch samples were taken to generate transition curves of weld metal after strain ageing and compared to the as-welded condition.

Development of X90 and X100 Steel Grades for Seamless Linepipe Products

2014 ◽  
Author(s):  
Diana Toma ◽  
Silke Harksen ◽  
Dorothee Niklasch ◽  
Denise Mahn ◽  
Ashraf Koka
Keyword(s):  
Wall Thickness ◽  
Deep Water ◽  
High Strength ◽  
Oil And Gas Industry ◽  
Pipe Material ◽  
Line Pipe ◽  
Materials Development ◽  
Additional Tool ◽  
Technical Requirements ◽  
Steel Grades

The general trend in oil and gas industry gives a clear direction towards the need for high strength grades up to X100. The exploration in extreme regions and under severe conditions, e.g. in ultra deep water regions also considering High Temperature/High Pressure Fields or arctic areas, becomes more and more important with respect to the still growing demand of the world for natural resources. Further, the application of high strength materials enables the possibility of structure weight reduction which benefits to materials and cost reduction and increase of efficiency in the pipe line installation process. To address these topics, the development of such high strength steel grades with optimum combination of high tensile properties, excellent toughness properties and sour service resistivity for seamless quenched and tempered pipes are in the focus of the materials development and improvement of Vallourec. This paper will present the efforts put into the materials development for line pipe applications up to grade X100 for seamless pipes manufactured by Pilger Mill. The steel concept developed by Vallourec over the last years [1,2] was modified and adapted according to the technical requirements of the Pilger rolling process. Pipes with OD≥20″ and wall thickness up to 30 mm were rolled and subsequent quenched and tempered. The supportive application of thermodynamic and kinetic simulation techniques as additional tool for the material development was used. Results of mechanical characterization by tensile and toughness testing, as well as microstructure examination by light-optical microscopy will be shown. Advanced investigation techniques as scanning electron microcopy and electron backscatter diffraction are applied to characterize the pipe material up to the crystallographic level. The presented results will demonstrate not only the effect of a well-balanced alloying concept appointing micro-alloying, but also the high sophisticated and precise thermal treatment of these pipe products. The presented alloying concept enables the production grade X90 to X100 with wall thickness up to 30 mm and is further extending the product portfolio of Vallourec for riser systems for deepwater and ultra-deep water application [1, 3, 4].

Qualification of TMCP Pipe for Severe Sour Service: Mitigation of Local Hard Zones

2019 ◽  
Author(s):  
B. D. Newbury ◽  
D. P. Fairchild ◽  
C. A. Prescott ◽  
T. D. Anderson ◽  
A. J. Wasson
Keyword(s):  
Oil And Gas ◽  
Steel Plate ◽  
Companion Paper ◽  
Test Methods ◽  
Pipe Material ◽  
Line Pipe ◽  
Hydrogen Damage ◽  
Current Test ◽  
Industry Practice ◽  
Sour Service

Abstract C-Mn steels are extensively used as line pipe material for sour service oil and gas applications, i.e. in the presence of hydrogen sulfide (H2S), because of their ease of fabrication, weldability and significantly lower cost compared to Corrosion Resistant Alloys (CRAs). However, use of C-Mn steel in sour conditions can be limited by its susceptibility to various hydrogen damage mechanisms such as sulfide stress cracking (SSC) and hydrogen induced cracking (HIC). Presently, there are several industry standards which provide guidelines for materials selection and qualification testing to ensure the integrity of carbon steel pipelines in sour service. In recent years, examples of line pipe susceptibility to SSC have occurred due to undetected Local Hard Zones (LHZs) produced during steel plate manufacture. A companion paper (Fairchild, et al, [1]) describes historical and one newly recognized root causes for LHZs. Due to this newly recognized root cause, the adequacy of the current industry practice for specifying and qualifying C-Mn line pipe for severe sour service should be evaluated. In this work, a new approach to monitoring steel plate manufacture during Thermo Mechanical Controlled Processing (TMCP) in order to manage LHZs is explained. Results from implementing this qualification approach will be discussed. In addition, several gaps were identified in the current test methods and various potential modifications to address these gaps were identified. Based on the results of these studies, recommendations to the test methods are made to improve the robustness in the materials qualification process used for sour pipeline projects.

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.

Evaluation of Welding Practices on Sour Service Performance of Carbon Steel Pipeline Girth Welds

2021 ◽  
Author(s):  
Harpreet Sidhar ◽  
Neerav Verma ◽  
Chih-Hsiang Kuo ◽  
Michael Belota ◽  
Andrew Wasson
Keyword(s):  
Carbon Steel ◽  
Service Performance ◽  
Steel Pipeline ◽  
Girth Welds ◽  
Sour Service

Use of C-Mn Linepipe for High H2S Service

2018 ◽  
Author(s):  
David Baxter ◽  
Erling Østby ◽  
Steven Chong ◽  
Asle Venås
Keyword(s):  
Internal Surface ◽  
Hard Material ◽  
Thickness Direction ◽  
Pipe Steels ◽  
Line Pipe ◽  
High Partial Pressure ◽  
Service Projects ◽  
Girth Welds ◽  
Mn Steel ◽  
Sour Service

There have been recent incidents associated with cracking and leaks in C-Mn line pipe steels exposed to high H2S service. The incidents led to pipeline replacement with very expensive CRA clad pipeline causing substantial project delays and project cost escalations. The incidents occurred when TMCP ACC steels were exposed to severe Region 3 environment as per domain diagram in NACE MR0175 (high partial pressure of H2S). The leaks were associated with longitudinal cracking which initiated at hard zones present on the parent pipe internal surface, and possibly also in girth welds. The hard spots were observed to be contained within a very shallow depth of the ID surface of the pipe. The pipe microstructure beyond the thin layer of the hard zones at the ID surface did not contain hard material. However, the cracks propagated through the parent pipe normal microstructure in the through thickness direction. Several of the operators are now concerned and uncertain on how to ensure the integrity of C-Mn pipelines in similar severe sour environments. Some operators have therefore introduced more stringent requirements for sour environment resulting in significant challenges to manufacture of line pipes and qualification of welding procedures that meet these new requirements. We also see different requirements being imposed by different operators. The use of CRA, clad/lined pipes or other exotic materials can solve the challenges, but are very expensive and can significantly reduce margins and make several sour service projects less viable. Several R&D institutions have already started to study the phenomena. DNV GL have also initiated a broad JIP that will look into the challenges, with the objective of developing an industry guideline for use of C-Mn line pipe for high H2S service. This paper will give background on the challenges associated with using C-Mn steel in high H2S service, describe the various uncertainties in detail, and describe how the JIP will address the challenges on a broad basis.

Microstructure and Mechanical Properties of Girth Weld HAZ in X80 Line Pipe With High Deformability for Strain Based Design Applications

2016 ◽  
Author(s):  
Yu Liu ◽  
Yezheng Li ◽  
Shuo Li ◽  
Zongbin You ◽  
Zhanghua Yin
Keyword(s):  
Mechanical Properties ◽  
Tensile Properties ◽  
Heat Input ◽  
Thermal Simulation ◽  
Impact Testing ◽  
Pipe Material ◽  
Line Pipe ◽  
Microstructure And Mechanical Properties ◽  
Girth Welding ◽  
Girth Welds

X80 line pipe with high longitudinal deformability (X80HD) has been developed and applied in the Strain Based Design (SBD) of pipelines in harsh environment such as seismic areas, permafrost areas, fault zones, etc. For SBD pipelines it is critical that the pipeline girth welds overmatch the tensile properties of the pipe material to avoid local strain accumulation in the girth weld during a strain event. Also, it is important that pipeline girth welds that may experience high strains in operation have sufficient toughness to ensure adequate resistance to failure by fracture. The objective of this research was to gain a better understanding of the influence of chemical composition and essential welding variables on microstructure and properties of the HAZ regions formed in X80HD pipeline girth welds. In this study, by using the weld thermal simulation approach, the peak temperatures (Tp, representative of the distance to the fusion boundary) and the cooling times, particularly between 800 °C and 500 °C (t8/5, representative of the weld heat input), identical to those occurring in the girth weld HAZ of three different X80HD pipe steels, were artificially reproduced. It should be noted that t8/5 is influenced by both heat input and preheat temperature. The weld peak temperatures, Tp, from 500 °C to 1300 °C, in 100 °C increment, whereas the cooling times t8/5 from 5 to 30 seconds were in 5, 15, and 30 seconds, associated with the heat input range of self-shielded flux cored arc welding (FCAW-S). The thermal simulation specimens on tensile properties, Charpy impact toughness, and Vickers hardness were tested and analyzed. Microstructures of these simulated HAZ were characterized by optical microscopy (OM) and scanning electron microscopy (SEM). Finally, the actual FCAW-S girth welding experiments were carried out. These girth welds were subjected to different testing for evaluation of microstructure and mechanical properties of X80HD girth welded joints. These included transverse weld tensile testing, microhardness map of the weld joint, Charpy V-notch impact testing of weld metal and HAZ, and microstructure analysis. The results demonstrated that softening occurs in the fine grained HAZ (FGHAZ) and the inter-critical HAZ (ICHAZ) of X80HD line pipe girth welds. The severity of HAZ softening depends on the steel chemistry and the heat input applied during girth welding. The metallurgical design of the X80HD pipeline steel and the optimization of the girth welding procedures were proposed.

Sign in / Sign up

Export Citation Format

Share Document