Development and Production of Helical-Two-Step (HTS) Pipes: Grades Up to API X70 for Sour Service Application

2012 ◽  
Author(s):  
Djordje Mirković ◽  
Volker Flaxa ◽  
Franz Martin Knoop
Keyword(s):  
Low Temperature ◽  
Pipeline Steel ◽  
Steel Production ◽  
Standard Test ◽  
Pipe Production ◽  
Two Phase ◽  
Steel Grades ◽  
Low Temperature Toughness ◽  
Service Application ◽  
Sour Service

Within the corresponding commercial and R&D projects five microalloyed pipeline steel grades have recently been developed and processed to spiral-welded pipes. For steel grades X52, X65, and X70 the aimed tensile properties, improved sour service resistivity, and low temperature toughness up to −40°C were reliably achieved. Influence of steel cleanliness, the non-metallic inclusions in particular, on sour gas resistibility has been investigated by means of ultrasonic testing of hydrogen charged HIC (Hydrogen Induced Cracking) samples and SEM (Scanning Electron Microscope) analyses of HIC fracture surfaces. The results have been used to optimize the applied process parameter in steel production and coil processing. The ladle metallurgical treatment and soft reduction were consistently applied within narrow process tolerances enabling high steel cleanness and slab centerline quality, which are both indispensable for sour service application. Subsequent TMCP (Thermo Mechanical Processing) wide strip hot rolling and cooling parameters were selected to prevent a two-phase finish rolling and to obtain a predominating acicular ferritic microstructure. For pipe production, attention was paid to minimize the residual stresses, due to both pipe-forming and welding. The alloying approach is based on the classical sour lean NbTi steel composition, modified by varying Cu, Ni, Cr, and Mo contents to achieve the targeted specification. The processed spiral-welded pipes were formed to diameters between 762 and 1372 mm with a wall thickness of 13.7 to 16.0 mm. CVN (Charpy V-Notch) values were higher than 360 J/cm2 and DWTT (Drop Weight Tear Test) higher than 60% SA (Shear Area) at −40°C. The samples also showed outstanding HIC resistivity. Being proved with standard test conditions according to NACE TM0284 solution A, the CAR (Crack Area Ratio) average value of pipe samples was less than 1% for grades up to X65 and less than 5% for X70 grades. The 4-point-bending SSC (Sulphide Stress Cracking) tests at 80% of SMYS according to NACE TM0177 and ASTM G39 showed no SSC cracks for all projects. Finally, the results of one specific R&D project are presented to demonstrate that even for API X70 grade spiral-welded pipes (OD 1016×16 mm) mechanical properties, e.g. high-strength, ductility, and low temperature toughness has been successfully combined with sour service resistivity.

Development of X80M Line Pipe Steel for Spiral Welded Pipes With Low Temperature Toughness and Excellent Weldability

2014 ◽  
Author(s):  
Nuria Sanchez ◽  
Özlem E. Güngör ◽  
Martin Liebeherr ◽  
Nenad Ilić
Keyword(s):  
Low Temperature ◽  
Life Cycle Cost ◽  
Volume Fraction ◽  
Large Diameter ◽  
Pipe Production ◽  
Strain Accumulation ◽  
Long Distance ◽  
Line Pipe ◽  
Low Temperature Toughness ◽  
Welded Pipe

The unique combination of high strength and low temperature toughness on heavy wall thickness coils allows higher operating pressures in large diameter spiral welded pipes and could represent a 10% reduction in life cycle cost on long distance gas pipe lines. One of the current processing routes for these high thickness grades is the thermo-mechanical controlled processing (TMCP) route, which critically depends on the austenite conditioning during hot forming at specific temperature in relation to the aimed metallurgical mechanisms (recrystallization, strain accumulation, phase transformation). Detailed mechanical and microstructural characterization on selected coils and pipes corresponding to the X80M grade in 24 mm thickness reveals that effective grain size and distribution together with the through thickness gradient are key parameters to control in order to ensure the adequate toughness of the material. Studies on the softening behavior revealed that the grain coarsening in the mid-thickness is related to a decrease of strain accumulation during hot rolling. It was also observed a toughness detrimental effect with the increment of the volume fraction of M/A (martensite/retained austenite) in the middle thickness of the coils, related to the cooling practice. Finally, submerged arc weldability for spiral welded pipe manufacturing was evaluated on coil skelp in 24 mm thickness. The investigations revealed the suitability of the material for spiral welded pipe production, preserving the tensile properties and maintaining acceptable toughness values in the heat-affected zone. The present study revealed that the adequate chemical alloying selection and processing control provide enhanced low temperature toughness on pipes with excellent weldability formed from hot rolled coils X80 grade in 24 mm thickness produced at ArcelorMittal Bremen.

Guidelines for Production of API Pipelines Steels Suitable for Hydrogen Induced Cracking (HIC) Service Applications

2010 ◽  
Author(s):  
Douglas G. Stalheim ◽  
Bernhard Hoh
Keyword(s):  
Mechanical Property ◽  
Natural Gas ◽  
Pipeline Steel ◽  
Steel Production ◽  
The Other ◽  
Corrosion Mechanism ◽  
Pipeline Steels ◽  
Hydrogen Induced Cracking ◽  
Oil And Natural Gas ◽  
Sour Service

Worldwide oil and natural gas reserves can be classified as either sweet or sour service. The sour service classified oil and natural gas reserves contain some level of H2S making the product flowing through a steel pipeline corrosive. Due to this, the majority of the oil and natural gas reserves that have been drilled are of the sweet service nature. However as demand continues and supplies change, many of the remaining oil and natural gas reserves contain the H2S component and are of a sour service nature. These oil and natural gas reserves containing the H2S component through a corrosion mechanism will allow for diatomic hydrogen — in the presence of moisture — to disseminate to monatomic hydrogen and diffuse into the pipeline steel microstructure. Depending on the microstructure and level of cleanliness the monatomic hydrogen can become trapped at areas of high residual stress, recollect to diatomic hydrogen and creating partial pressures that exceed the tensile strength of the steel resulting in cracking. Therefore transmission pipelines are being built to transport sour service oil or natural gas requires steels with hydrogen induced cracking (HIC) resistance. Alloy designs, steel making processing, continuous casting, plate or strip rolling, pipe forming, and last not least corrosion testing are all key components in producing pipeline steels that are resistant to HIC applications and meeting the NACE TM0284 specifications. However, producing steels that have good HIC performance do not necessarily meet other mechanical property requirements such as strength and YT ratios. Balance has to be achieved to meet not only the HIC requirements but the other required mechanical properties. Mastering this complex HIC process poses a serious challenge to pipe producers and their primary material suppliers. The capability of producing HIC steel grades according to critical specifications and/or standards clearly distinguishes excellent steel producers from good steel makers. This paper will discuss the basics of the hydrogen induced cracking phenomenon, the requirements of the NACE TM0284 specification and give guidelines for steel production of API pipeline steels that not only can meet the specification requirements the NACE testing but also fulfill the other mechanical property requirements.

Fracture and Crack Propagation Behavior of 560 MPa Microalloyed Pipeline Steel under Different Cooling Schedules

2017 ◽  
Vol 898 ◽  
pp. 1094-1102 ◽  
Author(s):  
Jin Hua Zhao ◽  
Dong Fang Li ◽  
Guo Yuan ◽  
Xue Qiang Wang ◽  
Rui Hao Li ◽  
...  
Keyword(s):  
Grain Size ◽  
Low Temperature ◽  
Crack Propagation ◽  
Pipeline Steel ◽  
Crack Arrest ◽  
Dominant Factor ◽  
Cooling Schedules ◽  
Effective Grain Size ◽  
Mixed Microstructure ◽  
Low Temperature Toughness

Three kinds of pipeline steel with different microstructures were fabricated by varying cooling schedules during thermo-mechanical controlled processing (TMCP). Charpy impact property of the pipeline steels were obtained, and the fracture and crack-arrest mechanisms were further studied. The results indicated that the steels were classified into two kinds according to their microstructures, the mixture of acicular ferrite (AF), quasi-polygonal ferrite (QF), granular bainite (GB) and small fraction of degenerate pearlite (DP), and the mixed microstructure of AF and GB, respectively. The processed steel with microstructure of AF and GB exhibited more excellent low-temperature toughness and crack-arrest properties with upper shelf energy of ~281 J and energy transition temperature of ~-76°C. The mixed microstructure (AF + GB) possessing smaller effective grain size hindered the propagating of crack and consumed large amount of energy during fracture. The effective grain size of microstructure was the dominant factor controlling low-temperature toughness and crack-arrest properties of pipeline steel, which increased the high-angle boundary length per unit area and further increased the crack propagation energy during fracture.

Research and Development of Deep-Sea Pipeline Steel

2010 ◽  
Vol 152-153 ◽  
pp. 1492-1498
Author(s):  
Jin Qiao Xu ◽  
Bin Guo ◽  
Lin Zheng ◽  
Yin Hua Li ◽  
Le Yu
Keyword(s):  
Low Temperature ◽  
Deep Sea ◽  
Pipeline Steel ◽  
High Strength ◽  
Steel Company ◽  
Line Pipe ◽  
Iron And Steel ◽  
Company Group ◽  
Pipeline Project ◽  
Low Temperature Toughness

This paper provides a detailed description of deep-sea pipeline steel developed at Wuhan Iron and Steel Company(Group), WISCO for short. The thickness of the trial produced plates is 28mm. The chemical composition of low C-high Mn-Nb-Ti with proper content of other alloys and thermo-mechanical controlled process were applied. The results show that the deep-sea pipeline steel developed at Wuhan Iron and Steel Company has a good match of high strength, low temperature toughness and excellent deformability with fine uniform microstructure. The LSAW line pipe manufactured by JCOE method has high strength, good low temperature toughness and low yield ratio which comprehensively meet the requirements of the South China Sea Liwan pipeline project.

Effects of Cooling Processes on Microstructure Evolution of X80 Pipeline Steel

2014 ◽  
Vol 788 ◽  
pp. 378-383 ◽  
Author(s):  
Feng Qin Ji ◽  
Guo Dong Wang
Keyword(s):  
Low Temperature ◽  
Pipeline Steel ◽  
Bainitic Ferrite ◽  
Development Trend ◽  
Optical Microscope ◽  
Granular Bainite ◽  
X80 Pipeline Steel ◽  
Pipeline Steels ◽  
Low Temperature Toughness ◽  
Strength And Plasticity

With the development of pipeline industry, the pipeline steels with higher strength and plasticity, better low-temperature toughness and weldability are the main development trend. For bainitic pipeline steels, M/A constituent is the main hard phase. Although the M/A constituent can enhance the strength, the larger block-form M/A constituent can deteriorate low-temperature toughness. Therefore, it is essential to further investigate how to refine the M/A constituent. In the present paper, X80 pipeline steel was cooled to room temperature with various cooling paths after hot compression deformation at the temperature of 800oC. The evolution of microstructure of X80 pipeline steel has been analyzed by optical microscope (OM) and scanning electron microscope (SEM). The experimental results show that increasing the cooling rate can significantly refine M/A constituent and promote the formation of granular bainite, and the bainitic ferrite can be also greatly refined. In addition, the effects of five final temperatures of fast cooling were also investigated.

The Analysis of Low Temperature Toughness on X80 Pipeline Steel Welded Joint

2018 ◽  
Vol 71 (10) ◽  
pp. 2517-2526 ◽  
Author(s):  
Bin Wang ◽  
Yingchao Xu ◽  
Jing Hu ◽  
Senfeng Zhang ◽  
Chengwu Cui ◽  
...  
Keyword(s):  
Low Temperature ◽  
Welded Joint ◽  
Pipeline Steel ◽  
X80 Pipeline Steel ◽  
Low Temperature Toughness

Research and Development of Heavy Wall X80 Transmission Pipeline Steel With High Deformation Characteristics for Polar Environments at Shougang Steel

2012 ◽  
Author(s):  
Chunhe Zha ◽  
Zhonghang Jiang ◽  
Wenjun Wang ◽  
Jiading Li ◽  
Shaopo Li ◽  
...  
Keyword(s):  
Low Temperature ◽  
Research And Development ◽  
Pipeline Steel ◽  
Design Strategy ◽  
Pipe Production ◽  
Operating Pressure ◽  
Plate Mill ◽  
Strata Movement ◽  
High Deformation ◽  
Transmission Pipeline

Oil and gas transmission pipeline steels with high deformation capability are required for environments (earthquake zones, permafrost zones, forest heave, deep sea applications, etc.) where large strata movement may occur. When large strata movement occurs the pipeline is exposed to large plastic deformations that can result in failure. Transmission pipelines that must operate in these environmental conditions utilize a strain based design strategy to protect the pipeline from failure. This strain based design strategy for these transmission pipeline environments requires that the steel design used for pipe production must not only have the capability to withstand the high internal operating pressure but must also have good deformation resistance characteristics. Shougang Steel has conducted research into the metallurgical design required for heavy wall X80 transmission pipeline steel with high deformation and good low temperature mechanical property characteristics. This research coupled with the production capability of the Shougang Steel’s Qinhuangdao China (Shouqin) 4.3 m heavy wide plate mill has resulted in the successful production of a cost effective low C-Nb X80 alloy design with good deformation and low temperature toughness capabilities suitable for applications such as the natural gas TCPL/ExxonMobil proposed Alaskan Pipeline Project. This paper will discuss Shougang Steel’s research and development of heavy wall X80 pipeline steel. Key process parameter and equipment capabilities of the Shouqin 4.3 m wide heavy plate mill along with heavy wall X80 production results will be discussed.

Sign in / Sign up

Export Citation Format

Share Document