Design of Pipeline Damage for the BP X100 Operational Trial

Author(s):  
Robert M. Andrews ◽  
James Johnson ◽  
Julie Crossley

As part of an ongoing pipeline technology program for BP Alaska, a 1 km, 48-inch diameter, X100 demonstration pipeline was constructed and operated for a period of two years. Artificial defects were introduced into one of the two test sections. These defects were intended to demonstrate that current assessment methods could be used to predict the behaviour of pipeline defects in a very high strength steel under realistic conditions including accelerated pressure cycling and a range of cathodic protection levels. The defects included in the trial were volumetric corrosion, mechanical damage, arc strikes and girth weld defects. The volumetric corrosion defects included both isolated defects and pairs of interacting defects. All the defects and details such as the girth welds were assessed for fatigue failure in addition to failure at the Maximum Operating Pressure. This paper describes the design of the defects for the trial. The defects were designed to be close to failure, so as to provide a realistic test of the predictive methods. Current methods were used including the Pipeline Defect Assessment Manual (PDAM) and ongoing work sponsored by PRCI.

Author(s):  
David J. Miles ◽  
Tim J. M. Bond ◽  
Raymond N. Burke ◽  
Ruben van Schalkwijk

A new technology for external rehabilitation of pipelines, known as XHab™, has been developed. This method involves wrapping multiple layers of ultra-high strength steel strip (UHSS) in a helical form continuously over an extended length of pipeline using a dedicated forming and wrapping machine. The reinforcement afforded by the strip can be used to bring a defective section of pipe (e.g. externally corroded or dented) back to its original allowable operating conditions, or even to increase the allowable operating pressure if the desired operating conditions exceed the original pipeline design limits. This paper describes the full scale burst testing and analysis of defective pipes which have been repaired using the XHab process. The full scale test sections are 30″ × 0.5″ API 5L X52 DSAW pipe and include the following specimens: • Bare pipe with no defects; • Bare pipe with single machined defect; • Wrapped pipe with single machined defect and designed reinforcement; • Wrapped pipe with single machined defect and insufficient reinforcement; • Wrapped pipe with interacting defect array and designed reinforcement. The above full scale burst tests are supplemented by FEA models using ABAQUS. The material models for the steel pipe, UHSS strip, defect patch material and strip adhesive are based on measured data from the batch tests and tuned against the control burst test results. The structural behavior in the individual metallic and non-metallic elements can therefore be examined more closely, particularly in the region of the defect and where the wrapped strip crosses seam and girth welds.


Author(s):  
Luyao Xu ◽  
Frank Y. Cheng

In this work, a finite element (FE) model was developed to simulate the complex stress/strain conditions potentially exerted on the northern pipelines due to the synergism of internal pressure, soil strain and local stress/strain concentration at corrosion defects. The effects of pre-strain on corrosion of the steel and the pipeline failure pressure were investigated. Results demonstrated that a high intensity stress/strain field generates preferentially at the bottom of corrosion defect. The increase of operating pressure would increase the stress concentration at defect and the plastically deformed area. Both tensile and compressive soil strains increase the stress intensity and plastic deformation. Thus, a pipe containing corrosion defects or mechanical dents is susceptible to hoop cracking or local bulking under the tensile and compressive soil strains, respectively. Moreover, while an elastic strain enhances slightly the steel corrosion, the effect of plastic strain is much remarkable. In optimal pipeline design, the reliable risk assessment of high-strength steel pipelines should consider the corrosion enhancement and defect propagation under the complex stress/strain conditions.


Author(s):  
Zengmeng Zhang ◽  
Jinkai Che ◽  
Peipei Liu ◽  
Yunrui Jia ◽  
Yongjun Gong

Compared with pneumatic artificial muscles (PAMs), water hydraulic artificial muscles (WHAMs) have the advantages of high force/weight ratio, high stiffness, rapid response speed, large operating pressure range, low working noise, etc. Although the physical models of PAMs have been widely studied, the model of WHAMs still need to be researched for the different structure parameters and work conditions between PAMs and WHAMs. Therefore, the geometry and the material properties need to be considered in models, including the wall thickness of rubber tube, the geometry of ends, the elastic force of rubber tube, the elongation of fibers, and the friction among fiber strands. WHAMs with different wall thickness and fiber materials were manufactured, and static characteristic experiments were performed when the actuator is static and fixed on both ends, which reflects the relationship between contraction force and pressure under the different contraction ratio. The deviations between theoretical values and experimental results were analyzed to investigate the effect of each physical factor on the modified physical model accuracy at different operating pressures. The results show the relative error of the modified physical model was 7.1% and the relative error of the ideal model was 17.4%. When contraction ratio is below 10% and operating pressure is 4 MPa, the wall thickness of rubber tube was the strongest factor on the accuracy of modified model. When the WHAM contraction ratio from 3% to 20%, the relative error between the modified physical model and the experimental data was within ±10%. Considering the various physical factors, the accuracy of the modified physical model of WHAM is improved, which lays a foundation of non-linear control of the high-strength, tightly fiber-braided and thick-walled WHAMs.


2013 ◽  
Vol 32 ◽  
pp. 209-219 ◽  
Author(s):  
Bin Ma ◽  
Jian Shuai ◽  
Dexu Liu ◽  
Kui Xu

Author(s):  
Peter Song ◽  
Doug Lawrence ◽  
Sean Keane ◽  
Scott Ironside ◽  
Aaron Sutton

Liquids pipelines undergo pressure cycling as part of normal operations. The source of these fluctuations can be complex, but can include line start-stop during normal pipeline operations, batch pigs by-passing pump stations, product injection or delivery, and unexpected line shut-down events. One of the factors that govern potential growth of flaws by pressure cycle induced fatigue is operational pressure cycles. The severity of these pressure cycles can affect both the need and timing for an integrity assessment. A Pressure Cycling Monitoring (PCM) program was initiated at Enbridge Pipelines Inc. (Enbridge) to monitor the Pressure Cycling Severity (PCS) change with time during line operations. The PCM program has many purposes, but primary focus is to ensure the continued validity of the integrity assessment interval and for early identification of notable changes in operations resulting in fatigue damage. In conducting the PCM program, an estimated fatigue life based on one month or one quarter period of operations is plotted on the PCM graph. The estimated fatigue life is obtained by conducting fatigue analysis using Paris Law equation, a flaw with dimensions proportional to the pipe wall thickness and the outer diameter, and the operating pressure data queried from Enbridge SCADA system. This standardized estimated fatigue life calculation is a measure of the PCS. Trends in PCS overtime can potentially indicate the crack threat susceptibility the integrity assessment interval should be updated. Two examples observed on pipeline segments within Enbridge pipeline system are provided that show the PCS change over time. Conclusions are drawn for the PCM program thereafter.


2013 ◽  
Vol 549 ◽  
pp. 172-179 ◽  
Author(s):  
Amir Hassannejadasl ◽  
Daniel E. Green

Hydropiercing is an efficient way of piercing holes in mass produced hydroformed parts with complex geometries. By driving piercing punches radially into a hydroformed and fully pressurized tube, holes will be pierced and extruded into the tube-wall. Recent experimental studies have shown that the formability of advanced high strength steel (AHSS) tubes can be increased with the application of internal pressure. In this study, three-dimensional finite element simulations of a tube hydropiercing process of a dual phase steel (DP600) were performed in LS-DYNA, using phenomenological, micromechanical and combined damage criteria. Damage was included in the numerical analysis by applying constant equivalent plastic strain (CEPS), the Gurson-Tvergaard-Needleman (GTN), and the Extended GTN (GTN+JC) model. In order to calibrate the parameters in each model, a specialized hole-piercing fixture was designed and piercing tests were carried out on non-pressurized tube specimens. Of the various ductile fracture criteria, the results predicted with the GTN+JC model, such as the punch load-displacement, the roll-over depth, and the quality of the clearance zone correlated the best with the experimental data.


Author(s):  
Alfonso Izquierdo ◽  
Hector Quintanilla ◽  
Gilles Richard ◽  
Ettore Anelli ◽  
Gianluca Mannucci ◽  
...  

The technological evolution in the offshore sector points out a trend towards an increasing use of high strength steels (grade 80ksi and higher), for both pipelines and risers. Pipeline specifications for deepwater offshore fields demand developments in design criteria (i.e. limit state design), welding, installation, and laying technologies. As long as the market goes deeper in offshore exploration and production, the market trend is to use heavier pipes in steel grade X65/X70 and some technological limits from several fronts are faced and more attractive becomes for the market to have a lighter high strength 100ksi seamless steel grade. The joint industrial program (JIP), termed “Seamless 100 ksi weldable” launched by Tenaris in order to address the complex design issues of high strength Q&T seamless pipes for ultra deep water applications has been finalized. The 100ksi steel grade has been achieved in two wall thickness 16 mm and 25 mm. The main results from both phase I devoted to the development and production of seamless pipes with minimum 100ksi and phase II devoted to evaluate the high strength seamless pipe weldability will be addressed in this paper. Main microstructural features promoting the best strength-toughness results obtained from phase I and the results from phase II, where the heat affected zone (HAZ) characterization made using stringent qualifying configuration such as API RP2Z and the promising results after qualifying the girth welds simulating a typical offshore operation and the Engineering Critical Assessment for installation will be addressed. The results from this development are of interest of all oil & gas companies who are facing as an output from the design project analysis the need to have high strength seamless pipes.


2017 ◽  
Vol 898 ◽  
pp. 1063-1068
Author(s):  
Deng Zun Yao ◽  
Zhi Wen Li ◽  
Jian Wu Liu ◽  
Lin Chen

In the pipeline construction, the girth welds tend to be the weakness because of defects and microstructural heterogeneities. The importance of suitable assessment of various defects in the weld is not only to prevent the cracks from unstable growth to cause catastrophic accident but also can effectively reduce the weld repair to reduce construction cost. Although many welding defects assessment methods and codes have been applied in this field, there are many differences among them. In this paper, the application of weld defect assessment methods was extensively studied. The key points of ECA applications, such as the pipeline axial stress and toughness, have been introduced. Furthermore, some suggestions were given on the application of girth weld ECA assessment.


Author(s):  
Nicholas J. Venero ◽  
Tim J. M. Bond ◽  
Raymond N. Burke ◽  
David J. Miles

A new technology for external rehabilitation of pipelines, known as XHab™, has been developed. This method involves wrapping multiple layers of ultra-high strength steel (UHSS) strip in a helical form continuously over an extended length of pipeline using a dedicated forming and wrapping machine. The reinforcement afforded by the strip can be used to bring a defective section of pipe (e.g. externally corroded or dented) back to its original allowable operating conditions, or even to increase the allowable operating pressure if the desired operating conditions exceed the original pipeline design limits. This paper describes the design, manufacture and testing process for a self-propelled wrapping machine for in-field rehabilitation. The wrapping apparatus consists of several major components including an opening sufficiently wide to receive the pipe, a movement assembly, a winding head, a preforming device, an accumulator and an oscillating adhesive applicator. The wrapping apparatus uses the winding head to wrap the reinforcing steel strip around the pipe. The movement assembly uses a pair of tracks in contact with the pipe to drive the wrapping apparatus along which enables helical wrapping of the reinforcing strip material. The oscillating adhesive assembly applies structural adhesive to the pipe immediately before the strip is wound. The winding head, motive assembly and adhesive applicator are electronically synchronized to one another to enable precise control of pitch and adhesive volume. The paper also describes the field application of XHab including mobilization/demobilization of equipment and interaction with other rehabilitation equipment, as well as specific aspects such as initiation and termination of wrapping, protection of rehabilitated area and implementation of cathodic protection.


Author(s):  
Chris Alexander ◽  
Salem Talbi ◽  
Richard Kania ◽  
Jon Rickert

Abstract A study was conducted to evaluate two composite repair technologies used to reinforce severe corrosion and thru-wall leaking defects in thin-walled pipe materials; conditions where the welding of conventional Type B steel sleeves cannot be conducted. This program involved the reinforcement of simulated 85% corrosion defects in 6.625-inch × 0.157-inch, Grade X52 pipe materials subjected to cyclic pressure and burst testing. The test matrix also included repaired pipe samples with thru-wall defects that were pressurized using nitrogen gas and buried for 90 days. The program was comprehensive in that it evaluated the following elements involving a total of 81 reinforced corrosion defects. • Corrosion features with a depth of 85% of the pipe’s nominal wall thickness in thin-walled pipe material (i.e., 0.157 inches, or 4 mm). • Thru-wall defects having a diameter of 0.125 inches (3 mm). • Repairs made with leaking defects having 100 psig (690 kPa) internal pressure. • Strain gage measurement made in non-leaking 85% corrosion defects; it should be noted that the remaining “15%” ligament was 0.024 inches (0.6 mm); to the author’s knowledge, no high-pressure testing has ever been conducted on such a thin remaining wall. • Long-term 90-day test that included pressurization with nitrogen gas, followed by relatively aggressive pressure cycling up to 80% SMYS followed by burst testing. This is the first comprehensive study conducted by a major transmission pipeline operator evaluating the performance of competing composite technologies used to reinforce severe corrosion features with thru-wall defects. The reinforcement of leaks has not been accepted by regulatory bodies such as the Canadian Energy Regulator (CER), or the U.S. Pipeline and Hazardous Materials Safety Administration (PHMSA). A goal of the current study is to validate composite repair technologies as a precursor to regulatory approval. The results of this study indicate that viable composite repair technologies exist with capabilities to reinforce leaks in pipelines that experience operating conditions typical for gas transmission systems (i.e., minimal pressure cycling).


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