Refurbishment of a 230 KM Oil Pipeline With Longitudinal Seam Weld Fatigue Cracking Problem

2002 ◽  
Author(s):  
Marianela Ledezma ◽  
Jose´ G. Aranguren ◽  
Fabrizio Paletta
Keyword(s):  
Fatigue Cracking ◽  
Management Plan ◽  
Maintenance Cost ◽  
Defect Tolerance ◽  
Critical Crack ◽  
Oil Pipeline ◽  
Seam Weld ◽  
Weld Fatigue ◽  
Pressure Changes ◽  
Longitudinal Seam

Recently, a Petro´leos de Venezuela S. A. (PDVSA) oil pipeline, 230 Km (143 miles) in length and 660 mm (26 in.) in diameter, had a leak in the longitudinal seam weld of one of its sections. The analysis of this failure revealed that the leakage was originated in a fatigue crack which nucleated at a stress concentrator associated to a weld defect, and it propagated due to the cyclic stresses induced by the internal pressure changes. Partial external inspection of the pipeline revealed that the problem was extended to other sections. This paper summarizes the actions taken for the refurbishment of the oil pipeline which included: 1- the management plan set to face the problem; 2- the inspection of the pipeline, externally and internally; 3- the analysis of the inspection results; 4- the defect tolerance assessment / fitness-for-purpose study, to estimate both, the critical crack sizes as well as the crack propagation rates; 5- the development of repair procedures, and, 6- the determination of future inspection and maintenance recommended programs. All of it, with the main purpose of maintaining the operation of this line with complete guarantee of its integrity. Thanks to these actions, it has been possible to prevent additional failures in the same pipeline as well as to reduce in about MM$ 25 the maintenance cost associated with it.

An Improved Methodology for Prioritizing Pipelines With Respect to Fatigue Cracking of Seam Weld Flaws

2020 ◽  
Author(s):  
Michael Turnquist ◽  
Nader A. Al-Otaibi ◽  
Nauman Teshin ◽  
Mohammed A. Al-Rabeeah
Keyword(s):  
Additional Data ◽  
Fatigue Cracking ◽  
Primary Concern ◽  
Operating Pressure ◽  
Electric Resistance ◽  
Seam Weld ◽  
Pressure Cycle ◽  
Weld Fatigue ◽  
Longitudinal Seam ◽  
Submerged Arc

Abstract The threat of pressure cycle induced fatigue cracking of flaws associated with the longitudinal seam weld continues to be a primary concern for pipeline operators. Cyclic pressure loading can cause initial manufacturing flaws in a seam weld to sharpen and grow over time. While this behavior is most prevalent in pre-1979 electric resistance welds (ERW) and electric flash welds (EFW), historical data also shows that submerged arc welds (SAW) have been observed to develop cracks at the toe of the weld, and those cracks have exhibited fatigue growth from transit fatigue, operating pressure cycles, or both. When managing a large pipeline network, it is important to understand which pipelines exhibit higher priority with respect to seam weld fatigue cracking. While there are industry-accepted methodologies used to prioritize pipelines with respect to seam weld integrity (TTO-5 [1] and API RP 1176 [2] being the most well-known), these methodologies can be improved upon when specifically considering fatigue. Saudi Aramco and Quest Integrity developed a detailed methodology to determine a prioritization for a group of pipelines specifically with respect to seam weld fatigue cracking. This improved methodology was specially tailored to consider additional data available in Saudi Aramco’s records to rank the likelihood for a fatigue failure to occur. This initial prioritization will be used to implement a more rigorous program to manage their assets. Additional data gathered in subsequent assessments can be included to refine the prioritization. The primary metrics used to determine the prioritization are pressure cycle aggressiveness, predicted remaining life with respect to recent hydrostatic testing, and the API 1176 Annex B prioritization classification.

Evaluation of Existing Fracture Mechanics Models for Burst Pressure Predictions, Theoretical and Experimental Aspects

2014 ◽  
Author(s):  
Samarth Tandon ◽  
Ming Gao ◽  
Ravi Krishnamurthy ◽  
Shahani Kariyawasam ◽  
Richard Kania
Keyword(s):  
Fracture Mechanics ◽  
High Speed ◽  
Base Material ◽  
Element Model ◽  
Burst Pressure ◽  
Critical Crack ◽  
Integrity Assessment ◽  
Seam Weld ◽  
Crack Location ◽  
Weld Area

The predictions of burst pressure and leak/rupture have significant impact on the pipeline integrity assessment results, and subsequently on the extent of the required mitigation and re-inspection interval. There are models available for burst pressure and leak/rupture prediction in the literature, namely API-579, CorLas®, and NG-18 (Modified Ln-Sec). In this paper, evaluation of existing fracture mechanics models for burst pressure and leak/rupture prediction for external crack and crack like features including stress corrosion cracks (SCC) are performed. Both theoretical and practical aspects of each model are discussed in detail. An experiment is set up to conduct fifteen full scale burst tests of 20-inch, 34-inch and 36-inch diameter joints removed from the pipeline field. Among them, seven pipe joints are with base material SCC, four joints with seam weld cracks, three joints with linearly aligned crack-like features surrounded with shallow base material SCC, and one joint with crack-like feature in the Weld area. A high speed camera is utilized to capture rupture events. The rupture events can be stable tearing, crack coalescence and unstable propagation of a critical crack or multiple closely aligned cracks in a crack colony which are responsible for the rupture. Detailed profile measurements of the critical crack/s for burst pressure predictions are done from the fracture surfaces. Relevant material properties are measured for each joint in base material or seam weld location depending on the crack location. Burst pressure predictions are performed with models available in API-579, CorLas®, and Modified NG-18. An elastic-plastic finite element model is generated to quantify the effective stress intensity factor with and without the end cap effects during the burst testing. The accuracy and conservatism of the models evaluated are analyzed. Implications of the findings are discussed.

Analysis of Hot Oil Pipeline Stress Influencing Factors

2014 ◽  
Vol 887-888 ◽  
pp. 899-902
Author(s):  
Xiao Nan Wu ◽  
Shi Juan Wu ◽  
Hong Fang Lu ◽  
Jie Wan ◽  
Jia Li Liu ◽  
...  
Keyword(s):  
Crude Oil ◽  
High Viscosity ◽  
Analysis Model ◽  
Long Distance ◽  
Oil Pipeline ◽  
Software Analysis ◽  
Key Points ◽  
Temperature And Pressure ◽  
Pressure Changes ◽  
The Impact

In order to reduce the viscosity of crude oil for transport, we often use the way of heating delivery for high pour point, high wax, and high viscosity oil. Crude oil at high temperature, through long-distance transmission, the temperature and pressure changes on the piping stress greater impact. In this paper, in order to explore the main factor of hot oil pipeline stress and the location of key points, we build the XX hot oil pipeline stress analysis model used CAESAR II software, analysis of the impact of changes in temperature and pressure on piping stress when hot oil pipeline running, draw hot oil pipeline stress distribution, clearly identifies the location of key points of stress concentration, and we have come to that temperature is a major factor in generating pipe stress.

Integrity Evaluation of an Older Vintage ERW Pipeline

2002 ◽  
Author(s):  
Geoff B. Rogers ◽  
Steve C. Rapp ◽  
Garry M. Matocha
Keyword(s):  
Planning Process ◽  
Ultrasonic Inspection ◽  
Mechanical Damage ◽  
Project Planning ◽  
Operating Pressure ◽  
Seam Weld ◽  
Weld Defects ◽  
Natural Gas Pipeline ◽  
Longitudinal Seam ◽  
Future Project

As part of a program to increase the operating pressure of a 20” (508.0mm) natural gas pipeline, a careful plan was developed and executed to ensure the integrity of the pipeline. The pipeline was built in 1943 using linepipe produced having a DC ERW longitudinal seam weld and travels along a densely populated route in the suburbs of Philadelphia. The work plan included ILI inspection methods to detect corrosion (MFL tool), mechanical damage (geometry tool), and ERW seam weld defects (TFI MFL tool). After the anomalies were identified and the necessary pipe replacements were completed, the pipeline was hydrostatically tested prior to being returned to service at the newly established operating pressure. The paper will describe the project planning process used to ensure the fitness and reliability of the pipeline and provide a review of the ILI results, excavations, pipe replacements, and hydrostatic test experiences. Of particular interest were the capabilities and limitations of the TFI tool to detect, discriminate, and size ERW seam weld defects. Seam weld defects were evaluated using ILI inspection methods and in many cases field prove-up ultrasonic inspection methods. When an ERW defect was confirmed by field NDT prove-up, the pipe section was removed and metallographic work was conducted to characterize the ERW flaw size and nature. A correlation was then possible between the sizing capability of the TFI tool, the ultrasonic prove-up method, and the actual defect size. All this information is useful to establish a level of confidence in defect sizing for future project needs. The final validation of the pipeline fitness at the higher operating pressure was established through the successful hydrostatic test. A short summary will be given on how the pipeline fitness was qualified and demonstrated.

Identifying and Sizing Axial Seam Weld Flaws in ERW Pipe Seams and SCC in the Pipe Body Using Ultrasonic Imaging

2016 ◽  
Author(s):  
Harvey Haines ◽  
Lars Hörchens ◽  
Pushpendra Tomar
Keyword(s):  
New Technologies ◽  
Ultrasonic Imaging ◽  
Three Dimensional ◽  
Low Frequency ◽  
Fatigue Cracking ◽  
Seam Weld ◽  
Current State ◽  
Pressure Cycle ◽  
Ultrasonic Phased Array ◽  
Resistance Weld

A significant portion of the global energy pipeline infrastructure is constructed with pipe materials manufactured using the Electric Resistance Weld (ERW) process. The longitudinal seam of these ERW pipelines may contain manufacturing flaws and anomalies that can grow over time through pressure cycle fatigue and result in a pipeline integrity failure. These flaws/anomalies can be present in both vintage pipe (generally pre-1970) manufactured using a low frequency ERW process and more modern pipe that is manufactured using a high frequency ERW process. ERW seam anomalies are challenging to detect, discriminate, and size with current In-Line Inspection and In-Ditch NDE inspection technologies, which is driving the industry to better understand current inspection industry performance and to develop new technologies for ERW seam anomaly inspection. Ultrasonic (UT) imaging using inverse wave field extrapolation (IWEX) is an emerging NDE technique that is being applied to improve discrimination and sizing of anomalies in pipelines. This paper will describe the IWEX development, the challenges related to seam weld integrity and assessment and SCC assessment, and results from studies to evaluate performance. Ultrasonic imaging is also compared to the current state-of-the-art techniques such as ultrasonic phased array (PA). A goal of the project is to produce images capable of discriminating cold welds, surface breaking hook cracks, non-surface breaking upturned fiber indications, poor trim, offset plate edges, and anomalies with fatigue cracking. The goal is to size all of the cracks in a SCC colony and produce a three-dimensional map of the area. In mapping these anomalies the sizing needs to be sufficiently accurate to qualify in-line inspection tools used for crack inspection.

Evaluation of Historical Longitudinal Seam Weld Failures in Grades 11, 12, and 22 Materials

2008 ◽  
Author(s):  
Marvin J. Cohn ◽  
Steve R. Paterson
Keyword(s):  
Hoop Stress ◽  
Seam Weld ◽  
Failure Data ◽  
Weld Failure ◽  
Curve Fit ◽  
Power Utilities ◽  
Term Creep ◽  
Longitudinal Seam ◽  
Grade 11

Since the catastrophic HEP seam weld failures of Mohave (1985) and Monroe (1986), electric power utilities have become more interested in developing and implementing examination and fitness-for-service evaluations of their HEP systems. At least 30 failures or substantial cracks in Grade 11 (1-1/4Cr – 1/2Mo), Grade 12 (1Cr – 1/2Mo) and Grade 22 (2-1/4 Cr – 1Mo) pipe longitudinal seam welds or clamshell welds have occurred from 1979 through 2000. This paper provides a statistical analysis of well-characterized Grade 11, Grade 12, and Grade 22 longitudinal seam weld failures or substantial cracks developed by long term creep rupture damage. Considering several applicable hoop stress parameters, linear regression analyses were performed to minimize scatter about a log stress versus Larson Miller Parameter (LMP) curve fit. Each of six applicable hoop stress equations was evaluated to determine the best fit stress space for the longitudinal seam weld failure data. These service experience industry data include pipe thicknesses ranging from 0.5 to 4.5 inches and failure times ranging from 71,000 to 278,000 hours.

scholarly journals Improvement of notch toughness and soundness in longitudinal seam weld of line pipe.

1986 ◽  
Vol 26 (5) ◽  
pp. 379-386 ◽  
Author(s):  
Kazutaka AKAO ◽  
Toshio ISHIHARA ◽  
Toyofumi KITADA ◽  
Yukio NISHINO ◽  
Naoki OKUDA ◽  
...  
Keyword(s):  
Notch Toughness ◽  
Line Pipe ◽  
Seam Weld ◽  
Longitudinal Seam
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