Performance Evaluation of Above Ground Surveys for Locating External Corrosion in Pipelines

2002 ◽  
Author(s):  
Clive R. Ward ◽  
Marcus McCallum ◽  
Gary L. Masters ◽  
Andrew Francis
Keyword(s):  
Structural Reliability ◽  
Large Diameter ◽  
Operating Pressure ◽  
Integrity Assessment ◽  
Direct Assessment ◽  
Site Investigations ◽  
Transmission Pipeline ◽  
True Condition ◽  
Using Data ◽  
External Corrosion

Integrity management regulations require operators of high-pressure gas pipelines to consider various threats to pipeline integrity including time-dependent degradation due to corrosion. Depending on factors including age and operating pressure, a pipeline will require periodic integrity assessment. Methods available for assessing external corrosion are in-line inspection, pressure testing, or Direct Assessment, which is the subject of this paper. An analysis was conducted on data from a large diameter gas transmission pipeline built in the 1960’s. A 30Km section was investigated, using data spanning an 18-year period. The records analyzed included above ground surveys, high-resolution in-line inspection surveys, and site investigations. Assuming the in-line inspection represents true condition, it was found that the above ground surveys produced indications at between 80% and 90% of the in-line inspection features. Approximately 35% of the survey indications did not correspond to in-line inspection features. This information should benefit those wishing to implement Direct Assessment programs using Structural Reliability Analysis techniques.

Extending the In-Line Inspection Interval for a Gas Pipeline Using Direct Assessment

2008 ◽  
Author(s):  
Marcus McCallum ◽  
Graham Ford ◽  
Andrew Francis
Keyword(s):  
Natural Gas ◽  
Structural Reliability ◽  
Probabilistic Approach ◽  
Gas Pipeline ◽  
Time Dependent ◽  
Time Interval ◽  
Operating Pressure ◽  
Direct Assessment ◽  
Ground Survey ◽  
External Corrosion

RWE npower own and operate a 12km long 8″ diameter natural gas pipeline that supplies natural gas from the National Transmission System (NTS) to a CHP unit. The pipeline has a nominal wall thickness of 6.35mm, is constructed from API 51 X42 grade steel and has a maximum operating pressure of 75barg. The pipeline was commissioned about 8 years ago and has been operating safely since that time. The pipeline was designed in accordance with BS 8010 Parts 1 and 2, with consideration given to the Institute of Gas Engineers Recommendations, IGE/TD/1, IGE/TD/9 and IGE/TD/12. One of the requirements of IGE/TD/1 is that the time interval between in-line inspections should not normally exceed 10 years. However, IGE/TD/1 Edition 4 allows the time interval to be exceeded if justification can be demonstrated using risk based techniques. For older pipelines it is often possible to determine the required time dependent failure probability based on the results of previous ILIs. This allows the time to next ILI to be determined. This time will depend on what has been found previously and values of other pipeline parameters. However, in the case of this pipeline there are no previous ILI data. In view of the above a probabilistic approach to External Corrosion Direct Assessment (ECDA) was adopted. The method makes use of the results from the above ground surveys rather than ILI data. However, in this instance, rather than being used to determine the time interval to the next above ground survey the method was used to determine the time interval to the next (first) ILI. The method is based on structural reliability analysis (SRA) which is used to determine the time dependent probability of failure based on available data. In view of the quantity and quality of the available above ground survey data it was possible to use the method to extend the time to the next ILL by several years.

Integrity Assessment of Non-Piggable Pipeline Through Direct Assessment

2013 ◽  
Author(s):  
Jai Prakash Sah ◽  
Mohammad Tanweer Akhter
Keyword(s):  
Hydrostatic Pressure ◽  
Natural Gas ◽  
Stress Corrosion ◽  
Health Assessment ◽  
Assessment Method ◽  
Pipeline System ◽  
Internal Corrosion ◽  
Integrity Assessment ◽  
Direct Assessment ◽  
External Corrosion

Managing the integrity of pipeline system is the primary goal of every pipeline operator. To ensure the integrity of pipeline system, its health assessment is very important and critical for ensuring safety of environment, human resources and its assets. In long term, managing pipeline integrity is an investment to asset protection which ultimately results in cost saving. Typically, the health assessment to managing the integrity of pipeline system is a function of operational experience and corporate philosophy. There is no single approach that can provide the best solution for all pipeline system. Only a comprehensive, systematic and integrated integrity management program provides the means to improve the safety of pipeline systems. Such programme provides the information for an operator to effectively allocate resources for appropriate prevention, detection and mitigation activities that will result in improved safety and a reduction in the number of incidents. Presently GAIL (INDIA) LTD. is operating & maintaining approximately 10,000Kms of natural gas/RLNG/LPG pipeline and HVJ Pipeline is the largest pipeline network of India which transports more than 50% of total gas being consumed in this country. HVJ pipeline system consists of more than 4500 Kms of pipeline having diameter range from 04” to 48”, which consist of piggable as well as non-piggable pipeline. Though, lengthwise non-piggable pipeline is very less but their importance cannot be ignored in to the totality because of their critical nature. Typically, pipeline with small length & connected to dispatch terminal are non-piggable and these pipelines are used to feed the gas to the consumer. Today pipeline industries are having three different types of inspection techniques available for inspection of the pipeline. 1. Inline inspection 2. Hydrostatic pressure testing 3. Direct assessment (DA) Inline inspection is possible only for piggable pipeline i.e. pipeline with facilities of pig launching & receiving and hydrostatic pressure testing is not possible for the pipeline under continuous operation. Thus we are left with direct assessment method to assess health of the non-piggable pipelines. Basically, direct assessment is a structured multi-step evaluation method to examine and identify the potential problem areas relating to internal corrosion, external corrosion, and stress corrosion cracking using ICDA (Internal Corrosion Direct Assessment), ECDA (External Corrosion Direct Assessment) and SCCDA (Stress Corrosion Direct Assessment). All the above DA is four steps iterative method & consist of following steps; a. Pre assessment b. Indirect assessment c. Direct assessment d. Post assessment Considering the importance of non-piggable pipeline, integrity assessment of following non piggable pipeline has done through direct assessment method. 1. 30 inch dia pipeline of length 0.6 km and handling 18.4 MMSCMD of natural gas 2. 18 inch dia pipeline of length 3.65 km and handling 4.0 MMSCMD of natural gas 3. 12 inch dia pipeline of length 2.08 km and handling 3.4 MMSCMD of natural gas In addition to ICDA, ECDA & SCCDA, Long Range Ultrasonic Thickness (LRUT-a guided wave technology) has also been carried out to detect the metal loss at excavated locations observed by ICDA & ECDA. Direct assessment survey for above pipelines has been conducted and based on the survey; high consequence areas have been identified. All the high consequence area has been excavated and inspected. No appreciable corrosion and thickness loss have observed at any area. However, pipeline segments have been identified which are most vulnerable and may have corrosion in future.

An External Corrosion Direct Assessment Module for a Pipeline Integrity Management System

2006 ◽  
Author(s):  
Menno T. van Os ◽  
Piet van Mastrigt ◽  
Andrew Francis
Keyword(s):  
Management System ◽  
Structural Reliability ◽  
Individual Performance ◽  
Corrosion Activity ◽  
Time Saving ◽  
Survey Techniques ◽  
Direct Assessment ◽  
Integrity Management ◽  
External Corrosion ◽  
The Individual

A significant part of the high pressure gas transport system of Gasunie cannot be examined by in-line inspection techniques. To ensure safe operation of these pipelines, an External Corrosion Direct Assessment (ECDA) module for PIMSLIDER (a pipeline integrity management system) is currently under development. The functional specifications of this module are based on NACE RP0502-2002, a recommended practice for ECDA. In addition to this, a new probabilistic methodology has been adopted, to take account for uncertainties associated with ECDA and to quantify the contributions from aboveground surveys and excavations to the integrity of a pipeline. This methodology, which is based on Structural Reliability Analysis (SRA) and Bayesian updating techniques, is presented in more detail in paper IPC2006-10092 of this conference. The DA module of PIMSLIDER enables computerized storage, retrieval and processing of all appropriate pipeline data and therefore guarantees highly accurate, reproducible and time saving integrity analyses of the Gasunie grid. Another important function of this system is the ability to use the complete database of all pipelines to pre-assess the integrity of a particular pipeline. This automated retrieval of data from pipelines with similar characteristics and/or environmental conditions results in a substantial increase of accessible data and enables Gasunie to improve the reliability of applied statistics throughout the process. As a consequence, the overall cost of inspections and excavations can be greatly reduced. In the Pre-Assessment phase, the DA module assists the integrity manager in gathering and analyzing data necessary to determine the current condition of a pipeline. After collection and visualization of the available data, the user can identify suitable ECDA regions. Furthermore, the gathered data are used to construct prior distributions of parameters relevant to the SRA model, such as the number and size of corrosion defects and pipeline-related parameters. In the Indirect Inspections step, the DA module allows the user to store and analyze the data from aboveground surveys, in order to identify and define the severity of coating faults and areas at which corrosion activity may occur. The probabilistic methodology accounts for the individual performance of each applied survey technique in terms of missed defects and false indications, in general a major source of uncertainty in ECDA. In the Direct Examinations phase, excavations are carried out to collect data to assess possible corrosion activity. Subsequently, the ECDA module uses this information to update, among other things, the parameters concerning the performance of survey techniques, the number of defects and the corrosion rate. As a result, updated failure frequencies are calculated for each ECDA-region (after each excavation if required), which are then used by the DA module to advise the integrity manager if additional mitigating activities are necessary, or by defining a reassessment interval.

KOC’s Integrity Management Program for Non-Piggable Pipelines: A Case Study

2010 ◽  
Author(s):  
Ashish Khera ◽  
Abdul Wahab Al-Mithin ◽  
James E. Marr ◽  
Shabbir T. Safri ◽  
Saleh Al-Sulaiman
Keyword(s):  
Risk Analysis ◽  
Systematic Evaluation ◽  
Pipeline System ◽  
Pipeline Network ◽  
Integrity Assessment ◽  
Direct Assessment ◽  
Integrity Management ◽  
Management Techniques ◽  
External Corrosion

More than half of the world’s oil and gas pipelines are classified as non-piggable. Pipeline operators are becoming aware there are increased business and legislative pressures to ensure that appropriate integrity management techniques are developed, implemented and monitored for the safe and reliable operation of their pipeline asset. The Kuwait Oil Company (KOC) has an ongoing “Total Pipeline Integrity Management System (TPIMS)” program encompassing their entire pipeline network. In the development of this program it became apparent that not all existing integrity management techniques could be utilized or applied to each pipeline within the system. KOC, upon the completion of a risk assessment analysis, simply separated the pipelines into two categories consisting of piggable and non-piggable lines. The risk analysis indicated KOC’s pipeline network contains more than 200 non-piggable pipelines, representing more than 60% of their entire pipeline system. These non-piggable pipelines were to be assessed by utilizing External Corrosion Direct Assessment (ECDA) for the threat of external corrosion. Following the risk analysis, a baseline external corrosion integrity assessment was completed for each pipeline. The four-step, iterative External Corrosion Direct Assessment (ECDA) process requires the integration of data from available line histories, multiple indirect field surveys, direct examination and the subsequent post assessment of the documented results. This case study will describe the available correlation results following the four steps of the DA process for specific non-piggable lines. The results of the DA program will assist KOC in the systematic evaluation of each individual non-piggable pipeline within their system.

Complete Integrity Assessment of a Non-Piggable Multi-Diameter Cross Country Pipeline in a Network Shared by Multiple Electrically Continuous Parallel Pipelines

2021 ◽  
Author(s):  
Amit Mishra ◽  
Saurabh Vats ◽  
Carlos A. Palacios T. ◽  
Himanshu Joshi ◽  
Ishan Khurana
Keyword(s):  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Accurate Data ◽  
Internal Corrosion ◽  
Integrity Assessment ◽  
Direct Assessment ◽  
Integrity Management ◽  
The Subject ◽  
Cross Country ◽  
External Corrosion

Abstract A complete Pipeline Integrity Management System is the need of the hour. Apart from keeping in mind the enormous environment concerns in this rapidly dwindling era of hydrocarbons, a successful pipeline owner always strives to profitably operate their precious assets. To operate a pipeline efficiently, a plan is required to maintain its health and increase the remaining life. Various types of pipelines pose various problems which the owner needs to resolve systematically and with a well-ordered approach. A similar challenge was faced by a refinery in India. The refinery has a design capacity to process 15 MMTPA of crude per annum. The imports and exports are carried out through the local Port Trust which is one of the deepest inner harbour on the west coast. Multiple pipelines run to and from the refinery and the port trust (approximate distance — 10 km). The subject pipeline in question currently transports Mixed Xylene (MX) from refinery to port. The pipeline has a diversified operating history with various other products being transferred in the past. However, the pipeline is used very scarcely. The problem posed by the subject pipeline was similar to what many other cross-country pipelines face — the pipeline was not piggable. Five (5) other parallel pipelines share the same right-of-way, all of which are piggable and have their integrity assessment performed via Intelligent Pigging on a planned basis. There was also a concern about collecting the most accurate data since the pipeline had not undergone an integrity assessment since its commissioning in 2001. However, it was yearly pressure tested to ensure integrity of the pipeline. Parallel pipelines pose a bigger challenge for obtaining accurate data for a particular pipeline amongst them. Keeping all this in mind, a complete integrity management was planned for the MX pipeline and thus concluded on performing a turnkey Direct Assessment (DA) program. The DA program included Internal Corrosion Direct Assessment (ICDA) to assess and manage the threats of internal corrosion, External Corrosion Direct Assessment (ECDA) for external corrosion threats and Stress Corrosion Cracking Direct Assessment (SCCDA) for determining susceptibility towards the threat of stress corrosion cracking on the pipeline. Utilization of latest technologies helped in adapting and overcoming the multiple problems faced by legacy technologies especially in difficult ROW conditions and complex pipeline networks, such as the MX pipeline. This paper provides an insight into how an operator can combine latest available technologies and deploy it in unison with the complete integrity management plan.

A Robust Approach to Pipeline Integrity Management Using Direct Assessment Based on Structural Reliability Analysis

2004 ◽  
Author(s):  
Marcus McCallum ◽  
Andrew Francis ◽  
Tim Illson ◽  
Mark McQueen ◽  
Mike Scott ◽  
...  
Keyword(s):  
Reliability Analysis ◽  
Structural Reliability ◽  
Voltage Gradient ◽  
Pipeline System ◽  
Pipe Failure ◽  
Internal Corrosion ◽  
Direct Assessment ◽  
Structural Reliability Analysis ◽  
Integrity Management ◽  
External Corrosion

Approximately 1450 km (900 miles) of a 4020-km (2500 mile) natural gas pipeline system operated by Crosstex Energy Service L.P in Texas are subject to the Texas Railroad Commission’s (TRRC) integrity management rules. Consequently, in preparation for the construction of an extensive and robust integrity management program, Crosstex commissioned Advantica to assist in the development and application of a pilot study on a 13.4 km (8.3 mile) section of a 14” pipeline. The purpose of the study, which is based on Structural Reliability Analysis (SRA), was to compare the level of integrity that could be inferred from the use of Direct Assessment (DA) techniques with the level that could be inferred from ILI results. Based on a preliminary assessment of available data, the study identified both external and internal corrosion as potential threats to integrity. SRA was used in conjunction with ‘Bayesian Updating’ to determine the probability of pipe failure due to external corrosion, taking account of results from above-ground measurements and a number of bell-hole excavations. The above-ground survey techniques utilized included Close Interval Survey (CIS) and Direct Current Voltage Gradient (DCVG). A similar approach was adopted to address the threat due to internal corrosion, but hydraulic modelling was substituted for the above-ground measurements. A third study based on SRA was used to determine the combined probability of failure due to both internal and external corrosion taking account of ILI results. The outcome of the analyses demonstrated that the level of integrity that could be inferred from the use of Crosstex’ DA methodology was similar to that which could be inferred from the use of ILI. The results were presented to the TRRC for review and approval. This paper gives a detailed description of the SRA based methodology that was employed by Crosstex and presents the results that clearly demonstrate the comparability of ILI and DA for the purpose of integrity management.

Pipeline Failure Investigations: Analytical Techniques and Case Studies

1996 ◽  
Author(s):  
Brian R. Wilson
Keyword(s):  
Case Studies ◽  
Large Diameter ◽  
Analytical Techniques ◽  
Pipe Failure ◽  
Line Pipe ◽  
Failure Investigation ◽  
Transmission Pipeline ◽  
Cause Of Failure ◽  
Pipeline Failure ◽  
External Corrosion

There are a number of analytical techniques which can be employed during the course of a pipeline failure investigation to assist in the collection of all the pertinent information essential to determining the cause of failure. The key is to select the appropriate analytical techniques at the beginning of the investigation and involve experienced and qualified people in every facet of the examination and testing process. Case studies described in this paper involve stress corrosion cracking, external corrosion on a gas transmission pipeline, cracking of fibreglass line pipe, failure of a new mechanical interference fit pipeline joint and mill defects in a large diameter submerged arc weld seam.

Pipeline Corrosion Integrity Management by Direct Assessment

2015 ◽  
Author(s):  
Shailesh Javia
Keyword(s):  
Integrated Approach ◽  
Assessment Process ◽  
Regulatory Requirements ◽  
Integrity Assessment ◽  
Advantages And Disadvantages ◽  
Direct Assessment ◽  
Pipeline Segment ◽  
Integrity Management ◽  
Post Assessment ◽  
Pipeline Corrosion

Integrity management of pipelines is a systematic, comprehensive and integrated approach to proactively counter the threats to pipeline integrity. Pressure testing, in-line inspection and direct assessment methods are used to verify the integrity of a buried pipeline. The Paper Discuses Direct Assessment Methodologies for Hydrocarbon Non Piggable Pipelines. Advantages and Disadvantages of Direct Assessment methodology and DA Protocols. The DA process accomplishes this by utilizing and integrating condition monitoring, effective mitigation, meticulous documentation and timely structured reporting processes. DA is a structured, iterative integrity assessment process through which an operator may be able to assess and evaluate the integrity of a pipeline segment. TIME DEPENDENT THREATS INEVITABLY LED TO NUMEROUS FAILURES WITH A COMMON DEFINING MECHANISM OR SOURCE – CORROSION. This Paper will focus on internal, external and stress corrosion cracking direct assessment along with pre and post assessment, quality assurance, data analysis and integration, and remediation and mitigation activities. This paper will discuss some of the regulatory requirements for Pipeline Integrity Management System.

Pressure Cycling Monitoring Helps Ensure the Integrity of Energy Pipelines

2010 ◽  
Author(s):  
Peter Song ◽  
Doug Lawrence ◽  
Sean Keane ◽  
Scott Ironside ◽  
Aaron Sutton
Keyword(s):  
Fatigue Life ◽  
Pipeline System ◽  
Outer Diameter ◽  
Operating Pressure ◽  
Potential Growth ◽  
Integrity Assessment ◽  
Pressure Cycling ◽  
Pressure Cycle ◽  
Primary Focus ◽  
Pump Stations

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.

Evaluation of New In-Ditch Methods for Measurement and Assessment of External Corrosion

2014 ◽  
Author(s):  
Pablo Cazenave ◽  
Katina Tiñacos ◽  
Ming Gao ◽  
Richard Kania ◽  
Rick Wang
Keyword(s):  
New Technologies ◽  
3D Scanning ◽  
Primary Objective ◽  
Scanning System ◽  
Calculation Methods ◽  
Integrity Assessment ◽  
External Corrosion ◽  
Non Destructive ◽  
Scanning Systems ◽  
Inspection Performance

New technologies for in-ditch non-destructive evaluation were lately developed and are becoming of mainstream use in the evaluation of external corrosion features for both In-Line-Inspection performance evaluation and pipeline integrity assessment. However, doubt was cast about the reliability and repeatability of these new technologies (hardware and processing software) when compared with those used in the traditional external-corrosion in-ditch measurement and the reliability of the pipeline integrity assessment calculations (PBurst) embedded in their software when compared with industry-wide accepted calculation methods. Therefore, the primary objective of this study is to evaluate the variation and repeatability of the measurements produced by these new technologies in corrosion feature profiling and associated PBurst calculations. Two new 3D scanning systems were used for the evaluation of two pipe samples removed from service which contain complex external corrosion features in laboratory. The reliability of the 3D scanning system in measuring corrosion profiles was evaluated against traditional profile gage data. In addition, the associated burst pressures reported by the systems were compared with results obtained using industry-widely used calculation methods. Also, consistencies, errors and gaps in results were identified. In this paper, the approach used for this study is described first, the evaluation results are then presented and finally the findings and their implications are discussed.

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