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.

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.

External Corrosion and Internal Corrosion Direct Assessment Validation Project

2004 ◽  
Author(s):  
Carl A. Mikkola ◽  
Christina L. Case ◽  
Kevin C. Garrity
Keyword(s):  
Natural Gas ◽  
Final Report ◽  
Internal Corrosion ◽  
Assessment Development ◽  
Direct Assessment ◽  
Natural Gas Pipeline ◽  
Assessment Validation ◽  
External Corrosion ◽  
Development And Validation ◽  
To Receive

In January, 2003, Enbridge Midcoast Energy, L.P., a subsidiary of Enbridge Energy Partners, L.P., implemented a comprehensive direct assessment development and validation project for its Natural Gas Business segment; a project intended to demonstrate the validity of External Corrosion and Internal Corrosion Direct Assessment (ECDA and ICDA). The work began in January 2003 and was concluded in June 2003. The primary goal of the project was to demonstrate that External Corrosion Direct Assessment and Internal Corrosion Direct Assessment as performed in compliance with the NACE and INGAA methodologies could be used to effectively verify and manage the integrity of non-piggable and non-interruptible natural gas pipeline segments. The programs were validated by in-line inspection (ILI) using high-resolution magnetic flux leakage tools and field verification digs. The objective of the project was to receive approval from the Texas Railroad Commission to use direct assessment (“DA”), where demonstrated to be appropriate, for integrity verification and management of pipeline systems that are not verifiable through other approved means. The Enbridge DA Validation Project was successfully completed and is considered to be one of the leading DA validation projects undertaken to date in the U.S. A total of 12,000 manhours and over $1MM was expended in performing the pre-assessment to identify a candidate pipeline, develop detailed procedures for DA execution and implementation, perform indirect surveys, modify pipe and complete cleaning pig runs, gauge pig runs, dummy pig runs, intelligent pig runs, perform detailed direct examinations and perform detailed analysis of the results including the preparation of the final report. This paper is intended to describe the steps that Enbridge took in validating DA.

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.

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.

Using Ultrasound to Gauge Pipeline Internal Corrosion With Coating for ICDA

2006 ◽  
Author(s):  
Qingshan Feng ◽  
Zupei Yang
Keyword(s):  
Test Time ◽  
Thickness Gauge ◽  
Internal Corrosion ◽  
Direct Assessment ◽  
Metal Thickness ◽  
Integrity Management ◽  
External Corrosion ◽  
Key Steps ◽  
Thickness Measurements ◽  
Non Destructive

Internal corrosion direct assessment (ICDA) for pipeline enhances the abilities to assess internal corrosion in pipeline and is based on the principle that corrosion is most likely where water first accumulates. ICDA employs the same four-step process as all other direct assessment methods. The important step is direct examinations: the pipeline is excavated and examined at locations prioritized to have the highest likelihood of corrosion. A variety of inservice non-destructive examination processes are available to pipeline operators to inspect for internal corrosion. Manual assessment of internal corrosion is considered more challenging than normal external corrosion assessments since the corrosion feature is not visible and must be interpreted by the ultrasonic response, but in the past ultrasonic test need always remove the coating and then measure on the surface of bare pipe, which brings the measurement point of the pipe body more risk because of weaker quality of patch coating. Recently, advances in the design of ultrasonic corrosion thickness gauges utilizing dual element transducers have made it possible to take accurate metal thickness measurements while coatings need not to be removed. This feature is often referred to as echo-to-echo thickness measurements. Using the ultrasound thickness gauge to measure pipeline internal corrosion while external coatings need not to be removed can keep the integrity of coating, make pipeline operating and monitoring more economical and improve inspection activities to estimate corrosion in pipelines for ICDA. Gauge equipment requirement, Measurement procedures and Accuracy were validated in laboratory. How to arrange the gauge locations, interval test time and data treatment and analysis also are the key steps of ICDA for integrity management.

Self Directed Integrity Assessment of Non-Piggable Pipelines

2015 ◽  
Author(s):  
Ashish Khera ◽  
Rajesh Uprety ◽  
Bidyut B. Baniah
Keyword(s):  
Oil And Gas ◽  
Oil And Gas Industry ◽  
Management Plan ◽  
Gas Industry ◽  
Internal Corrosion ◽  
Integrity Assessment ◽  
Regulatory Standards ◽  
The Us ◽  
Integrity Management ◽  
External Corrosion

The responsibility for managing an asset safely, efficiently and to optimize productivity lies solely with the pipeline operators. To achieve these objectives, operators are implementing comprehensive pipeline integrity management programs. These programs may be driven by a country’s pipeline regulator or in many cases may be “self-directed” by the pipeline operator especially in countries where pipeline regulators do not exist. A critical aspect of an operator’s Integrity Management Plan (IMP) is to evaluate the history, limitations and the key threats for each pipeline and accordingly select the most appropriate integrity tool. The guidelines for assessing piggable lines has been well documented but until recently there was not much awareness for assessment of non-piggable pipelines. A lot of these non-piggable pipelines transverse through high consequence areas and usually minimal historic records are available for these lines. To add to the risk factor, usually these lines also lack any baseline assessment. The US regulators, that is Office of Pipeline Safety had recognized the need for establishment of codes and standards for integrity assessment of all pipelines more than a decade ago. This led to comprehensive mandatory rules, standards and codes for the US pipeline operators to follow regardless of the line being piggable or non-piggable. In India the story has been a bit different. In the past few years, our governing body for development of self-regulatory standards for the Indian oil and gas industry that is Oil Industry Safety Directorate (OISD) recognized a need for development of a standard specifically for integrity assessment of non-piggable pipelines. The standard was formalized and accepted by the Indian Ministry of Petroleum in September 2013 as OISD 233. OISD 233 standard is based on assessing the time dependent threats of External Corrosion (EC) and Internal Corrosion (IC) through applying the non-intrusive techniques of “Direct Assessment”. The four-step, iterative DA (ECDA, ICDA and SCCDA) 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 paper presents the case study where the Indian pipeline operators took a self-initiative and implemented DA programs for prioritizing the integrity assessment of their most critical non-piggable pipelines even before the OISD 233 standard was established. The paper also looks into the relevance of the standard to the events and other case studies following the release of OISD 233.

Predicting Corrosion Rates for Onshore Oil and Gas Pipelines

2006 ◽  
Author(s):  
J. M. Race ◽  
S. J. Dawson ◽  
L. Stanley ◽  
S. Kariyawasam
Keyword(s):  
Corrosion Rate ◽  
Growth Rates ◽  
Oil And Gas ◽  
Cost Effective ◽  
Management Plan ◽  
Assessment Method ◽  
Internal Corrosion ◽  
Corrosion Rates ◽  
External Corrosion ◽  
Comparison Of The Results

One of the requirements of a comprehensive pipeline Integrity Management Plan (IMP) is the establishment of safe and cost effective re-assessment intervals for the chosen assessment method, either Direct Assessment (DA), In-Line Inspection (ILI) or hydrotesting. For pipelines where the major threat is external or internal corrosion, the determination of an appropriate re-inspection interval requires the estimation of realistic corrosion growth rates. The Office of Pipeline Safety (OPS 2005) estimate that the ability to accurately estimate corrosion rates may save pipeline companies more than $100M/year through reduced maintenance and accident avoidance costs. Unlike internal corrosion, which occurs in a closed system, the rate of the external corrosion reaction is influenced by a number of factors including the water content of the soil, the soluble salts present, the pH of the corrosion environment and the degree of oxygenation. Therefore the prediction of external rates is complex and there is currently no method for estimating corrosion rates using either empirical or mechanistic equations. This paper describes a scoring model that has been developed to estimate external corrosion growth rates for pipelines where rates cannot be estimated using more conventional methods i.e., from repeat in-line inspection data. The model considers the effect of the different variables that contribute to external corrosion and ranks them according to their effect on corrosion growth rate to produce a corrosion rate score. The resulting score is then linked to a corrosion rate database to obtain an estimated corrosion rate. The methodology has been validated by linking the calculated corrosion rate scores to known corrosion rate distributions that have been measured by comparison of the results from multiple in-line inspection runs. The paper goes on to illustrate how the estimated corrosion rates can be used for the establishment of reassessment intervals for DA, ILI and hydrotesting, comparing the benefits of this approach with current industry recommended practice and guidance.

Pipeline Failures Resulting From Interacting Integrity Threats

2016 ◽  
Author(s):  
Gregory T. Quickel ◽  
John A. Beavers
Keyword(s):  
Natural Gas ◽  
Hydrogen Embrittlement ◽  
Stress Corrosion ◽  
Corrosion Fatigue ◽  
Stress Corrosion Cracking ◽  
Corrosion Cracking ◽  
Time Dependent ◽  
Internal Corrosion ◽  
Pipeline Failures ◽  
Fatigue Corrosion

All pipelines contain manufacturing and construction anomalies that typically are stable with time and are not generally considered to be integrity threats. These include laminations, seam weld anomalies, girth weld anomalies, and shallow dents. There also are time-dependent integrity threats to buried natural gas and petroleum pipelines. These include external and internal corrosion, fatigue, corrosion fatigue, stress corrosion cracking (SCC), and hydrogen embrittlement. Unexpected failures can occur when the time dependent integrity threats are coupled with these stable anomalies. This paper describes several of these interactions.

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.

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.

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