Internal Corrosion Direct Assessment for Pipelines Carrying Wet Gas - Methodology

2004 ◽  
Author(s):  
Oliver Moghissi ◽  
Deanna Burwell ◽  
Rick Eckert ◽  
Jose Vera ◽  
Narasi Sridhar ◽  
...  
Keyword(s):  
Corrosion Rate ◽  
Flow Regimes ◽  
Distribution Model ◽  
Liquid Volume ◽  
Internal Corrosion ◽  
Integrity Verification ◽  
Direct Assessment ◽  
Wet Gas ◽  
Pipeline Segment ◽  
Flow Effects

An Internal Corrosion Direct Assessment methodology is proposed for wet gas pipelines (WG-ICDA). Wet gas systems (i.e., those normally containing liquids) include storage and gathering systems with large gas-to-liquid volume ratios. Wet gas systems are not well represented by ICDA for normally dry gas, and existing corrosion models applied to wet gas systems are not sufficiently targeted at integrity verification. The essential focus of WG-ICDA compared to other internal corrosion models is the discrimination of conditions along the length of a pipeline so that possible local integrity threats with respect to internal corrosion are identified and mitigated. The basis of WG-ICDA is to prioritize locations along a pipeline segment by factors of traditional corrosion rate, flow effects, and other influencing factors. Corrosion rate depends on gas quality, liquid chemistry, pressure, and temperature. The corrosion rate can be normalized because WG-ICDA as integrity verification only concerns itself with corrosion distribution (i.e., the location along a pipeline segment where corrosion is more severe than other locations). Flow effects include possible flow regimes and the presence of water from condensation (at locations of heat loss). Expected possible flow regimes are stratified, slugging, and annular. The final term captures other factors influencing corrosion rate distribution. These factors include corrosion inhibition (batch and continuous, solubility and dispersibility in hydrocarbon and aqueous phases), biocide treatments, hydrocarbon condensates (including emulsion characteristics), maintenance pigging, bacteria, solids/scale, and other products. WG-ICDA follows the same four-step process as all other Direct Assessment (DA) methods: 1) Pre-Assessment: Data is collected, a feasibility analysis is performed, and the pipeline segment is divided into regions. 2) Indirect Inspections: Measurements are taken or calculations are performed to prioritize locations along a particular pipeline segment for susceptibility to corrosion. For WG-ICDA, the factors contributing to the distribution of corrosion will be included and an initial assumption about corrosion distribution will be made. WG-ICDA is sufficiently flexible to allow the use of existing wet gas models within the framework of the overall process. 3) Direct (or Detailed) Examinations: The pipe is excavated and examined at locations prioritized to have the highest likelihood of corrosion. The examination must have sufficient detail to determine the existence, extent, and severity of corrosion. Examination of the internal surface of a pipe can involve non-destructive examination methods sufficient to identify and characterize internal defects. 4) Post-Assessment: Analysis of the indirect and direct examination data is performed to determine overall pipeline integrity, prioritize repairs, and set the interval for the next assessment. If the results of excavations do not match the original assumption, the corrosion distribution model will be updated to guide the next excavations (i.e., the operator returns to step 2).

scholarly journals A Numerical Corrosion Rate Prediction Method for Direct Assessment of Wet Gas Gathering Pipelines Internal Corrosion

Energies ◽  
2012 ◽  
Vol 5 (10) ◽  
pp. 3892-3907 ◽  
Author(s):  
Kexi Liao ◽  
Quanke Yao ◽  
Xia Wu ◽  
Wenlong Jia
Keyword(s):  
Corrosion Rate ◽  
Prediction Method ◽  
Internal Corrosion ◽  
Direct Assessment ◽  
Rate Prediction ◽  
Wet Gas

Water treatment to reduce internal corrosion in the drinking water distribution system in Oslo

2001 ◽  
Vol 1 (3) ◽  
pp. 91-96 ◽  
Author(s):  
L.J. Hem ◽  
E.A. Vik ◽  
A. Bjørnson-Langen
Keyword(s):  
Water Treatment ◽  
Corrosion Rate ◽  
Distribution System ◽  
Water Distribution ◽  
Treatment Plant ◽  
Water Treatment Plant ◽  
Corrosion Monitoring ◽  
Copper Corrosion ◽  
Iron Corrosion ◽  
Internal Corrosion

In 1995 the new Skullerud water treatment plant was put into operation. The new water treatment includes colour removal and corrosion control with an increase of pH, alkalinity and calcium concentration in addition to the old treatment, which included straining and chlorination only. Comparative measurements of internal corrosion were conducted before and after the installation of the new treatment plant. The effect of the new water treatment on the internal corrosion was approximately a 20% reduction in iron corrosion and a 70% reduction in copper corrosion. The heavy metals content in standing water was reduced by approximately 90%. A separate internal corrosion monitoring programme was conducted, studying the effects of other water qualities on the internal corrosion rate. Corrosion coupons were exposed to the different water qualities for nine months. The results showed that the best protection of iron was achieved with water supersaturated with calcium carbonate. Neither a high content of free carbon dioxide or the use of the corrosion inhibitor sodium silicate significantly reduced the iron corrosion rate compared to the present treated water quality. The copper corrosion rate was mainly related to the pH in the water.

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.

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.

Validating ILI Accuracy Using API 1163

2014 ◽  
Author(s):  
Lucinda Smart ◽  
Harvey Haines
Keyword(s):  
Burst Pressure ◽  
Metal Loss ◽  
Internal Corrosion ◽  
Know How ◽  
Pressure Calculation ◽  
Loss Data ◽  
Pipeline Segment ◽  
External Corrosion ◽  
Corrosion Pits

It is important to validate the accuracy of in-line inspection (ILI) tools to know how many excavations are needed to maintain the integrity of a pipeline segment. Performing sufficient excavations is important to ensure there are no defects left in the pipeline that have even a remote chance of failure. In some cases additional excavations may be necessary to ensure safety where in other cases no excavations may be necessary. This paper looks at using spatially recorded metal-loss data collected “in-the-ditch” to measure the accuracy of ILI tool results. Examples of spatial in-ditch data are laser scans for external corrosion and UT scans for internal corrosion. Spatially mapped metal loss, because all of the corrosion area is mapped, has the advantage of allowing more comparisons to be made for a given corrosion area and also allows the interaction among corrosion pits to be studied for examining burst pressure calculation accuracy. From our studies we find the depth error for shallow corrosion 10%–20% wt deep is often not representative of deeper corrosion in the same pipeline and the interaction criteria for ILI tools needs to be larger than the interaction criteria for in-ditch data. Examples are shown with these types of results, and by interpreting the results in conjunction with API 1163, certain ILI runs are shown that require no excavations where others may require additional excavations than suggested by normal +/−10% wt ILI data.

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.

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.

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