Details:

Creators:
Farrag, Khalid
Corporate Creators:
Gas Technology Institute
Corporate Contributors:
United States. Pipeline and Hazardous Materials Safety Administration
Subject/TRT Terms:
[+]
Corrosion Corrosion Resistance Databases Field Tests Maintenance And Preservation Pipelines Pipeline Safety Reseach Hub Validation
Publication/ Report Number:
DOT Project No. 256 ; GTI Project Number: 20753
DOT Project No. 256 ; GTI Project Number: 20753 Less -
Resource Type:
Tech Report
Geographical Coverage:
United States
TRIS Online Accession Number:
01494434
Edition:
Final Report
Corporate Publisher:
Gas Technology Institute
Abstract:
The research project evaluated the use of the Linear Polarization Resistance (LPR) and the Electric Resistance (ER) technologies in estimating the external corrosion growth rates of buried steel pipelines. This was achieved by performing laboratory and field tests to evaluate the technologies and correlating the results with other methods such as measurements of weight‐ loss of buried coupons. The LPR method provides instantaneous estimates of corrosion potential. The results may be used to identify corrosion upsets due to the changes of soil conditions and, consequently, help initiating remedial action. However, the laboratory and field measurements of corrosion rates using the LPR device showed uncertainty about their validity in partially and totally dry soils, which makes it difficult to obtain a reliable estimate of the general corrosion rate. Additionally, the average long‐term measurements of the LPR in the field did not correlate with the general corrosion rates from weight‐loss measurements of buried coupons. The electrical resistance (ER) method measures the metal loss of an alloy having a composition similar to the pipe material and the device is suited to estimate corrosion rates of unprotected pipes in environments having either poor or non‐continuous electrolytes such as soil. Field measurements of corrosion rates were performed using the ER probes in eleven sites at four natural gas distribution companies. Additionally, five test sections were constructed at the GTI testing facility to evaluate the soil types which are not represented in the utility sites. The results of the measurements showed that the ER device provides consistent long‐term measurements of corrosion rate. Field applications of the ER method demonstrated that the technology is an efficient one to obtain the long‐term corrosion growth rate of the pipe without the need for field excavation. Field monitoring of the ER devices continues at the utility sites to enhance the estimation of the corrosion rates of the pipeline sections at the monitored locations. External pipe corrosion is affected by a significant number of soils and environmental parameters including soil resistivity, water content, pH, soluble salts, and oxygen concentration, which makes it difficult to determine an accurate estimate of corrosion rates. The report presents the effects of these parameters on the corrosion growth rates from the established relationships in the literature. A procedure for estimating the corrosion rate based on soil properties was developed to improve the determination of the reassessment intervals of pipelines subjected to the integrity management requirements. The procedure builds on correlations with soil properties from the field measurements, historical data, and an earlier field study by the National Institute of Standards and Technology (NIST). The procedure was incorporated in a web‐based computer program to identify the soils with high corrosion potential and to provide a simplified approach for the estimation of corrosion growth rate from the measured soil parameters.
Format:
PDF
Funding:
DTPH56-08-T-000022
Collection(s):
US Transportation Collection PHMSA Collection
Main Document Checksum:
[+]
urn:sha256:e727d12f50ff4ca6f9a92302e4e768c37a96ca9211faaadda5435e335676ae4b
Download URL:
https://rosap.ntl.bts.gov/view/dot/34648/dot_34648_DS1.pdf
File Type:

Supporting Files

• No Additional Files

More +