Abstract
In the buried natural gas pipelines, many defects may occur by construction faults, corrosion, third-party interference and ground movement. When a segment of a pipeline is found to be defective, one of the repair methods is to remove its contents and cut out the defective segment after shutting down the pipeline. However, the cost is extremely high in terms of venting and disrupting the gas supply. Therefore, most pipeline companies have developed in-service repair methods without removing the line from service. In general, in order to avoid removing the line from service, direct deposition of weld metal, full-encirclement sleeve, patches, stopple fittings, half-sole and branch connections are required. There are three important concerns in the sleeve-repair welding like other methods of in-service repair-welding. The first concern is the possibility of burn-through which is due to the localized heating and loss of meterial strength on the inner surface of pipe during the welding process. The pipe wall may burst under internal pressure if the loss in strength is too great. The second concern is the high cooling rates by the flowing gas which quickly removes heat from the pipe wall, resulting in accelerated cooling of the weld. Such rapid cooling rates
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Citation Formats
Kim, W S, Kim, Y P, and Baek, J H.
A study on the development of repair procedure for gas pipelines.
Korea, Republic of: N. p.,
1999.
Web.
Kim, W S, Kim, Y P, & Baek, J H.
A study on the development of repair procedure for gas pipelines.
Korea, Republic of.
Kim, W S, Kim, Y P, and Baek, J H.
1999.
"A study on the development of repair procedure for gas pipelines."
Korea, Republic of.
@misc{etde_20176786,
title = {A study on the development of repair procedure for gas pipelines}
author = {Kim, W S, Kim, Y P, and Baek, J H}
abstractNote = {In the buried natural gas pipelines, many defects may occur by construction faults, corrosion, third-party interference and ground movement. When a segment of a pipeline is found to be defective, one of the repair methods is to remove its contents and cut out the defective segment after shutting down the pipeline. However, the cost is extremely high in terms of venting and disrupting the gas supply. Therefore, most pipeline companies have developed in-service repair methods without removing the line from service. In general, in order to avoid removing the line from service, direct deposition of weld metal, full-encirclement sleeve, patches, stopple fittings, half-sole and branch connections are required. There are three important concerns in the sleeve-repair welding like other methods of in-service repair-welding. The first concern is the possibility of burn-through which is due to the localized heating and loss of meterial strength on the inner surface of pipe during the welding process. The pipe wall may burst under internal pressure if the loss in strength is too great. The second concern is the high cooling rates by the flowing gas which quickly removes heat from the pipe wall, resulting in accelerated cooling of the weld. Such rapid cooling rates promote the formation of hard heat affected zone microstructure making these welds susceptible to hydrogen cracking. The third concern is for the load carrying ability, such as tensile strength, fracture toughness and fatigue strength. This study was taken to investigate the effect of in-service welding conditions and assess the mechanical properties for the direct deposition welding and sleeve-repair welding of in-service gas pipelines and develope the welding procedure specification for in-service pipeline repair. 81 figs., 40 tabs.}
place = {Korea, Republic of}
year = {1999}
month = {Jun}
}
title = {A study on the development of repair procedure for gas pipelines}
author = {Kim, W S, Kim, Y P, and Baek, J H}
abstractNote = {In the buried natural gas pipelines, many defects may occur by construction faults, corrosion, third-party interference and ground movement. When a segment of a pipeline is found to be defective, one of the repair methods is to remove its contents and cut out the defective segment after shutting down the pipeline. However, the cost is extremely high in terms of venting and disrupting the gas supply. Therefore, most pipeline companies have developed in-service repair methods without removing the line from service. In general, in order to avoid removing the line from service, direct deposition of weld metal, full-encirclement sleeve, patches, stopple fittings, half-sole and branch connections are required. There are three important concerns in the sleeve-repair welding like other methods of in-service repair-welding. The first concern is the possibility of burn-through which is due to the localized heating and loss of meterial strength on the inner surface of pipe during the welding process. The pipe wall may burst under internal pressure if the loss in strength is too great. The second concern is the high cooling rates by the flowing gas which quickly removes heat from the pipe wall, resulting in accelerated cooling of the weld. Such rapid cooling rates promote the formation of hard heat affected zone microstructure making these welds susceptible to hydrogen cracking. The third concern is for the load carrying ability, such as tensile strength, fracture toughness and fatigue strength. This study was taken to investigate the effect of in-service welding conditions and assess the mechanical properties for the direct deposition welding and sleeve-repair welding of in-service gas pipelines and develope the welding procedure specification for in-service pipeline repair. 81 figs., 40 tabs.}
place = {Korea, Republic of}
year = {1999}
month = {Jun}
}