Break Reduction/Life Extension Program for Cast and Ductile Iron Water Mains

2003 ◽  
Author(s):  
George A. Gehring, Jr. ◽  
Dale Lindemuth ◽  
Walter T. Young
Keyword(s):  
Ductile Iron ◽  
Life Extension ◽  
Water Mains ◽  
Extension Program

Statistical approach for describing failures and lifetimes of water mains

1998 ◽  
Vol 38 (6) ◽  
pp. 209-217 ◽  
Author(s):  
Jianhua Lei ◽  
Sveinung Sægrov
Keyword(s):  
Data Base ◽  
Ductile Iron ◽  
Counting Process ◽  
Statistical Approach ◽  
Process Models ◽  
Average Lifetime ◽  
Maintenance Practice ◽  
Water Mains ◽  
Near Future

This paper demonstrates the statistical approach for describing failures and lifetimes of water mains. The statistical approach is based on pipe inventory data and the maintenance data registered in the data base. The approach consists of data pre-processing and statistical analysis. Two classes of statistical models are applied, namely counting process models and lifetime models. With lifetime models, one can estimate the probability which a pipe will fail within a time horizon. With counting process models one can see the deteriorating (or improving) trend in time of a group of “identical” pipes and their rates of occurrence of failure (ROCOF). The case study with the data base from Trondheim municipality (Norway) demonstrates the applicability of the statistical approach and leads to the following results: 1). In the past 20 years, Trondheim municipality has experienced approximately 250 to 300 failures per year. However, the number of failures per year will significantly increase in the near future unless better maintenance practice is implemented now. 2). Unprotected ductile iron pipes have a higher probability of failures than other materials. The average lifetime of unprotected ductile iron pipes is approximately 30 to 40 years shorter than the lifetime of a cast iron pipe. 3). Pipes installed 1963 and 1975 are most likely to fail in the future; 4) The age of a pipe does not play a significant role for the remaining lifetime of the pipe; 5). After 2 to 3 failures, a pipe enters a fast-failure stage (i.e., frequent multiple between failures).

Initial Implementation of IHI Zone Logic Technology at Philadelphia Naval Shipyard

1989 ◽  
Vol 5 (02) ◽  
pp. 79-89
Author(s):  
Koichi Baba ◽  
Takao Wada ◽  
Soichi Kondo ◽  
M. S. O'Hare ◽  
James C. Schaff
Keyword(s):  
Service Life ◽  
Life Extension ◽  
Initial Application ◽  
Initial Implementation ◽  
Late Fall ◽  
The Future ◽  
Service Life Extension ◽  
Extension Program ◽  
Technical Services

Philadelphia Naval Shipyard's application of zone logic to ship overhaul is neither small nor isolated. PNSY started its implementation of zone logic in the late fall of 1986, targeting the Service Life Extension Program (SLEP) for USS Kitty Hawk (CV-63) as the initial application. The technical services of Ishikawajima-Harima Heavy Industries Co., Ltd. (IHI), Japan were contracted to assist in this transition. This implementation on the Kitty Hawk is not a trial effort but involves about one third of the production man-days and covers over one half of the compartments on the ship. The actual SLEP production work on Kitty Hawk began in January 1988. Even though it is early in the three-year SLEP, zone logic already is proving its worth. This paper explains the zone logic methods and methodology applied at PNSY on Kitty Hawk. It also discusses the future of zone logic at PNSY and its continued application.

scholarly journals Pipe–soil interaction analysis of jointed water mains

1996 ◽  
Vol 33 (3) ◽  
pp. 393-404 ◽  
Author(s):  
B Rajani ◽  
C Zhan ◽  
S Kuraoka
Keyword(s):  
Ductile Iron ◽  
Interaction Analysis ◽  
Water Pressure ◽  
Urban Infrastructure ◽  
Developed Countries ◽  
Temperature Influence ◽  
Average Life ◽  
Winkler Model ◽  
Water Mains ◽  
Water Main

Water mains are important lifelines of modern urban infrastructure. However, in most developed countries, the average life of these cast or ductile iron pipes approaches 50–75 years. In recent years, the disruption of water sevices as a consequence of water main breaks is on the rise in most Cadadian cities. This paper describes the developement of a simplified Winkler model to stimulate the responses of a jointed water main subjected to differential temperature change and water pressure. The simplified Winkler model accounts for axial and radial restraints offered by the surronding soil. In spite of its simplicity, the Winkler model is able to predict the overall response of strains and stresses, which confirms satisfactorily some of heuristic and documented observations on water main breaks. Key words: water main breaks, pipe–soil interaction, temperature influence, Winkler model.

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