Impact of Moisture and Remaining Life Estimation

2017 ◽  
pp. 329-360
2016 ◽  
Vol 126 ◽  
pp. 129-137 ◽  
Author(s):  
Igor A. Chaves ◽  
Robert E. Melchers ◽  
Lizhengli Peng ◽  
Mark G. Stewart

Author(s):  
K. Nihei ◽  
O. Muragishi ◽  
T. Kobayashi ◽  
K. Ohgaki ◽  
A. Umeda

1999 ◽  
Vol 6 (4) ◽  
pp. 233-243 ◽  
Author(s):  
N.K Mukhopadhyay ◽  
S.Ghosh Chowdhury ◽  
R.K Sinha ◽  
D.K Bhattacharya ◽  
S Chaudhuri

Author(s):  
Parththeeban Murugathasan ◽  
Ashutosh Sutra Dhar ◽  
Suborno Debnath ◽  
Abu Muntakim ◽  
Kshama Roy

Abstract The current finite element (FE) assessment methods of dented pipes are based on specific dent profiles, which are generally created based on the shape of indenters. However, the actual dent profile in real case scenarios is mostly irregular in shape, depending on the cause of damage. In this paper, FE analyses of dented pipes using inline inspection (ILI) data are presented. Based on the ILI data, the dent profile is generated by applying the nodal displacements to all the pipe nodes. The validation of this nodal displacement approach is discussed in this paper. Besides, a parametric study is carried out to study the behavior of dent for different dent depth, pipe geometry, and pipe grades. The significance of residual stresses generated during the dent formation on the behavior of dented pipe during the service life is also discussed. Finally, the remaining life estimation of dented pipes according to the API 579-1 is presented using FE analysis results.


Author(s):  
Pathmanathan Rajeev ◽  
Monzur Imteaz ◽  
Emad Gad

Over the last few years, several failures in transmission and distribution water/gas pipelines have been reported around the world. The failure of buried pipeline is controlled by several factors, such as pipe material, soil corrosion, internal and external loading, etc. Among these, soil corrosion makes a significant contribution towards failure mode and mechanisms in buried pipes, yet few studies have been done. Although a number of corrosion models have been developed over the years, the applicability of the model predominantly depends on the type of soil and its moisture change over time at the pipe depth. By incorporating a corrosion model, the remaining life of the pipe can be estimated on the basis of applied traffic and pressure loads, which determine the stresses in the pipe segment. Depending on the model, the estimation can show significant variability, and consequently affect the pipe renewal and rehabilitation plans that ultimately have economic impacts. Therefore, it is important for the pipeline asset owners to understand the effect of corrosion models in the remaining life calculation. This paper reviews briefly the available corrosion models and the sensitivity of each parameter in pipe corrosion pit properties and in the remaining life estimation. Finally, a comparison among the corrosion models on the basis of the remaining life estimation is provided to improve the renewal plan.


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