Stochastic modelling of perfect inspection and repair actions for leak–failure prone internal corroded pipelines

Abstract

To enhance the performance of any facility, reduce cost and failure probability involves proper inspection and repair decisions. To be able to establish the cost of repair and inspection of corroded pipelines at different stages of the corrosion defect depths growth, Markov modelling technique was adopted. This model formulated an inspection and repair technique, which has the potentials of aiding policy makers in maintenance management of internally corroded pipelines. The transition states were determined using the Remaining Useful Life (RUL) of the pipelines whilst Weibull distribution was used for calculating the corrosion wastage rates at the lifecycle transition phases. Monte Carlo simulation and degradation models were applied for determining future corrosion defect depth growth, in a bid to establish periodic inspection and repair procedures and their costs. Data from an onshore pipeline inspected with Magnetic Flux Leakage (MFL) in-line-inspection (ILI) technique was used to test the validity of the model. The results obtained indicates that the model has practical applications for inspection and repairs of aged-internally corroded pipelines.

Industry practices on the rework of defective products: survey results

“…The rework time or replacement also influences other costs and deadlines that may cause customers loss, dissatisfaction or other contractual penalties. Rework may require other methods, resources or materials beyond those already used in production, which also demands extra costs (Arabian et al , 2013; Lim et al , 2015; Malik et al , 2016; Ossai et al , 2016; Sailaja et al , 2015).…”

“…A simplistic analysis of rework is to compare the value of the discarded product (aggregated costs) with the rework cost. Products in the final stages of manufacturing tend to be reworked and products in early stages tend to be discarded (Chopra and Garg, 2011, 2012; Malik et al , 2016; Ossai et al , 2016; Sailaja et al , 2015; Schiffauerova and Thomson, 2006).…”

“…In companies, quality improvement efforts focus on failures, as they present the highest initial potential of reducing quality costs. In the long term, other cost reduction measures should be taken, evaluating direct and indirect costs without added value as operational waste (Arabian et al , 2013; Fons, 2012; Jaju et al , 2009; Malik et al , 2016; Ossai et al , 2016; Sailaja et al , 2015; Schiffauerova and Thomson, 2006).…”

Modeling of pipeline corrosion degradation mechanism with a Lévy Process based on ILI (In-Line) inspections

“…The jumps are non-negative and happen infinitely often in any finite time interval, properties that makes these processes suitable to model progressive degradation. In fact in most cases, corrosion defects can be modeled rather accurately using a gamma distribution [5,17,20,34,35]. In what follows, the basic properties of these processes are briefly described below.…”

“…This analysis is commonly preferred from other acceptable methods reported in the Code of Federal Regulation for Liquids and Gases (CFR 192 and 195) to assess the mechanical integrity of pipelines [14]. The results of an ILI inspection are central to define a maintenance policy based on the pipeline condition [7,[15][16][17]. Overall, these policies seek to minimize the total expected life-cycle costs (i.e., construction, inspections, failures, and repairs) based on continuous degradation models.…”