ESTIMATE HAZARD RATE MODEL IN PIPELINE OIL USING WEIBULL AND GENERALIZED EXTREME VALUE DISTRIBUTION (GEV)

• Main Author: Widyawan Mahdiyasa, Adilan
• Format: Theses
• Language: Indonesia
• Subjects: Matematika
• Online Access: https://digilib.itb.ac.id/gdl/view/34812
• Institution: Institut Teknologi Bandung

Pipeline is a very important component in the oil and gas industry. Its main function is to deliver oil or gas from one place to another. Pipeline need to be checked or periodic inspection in order to avoid damage that can lead to loss of material or non-material. In general, the pipeline is made of metal, so it is susceptible to get corrosion. Corrosion is the deterioration in metals caused by chemical or electrochemical reaction with its environment. This chemical or electrochemical reaction will produce a new compound which is undesirable. Corrosion can occur when there are three elements, that are anode, cathode, and an electrolyte solution. Anode is location where oxidation reactions occur. At anode metal layer depletion will occur. Cathode is location where reduction reaction occur. Electrolyte solution containing ions, that are free to accept or give electrons. Thus allowing the electrons move from anode to cathode. Pipeline also receives stress from loads that works in pipeline. There are three types of loads received by the pipeline that are sustain loads, thermal loads and occasional loads. Sustain loads is load that happen continuously in the pipeline. Thermal loads is load that arises due to thermal expansion occurs in the pipeline. Occasional loads is load that sometimes appears on the pipeline and it is happen in short time. In general stress on the pipe can be grouped into two, that are normal stress and shear stress. Normal stress is stress that has direction perpendicular to the pipeline. Normal stress divided into three that are longitudinal stress, tangential stress and radial stress. Shear stress is stress that has direction parallel to the pipeline. Shear stress is divided into two stress that are shear stress because forces shear and shear stress because tension moments. Corrosion and stress are two aspect that affect the rate of failure of the pipeline. It is required method that can predict the failure time of the pipeline caused by corrosion accurately. One of them is to use a probabilistic method. Advantages of using probabilistic methods that are give guarantees in the form of probability, represents a real phenomenon, and utilize the data generated by advance measuring tools There are three inspection methods that are used the first is ILI (In Line Inspection), the second is LRUT (Long Range Ultrasonic Testing), and the third is MTM (Magnetic Tomography Method). ILI inspection methods used on pipeline with a diameter more than 16 inches. ILI inspection method provides damage dimension due to corrosion in the form of depth, length, and width of corrosion. MTM inspection methods used on pipeline with a diameter less than 16 inches. The results of the MTM inspection method are data on allowable operating pressure for each location of corroded pipeline. Additionally MTM inspection method also provides design pressure of the pipeline. LRUT inspection method is used to inspect pipeline that can not be inspected by the MTM method and LRUT method. The results of the LRUT inspection method provides dimensional data defects caused by corrosion and scratches. In this thesis, the important aspect to be discussed is estimated hazard rate of pipelines oil using Generalized Extreme Value (GEV) and Weibull distribution. GEV distribution is thick tail distribution and has three parameters shape parameter, scale parameter, and location parameter. So it is expected to model the reliability of the pipeline properly. Weibull distribution is very often used in modeling the reliability object. Weibull distribution is a thick tail distribution with two parameters: the shape parameters and location parameters. The results indicate that the GEV distribution will give a greater failure rate for pipeline.