Software Model System Quantifies Corrosion In Dry Gas Pipelines

Current internal corrosion direct assessment (ICDA) methods for dry natural gas pipelines do not assess the extent of corrosion damage due to availability of water in the presence of CO2, H2S etc. That is because the assessment is a complex task beyond the scope of most present-day ICDA models. A new system aims to fill that need.

The PredictPipe™ software system is capable of performing the necessary flow modeling to identify the critical water accumulation zones in a pipeline, quantify water hold up and assess the effect of various process parameters on the potential for corrosion damage. (Author’s note: PredictPipe™ is a trademark of Honeywell International, Inc.) This software provides the necessary tools to perform ICDA, minimize cost of operating pipeline inspection programs, and develop safe pipeline operating procedures in a pro-active manner.

This software provides the functionalities of an advanced flow model and also the capabilities of a comprehensive corrosion prediction tool. It identifies water accumulation zones based on critical angle computation, calculates water holdup and accounts for water phase behavior, determines the wall shear stress and predicts potential worst-case corrosion rates for susceptible pipeline segments.

Program Interface And Functionality

The various aspects of the program, highlighting its ease of use in facilitating the application of ICDA methodology and providing pipeline operators with a broad view of the health of the pipeline, are presented in this section.

The software system provides comprehensive functionality to assist in performing effective ICDA and protect against costly pipeline failures. It is an easy-to-use graphical tool that integrates the effects of a complex set of environmental parameters based on extensive literature, data, lab testing and field experience to map potential corrosion hot spots and provide a birds eye view of the health of a pipeline system.

The program interface is shown in Figure 1. While this program uses a complex computational model for determining the corrosion rate, the ease-of-use in applying the system to obtain meaningful answers is evident. The first step in generating a consultation is to specify the production data, which is done by clicking on the production data button on the main screen. The production data in terms of gas production, total water content (higher numbers are used to simulate a water carry over), H2S mol% and CO2 mol%.

Figure 1: Program Startup Screen.

The next step is to provide ionic data for water that is carried over. This helps in computing the ionic strength and also encompasses effects of bicarbonates on pH and chlorides etc. on corrosion rates.