Intelligent pigs

Another tool the interstates use to maintain their pipelines is a device known as an intelligent pig. Propelled through the pipeline with the gas stream, these devices, taking thousands of measurements with electronic sensors that can be analyzed later by computers, can inspect pipeline interior walls for corrosion or other defects and remove accumulated debris from a section of pipeline. Pipelines also use state-of-the-art coating and cathodic protection to battle corrosion. 

Inspection pigs (also referred to as in-line inspection pigs, smart pigs, and intelligent pigs ) are used to collect data (including, but not limited to, corrosion) from within the pipe using two methods ... 

Figure 4.39 schematically shows the components of a typical intelligent pig. ... 

Existence of advanced tools that makes it possible to deal satisfactorily with most of the objectives required fi om intelligent pigging operations, at least for metal loss corrosion... 

Intelligent pigs produce inspection data, i.e., facts, whilst monitoring data, prevention procedures, etc. are only trends... 

Costs including (a) unpredictable costs such those of the pipeline preparation (modification of pig traps, replacement or removal of restrictions, cleaning, etc.), and (b) rather predictable costs of the provision of the intelligent pig tool, and the analysis and interpretation of the data... 

FIGURE 4.40 Some of important pros and cons of smart pigs. (Adapted from Roche M. et al., Intelligent pigging policy, Recent experience and needs of a petroleum operator, Paper No. 49, Corrosion 96, NACE,... 

Internal corrosion in a gas pipeline may be detected by sophisticated methods such as intelligent pigging, which travels inside the pipe with the flow of the fluid and measures all information such as thickness loss, pitting, and other types of corrosion. 

Other methods include use of intelligent pigging as well as corrosion prediction models developed by C. De Waard and some other modifications that have been published and commercialized by several other investigators. However, after prediction and/or detection of corrosion incidents inside the pipelines, the most cost-effective method of control is the use of corrosion inhibitors. These are usually amine based and are thus water dispersible. They are usually blended with vapour phase inhibitors and probably some flow enhancers. 

Corrosion Detection Using Intelligent Pigs, Corrosion Information Compilation Series, Pipeline Corrosion, NACE International, Houston, TX, 1999. 

In-line inspection (ILI) tools, also commonly called "smart" or "intelligent pigs," are cylinder-shaped electronic devices used by the pipeline industry to detect loss of metal and in some cases deformations... 

---