Corrosion monitoring programs

Corrosion is by far the most serious hazard of pipeline incidents. It is imperative that adequate corrosion monitoring programs be provided for all hydrocarbon pipelines. Order crude oil pipelines operating at elevated temperatures appear more susceptible to corrosion failures than other pipelines. 

Essential considerations for launching a corrosion monitoring program... 

Chemical analyses. Different types of chemical analyses can provide valuable information in corrosion monitoring programs. Measurements of pH, conductivity, dissolved oxygen, metallic and other ion concentrations, water alkalinity, concentration of suspended solids, inhibitor concentrations, and scaling indices all fall within this domain. Several of these measurements can be made on-line using appropriate sensors. 

Differential weld corrosion has been found to be particularly problematic in oil and gas flow lines. Even minor differences in composition and microstructure have been found to result in severe preferential galvanic dissolution of pipeline weldments. The selection of welding consumables and welding procedures to minimize this risk is critical. However, even with these precautions, operating conditions can induce severe preferential weld corrosion. On-line corrosion monitoring programs have been conducted in oil and gas pipelines to identify these operating conditions and to optimize the application of corrosion inhibitors to control the problem. 

The best way to combat corrosion is to maintain an effective corrosionmonitoring program to supplement good preventative measures. It is also very important to keep complete records of monitoring programs, control programs and failures that occur. The importance of well-qualified responsible personnel cannot be overemphasized as effective corrosion control depends on their efforts [201,204,205]. 

Review water treatment program history, including corrosion monitoring results using metal coupons or Corrator probes (or similar ones). 

Computers and programs are also important in corrosion monitoring systems, such as an automated constant rate extension system (A Cert) shown schematically in Figure 5.5. This system may be used for conducting corrosion and cracking evaluation tests. The system is capable of initiation and conducting tests as well as data acquisition and analysis. There is very little human intervention and the system is capable of corrosion evaluation in environments which are difficult to simulate. This system is a... 

It is very important to monitor the amount of seale on mbes to measure coking/ fouling/corrosion rates. This can be achieved by a thermoeouple and infrared pyrometer monitoring program. The scales on mbe inerease TWT or skin tempera-mre. 0.01 in. scale on mbe could raise mbe surface temperature by 100 °F. The common way to get rid of scale is to sandblast the scale off the mbes while ceramic coating on tubes is a preventive measure however, the later is expensive. 

Corrosion testing is used to select materials of construction, and to monitor the performance of selected materials of construction in service. Availability of the materials should be considered when developing corrosion test programs. Corrosion acceptance testing is performed to ensure that specific corrosion-resistant alloys are manufactured without impairing their corrosion resistance. 

Corrosion monitoring is an integral part of any water treatment program. It is used to determine treatment effectiveness and to establish the optimum level of chemical treatment that is most cost effective, not necessarily the cheapest per pound. 

Acoustic leak detection methods such as illustrated in Fig. 8.4 may find already broken or damaged pipes [7]. However, corrosion monitoring possibly may identify areas where corrosion activity on pipes is likely while the remote field effect can inspect pipes to find damage before they fail. A complete diagnostic program is likely to use all these inspection methods. 

Foaming of amine solutions and corrosion of amine units are best controlled by a comprehensive amine solution monitoring program. Pauley (1S191) suggests that the following amine solution tests be performed by an outside laboratory ... 

Figure 6.1 Integration of corrosion inspection and monitoring programs for producing management information.

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