Pragmatic Effects of Flow on Corrosion Prediction

Pragmatic Effects of Flow on Corrosion Prediction    

Recent design studies  regarding deep Gulf of Mexico (GOM ) subsea flowlines have revealed many challenges, the most onerous  being  that once designed, installed and placed in operation, pipeline in-situ monitoring and integrity management are proving very difficult and expensive.  The methods  to do the work exist but the logistics and practices often present formidable questions,  significant testing, and  difficult justification. Such experiences  have emphasised the need to identify,  understand, develop, and corroborate critical relationships between corrosion mechanisms, and flow regimes, and tailor the predictions accordingly.  In practice this  often  reduces to a consensus based acceptability and pragmatic interpretation of the effects of flow on general and localized corrosion. Most importantly the identification of  positions, or sites, within the  pipeline internal surface where maximum corrosion stimulus may be expected to occur, thereby allowing better understanding, mitigation, monitoring, and  therefore more meaningful control over the full life cycle.   Needless to say once corrosion problems arise under deep water pipeline applications, modifications or resolutions are extremely challenging and possibly cost prohibitive. This driver has  however accelerated growth in the subject matter, largely by enforcing a better determination of corrosion  through propensity and risk assessments at the detail design stage of  pipeline projects.  Case histories  are discussed to illustrate the methodology, and potential commercial advantages.