Corrosion and Proteccion

Cuernavaca, Mexico

Corrosion and Proteccion

Cuernavaca, Mexico
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Gonzalez J.L.M.,PEMEX | Betancourt E.R.,PEMEX | Ramirez R.,Corrosion and Proteccion | Gomez L.M.,Corrosion and Proteccion | Simon A.G.,Corrosion and Proteccion
Proceedings of the Biennial International Pipeline Conference, IPC | Year: 2014

Some pipeline operators evaluate risk on an individual pipeline basis even if the right of way (ROW) is shared with other pipelines. Determining a ROW strip risk condition may be complex or quite simple, according to the model adopted by the analyst. If the pipelines allocated in a shared ROW belong to different operators it is very likely that they apply different methods to evaluate a risk condition. The relative risk contribution cannot be added to estimate the risk of a ROW strip. In Mexico insurance companies request studies of collective risk in pipelines to decide whether to increase a prime or reduce coverage. This request does not have technical support or engineering guidelines to perform the analysis. In Pemex there are few documented events where a pipeline failure affects parallel pipelines, known as collateral damage. There are some methods to estimate a potential collateral damage as a function of soil damping and separation between pipelines (Ref.2). This scheme applies for gas pipelines and has to be complemented with an ignition scenario probabilistic analysis. In the case of hazardous liquids scenarios of leak and rupture have to be considered, including potential shed routes, product concentration sites and operator response capability. Since risk is assessed with particular and specific attributes of a pipeline the probability of failure cannot be directly added to adjacent pipelines. There are some failure mechanisms common for pipelines sharing the ROW, such as external corrosion and stress corrosion cracking (SCC), with different intensity when considering coating and corrosion protection (CP) efficiency. Internal corrosion depends on other factors such as product features so it does not necessarily repeat with the same magnitude in all pipelines. Pipeline threats can be expected to be the same in this case - with different intensity. For instance, third party activity and weather can threaten all pipelines allocated in the same ROW. These pipelines may present similar symptoms with different magnitude. Cover depth, additional protection and wall thickness play an important role in reducing third party (TP) and weather and outside forces (WOF) threats. The paper provides risk results of a ROW strip based on probability of failure values. Pipelines with biggest risk contribution were identified and integrity management alignment diagrams were obtained to correlate with risk values. A simple algorithm was developed to process risk results in terms on shared ROW buffer dimensions. The study is complemented with the results of a consequence simulation analysis for a gas pipeline. Copyright © 2014 by ASME.


Gonzalez J.L.M.,PEMEX | Taylor I.P.,PEMEX | Aguilar J.C.,Corrosion and Proteccion | De La Escalera L.M.,Corrosion and Proteccion
Proceedings of the Biennial International Pipeline Conference, IPC | Year: 2014

The oil and gas industry has three major segments: upstream, midstream and downstream. Upstream is frequently referred to as exploration & production. The midstream segment involves transportation, storage and marketing of oil and gas products. Transportation options may vary from small connector pipelines to massive cargo vessels covering transocean routes. Most oil types may be transported in their original condition, while natural gas needs to be either compressed or liquefied for transmission. Storage helps to balance fluctuations between supply and demand of energy products. Downstream covers the refining and processing of hydrocarbons into usable products. Each segment has facilities to support one or various processes. Terminals include pipeline, rail, trucks and cargo transmission which imply a complex model to cover the whole facility to evaluate risk and reliability with all processes and functions involved. Before addressing the logistics of each midstream component the reliability of the involved assets needs to be evaluated. First to be considered is terminal location with respect to upstream and downstream. Onshore and maritime terminals have several components in common and two main processes may coexist (storage and distribution). All terminal components represent circuits with a specific sub process or function. Some circuits have a serial arrangement so they are highly dependent on each other's reliability. Also some circuits develop parallel processes with null or low impact on the terminal main process; however they may influence the facility risk in terms of probability of failure and consequences. Support and auxiliary circuits play an important role in terminal reliability since they could affect performance and continuity. There are circuits thought of as transmission and logistics elements, and that reliability is highly dependent on mechanical integrity to perform a specific function. Maritime terminals may have a circuit of SPM (Single Point Mooring) buoys for loading or uploading product. The analysis model has to include every circuit to cover any possible arrangement and configuration. The model is supported by a processes mapper that allows the user to define serial, parallel and support processes based on a logistics scheme in terms of reliability and mechanical integrity. The developed model provides results to support decision making for product transmission and distribution and addresses the importance of terminals in terms of risk and reliability for logistics planning. The terminals model is supported by 16 algorithms that may be used according to operator needs by simply activating or deactivating circuits to obtain values for probabilities of failure that predict any potential service interruption. Copyright © 2014 by ASME.

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