Dead-legs are potentially the most critical components within a piping system to assess against corrosion degradation. The root cause of the issue relates to fluid being stagnant inside a dead-leg and separated from the main flow stream which in turn creates the condition prone to activate certain corrosion mechanism such as under deposit attack, etc. API RP 570[8] requires inspection to be carried out at these sub-components however still not very clear on how the corrosion rate may be different to the main line. When carrying out Risk-Based inspection as per API RP 581[1], the damage factor as the index for likelihood of failure is tripled if a very comprehensive inspection has not been carried out on a deadleg. Nerveless it is understandable that a universal methodology cannot be implemented due to the large variation of product (and consequently corrosion rate) within the piping system across all process plants using API documents as their assessment guideline. To overcome this issue, ADMA OPCO together with TWI have developed a guideline document (GDL-059[6]) to address specific requirements to identify and assess deadlegs within ADMA OPCO offshore and on-shore process piping. GDL-059[6] provides recommendations on how to identify a deadleg, and once it is identified, how to gather the information required for further assessment. As it is neither practical nor economical to carry out a comprehensive inspection at each deadleg within short time interval, recommendations are also provided on how to evaluate a relative corrosion rate of a deadleg to its parent piping system. Contributing factors to the higher corrosion rate at deadlegs such as dimensions and orientation of the deadleg together with the nature and velocity of the flow were examined using qualitative and quantitative approach. Recommended values of relative corrosion rates are provided and a decision making process is given in-line with API RP and API RP philosophy.