API-5L tracking methods are generally used to identify produced pipe lines specifications in gas and oil industries. However, pre-assembly operations such as shot blasting or long time open air storage of the pipes in bad atmospheric conditions may cause to erode the marked information on the pipes in which make the tracking impossible. In this study, laser engraving is introduced as a permanent tracking method for gas pipes to solve the challenges associated to the traditional marking methods. To do so, a comprehensive study of laser engraving experiments on three types of commercial API materials, including grade B, X52 and X70, were carried out. Using the full factorial design of experiments approach the influence of laser power, scan speed and spacing, scan numbers and the laser frequency on engraved depth were investigated. It was found that laser power and scanning speed had the most significant effect on the engraved depth. After deriving the optimum process parameters for the defind engraved depth, a wide range of engraved test specimens were prepared for metallography, micro hardness, tensile, impact, surface roughness, flatting and corrosion tests. Microstructure observations as well as the results of measuring micro hardness near the engraved areas showed no significant heat affected zone area on all three studied grades. In addition, the results of tensile and impact tests illustrated that laser engraving remained no destructive effect on the samples. Surface roughness decreased after engraving and flatting test was passed successfully. After that, corrosion test applied on all three grades. It was seen that while the engraving had little effect on the corrosion of grade B material, i.e. 8 and 7 mils per year for the engraved and virgin samples respectively, the corrosion resistance of X52 and X70 engraved sample were weaken significantly. It was then suggested to apply a coating primer upon engraving of such materials. The results of this study can be used to draw up permanent tracking standard to be attached National Iranian Gas Standard (IGS). Keywords: Laser engraving, API Pipes, Full factorial DOE, Tensile test, Impact test, Micro Hardness test, Corrosion test, Shot blasting, Coating
