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54 MAY 2017 MATERIALS PERFORMANCE NACE INTERNATIONAL: VOL. 56, NO. 5 Results and Discussion Wall thickness data generated by the EFM system was collected once a week and a data management analysis tool system was used for data interpretation and analy- sis. All spools were longitudinally sectioned to conduct visual inspection for the inter- nal surface of each spool. The results of each spool will be discussed separately in the following section. Spool 1 Visual inspection showed minor metal loss and corrosion products were deposited onto a pipe wall and formed a hard film. The EFM results showed no detectable metal loss, as can be seen in Figure 3. In contrast, the U T technique detected a metal loss of 0.06 mm (2.4 mils), which is equivalent to a corrosion rate of 0.122 mm/y (4.4 mils/y). For comparison purpose between EFM a n d U T re a di n g s , si x l o c a t i o n s w e re selected on the 6 o'clock position of Spool 1. Figure 4 shows the average metal loss of these locations measured by both EFM and UT. The results revealed that the EFM tech- nique could not detect any minor changes in metal loss for all six locations, while the detected metal loss by the UT technique was in the range of 0.03 to 0.12 mm (1.2 to 4.7 mils) for Locations 1 through 5. There was no metal loss detection at Location 6 for both techniques. Spool 2 The condition of Spool 2 was made more aggressive than the condition of Spool 1 by adding field deposits to simulate actual field conditions. The EFM results revealed that no metal loss was noticed at this condition. The UT results showed that the average detected metal loss was ~0.097 mm (3.8 mils), as shown in Figure 5. The average corrosion rate was 0.194 mm/y (7.6 mpy). The effect of adding actual field deposits into the spool was clearly observed where the average detected metal loss increased from 0.06 to 0.097 mm. Spool 3 In this spool, 10% HCl solution was uti- lized to create a harsh environment. Higher metal loss inside the spool was observed as FIGURE 3 Remaining wall thickness for Condition 1 detected by EFM. FIGURE 4 Average detected metal loss by UT and EFM. FIGURE 5 Average detected metal loss by UT and EFM. MATERIALS SELECTION & DESIGN