**Author details**

174 Nuclear Power – Practical Aspects

reach a minimum value in the fully developed region.

proposed correlation and the UT measurements uncertainty.

**70%**

**Figure 12.** Effect of the upstream distance on the wear rate


0

50

100

**Effect of Close Proximity (%)**

150

200

previously correlated by Kastner et al. (1990) as:

The other set of UT data is collected for 90o elbows located at different distances (L) from the upstream component are presented. The ratio (L/D) is used to represent the nondimensional upstream distance with respect to the pipe diameter. As discussed before, a component that has another component located close upstream is expected to experience more turbulence which increases the FAC rate. On the other hand, it is expected that the effect of the turbulence produced from the upstream component becomes much less as the distance from the upstream component increases as shown in Fig. (12). It should be noted that the extent of the proximity effect as shown in Figure (6) is 0 to 5 piping diameters as the a average increase in the wear rate is equal to 70 % (with a standard deviation of 50%) which approximately the same as for elbows within 1D from the upstream components. As the distance between the two components increases the change in the wear rate decreases to

A general trend between the increase in the wear rate and the non-dimensional upstream distance (L/D) is obtained using the average values in the wear rates at different (L/D). The additional effect of the component located upstream close to another component is

0.231 Effect of Proximity % 100

The average values of FAC wear rate in Fig. (12) are compared to the empirical equation proposed by Kastner et al. [28] and found to be in good agreement with the present data shown in Fig. (13). However, the correlation tends to over predict the data as the distance between the components approaches zero which can be attributed to the accuracy of the

> 0 5 10 15 **L/D**

*L <sup>D</sup> e* 

**21% 10%**

(33)

Station A Station B Station C Station D

> Wael H. Ahmed *Department of Mechanical Engineering, King Fahd University of Petroleum & Minerals, Dhahran, Saudi Arabia*
