Table. 4, Table. 5 and Table. 6 show the obtained temperatures at the inner edge of feed water inlet pipe, Ti and temperatures at the outer edge of the pipe, to corresponding to temperatures at a point located in r = 3 r1 from the center of the pipe.
Table. 4 Temperatures at the inner edge, Ti and temperatures at the outer edge, T0 in case of pipe diameter; 25A (sch 80)
Table. 5 Temperatures at the inner edge, Ti and temperatures at the outer edge, T0 in case of pipe diameter; 32A (sch 80)
Table. 5 Temperatures at the inner edge, Ti and temperatures at the outer edge, T0 in case of pipe diameter; 40A (sch 80)
Circumferential stress on large thickness pipe corresponding to boiler drum with feed water inlet pipe was calculated according to temperatures shown in Table. 4. The result is shown in Fig. 6. Maximum stress of about 180 Mpa is observed at the inner edge of the pipe in case of the saturated boiler water temperature of 220℃, and the stress decreases immediately as distance from the inner edge increases.
Fig. 6 Thermal stress distribution in case of feed water inlet pipe diameter of 25A (sch80)
Moreover, minus stress is observed at a point located in r = 3 r1. In Fig. 6, the inner radius is 12.5 mm, the point located in r = 3 r1 is 37.5 mm as same as shown in Fig.3.
Fig. 7 shows the result of calculation of circumferential stress distribution in case of feed water inlet pipe diameter of 32A (sch80). The inner radius and point located in r = 3 r1 are 16.5 mm and 49.4 mm respectively in Fig. 7. Maximum stress of about 170 Mpa (N/mm2) at the saturated boiler water temperature of 220℃ is observed at the inner edge of the feed water inlet pipe as same as the result shown in Fig. 6
Fig. 7 Thermal stress distribution in case of feed water inlet pipe diameter of 32A (sch80)
Fig. 8 shows the result of calculation of circumferential stress distribution in case of feed water inlet pipe diameter of 40A (sch80). The inner radius and a point located in r = 3 r1 are 19.2 mm and 57.6 mm respectively in Fig. 8. Maximum stress of about 160 Mpa is observed at the inner edge of the pipe.
Fig. 8 Thermal stress distribution in case of feed water inlet pipe diameter of 40A (sch80)
