PSI - Issue 20

Ivanov V.N. et al. / Procedia Structural Integrity 20 (2019) 222–229

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Ivanov V.N. et al. / Structural Integrity Procedia 00 (2019) 000–000

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The duration of repair work in emergency situations can be estimated using the following formula when the heating system of a building is completely turned off: œ ൏ ߚ ή ୏ భ ሺ୲ ౟౤౪ ି୲ ౥౫౪ ሻ ሺ୲ ౬ౡ ି୲ ౥౫౪ ሻ (3) The air temperature t vk should not create conditions for the freezing of water in pipes and heating appliances. The permissible minimum value of the internal temperature of the room in case of an accident, t vk = 10 ... 12°C is an indicator of the critical thermal condition of the building, since this makes the temperature conditions extremely unfavorable for a person and emergency conditions for the work of engineering equipment are created. For the specified conditions, z at t vk = 10° С and t o = -30° С lies in the range of 6 ... 18 h. If t o goes down to -55° С , then z decreases to 3 ... 10 h.

t i , С

24

20

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16

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12

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8

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4

6

0

0

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z,

Fig. 3. Graph of t = f (z) for different values β and t i :1- β =100, t int =22  С , t out =  55  С ; 2- β =100, t int =22  С , t out =  30  С ; 3- β =50, t int =22  С , t out =  55  С ; 4- β =100, t int =18  С , t out =  55  С ; 5- β =100, t int =18  С , t out =  30  С ; 6- β =50, t int =18  С , t out =  55  С For example, turning off the light in the village of Borogontsy caused the boilers to stop. Due to an incorrect calculation of the cooling time of the internal air temperature of a building, 65% of the heating systems were frozen, the reason being the late late discharge of water from the heating system. Another example, in the village of Olenyok, there was also a light cut-off, hurried, flushed the system, switched on electricity, incurred high costs with filling the system with imported water, starting the system, later 2 residential houses were frozen. Indicator maintainability is the probability of recovery of the system element within the allowable time z a , proveded by Ivanov (2001), Villemeur (1992), Valinc  ius (1992). To eliminate the failure within this time by a probability of 0.9, it is necessary that z rec = 0.433·z a . In this case, the permissible time should be (2.3) ... (4.6) hours.