PSI - Issue 59

Mariia Serediuk et al. / Procedia Structural Integrity 59 (2024) 763–770 Mariia Serediuk et al. / Structural Integrity Procedia 00 (2019) 000 – 000

765

3

states and failures of the linear part in the past are studied (retrospection), and based on these data, structural reliability is predicted in the future (determination of the probability of failure-free operation). At the same time, diagnosis of the condition of the pipeline wall and insulation, determination of the influence of external factors on the condition of the insulation and pipeline wall, and determination of the position of the pipeline in the ground are carried out. Based on the results of the research, the DB values for different pipelines are determined and their comparison is made. However, the object's impact on the environment is not taken into account in any way. Therefore, we suggest introducing the environmental impact factor (KE) into the equation for determining the defective score:

m



( )

( P U

0)

P t



j

j

  

  

(1)

  

  

,

n

b

a

total   L 

1

j



DB K 

k L

. a і a і .

E

bL

1

1

a

i





total

where P(t) is the probability of failure-free operation of the pipeline based on retrospective analysis; Pj(Uj>0) is the probability of trouble-free operation of the gas pipeline under the influence of influences and loads on it; Uj=Rj-Sj – the difference between the carrying capacity of the gas pipeline and its limit state in terms of strength, stability, deformability and crack resistance (j=1...4; m = 4); L total – the total length of the evaluated section; b – the total number of destructive and aggressive factors of negative impact on the pipeline; n a – the number of areas with destructive or aggressive factors that have a negative impact on the pipeline; k a .і – weight coefficients of destructive or aggressive factors of negative impact on the pipeline; L a .і - lengths of pipeline sections with a certain type of destructive or aggressive factors that have a negative impact on the pipeline. Taking into account the environmental impact factor, during the rejection of pipelines or their objects according to DB , it is possible to establish the degree of their impact on the environment. This will make it possible to decommission the objects of pipeline systems and linear sections, which have a more negative impact on the environment, from the point of view of pollution due to industrial emissions of harmful substances or due to leaks of the transported product due to depressurization. The environmental impact factor can be determined by the formula where n – Is the total number of comparison parameters, which can include: volumes of greenhouse gas emissions, enterprise hazard category, transported product hazard category, etc.; k i – is the weight coefficient of the ith comparison parameter; P i max – is the maximum value of the i-th comparison parameter among objects to be rejected; P i – is the value of the i-th comparison parameter of the object for which the DB is defined. Let us consider two imaginary pipelines for which Zapukhlyak et al. (2022a) calculated the defective score (it was established that for pipeline 1 the defective score is DB = 0.48, and for pipeline 2 – DB = 0.57) and we will conduct a comparative evaluation of them according to the proposed method taking into account KE. Table 1 shows their comparison parameters. max 1 n i P E K k    i i i P       (2)

Table 1. Characteristics of imaginary pipelines. Parameter

Pipeline 1

Pipeline 2

Appointment

Gas pipeline

Gas pipeline

Diameter DN , mm

1400

1400

Volume of greenhouse gas emissions at the compressor station, t/year ( k i = 0.9)

650

783

3

31.7  10 3

Enterprise hazard category ( k i = 0.3)

48.5  10