PSI - Issue 59

Roman Hrabovskyy et al. / Procedia Structural Integrity 59 (2024) 112–119 Roman Hrabovskyy et al. / Structural Integrity Procedia 00 (2024) 000 – 000

115

4

At that, the first sample was loaded to point F (Fig. 4a, b), and the next samples were loaded to points 4 – 1 (Figs. 4a, b), here the fixation of the crack static growth (Δ a ) was carried out repeatedly by loading the samples until their fracture. The critical value of J cr -integral was determined similarly for operated steels. The results of experimental investigations are given in Fig. 2 (points А i , В i , С i , where i = 1, 2), Fig. 4 and in Table 1.

P

l=(0,45-0,55)t

b

t

P/2

P/2

L=4t

d=0,3t

Fig. 3. Bending scheme of a sample made of the main pipeline pipe for static crack resistant testing.

a

b

10000 12000 14000

10000

* 4 C

2 3

F

1

P, N

* 4 C

3

P, N

1 2

8000

F

0 2000 4000 6000 8000

6000

4000

2000

0

0

1

2

3

4

5

6

0

1

2

3

4

5

6 f, mm

f, mm

c

d

1000 1250

1000

M

M

N 4 N 3

N 2

N 2

N 3

N N 1

N N 1

N 4

750

J, kN/m

J, kN/m

0 250 500 750

500

M

M

J c

250

J c

0

0 1

0 3

0 4

0 2

0

0 1

0 2

0 3

0 4

0

0,0

0,5

1,0

1,5

2,0

2,5

0,0

0,5

1,0

1,5

2,0

2,5

Δ а, mm

Δ а, mm

Fig. 4. The load – bending diagram (a, b) and the J cr -integral determination (c, d) of non-operated 17H1S (a, c) and 10H2BТ (b, d) steels.

Table 1. Critical dimensions of crack-like semi-elliptical defects.

Type of defect

Critical fracture toughness

Pipe wall thickness

Operation time, years

Steel

Corrosion pit ( a / c ) cr =1/2.5

Corrosion furrows ( a / c ) cr =1/25

t , mm

( a / t ) cr 0.725 0.670 0.645 0.692 0.632 0.595

2 c cr , mm

( a / t ) cr 0.547 0.494 0.480 0.514 0.473 0.442

2 c cr , mm

J cr , kN/m 207.8 ( А i ) 115.1 ( В i ) 97.0 ( С i ) 275.2 ( А i ) 169.9 ( В i ) 126.7 ( С i )

0

12.0 11.8 11.7 15.7 15.5 15.4

43.5 39.5 37.7 54.3 49.0 45.8

328.2 291.5 280.8 403.5 366.6 340.3

17H1S

30 45

0

28 42

10H2BТ