PSI - Issue 22

Yaorong Feng et al. / Procedia Structural Integrity 22 (2019) 219–228 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

227

9

gas composition is shown in table 1; (d) test temperature 10~20 ℃ ; (e) backfill depth 1.2 m, backfill soil for local soil. The specific test conditions and results are as follows: (a) Tubular type: the western section adopts SSAW pipe, the eastern section adopts LSAW pipe; (b) Pressure and temperature: 12±0.05 MPa (Design factor =72%), 10~20 ℃ ; (c) Steel pipe: steel grade X80, pipe diameter 1219mm, SSAW pipe wall thickness 18.4 mm, LSAW pipe wall thickness 19.1 mm, TMCP process, selection of steel pipe without RUS; (d) Full-scale burst test results: Predicted crack arrest toughness of 215J, the experimental results of the SSAW pipe at 198J stop cracking, the LSAW pipe cracks through the 179J steel pipe, in the second steel pipe 233J stop cracking.

(a) full-scale gas burst test scenario

(b) burst tested pipe morphology

Fig. 7 full-scale gas burst test scenario and tested pipe morphology The statistical analysis of the actual production data shows that the average value of the Charpy impact energy of the domestic X80 grade and φ1219x18.4mm SSAW pipe body is 303J, which is much higher than the required crack arrest impact energy 220J. The reasonable determination of the crack arrest toughness guarantees the essential safety of the X80 pipeline in the 2 nd WEGP. The experimental results also show that the crack arrest capacity of SSAW pipe is better than that of LSAW pipe. 5. Conclusions (1) Based on the relevant international standards and evaluation methods, the requirement of crack initiation control and brittle fracture control for X80 pipeline of the 2 nd WEGP are put forward. (2) Based on the international full-scale burst test database, BTC model and GasDecom software, the crack arresting toughness requirement of the 2 nd WEGP is systematically studied, and the fracture control scheme of the 2 nd WEGP is determined on the basis of different fracture criteria and the principle of considering safety and economy. (3) On this basis, the full-scale burst test of X80 pipeline was successfully carried out. The crack arrest ability of X80 SSAW pipe is verified for the first time, and a new crack arrest toughness correction factor is obtained. The results show that the crack arrest ability of SSAW pipe is better than that of LSAW pipe. Acknowledgements The authors sincerely thank TGRI of CNPC for allowing the publication of this paper, colleagues for their assistance, and Italian CSM for their assistance in the full-scale burst test. References Jiahua Pan. Analysis of fracture mechanics of oil and gas pipelines. Beijing: Petroleum Industry Press (in Chinese), 1989:14-48. Starostin V. Pipeline disaster in the USSR: it had to happen, yet it could have been averted. Pipes & Pipelines Int, 1990: 35(2), 7-8. Ba Yang, Dianxiu Xia, Qingjin Wang. Failures in sour services of Southwestern China. PVP-Vol.315, 33-37, Honolulu, Hawaii, July23-27, 1995. Xuemei Lin. Failure analysis of Sichuan gas transmission trunk Line. Oil Country Tubular Goods(in Chinese) , 1998,6 (2): 27~30.