中国石油集团石油管工程技术研究院 C N P C T U B U L A R G O O D S R E S E A R C H I N S T I T U T E

Transcription

1 中国石油集团石油管工程技术研究院 C N P C T U B U L A R G O O D S R E S E A R C H I N S T I T U T E Gazprom VNIIGAZ IV International Scientific and Technical Seminar Improvement of Reliability of Main Gas Pipelines Subject to Stress Corrosion Cracking

2 Introduction TGRI is directly affiliated to CNPC, founded in 1981 in City of Xi an, the only one research institute focusing on tubular goods research and technology in China; 80% with Master Degree under the age of 40, 46 with PhD degree, one CEA and 6 national and provincial experts. CNPC+SINOPEC+CNOOC Oil and Gas Field Pipeline Operation Company Steel & Pipe Company Petroleum chemical Company Refinery Tools Company Pipeline & OCTG Material science and engineering Mechanics and fracture control Corrosion and protection Failure analysis Safety assessment and risk management Full scale testing NDT and inspection

3 Where We Are? Great Wild Goose Pagoda Terra Cotta Warriors

4 TGRI s Roles Quality & Inspection Center Innovative R&D Center Tubular Goods Engineering Tubular Goods Engineering Service Technical Service Center

5 International Communications & Collaborations C-FER (Canada) TRANSCANADA (Canada) CSM (Italy) Ohio University (US) STRESS (US) BATTELLE (US) EMCC (US) MICROALLOYING(US) CBMM(BRAZIL) TWI (UK) Nippon Steel (Japan) JFE (Japan) TENARIS (Argentina) V&M GL (Germany) POSCO (South Korea)

6 International Conference hosted by TGRI Ultra High Strength Line Pipe Technology International Conference High strength Line Pipe Technology and Application International Conference Pipeline and Material International Conference Tubing String and Material International Conference International Conference for Petroleum Tubular Goods, Equipment and Materials was held in April annually, which was co-hosted by TGRI and API. Hope to meet you in 2019 in Xi an. High strength Line Pipe Technology and Application International Conference Tubing String and Material International Conference International Conference for Petroleum Tubular Goods, Equipment and Materials

7 Key Facilities at TGRI With capacity of testing metallic materials, non-metallic materials, composite materials Full-scale equipment for testing tubing/casing, Line pipe, valves, tools.

8 Key Facilities at TGRI (cont.)

9 Research Background Gas pipeline from Middle Asia Gas pipeline from Russia Gas transmission line is over 100,000km in China 1996 OD660 X60 6.4MPa Shaanjing pipeline OD1016 X70 10MPa---West-East Pipeline I OD1219 X80 12MPa---West-East Pipeline II OD1422 X80 12MPa---Sino-Russia East line X90/X100 are developed and trial section are planning Gas pipeline from Myanmar

10 OUTLINE 1 Effect of small-amplitude stress fluctuation on high grade pipeline SCC 2 Effect of cathodic Protection on high grade pipeline SCC 3 Effect of residual stress on high grade pipeline SCC 4 Pipeline research activities at TGRI

11 Experimental Coupons: the samples were machined from Φ mm LSAW X80 pipe, one group was cut from pipe body and one group from weld joint. Pre-crack: The depth of wire-cut is 2mm, the length of pre-crack is 1mm, length of residual ligament is 5mm. Applied load: The Maximum applied load is 100%δs and 85%δs, R ratio is 0.85 and 0.75, the frequency is 0.02Hz. Solution: NS 4 solution, purged with 5%CO 2 +95%N 2. Composition KCl NaHCO 3 CaCl 2 2H 2 O MgSO 4 2H 2 O ph Content (mg/l) Schematic diagram of pre-crack sample Instron8810 for fatigue test

12 Experimental: Small-amplitude stress fluctuation Condition 1: S100R75 100%δs Condition 2: S85R75 85%δs 100%δs %δs 0.75 Condition 3: S100R85 100%δs Condition4: S85R85 85%δs 100%δs %δs 0.85

13 Results and discussion Influence of small-amplitude stress fluctuation on cracking behavior of X80 weld joint The crack propagation is directly associated with stress ratio and stress level, the crack propagation rate (da/dn) is in order: S100R75>S85R75>S100R85>S85R85..

14 Results and discussion Influence of small-amplitude stress fluctuation on cracking behavior of X80 weld joint Condition1: S100R75 Condition2: S85R75 Test duration is 180h Crack propagation rate is da/dn is mm/n Fracture! Test duration is 272h Crack propagation rate is da/dn is mm/n Fracture! Condition3: S100R85 Condition4: S85R85 Test duration is 336h Crack propagation rate is da/dn= mm/n Test duration is 360h Crack propagation rate is da/dn= mm/n

15 Experimental: Static stress Condition 1: Weld joint 100%δs Condition 2: Weld joint 85%δs Weld Joint 100%δs Weld Joint 85%δs Condition 3: Pipe body 100%δs Condition 4: Pipe body 85%δs 100%δs 85%δs

16 Results and discussion Influence of static stress on cracking behavior of X80 weld joint Weld joint 100%δs Weld joint 85%δs Pipe body 100%δs Pipe body 85%δs Weld joint 100%δs Weld joint 85%δs Pipe body 100%δs Pipe body 85%δs The crack propagation is directly associated with stress level and material type, the crack propagation rate (da/dn) is in order: Weld joint 100%δs>> Weld joint 85%δs >Pipe body 100% δs> Pipe body 85% δs.

17 Results and discussion Influence of static stress on cracking behavior of X80 weld joint Condition1: Weld joint 100%δs Condition2: Weld joint 85%δs Test duration is 384h Crack propagation rate is da/dn is mm/n Test duration is 384h Crack propagation rate is da/dn is mm/n Condition3: Pipe body 100%δs Condition4: Pipe body 85%δs Test duration is 384h Crack propagation rate is da/dn= mm/n Test duration is 384h Crack propagation rate is da/dn= mm/n

18 Summary-1 Small-amplitude stress fluctuation Stress ratio value has the greatest influence on crack propagation rate of LSAW X80 pipeline, the crack propagation rate increased with the decreasing of stress ratio value. The crack propagation rates of S100R75, S85R75, S100R85, S85R85 are in orders of mm/n> mm/n> mm/n> mm/n Static Stress Under static stress of 100%δs, the crack propagation rate of weld joint is four times of pipe body; Under static stress of 85%δs, the crack propagation rate of weld joint is three times of pipe body. The SCC susceptibility of LSAW X80 pipe weld joint is higher than that of pipe body. Small-amplitude stress fluctuation VS Static Stress Compared to static stress, the small-amplitude stress fluctuation has enhanced effect on crack propagation rate on LSAW X80 Pipeline.

19 OUTLINE 1 Effect of small-amplitude stress fluctuation on high grade pipeline SCC 2 Effect of cathodic Protection on high grade pipeline SCC 3 Effect of residual stress on high grade pipeline SCC 4 Pipeline research activities at TGRI

20 Experimental Coupons: the samples were machined from X90 Φ (LSAW) and X90 Φ mm (SSAW), one group was cut from pipe body, one group from weld joint (LSAW), and one group from weld joint (SSAW). Test condition: strain rate is 10-6 mm/s, applied cathodic potentials are OCP, -1000mV, -1200mV (SCE). Solution: NS 4 solution, purged with 5%CO 2 +95%N 2. Composition KCl NaHCO 3 CaCl 2 2H 2 O MgSO 4 2H 2 O ph Content (mg/l) Schematic diagram sample Instron8810 for fatigue test

21 Results and discussion SCC susceptibility of X90 (LSAW) OCP Pipe body OCP Weld joint The strain after fracture(δ) and percentage reduction of area (Ψ) decreased with the negative shift of applied potential, while SCC susceptibility in terms of I δ and I Ψ increased with the negative shift of applied potential.

22 SCC susceptibility of X90 (LSAW) Results and discussion Pipe body Weld joint Pipe body Weld joint OCP OCP According to the values of I δ and I Ψ, SCC susceptibility of weld joint is higher than that of pipe body with the negative shift of applied potential.

23 Weld joint Pipe body SCC susceptibility of X90 (LSAW) Results and discussion In air OCP -1000mV -1200mV

24 Results and discussion SCC susceptibility of X90 (SSAW) OCP Pipe body OCP Weld joint The strain after fracture(δ) and percentage reduction of area (Ψ) decreased with the negative shift of applied potential, while SCC susceptibility in terms of I δ and I Ψ increased with the negative shift of applied potential.

25 SCC susceptibility of X90 (SSAW) Results and discussion Pipe body Weld joint Pipe body Weld joint OCP OCP According to the values of I δ and I Ψ, SCC susceptibility of weld joint is higher than that of pipe body with the negative shift of applied potential.

26 Weld joint Pipe body SCC susceptibility of X90 (SSAW) Results and discussion In air OCP -1000mV -1200mV

27 Summary-2 The strain after fracture(δ) and percentage reduction of area (Ψ) decreased with the negative shift of applied potential, while SCC susceptibility in terms of I δ and I Ψ increased with the negative shift of applied potential. SCC susceptibility of weld joint is higher than that of pipe body with the negative shift of applied potential. X90 (LSAW) X90 (SSAW) The strain after fracture(δ) and percentage reduction of area (Ψ) decreased with the negative shift of applied potential, while SCC susceptibility in terms of I δ and I Ψ increased with the negative shift of applied potential. SCC susceptibility of weld joint is higher than that of pipe body with the negative shift of applied potential. X90 (LSAW) VS X90 (SSAW) The susceptibility of X90 (SSAW) is somewhat higher than that of X90 (LSAW).

28 OUTLINE 1 Effect of small-amplitude stress fluctuation on high grade pipeline SCC 2 Effect of cathodic Protection on high grade pipeline SCC 3 Effect of residual stress on high grade pipeline SCC 4 Pipeline research activities at TGRI

29 Experimental Coupons: the samples were machined from X80 Φ (LSAW), one group without residual stress, and three groups with different levels of residual stress. Test method: FPB (90%δs,70%δs, and 50%δs ) and SSRT (strain rate is m/s to m/s). Residual stress test: SHIMADZU XRD Solution: NS 4 solution, purged with 5%CO 2 +95%N 2. Preparation of FPB sample with residual stress Preparation of SSRT sample with residual stress

30 Residual stress of X80 (LSAW) Results and discussion Residual stress of pipe body:210~236mpa Residual stress of weld joint: 250~318MPa Residual stress of pipe body:110~160mpa Residual stress of weld joint: 225~303MPa Residual stress of pipe body:89~145mpa Residual stress of weld joint: 30~100MPa

31 Results and discussion SCC susceptibility of X80 (LSAW)-FPB Method No SCC was observed on X80 (LSAW) with different levels of residual stress(130, 150, 170 ) and applied stress (50%σs, 70%σs, 90%σs). Applied stress Residual stress Samples Results 50%σ s 70%σ s 90%σ s 130 Pre-deformation 150 Pre-deformation 170 Pre-deformation No Pre-deformation 130 Pre-deformation 150 Pre-deformation 170 Pre-deformation No Pre-deformation 130 Pre-deformation 150 Pre-deformation 170 Pre-deformation No Pre-deformation Pipe body 2 Weld joint 2 Pipe body 2 Weld joint 2 Pipe body 2 Weld joint 2 Pipe body 2 Weld joint 2 Pipe body 2 Weld joint 2 Pipe body 2 Weld joint 2 Pipe body 2 Weld joint 2 Pipe body 2 Weld joint 2 Pipe body 2 Weld joint 2 Pipe body 2 Weld joint 2 Pipe body 2 Weld joint 2 Pipe body 2 Weld joint 2 No crack No crack No crack No crack No crack No crack No crack No crack No crack No crack No crack No crack

32 Stress (MPa) Stress (MPa) Results and discussion SCC susceptibility of X80 (LSAW)-SSRT Method Pipe Body Weld Joint # -NS # -NS # -NS # -NS # -NS # -NS4 7 No pre-deformation-1# -NS4 8 No pre-deformation-1# -NS4 9 No pre-deformation-1# -Air 10 No pre-deformation-1# -Air # -NS # -NS # -NS # -NS # -NS # -NS4 7 No pre-deformation-1# -NS4 8 No pre-deformation-1# -NS4 9 No pre-deformation-1# -Air 10 No pre-deformation-1# -Air Strain (%) Strain (%)

33 Weld joint Pipe body Results and discussion SCC susceptibility of X80 (LSAW)-SSRT Method Samples Test Time Ratio Strain Ratio PRA Ratio Fracture Energy Ratio 130 Pre-deformation in NS Pre-deformation in NS Pre-deformation in NS No Pre-deformation In NS No Pre-deformation In air Samples Test Time Ratio Strain Ratio PRA Ratio Fracture Energy Ratio 130 Pre-deformation in NS Pre-deformation in NS Pre-deformation in NS No Pre-deformation In NS No Pre-deformation In air SCC susceptibility of X80 (LSAW) increased with residual stress introduced, weld joint is more susceptible to SCC under residual stress condition.

34 Summary-3 No SCC was observed on X80 (LSAW) with different levels of residual stress(130, 150, 170 ) and applied stress (50%σs, 70%σs, 90%σs). SCC susceptibility of X80 (LSAW) increased with residual stress introduced, weld joint is more susceptible to SCC under residual stress condition.

35 OUTLINE 1 Effect of small-amplitude stress fluctuation on high grade pipeline SCC 2 Effect of cathodic Protection on high grade pipeline SCC 3 Effect of residual stress on high grade pipeline SCC 4 Pipeline research activities at TGRI

36 Pipeline research activities at TGRI High performance pipeline R&D: Material selection and microstructure Fracture control: low temperature brittle fracture, ductile fracture arrest. Strain based design, high deformation pipeline and strain aging Corrosion and SCC control DC/AC stray current induced corrosion Inspection and integrity assessment Standard and specifications

37 Pipeline research activities at TGRI High strength pipeline(x70 and X80): from a follower to leader in world wide X70/X80 high strength pipe applied in large diamete r high pressure pipeline project, West-East Gas Pipeli ne I and II. Pipe grade from X52 to X80, diameter from Φ508 to Φ1219mm, and pressure from 6.4MPa to 12MPa. Greatly reduced pipeline purchase and construction cost, 10 billions RMB was saved in West-East Gas Pip eline II.

38 Pipeline research activities at TGRI Crack propagation and arrest: full-scale burst test Full-scale pipe burst test field in China X80 pipelines (48 ) X80 pipelines (56 )

39 Pipeline research activities at TGRI Crack propagation and arrest: full-scale burst test Influence on parallel pipeline from full-scale burst test of main pipeline Field image of parallel pipeline and burst pipeline Deformation measurement on parallel pipeline

40 Pipeline research activities at TGRI Tensile strain capacity assessment Strain field on crack tip Crack driving force (CTOD) Tensile strain capacity assessment (tangency approach)

41 Pipeline research activities at TGRI Tensile strain capacity assessment: Curved wide plate tensile test Load/CMOD vs. strain CWP specimens Fracture appearance R-curve from CWP test

42 Pipeline research activities at TGRI Tensile strain capacity assessment: Single-notched tensile test Multiple specimen or single specimen/unload compliance method. SY/T Standard test method for special properties of line pipe Part 2: single-edge notched tensile test (SENT). Multiple specimens method Single specimen/unload compliance method Fracture growth path

43 Pipeline research activities at TGRI Tensile strain capacity assessment: Sino-Myanmar pipelines Crack Driving Force Test No. Peak stress (MPa) Strain (%,LT-1) Strain (%,LB-1) WM FL Test No. Remote strain (%) Total crack growth (mm) CMOD (mm) WM FL Tensile Strain assessment by tangency approach (3.8% for WM, 5.4 for FL)

44 Pipeline research activities at TGRI Sino-Russia East pipeline 1422mm X80 pipe and induction heating bend pipe Developed D mm X80 induction heating bend pipe used in low temperature (- 45 ), composition design, fire bending, smelt and rolling technologies. 0.6%-1.0%Ni-based micro-alloy steel X80 three-way elbow was developed, which is 58mm in thickness using in low temperature of -45, the toughness and strength is satisfied with the standard requirements for Sino-Russia East pipeline. The variation of strength and impact energy of DN X80 three-way elbow (68mm in thickness)

45 Offering Energy Creating Harmony CNPC TGRI hopes to collaborate with GAZPROM VNIIGAZ in future, share pipeline research ideas and experiences. If you would like to learn more about TGRI, please visit