velocity assisted corrosion of api x 52 steel in 3
DESCRIPTION
The presentation deals with our study on the velocity affected corrosion of a line=pipe steel, API-X52 in sea water environment.TRANSCRIPT
VELOCITY-ASSISTED VELOCITY-ASSISTED CORROSION OF API X-52 CORROSION OF API X-52
STEEL IN 3. 5 % NaCl STEEL IN 3. 5 % NaCl SOLUTIONSOLUTION
DR. AMARNATH & DR. AMARNATH &
PROF.T. K. G. NAMBOODHIRIPROF.T. K. G. NAMBOODHIRI
DEPT. OF METALLURGICAL DEPT. OF METALLURGICAL ENGINEERING, BANARAS ENGINEERING, BANARAS
HINDU UNIVERSITYHINDU UNIVERSITY
INTRODUCTIONINTRODUCTION
Corrosion of metals in fluids enhanced Corrosion of metals in fluids enhanced by relative velocity of corrodentby relative velocity of corrodent
Corrosion increases with increasing Corrosion increases with increasing velocity, first by mass-transfer and then velocity, first by mass-transfer and then by surface shear forces.- Laminar flow. by surface shear forces.- Laminar flow.
In turbulent systems impingement In turbulent systems impingement attack and cavitation damage lead to attack and cavitation damage lead to increased corrosion. increased corrosion.
EROSION-CORROSION IN EROSION-CORROSION IN AQUEOUS SYSTEMSAQUEOUS SYSTEMS
EROSION-CORROSION
VELOCITY-ASSISTED
CORROSION IMPINGEMENT ATTACK CAVITATION-DAMAGE
EFFECT OF VELOCITY ONEFFECT OF VELOCITY ON MASS LOSS MASS LOSS
VELOCITY- ASSISTED CORROSION UNDER VELOCITY- ASSISTED CORROSION UNDER LAMINAR FLOWLAMINAR FLOW
IMPINGEMENT ATTACK-IMPINGEMENT ATTACK-TURBULENT FLOWTURBULENT FLOW
Under turbulent Under turbulent flow high velocity flow high velocity impact of fluids impact of fluids leads to removal of leads to removal of materialmaterial
Stress created by Stress created by fluid impact crack fluid impact crack or remove corrosion or remove corrosion product films and product films and expose fresh metalexpose fresh metal
CAVITATION DAMAGECAVITATION DAMAGE
Pressure variations Pressure variations in flowing liquids in flowing liquids lead to formation of lead to formation of bubbles or cavities. bubbles or cavities.
Under high Under high pressure, these pressure, these bubbles collapse bubbles collapse violently and violently and damage nearby damage nearby surface. surface.
AIM OF THE PAPERAIM OF THE PAPER
Line-pipe steels like API X-52 are used for Line-pipe steels like API X-52 are used for large diameter pipelines carrying crude, large diameter pipelines carrying crude, natural gas and petroleum products over natural gas and petroleum products over large distances, often under the sea. large distances, often under the sea.
Exposure to high velocity fluids within and Exposure to high velocity fluids within and the dynamic sea-environment outside the dynamic sea-environment outside make these pipelines susceptible to make these pipelines susceptible to erosion-corrosion. erosion-corrosion.
This paper evaluates the erosion-corrosion This paper evaluates the erosion-corrosion behaviour of API X-52 in flowing 3. 5 % behaviour of API X-52 in flowing 3. 5 % NaCl solutionNaCl solution
ExperimentalExperimental
Commercial API X-52 supplied by SAIL R&D, Commercial API X-52 supplied by SAIL R&D, Ranchi as 10 mm thick hot rolled plate. Ranchi as 10 mm thick hot rolled plate. Table 1- chemical compositionTable 1- chemical composition
Strips hot rolled to 2. 5 mm at 850 C. Some Strips hot rolled to 2. 5 mm at 850 C. Some strips cold rolled to 10, 30 and 50 % strips cold rolled to 10, 30 and 50 % reductions. Some strips annealed at 950 C, reductions. Some strips annealed at 950 C, furnace cooled or water quenched and furnace cooled or water quenched and tempered at 150 Ctempered at 150 C
Immersion tests for general corrosion. Immersion tests for general corrosion. Exposure on a parallel disk rotating Exposure on a parallel disk rotating assembly for velocity effects. Weight loss assembly for velocity effects. Weight loss measurements. measurements.
TABLE 1:CHEMICAL COMPOSITION OF TABLE 1:CHEMICAL COMPOSITION OF API X-52 STEEL API X-52 STEEL
Nominal Composition, Weight %Nominal Composition, Weight %
CC MnMn SiSi PP SS NbNb VV FeFe
0. 150. 15 1.251.25 0. 200. 20 0. 0270. 027 0. 0260. 026 0. 040. 04 0. 050. 05 BalaBalancence
PARALLEL DISK ROTORPARALLEL DISK ROTOR
RESULTSRESULTS
Mechanical Properties, Table 2Mechanical Properties, Table 2 MicrostructuresMicrostructures STATIC CORROSION: TABLE 3STATIC CORROSION: TABLE 3 VELOCITY-ASSISTED CORROSIONVELOCITY-ASSISTED CORROSION
Table 3Table 3 Mechanical properties of Mechanical properties of API X-52 steelAPI X-52 steel
conditionsconditions YSYS UTSUTS % el Hardness % el Hardness
(MPa) (MPa) (VPN)(MPa) (MPa) (VPN)
As-received 476As-received 476 595 595 30.0 30.0 180 180 10 % cold rolled10 % cold rolled 580 580 620 620 4.13 4.13 312 312 30 % cold rolled30 % cold rolled 610 610 679 679 2.40 2.40 339 339 50 % cold rolled50 % cold rolled 695 695 765 765 1.06 1.06 363 363 Q & T. 639Q & T. 639 972 972 10.3 10.3 389 389 AnnealedAnnealed 297 297 481 481 31.95 134 31.95 134
MICROSTRUCTURE OF API X-52MICROSTRUCTURE OF API X-52
As-received As-received (hot rolled) (hot rolled) steelsteel
MICROSTRUCTURE OF API X-52MICROSTRUCTURE OF API X-52
AnnealedAnnealed Quenched & Quenched &
temperedtempered
10 % cold rolled10 % cold rolled 30 % cold rolled30 % cold rolled 50 % cold rolled50 % cold rolled
Table 3. Static corrosion of API X-52 steel Table 3. Static corrosion of API X-52 steel 3.5% NaCl, 20 days’ exposure3.5% NaCl, 20 days’ exposure
ConditionsConditions Corrosion Corrosion
Rate, mddRate, mdd Hot rolledHot rolled 20 20 AnnealedAnnealed 23 23 Quenched & temperedQuenched & tempered 13 13 10 % Cold rolled10 % Cold rolled 18 18 30 % Cold rolled30 % Cold rolled 14 14 50 % Cold rolled50 % Cold rolled 19 19
VELOCITY-ASSISTED VELOCITY-ASSISTED CORROSIONCORROSION
API X-52 Steel, as-API X-52 Steel, as-received, 3. 5 % received, 3. 5 % NaClNaCl
Variation of Variation of corrosion rate with corrosion rate with time at three time at three velocitiesvelocities
Corrosion rate Corrosion rate increases with increases with increasing velocityincreasing velocity
VELOCITY ASSISTED VELOCITY ASSISTED CORROSIONCORROSION
Corrosion rate (Hot Corrosion rate (Hot rolled steel) increases rolled steel) increases with increasing with increasing velocity (0. 11 m/s to velocity (0. 11 m/s to 4. 62 m/s)4. 62 m/s)
At velocities above At velocities above 400 RPM(0. 86 m/s), 400 RPM(0. 86 m/s), the corrosion rate was the corrosion rate was found to be more than found to be more than that for a rotating that for a rotating cylinder with laminar cylinder with laminar flow. (Erosion-flow. (Erosion-corrosion)corrosion)
EFFECT OF THERMAL AND EFFECT OF THERMAL AND MECHANICAL TREATMENTSMECHANICAL TREATMENTS
Velocity-assisted Velocity-assisted corrosion changes corrosion changes with thermo with thermo mechanical mechanical treatmentstreatments
Increasing cold Increasing cold work decreases the work decreases the corrosion ratecorrosion rate
Q & T steel shows Q & T steel shows the lowest the lowest corrosion ratecorrosion rate
TABLE 4. EFFECT OF THERMOMECHANICAL TABLE 4. EFFECT OF THERMOMECHANICAL TREARMENTS ON CORROSIONTREARMENTS ON CORROSION
Thermo mechanical Treatment
Corrosion rate, mdd in 3. 5 % NaCl solution
Static24 hrs
Dynamic1. 36 m/s20 hrs.
Annealed 28 5054
Hot rolled 85 932
10 % C. R. 47 832
30 % C. R. 48 793
50% C. R. 70 671
Q & T 42 617
EFFECT OF HARDNESSEFFECT OF HARDNESS
Velocity-assisted Velocity-assisted corrosion corrosion decreases with decreases with increasing increasing hardness of the hardness of the steel. steel.
This dependence This dependence attributed to attributed to impingement impingement attack and/or attack and/or cavitation damage. cavitation damage.
CONCLUSIONSCONCLUSIONS
API X-52 steel undergoes erosion-API X-52 steel undergoes erosion-corrosion in flowing 3. 5 % NaCl corrosion in flowing 3. 5 % NaCl solution. solution.
Increasing velocity increases the Increasing velocity increases the corrosion rate, the increase corrosion rate, the increase dependent on the condition of steel. dependent on the condition of steel.
The dynamic corrosion of the steel The dynamic corrosion of the steel decreases with increasing hardness. decreases with increasing hardness.
LIST OF PUBLICATIONSLIST OF PUBLICATIONS Amarnath, M. M. Singh and T. K. G. Namboodhiri, Corrosion of Amarnath, M. M. Singh and T. K. G. Namboodhiri, Corrosion of
API X-52 grade line pipe steel in sodium chloride media, Trans. API X-52 grade line pipe steel in sodium chloride media, Trans. SAEST, 35 (2000), 85-90SAEST, 35 (2000), 85-90
Amarnath, T. K. G. Namboodhiri and S. N. Upadhyay, Flow Amarnath, T. K. G. Namboodhiri and S. N. Upadhyay, Flow Assisted Corrosion of API X-52 Steel in 3. 5% NaCl Solution, The Assisted Corrosion of API X-52 Steel in 3. 5% NaCl Solution, The Canadian Journal of Chemical Engineering, 80 (2002) (6), 456-Canadian Journal of Chemical Engineering, 80 (2002) (6), 456-464464
Amarnath and T. K. G. Namboodhiri, Effect of cold rolling on the Amarnath and T. K. G. Namboodhiri, Effect of cold rolling on the hydrogen-induced delayed failure of API X-52 line-pipe steel, hydrogen-induced delayed failure of API X-52 line-pipe steel, Trans. Indian Inst. Metals, 55 (2002), 25-30Trans. Indian Inst. Metals, 55 (2002), 25-30
G. Ananta Nagu, Amarnath and T. K. G. Namboodhiri, Effect of G. Ananta Nagu, Amarnath and T. K. G. Namboodhiri, Effect of heat treatments on the hydrogen embrittlement susceptibility of heat treatments on the hydrogen embrittlement susceptibility of API X-65 grade line-pipe steel, Bull. Mater. Sci. ,26 (2003)435-API X-65 grade line-pipe steel, Bull. Mater. Sci. ,26 (2003)435-439439
Amarnath, S. N. Upadhyay and T. K. G. Namboodhiri, Effect of Amarnath, S. N. Upadhyay and T. K. G. Namboodhiri, Effect of thermal and mechanical treatments on corrosion of API X-52 thermal and mechanical treatments on corrosion of API X-52 grade line-pipe steel in flowing 3. 5 % NaCl solution, Indian J. grade line-pipe steel in flowing 3. 5 % NaCl solution, Indian J. Chem. Technol. , 10 (2003) 611-614Chem. Technol. , 10 (2003) 611-614