DEFECT ASSESSMENT ON PIPE USED FOR TRANSPORT OF MIXTURE OF HYDROGEN AND NATURAL GAS

1 DEFECT ASSESSMENT ON PIPE USED FOR TRANSPORT OF MIXTURE OF HYDROGEN AND NATURAL GAS ABSTRACT Capelle, J. 1, Gilget, J. 1 and Pluvinage, G. 1 1 Laboatoie de mécanique Biomécanique Polymèe Stuctue (LaBPS), Ecole Nationale d Ingénieus de Metz (ENIM), Ile du Saulcy, Metz, 57045, Fance, capelle@enim.f The pesent aticle indicates the change of mechanical popeties of X52 gas pipe steel in pesence of hydogen and its consequence on defect assessment paticulaly on notch like defects. The pupose of this wok is to detemine if the tanspot of a mixtue of natual gas and hydogen in the actual existing Euopean natual gas pipe netwok can be done with a easonable low failue isk (i.e. a pobability of failue less than 10-6 ). To evaluate this isk, a deteministic defect assessment method has been established. This method is based on Failue Assessment Diagam and moe pecisely on a Modified Notch Failue Assessment Diagam (MNFAD) which has been poposed fo this wok. This MNFAD is coupled with the SINTAP failue cuve and allows detemining the safety facto associated with defect geomety, loading conditions and mateial esistance. The wok descibed in this pape was pefomed within the NATURALHY wok package 3 on Duability of pipeline mateial. 1.0 INTRODUCTION 1.1 Euopean Gas Netwok The Euopean gas pipelines netwok plays vey impotant ole fo national economies as well as global. This impotance will pemanently incease with pospective plans of intoducing of Euopean hydogen enegy infastuctue [1, 2] and the possible use of existing pipeline netwoks fo tanspotation of natual gas and hydogen mixtues. Within the Euopean poject NATURALHY [3], 39 Euopean patnes have combined thei effots to assess the effects of the pesence of hydogen on the existing gas netwok. ey issues ae duability of pipeline mateial, integity management, safety aspects, life cycle and socio-economic assessment and end-use. The wok descibed in this pape was pefomed within the NATURALHY wok package Duability of pipeline mateial. The causes of the failues of the gas pipelines ae vaious natues, Fig. 1. They can appea eithe by factue, o by leak (it depends of the natue of the fluid tanspoted). The majoity of these failues ae caused by pitting coosion o cacking by stess coosion, but thee ae also poblems elated to weld defects. Movements of gound (landslip, eathquake...) can also be the cause of damage on the buied pipelines. The ownes of pipelines study these poblems fo a long time and have a good knowledge of the methods allowing managing them. Extenal mechanical aggessions ae the cause of many poblems, Fig. 1. Indeed, it happens that pipelines ae damaged o pefoated accidentally at time of excavation wok. Cack initiation in and uptue emanating fom stess concentations ae at oigin of moe than 90% of sevice failues. The pesence of a geometical discontinuity such as a notch will cause weakening of the factue esistance of the pipeline, educe the coss section of the pipe, making it moe sensitive to the opeating pessue and loads caused by soil movements. In this pape, authos ae developed a new tool based on Failue Assessment Diagam, Stuctual INTegity Assessment Pocedue fo euopean industy (SINTAP), and the Volumetic Method. This tool allows to assess the nocivity of a notch type defect, in using two diffeent factos: the secuity facto and the safety facto.

Othes Geneal coosion Cack by coosion Geological causes (eathquake, landslip, ) Damage by contact Figue 1. Causes of the factue of pipelines in the couse of exploitation ecoded by the membes of the ACPRÉ of 1985 to 1995 [4] 1.2 Steel used The studied steel, API 5L X52, is taditionally fo pipelines manufactuing. This steel was the most common gas pipelines mateial fo tansmission of oil and gas duing 1950-1960. The standad chemical composition and mechanical popeties of this steel ae shown in tables 1 and 2. Table 1. Chemical composition of the steel (mass popotion in %). C Mn Si C Ni Mo S Cu Ti Nb Al 0.116 1.286 0.226 0.055 0.033 0.011 0.001 0.024 0.003 <0.02 0.034 Table 2. Mechanical popeties of API X52 [5]. E (GPa) Y (MPa) U (MPa) A% n (MPa) 203 453 524 14 0.0446 587.3 Whee E, Y, U, A%, n, and ae espectively the Young s modulus, yield stess, ultimate stess, ultimate elongation, hadening exponent, and hadening coefficient. The mateial stess stain behaviou is descibed by the Ludwik s law [5] accoding to: n = ε p (1) 2.0 DEFECT ASSESSMENT 2.1 Failue Assessment Diagam and SINTAP In this study, we chose to use a deteministic appoach, deive fom SINTAP pocedue and Failue Assessment Diagam (FAD). The SINTAP pocedue is based on the pinciple of factue mechanics and limit analysis, it is used to assess defects in stuctues, known o assumed. Philosophy of this appoach is eflected in the fact that data quality is eflected in the sophistication and accuacy of esults. To do this, thee ae seveal levels of analysis, moe and moe complex by allowing the data to obtain a specific esult. The lowest level povides the most consevative. All failue in elasto-plastic is chaacteized by a point in a diagam named Failue Assessment Diagam. This diagam accounts any kinds of failue: plastic collapse as well as bittle factue and elastic-plastic failue, Fig. 2. The FAD 2

exhibits a failue cuve as the citical non dimensional stess intensity facto vesus non dimensional stess o loading paamete and has been applied into seveal codes in conjunction with the stuctual integity of cacked stuctues. The intepolation between two limits states, is obtained by a cuve epesenting the factue limit, called Failue Integity Line. Many intepolation cuves have been poposed. We have chosen to use the cuve given by the SINTAP pocedue. The mathematical expessions of SINTAP default level pocedue with the afoementioned assumption can be witten as below [6]: f(l ) 1 2 2 2 0.6 L = 1 + 0.3 0.7 e L +, fo 0 L 2 1 whee L max 150 = 1+ Y 2.5, (2) wheein f (L), L, L max and Y ae espectively intepolating function, non dimensional loading o stess based paamete, the maximum value of non dimensional loading o stess based paamete and yield stess, espectively. 1,2 1,0 0,8 Bittle factue Zone Failue de Ruptue Zone 0,6 0,4 Secuity Zone Zone de sécuité 0,2 Cut off fo plastic collapse 0,0 0 0,2 0,4 0,6 0,8 1 1,2 S Figue 2. Failue Assessment Diagam The FAD, paametes ae defined as follows: Non dimensional stess Non dimensional applied stess intensity facto g S =, (3) y I =, (4) IC whee g,, y I and IC intensity facto. ae: goss stess, yield stess, stess intensity facto and citical stess Point A, on the Fig. 3 is the assessment point obtained afte calculation of the two paametes, and S. To have the safety facto based on the size of the defect, we need to know two othe points, O, oigin point of the diagam, and D, point coesponding to the intesection between the Failue Integity Line and staight line (OA). The value of the safety facto is given by the atio: OD f s, a =, (5) OA 3

1,2 1,0 C D Niveau de sécuité Safety level 0,8 0,6 E Secuity level Niveau de sûeté O B A 0,4 0,2 0,0 O O 0 0,2 0,4 0,6 0,8 1 1,2 S Figue 3. Secuity facto in a Failue Assessment Diagam In the same way, we can obtain the secuity facto, it is only necessay to eplace the point D, by the point E, intesection between the Secuity Level Line and staight (OA). 2.2 Modified Notch Failue Assessment Diagam The SINTAP pocedue intoduced peviously is only available fo one type of defect: cacks. Howeve, the goal of ou study concens the chaacteization of defects obtained by extenal intefeences. These defects ae consideed like notches. We have theefoe decided to adapt this pocedue to ou needs, and to use a Modified Notch Failue Assessment Diagam (MNFAD). The news paametes of the MFAD ae the following: ρ, app = ρ, ρ, c, (6) S = θθ 0, (7) R + R e = m 0 2, (8) Whee ρ,, app ρ,, c θθ,, 0 R and e R, ae espectively: Notch Stess Intensity Facto (NSIF) m applied, citical Notch Stess Intensity Facto, hoop stess, efeence stess, yield stess, and ultimate stength. It is impotant to emphasize that the toughness obtained though the intensity NSIF is dependent on notch adius. Having a dimensionless paamete, use the same failue cuve watheve the notch adius. The definition of the failue integity line and the secuity facto ae the same that fo the Failue Assessment Diagam. All opeating points in the MNFAD ae epesented by a pai of coodinates (S ; ρ, ). 2.3 Factue toughness in tem of ρc The factue toughness depends on notch adius. It is well known that the citical stess intensity facto is popotional to the squae oot of the notch adius below a citical value ρ c [7]. = ρ fo ρ ρ, c ρ c, (9) 4

5 ρ = fo ρ ρ c <, Ic c, (10) One notes that factue toughness measued on specimen with a notch adius geate than ρ c is denoted ρ,c. This incease of factue toughness with notch adius is due to the incease of notch plastic zone with notch adius and consequently the incease of total wok of factue. The citical notch adius coesponds to the fact that the notch plastic zone volume is equal to the factue pocess zone volume [8]. It appeas necessay to measue the factue toughness with the coesponding gouge adius. In the following, the notch adius ρ = 0.15mm is consideed as epesentative of a sevee defect and chosen fo consevative easons. This value compaed with othe obtained fom low stength steels is pobably below the citical notch adius value. The concept of the citical notch stess intensity facto and coesponding local factue citeion assume that the factue pocess equies a cetain factue pocess volume [7]. This local factue appoach is called the Volumetic Method. This volume is assumed as a cylinde with a diamete called the effective distance. Detemination of the effective distance is based on the bi-logaithmic elastic-plastic stess distibution ahead of the notch because the factue pocess zone is the highest stessed zone. This zone is chaacteized by an inflexion point in the stess distibution at the limit of zones II and zone III in Fig. 4. X ef 1 ef = yy ( ) Φ( )d X, (11) ef 0 Hee, ef, X ef, yy () and Φ() ae effective stess, effective distance, opening stess and weight function, espectively. This stess distibution is coected by a weight function in ode to take into account the distance fom notch tip of the acting point and the stess gadient at this point. The effective distance coesponds is to the inflexion point with the minimum of the elative stess gadientχ which can be witten as : 1 yy ( ) χ( ) = yy ( ), (12) The effective stess is consideed as the aveage value of the stess distibution within the factue pocess zone. The notch stess intensity facto is defined as a function of the effective distance and the effective stess [7]: ρ = ef 2πX ef, (13) and descibes the stess distibution in zone III as given by the following equation: ρ yy = ( 2π) α, (14) whee ρ is the notch intensity facto, α is the exponent of the powe function of the stess distibution a constant. Failue occus when the notch stess intensity facto ρ eaches the citical value, i.e. the notch factue toughness ρ, c which eflects the esistance to factue initiation fom the notch tip. The stess distibution ahead of the notch tip and along notch ligament is computed by Finite Element method fo the citical load defined by acoustic emission technique. The citical notch stess intensity facto ρ, c has been calculated using the effective distance and the effective stess obtained fom the elative stess gadient as descibed in Fig. 5.

Log( yy ()) ef Stess distibution along defect oot ρ = ef 2 π X ef I II III Factue Pocess Zone (FPZ) X ef Geometical defect Notch stess intensity vitual cack Log() Figue 4. Schematic distibution of elastic-plastic stess ahead of the notch tip on the line of notch extension and the notch stess intensity concept. xx (MPa) 1400 1200 eff 1000 800 600 400 4,5 3,5 2,5 1,5 0,5 Stess gadient (mm-1) 200 Stess distibution X eff -0,5 Stess gadient 0-1,5 0 0,05 0,1 0,15 0,2 0,25 0,3 0,35 0,4 0,45 0,5 Distance on the ligament unde the notch (mm) 3.0 TESTS Figue 5. Detemination of effective distance using the elative stess gadient method 3.1 Bust tests [9] Longitudinally notched pipes made in steel API X52 by diamete D=219 mm and wall thickness t=6.1 mm wee the object of study, Fig. 6. They wee tested fo bust unde intenal pessue, which is pesented in Fig. 6. Envionmental test conditions: 100% of dy efeenced natual gas (methane) and 100% of pue dy hydogen and fee oxygen (less than 1 ppm vol. esidual oxygen). To pefom tests, a dedicated cell was designed and manufactued. Automatic system fo pessue contol and test opeating accoding to the assigned sequence was developed [10]. The test cell consists of thee cylindical shells: tube-specimen, extenal cylinde and intenal cylinde. Two lids put down the tubespecimen and extenal cylinde. A special ing seals povide the compession. The extenal cylinde (d= 375 mm) is needed as a potective housing. The function of the axially aligned intenal cylinde (d= 165 mm) is to educe the hydogen (o hydogen/natual gas mixtue) bulk volume within testing tube. This is necessay because of safety equiements duing test pocedue. 6

D=219 mm =3.05 mm 61 mm t=6.1 mm a=3.05 mm Applied pessue, bas Bust pessue p=p* * 45 o dp = 12ba min Holding pessue p=20 bas dt dp = 12ba min dt L=1000 mm =0.15 mm T=96 hous T, hous Figue 6. Geomety of the notched pipe and bust cycle The main objective of the designed cell is ceating an additional space, which is filled by inet gas (agon) fo avoiding an emegency situation if leakage of hydogen/natual gas mixtue at the pipe bust occus. The geneal view of the designed test cell is given in Fig. 7. Hee, fo pictoial pesentation the potective housing is emoved. The automatic system fo pessue contol and test opeating accoding to the assigned sequence is pesented in Fig. 7. Tests wee caied out in special equipped laboatoy with two sepaate spaces. Fist oom is used fo pesonnel and opeating/contolling means. Second oom is intinsically safe space, whee the testing stand is located. Gas-cylindes with hydogen, natual gas, hydogen/natual gas mixtue and agon ae boxed outside of the building. Stainless steel gas pipelines ae used (intenal diamete d=6 mm, wall thickness t=2 mm). Befoe test, all pipelines and cavities of testing cell, cut-off valve and pessue tansmittes ae puged with agon. The automatic testing system povides the following capabilities: Gas pessue tansmission in the cavity of testing pipe unde assigned ate dp / dt. eeping an assigned intenal pessue in testing pipe constant duing given time T. Loading of the test pipe by intenal pessue unde given ate dp / dt up to tube bust Pemanent egistation of intenal pessue p = Φ( T ) in the tube-specimen duing test. Visualisation of function p = Φ( T ) in eal time on the PC monito fo each stage of test. Registation and detemining of the bust pessue * p = p. * p = p. Pemanent egistation of pessue on the extenal tube-specimen suface (space in testing cell that filled by agon) duing whole peiod of test. Venting of the test cell (hydogen/gas mixtue + agon) afte the tests ae finished. Safety valve and outlet of the gaseous mixtue to atmosphee. Notch Tube - Specimen Hydogen/Gas Mixtue Agon ACU PC Hydogen/Gas Mixtue + Agon Agon Agon Hydogen/Gas Mixtue Atmosphee Figue 7. Geneal view of designed testing equipment (potective housing is emoved) 7

3.2 Thee points bending tests Fo defects assessment of scatches and gouges, it is necessay to detemine factue toughness measued diectly on notched specimen [11]. Fo that we use a non standad specimen, named Roman Tile (RT) specimen, Fig. 8. The advantage of such a specimen geomety is to allow factue test in adial diection howeve the low thickness and the impotant cuvatue of the pipe. 40 mm 11 mm o 70 D=610mm t 0.2 t 45 =0.15mm Figue 8. Roman Tile specimen and notch geomety. The specimen is loaded by thee-point bending though a suppot A and suppoting olles B and C, Fig. 9. Suppot and olles wee poduced fom Poly Vinyl Chloide (PVC) to educe a fiction. All was monitoed fo a constant value of 0.02 mm/s. Test duation was of about 30 minutes. The V-notch with notch opening angle of 45 and oot adius of 0.15 mm was machined to a depth of size a simulating the expected gouge damage. Test specimens have notch aspect atio a / W = 0.2, W coesponding to the wall thickness. A special testing device has been developed fo this pupose. The bend-test fixtue was positioned on the closed loop hydaulic testing machine with a load cell of capacity ± 10 kn. 1 Angle = 60 A 4 2 C B 3 8 Figue 9. Roman Tile specimen fixtue and assembly 1 - connection with load cell; 2 - tansmitting component with ounded tip; 3 - connection of test assembly with the testing machine bottom; 4 Roman tile specimen

3.3 Hydogen electolytic chaging The study was conducted in a special soil solution NS4 with ph = 6.7, [12]. Chemical composition of this envionment is given in Table 3. In these conditions, i.e. in deoxygenated, nea-neutal ph solution, the hydogen atoms ae geneated on the steel suface by electochemical eduction of wate molecules: H2O+ e Hads + OH, (15) The adsobed hydogen atoms can subsequently combine into H 2 molecules by the chemical eaction: 2H ads H 2, (16) o the electochemical eaction: Hads + H2O+ e H2 + OH, (17) Table 3. Chemical composition of NS4 solution (gam/lite), [12] NaHCO 3 Cl CaCl 2 MgCl 2 H 2 O 0.483 0.120 0.137 0.131 Hee should be noted that, the absobed hydogen atom concentation unde the cathodic polaisation depends on the hydogen atom ecombination mechanisms. When the chemical eaction Eq. (16) dominates the hydogen atom ecombination, the applied cathodic polaisation enhances the geneation of hydogen atoms and thus the amount of hydogen atoms penetating into the steel. The absobed hydogen atom concentation will incease continuously with cathodic polaisation potential. In the case of electochemical eaction Eq. (17), dominating the hydogen atom ecombination, the cathodic polaisation pomotes the geneation of hydogen atoms though eaction Eq. (15), and simultaneously, enhances the hydogen atom ecombination though eaction Eq. (17). Thus, the ole of cathodic polaisation is to geneate hydogen atoms and also to ecombine hydogen atoms. Accounting the fact that a steady state condition of hydogen chaging cannot be imposed no obtained in a feely cooding situation, in the pesented study the following pocedue is made. Specimens wee hydogen chaged at constant polaisation potential E cath = 1000 mv SCE, which is slightly moe negative fo tested steel than fee coosion potential E co = 800 mv SCE. The specimens wee immesed into the cell with special NS4 solution and exposed unde constant potential of polaization, E cath. The suface of auxiliay electode was paallel to notch plane with the distance h = 20 mm. 4.0 RESULTS 4.1 Factue toughness Citical load was detected by acoustic emission as fo tests in ai, and hydogen condition [11]. The acoustic sensos have been potected against coosion fo tests unde hydogen electolytic. This citical load is then intoduced in a finite Element code to computed notch tip stess distibution. Then effective stess and effective distance ae combined though the Volumetic Method to obtain the citical notch stess intensity facto. Finite Element computing is made with the same stess stain cuve than fo ai because: thee is few diffeence of the behaviou in ai and in pesence of hydogen fo small stain, the hydogen affected volume is small compae with the total volume of specimens. 9

11 tests have been pefomed with ai condition, and 4 with hydogen electolytic condition (with 2 diffeent time of exposition, 145 hous and 330 hous). Results ae given in the following table: 4.2 Bust pessue Table 4. Factue toughness esults in tem of Ai 145 330 hous hous ρ ( MPa ) 57.21 47.68 41.78, c m Test esults showed that bust pessue fo test in methane is equal fo test in hydogen is equal p 122ba max = stength of notched pipes fo consideed testing conditions. ρ, c p 118 ba max = and bust pessue. Theefoe, thee is no gaseous hydogen effect on the 4.3 Mechanical popeties unde hydogen electolytic Tensile specimens have been used to chaacteize mechanical popeties of this steel in two envionment, ai and electolytic hydogen. Only a small pat of the specimen has been chaged unde hydogen, Fig. 10. The ultimate stength is few affected by hydogen concentation. Howeve, the elongation at factue is consideably educed as can be seen on Table 5. Isolation coating 4 mm Open metal suface 8 mm 8 mm Figue 10. Specimen used to the hydogen chaging. Table 5. Influence of hydogen concentation on tensile popeties of X52 steel. 10 Yield stess (MPa) Ultimate stength (MPa) Elongation at factue (%) Αi 453 524 14.03 Hydogen 479 547 11.44

4.4 Secuity and safety factos The MNFAD is then applied using the data epoted in tables 6 and 7. Table 6. Obtained values of effective distance, effective stess, notch stess intensity facto and hoop stess fo conditions descibed. ef (MPa m) X ef (mm) ρ (MPa m) θθ (MPa) 343 0.67 15.8 125 Table 7. Aveage of mateials popeties with and without hydogen; calculated values of paametes k and S.,c 0 u + y 2 k ρ ρ, c S = θθ 0 (MPa m) (MPa) Ai 57.21 496 0.276 0.252 Hydogen 44.73 513 0.35 0.244 The safety facto fo the same defect and fo the same sevice conditions, one fo mateial without hydogen embittlement, the second with hydogen embittlement ae then established. The coesponding values ae epoted in Fig. 11. One notes that hydogen embittlement leads to a eduction of the safety facto of 18.33%. 1,4 1,2 AIR HYDROGEN 1 0,8 R 0,6 0,4 0,2 0 Secuity facto AIR HYDROGEN INFLUENCE 2,97 2,55-14,21% Safty facto AIR HYDROGEN INFLUENCE 1,66 1,35-18,33% 0 0,2 0,4 0,6 0,8 1 1,2 L R Figue 11. Specimen used to the hydogen chaging. In hydogen condition, the secuity facto is deceased by 14%, but its value is always ove the conventional value of 2. The safety facto is somewhat moe affected, 18%. In sevee conditions, hydogen electolytic, the deceasing of the diffeent facto, is so acceptable. 11

5.0 CONCLUSIONS To assess nocivity of a pipe suface defect such as gouge, a modified Failue Assessment (MNFAD) as been established based on Volumetic Method (VM) of the notch factue Mechanics. This MNFAD is coupled with the SINTAP failue cuve and allows detemining the safety facto associated with defect geomety, loading conditions and mateial esistance. Detemination of the assessment point needs to detemine factue toughness in adial diection of low thickness and high cuvatue pipe. This has been done using a special specimen, the Roman Tile. Tensile popeties have been measued in electolytic hydogen chaging method. The obtained data coupled with the MNFAD method lead to the conclusion that in pesence of a sevee suface gouge defect, the eduction of the safety facto is 14 % but emains ove the conventional value of 2. These esults indicate the possibility to use the actual existing Euopean natual gas pipe netwok fo the tanspot of a mixtue of natual gas and hydogen. REFERENCES 1. Fenandes T. R. C., da Gaça Cavalho F. C. and M., HySociety in suppot of Euopean hydogen pojects and EC policy. Intenational Jounal of Hydogen Enegy, 30 (2005) 239-245 2. Mulde G., Hetland J. and Lenaes G. Towads a sustainable hydogen economy: Hydogen pathways and infastuctue. Intenational Jounal of Hydogen Enegy, 32, Issues 10-11 (2007) 1324-1331 3. NatualHy Poject, http://www.natualhy.net 4. Rappot de l enquête MH-2-95, Fissuation pa coosion sous tension des oléoducs et des gazoducs canadiens, Office National d Enegie, (1996) 5. J. Capelle, I. Dmytakh, J. Gilget, Ph. Jodin, G. Pluvinage, A compaison of expeimental esults and computations fo cacked tubes subjected to intenal pessue, Mateials and Technology 40, 233-237, (2006) 6. SINTAP: Stuctual Integity Assessment Pocedue, Final Repot E-U poject BE95-1462 Bite Euam Pogamme Bussels (1999). 7. G Pluvinage Factue and Fatigue emanating fom stess concentatos ; luwe, (2003). 8. Akoui O, Louah M, ifani A, Gilget G, Pluvinage G., The effect of notch adius on factue toughness J IC, Eng Fact Mech 65, pp 491-505, (2000) 9. J. Capelle, J. Gilget, I. Dmytakh, G. Pluvinage, Sensitivity of pipelines with steel API X52 to hydogen embittlement, Intenational Jounal of Hydogen Enegy 33, issue 24, pp 7630-7641, (2008) 10. Bust tests on pipes unde pessue of mixtue of hydogen and natual gas. Final epot on Subcontact No 1401-2005 of NATURALHY-Poject (Contact No SES6/2004/502661). apenko Physico-Mechanical Institute of National Academy of Sciences of Ukaine, Lviv, Ukaine (2006). 11. J. Capelle, J. Gilget, I. Dmytakh, G. Pluvinage, Hydogen effect on fatigue and factue esistance of a pipe steel, Stuctual Integity and Life, volume 9, n 1, pp. 9 14, (2009) 12. J. Capelle, I. Dmytakh, G. Pluvinage, Electochemical Hydogen Absoption of API X52 Steel and its Effect on Local Factue Emanating fom Notches, Stuctual Integity and Life, volume 9, n 1, pp. 3 8, (2009) 12