KIGAS Vol. 15, No. 5, October, 2011 (Journal of the Korean Institute of Gas) 운전압력상향을위한천연가스배관의신뢰성검토 백종현 김우식한국가스공사연구개발원 (2010 년 8 월 6 일접수, 2011 년 8 월 9 일수정, 2011 년 10 월 14 일채택 ) Reliability Assessment for Pressure Uprating of Natural Gas Transmission Pipelines Jong-hyun Baek Woo-sik Kim R&D Division, Korea Gas Corporation, Ansan 426-790, Korea (Received August 6, 2011; Revised August 9, 2011; Accepted October 14, 2011) 요약 국내천연가스주배관의가스공급최대허용운전압력이 6.86 MPa 로제한된현재상황에서배관관말압력저하를해소하기위해서는배관을증설할수밖에없는데이경우상당한비용이수반된다. 따라서기존배관과설비를활용한해결방안으로송출압력을더높여배관운전압력을상향조정하여공급하는방법을검토하였다. 배관에대한건전성검토결과, 현재시공된배관은 7.85 MPa 까지의운전압력에서도사용가능하며, 연성파괴에대한저항성을나타내는충격흡수에너지는 ASME B31.8 에서요구하는수치보다더높은값을가지고있으며, 외부충격손상시배관변형을위한소요하중은배관내압증가에따라증가하였다. 그러나배관의운전압력이증가함에따라가스폭발시피해범위는증가한다. Abstract - It is required to construct the pipelines to eliminate pressure drop at the end of transmission line under limitation of maximum operation pressure of 6.86 MPa, however, it highly costs to build the pipelines and takes time-consuming job. Higher operation pressure compared to current operating pressure has been considered to resolve the problem of pressure drop without modification of the existing pipelines and facilities. As a result of the integrity evaluation, the existing pipelines can be operated up to 7.85 MPa in terms of wall thickness and have higher Charpy impact energy than required value in the ASME B31.8. However, Increment of operation pressure gives rise to increase potential impact area if the pipelines burst due to third party damages. Key words : API 5L X65, charpy impact energy, potential impact area, uprating, wall thickness { 서론 Ý d œ d d Œ} Œ o m e d ds ~ ~ s u s j xv w oú r ~ d ds d ~ x x { 주저자 :jhbaek@kogas.re.kr w d. d } u 6.86MPa s u v ~ ~ s t sœ t ~ s w s. œ ~} v s tv ó ~ t s } s qjs s d [1,2]. 1984ë i 6.89MPa x ~ s 2006ëŸ { } ~ e 55% 2,863km ~ s 7.5~8.5 MPa - 1 -
백종현 김우식 ts, 35ë w} w 30 10.3~15.88 mm API X56, St53.7, St 60.7 ~ s 100km e s u 20% t g s [1,2]. d ~ t jt ~ d d v s Ú t ~} ~ g s d. d h s q s ~ x, p v s i s p odsœ s } p pts Ý, s, Ý } s s,, }s, p s v s t s x p u s h s qjd s s. t vt ~ t o d s ~Ý q ts w, vt ~ t ASME B31G, API 579 BS 7910 t od s{ n v } ~ s ~ p q t d s. s, t n t s s uy å f s qj ASME B31.8 API 5L u v s{, t ~ e s u od s i s } q t s [3-7]. t q s ~ qjt s t x ~, uy å od js nƒ t od, d p st d s t js u s Ý d ~ w 30 API X65 ~ ods. 운전압력상향에대한평가결과 d ~ t ~ p t odsœ s ~, nƒ s t, p st h} s u s ods. 배관두께검토 d ~ t ~ t qj s. Ý d ~ KGS FS451 code t x [8]. d ~ x s œ (1) ASME B31.8 part 841.1.1 os [9]. á Table 1. Required wall thickness with variation of internal pressure for API X65 of location class "Ga" and "Na" in KGS FS451 code Pressure (MPa) 6.86 7.85 8.23 (1) Ï žÿ t : ~ (mm) P : x (MPa) D o : ~ w (mm) S : t f (MPa) E : w (SAW, ERW Seamless ~=1) T : x (121 s=1) F : xx (0.8~0.4) Location class 1, Division 1=0.8 Location class 1, Division 2=0.72 Location class 2=0.6 Location class 3=0.5 Location class 4=0.4 Location classd 4 w xx 0.4 Ý d ~ s{. xx d 0.5 Location class 3 ~ Ú ~ s {. d 4 p j s } Ú s{ [8]. w 30 API X65 d } Ú ~ s x v ~ q 1 ÚhÝ. Ý 6.86MPa d ~ 14.6mm, 8.23MPa 17.5mm ~ d s s. Location Class (D.F) Wall thickness (mm) Thickness tolerance (%) "Ga" 14.60 16.60 "Na" 11.68 18.32 "Ga" 16.68 4.69 "Na" 13.34 6.71 "Ga" 17.50 0.00 "Na" 13.99 2.17 KIGAS Vol. 15, No. 5, October, 2011-2 -
운전압력상향을위한천연가스배관의신뢰성검토 Table 2. Required wall thickness and constructed wall thickness for API X65 at location class "Ga" and "Na" Location class (D.F) Ga (0.4) Na (0.5) Pressure (MPa) Calculated thickness (mm) Constructed thickness (mm) 6.86 14.60 17.5 7.85 16.68 17.5 6.86 11.68 14.3 7.85 13.34 14.3 Ú ~ Ý 6.86MPa ~ 11.68mm, 8.23MPa 13.99mm ~ d s s. d ~ ~ d 17.5mm œ ods Ý 8.23MPa 6.86MPa f s 16.6%Ÿ ds. u Ý d ~ } 17.5mm d ~ 8.23MPa Ý Ÿ d s. q 2 w 30 API X65 ~ d } Ú t x ~ } ~ Ý ÚhÝ. 7.85MPa w } ~ u s q ª ~ }. u } ~ 7.85MPa d s. 연성파괴에대한저항성 w 16 d ~ t f 40~80% ÚhÝ nƒ n s nƒ s s s [9]. nƒ s v jt s nƒ u API 5L SR5 ( u u ) API 5L SR6 (DWTT u ) s. u u w o 60% n, DWTT u w 40% n ÚhÝ s f q ods. nƒ s uy å (2)~ (5) s x s ASME B31.8 part 841.1.2 Fracture Control and Arrest" [9]. (a) Battelle Columbus Laboratories (BCL) œ á í Î Õ Ï Þ«ß ÎîÐ (2) Table 3. Minimum impact energy to arrest ductile fracture (unit: Joule) Location class (D.F) Ga (0.4) Na (0.5) Eqs. Pressure 6.86MPa 7.85MPa BCL 7.27 9.50 AISI 9.54 11.66 BGC 8.73 9.98 BSC 4.78 6.24 BCL 10.08 13.17 AISI 12.80 15.63 BGC 11.71 13.38 BSC 7.07 9.23 (b) American Iron and Steel Institute (AISI) œ á í ÐÎÒ ÎíÒ Þ«ß íò (3) (c) British Gas Council (BGC) œ á í ÐÎÒ «î íò (4) (d) British Steel Corporation (BSC) œ á í ÎÎÖ Ï «(5) CVN : uy å (ft-lb) R : ~ w (in.) t : ~ (in) P D o : (ksi), á Ï : x (ksi) : ~ w (in). (2)~ (5) ~ w, Ý t. (2) d uv, (4) d u v s, w Ú (3)} (5) fuv t q œ ~ t. q 3 w 30 API X65 ~ s d } Ú t v ~ uy å (2)~ (5) t ÚhÝ. d ~ t Ú ~ w d ó uy å ÚhÝ{. ASME B31.8 4 d ó uy å s (3) 7.85MPa ~ w 30 API X65-3 - ï d 15 5 2011 10
백종현 김우식 500 ) ( J y r g e n E t c a p Im y p r a h C 400 300 200 100 0 X65 - LT X65-45 o X65 - TL Design Temp. (-29 o C ~ 38 o C) -120-100 -80-60 -40-20 0 20 40 60 Test Temp.( o C) Table 4. Effect of internal pressure on the potential impact area Outer Diameter (in) 30 26 20 Operation pressure (MPa) Radius of potential impact (m) 6.86 199.1 7.85 212.8 6.86 172.5 7.85 184.5 6.86 132.7 7.85 141.9 Fig. 1. Charpy impact energy for API X65. ~ nƒ n s uy å 15.63J od. 1 ASTM E23 u o Ý d ~ API X65 ~ v uy å v s uv} Úh Ý q [10]. X65-LT u u ð t t ~ t, 45 o ~ t 45 o, X65-TL ~} ots t. Ý t ~ nƒd s w ~ t nƒd s, ð t t ~} ots TL uy å f nƒ t od. 1 x e X65-TL uy å vd g Ú, w uy å d uy f s{ -60 w nƒ o ÚhÝ. d ~ x uy å 350J ÚhÝ{, 350J uy å Ý 7.85MPa ASME B31.8 nƒ t s uy å 15.63J s y ó f. u } d ~ w 6.86MPa 7.85MPa t nƒ n s uy å u s{ s y ó f d {. 가스폭발시피해범위 d ~ t ~ p st u ASME B 31.8S ods. u { d } {v} t t v { d v} f u f s. { d s w d p t t w (6) t [11]. d p s st ~ w } ~ ~ w} Ý dt ds. á í ÐÎÒ ö (6) r = radius of the impact circle (m) d = outside diameter of the pipeline (mm), p = pipeline segment s maximum allowable operation pressure (kpa) q 4 Ý d d p st (6) t x v}. w 30 ~ Ý 6.86MPa w st w 199.1m Ý 7.85 MPa w 212.8m Ý 0.99MPa dt st w 13.7m ds., d ~ 6.86MPa 7.85MPa t w d p s st w 6.9% ds. 외부충격손상시소요하중효과 d ~ v mvt s v odsœ s h t ABAQUS Ver. 6.9 s s t [12]. ~ w 30, 17.5 mm w (D/t) d 43.54 p t ods. ~ s 8 g d (8-nodes isoparametric brick reduced integration KIGAS Vol. 15, No. 5, October, 2011-4 -
운전압력상향을위한천연가스배관의신뢰성검토 (a) indenter diameter : 80 mm (b) indenter diameter : 160 mm s u Ô w 80, 160 320mm s. mvt ~} u usœ s 0.3 x s surface p s. Brooker w 914mm, 6.4mm 12.5 mm API X70 ~ s s ~ ~j s s t jt ods Ý 0 12 MPa dt ~ ~j s 409kN 461kN ds, API X42 ~ w Ý 0 3MPa dt 162kN 165 kn ds { {s [13]. Liu w 24, 6.35mm w 36, 12.5mm API X52 API X65 ~ s s t v} ~ w, ~x mvt s Ý dt ds { {s [14]. 2 w 80, 160 320mm w s Ý w Ý 4, 8 16MPa w m Ÿ v s } s s t v}. s t ~ m Ÿ w, os, jt o w ~ u Ÿ ods. Ÿ os ~ Ÿ f s ~ h v t q. Ý w d Ý w s Ÿ m vt sœ t s. d ~ Ý w d s s t d q od, s Ý d t s s dt. 결론 d ~ t ~ t ods v} s g. (c) indenter diameter : 320mm Fig. 2. Force-dent depth with variation of initial internal pressure during denting element, C3D8R) s, ~ œss u, s p } s t w s 1/4 s. mvt 1) ~ xœ qjv}, u } API X65 ~ 7.85 MPaŸ d s. 2) u } API X65 ~ 7.85 MPa nƒ t ÚhÝ uy å d ASME B31.8 s ó f d {. - 5 - ï d 15 5 2011 10
백종현 김우식 3) ~ Ý dt d p st ds, 6.86 MPa 7.85 MPa ds st w 6.9% d s 4) u ~ u s s s ~ Ý d ds. 참고문헌 [1] Howard G. Murphy, Jr., Reconsideration of Maximum Allowable Operating Pressure: Costs and Benefits -Macroeconomic View, Proceeding of Reconsideration of Maximum Allowable Operating Pressure for Class Locations, March 21, (2006) [2] Mark Docherty, Experience with the Pressure Uprating of Gas Transmission Pipelines in the United Kingdom, Proceeding of Reconsideration of Maximum Allowable Operating Pressure for Class Locations, March 21, (2006) [3] Charanjit Jandu, Paul Cousens, Steve Wheat and Neil Bramley, An integrated integrity management approach to uprating high pressure gas transmission pipelines and above ground installations, IPC04-0604, Proceedings of International Pipeline Conference 2004, Calgary, Alberta, Canada, American Society of Mechanical Engineers, (2004) [4] Francis, A, Edwards, A.M. & Espiner, R.J., Guidelines For The Use of Structural Reliability and Risk Based Techniques To Justify Operation of Onshore Pipelines at Design Factors Greater Than 0.72, Proceedings of 21st World Gas Conference, Nice, (2000) [5] Rainer H., Thomas P., Two-step method verifies uprating of older german gas pipeline, Oil & Gas Journal, March 1, (2004) [6] API RP 579, Fitness-for-Service, American Petroleum Institute, (2007) [7] BS 7910, Guide to methods for assessing the acceptability of flaws in metallic structures, British Standards Institution, (1999) [8] Facility / Technical / Inspection / Safety Diagnosis Code for Pipes Outside of Producing and Supplying Places of Wholesale Gas Business, KGS FS451, (2009) [9] ASME B31.8 Gas Transmission and Distribution Piping Systems, (2010) [10] KOGAS Research Report, A study on fracture behavior of natural gas pipelines, (1997) [11] ASME B 31.8S Managing System Integrity of Gas Pipelines, (2010) [12] ABAQUS version 6.9, ABAQUS Inc., Rhode Island, USA, 2009. [13] Brooker D.C., Numerical modelling of pipeline puncture under excavator loading. Part II: Parametric study, Int. J. Pressure Vessels and Piping, Vol. 80, Issue 10, pp. 727~735, (2003) [14] J.H. Liu, A. Francis, Theoretical analysis of local indentation on pressured pipes, Int. J. Pressure Vessels and Piping, Vol. 81, pp. 931~939, (2004) KIGAS Vol. 15, No. 5, October, 2011-6 -