Next Energy, With KOGAS. 5 th April 2017 Chusung Son KOGAS

Transcription

1 Next Energy, With KOGAS 5 th April 2017 Chusung Son KOGAS

2 Contents 1. Introduction 2. Historical Trail 3. Diagnosis & Overhaul Decommissioning Preparation & Inspection Repair, Reinforcement & Restoration Commissioning 4. Conclusion Next Energy, With KOGAS

3 1. Introduction KOGAS is operating 69 LNG storage tanks in four LNG terminals with the capacity of 10,660,000kl. Terminal Tank No. Capacity(kl) Type Remark 1 ~ ,000 Membrane Pyeongtaek 11 ~ ,000 Above-ground 9%-Ni 15 ~ ,000 1 ~ ,000 9%-Ni Above-ground Incheon 11 ~ , ~ ,000 Membrane In-ground 1 ~ ,000 Tongyeong 13 ~ ,000 9%-Ni Above-ground ,000 1 ~ 9 200,000 9%-Ni Above-ground Samcheok Above-ground 10~12 270,000 9%-Ni (Under Construction) Next Energy, With KOGAS 1

4 1. Introduction Changing Circumstances for Tank s Operation A few tanks have deteriorated after many years(more than 15 years) of operation Performance of tank s auxiliaries has degraded for long term operation LNG storage tank s management criteria have been tightened following consolidation of the gas industry law and regulation in Korea Safety of internal tank has to be checked and guaranteed considering tank s deterioration The view of maintenance against LNG storage tank has to be changed to meet such circumstances. Diagnosis & Overhaul is its solution! Next Energy, With KOGAS 2

5 2. Historical Trail Status of Tank Diagnosis & Overhaul Terminal No. of Tank Period Status Main Overhaul Contents Conduction Pyeongtaek ~ Completion Steel Roof Membrane KOGAS Incheon ~ ~ ~ Completion In Progress Defect Repair Steel Roof 9% Ni Vapor Barrier Constructor KOGAS Tongyeong ~ In Progress Steel Roof 9% Ni Vapor Barrier KOGAS Next Energy, With KOGAS 3

6 2. Historical Trail Criteria of Tank Diagnosis & Overhaul After the First Overhaul Item DIke 9% Ni No Dike Membrane Remark Inspection Period Per Tank 1 Implementation Per 2 Years All of Tanks Steel Roof O O O Sealing Welding Reinforcement Inner Tank O O O Vapor Barrier O O X Non-destructive Inspection & Repair if required Auxiliaries O O O Renewal during operation stop Next Energy, With KOGAS 4

7 3. Diagnosis & Overhaul of Tank Membrane Tank Work Section Decommissioning Preparation Inspection before repair Repair, Reinforcement & Restoration Commissioning Work Breakdown Structure LNG pumping & natural vaporization Tank separation & quality verification N2 purge, aeration & tank opening Temporary equipment installation Disassembly at deck upper area Steel roof & membrane inspection (He/NH3 Test, PT, VBT, ATT) Roof repair, reinforcement & inspection Membrane repair & inspection Tank Test (Global & AE Test) Temp. equipment disassembly & Restoration N2 & FG purge Tank nozzle connection & cool-down LNG filling & pump test run Next Energy, With KOGAS 5

8 3-1. Decommissioning Pumping of LNG inside tank : Until the lowest liquid level Natural Vaporization : When -20 at membrane bottom Tank Isolation : Piping is blocked off by blanks & BL flanges Quality Verification : Sampling, Soundness Test, Global Test Nitrogen Purge : Supply BOG Recovery Flaring Vent Aeration : Until internal tank condition more than 20% of O 2 Tank Opening & Initial Entry Next Energy, With KOGAS 6

9 3-1. Decommissioning Tank Opening & Entry Field Control Center Pre-Safety Inspection Tank Opening Inspection of Deck & Bottom Tank manhole entrance installation Tank personnel management Tank isolation verification Air injection into tank Animal survival test : Canary, Hamster 1 pair (more than 12 hours) Manhole cover opening Gas dome spare nozzle opening Entry personnel : 3 persons O2 & gas concentration is measured at each stair landing on the entry ladder Verification of gas existence Next Energy, With KOGAS 7

10 3-2. Preparation Temporary Equipment Installation & Disassembly Crane Material Rack Equip. & Structure For Transportation Fall Prevention Scaffolding Protective Plywood & Corrugated Iron Scaffolding for Inspection of Roof Gondola for Membrane Inspection Electric Equipment Air Injection & Exhaust Fan Disassembly of Insulation & Plywood Next Energy, With KOGAS 8

11 3-3. Inspection Non-destructive Test for Steel Roof Object Method Q Section Visual / He R Section Visual / He Object Section Outside Area Main Body S Section Visual / He / NH 3 T Section Visual / He / NH 3 U Section Visual / He / NH 3 Base Material Nozzle Area Defect Repair Main & Stiffener Beam Lug & Bracing Area Base Material Lap Joint Visual Visual / He / ATT Visual / He / PT/ VBT Visual / PT / ATT/ VBT Visual / PT / VBT Visual / PT / VBT PT / He / ATT / VBT (S) (T) (U ) (Q) (R) Carbon Steel Stainless Steel Stainless Steel Next Energy, With KOGAS 9

12 3-3. Inspection Non-destructive Test for Membrane Object Method Welding Area Visual / NH 3 Wall Base Material Defect Repair Area Visual Visual / NH 3 / PT / VBT Welding Area Visual / NH 3 Bottom Base Material Defect Repair Area Visual Visual / NH 3 / PT / VBT Next Energy, With KOGAS 10

13 3-3. Inspection 1. Helium Test 2. NH 3 Test 3. PT 4. VBT 5. ATT He is injected in the space between steel roof outside area and concrete roof and then defects of material and welding area are inspected. Helium Injection Zone B(2 nd ) Zone A(1 st ) (S) (T) (U) (Q) Helium Injection (R) Carbon Steel Stainless Steel Stainless Steel Zone C(3 rd ) Zone D(4 th ) Zone A : Outer Roof (Q~R) Zone B : Outer Roof (S~U) Zone C : Nozzle Area Zone D : Lap Joint Welding The measured helium concentration value shall not exceed the initial helium concentration one at all of inspected areas. Next Energy, With KOGAS 11

14 3-3. Inspection 1. Helium Test 2. NH 3 Test 3. PT 4. VBT 5. ATT The gas mixed with nitrogen and ammonia is injected into IBS and ammonia response paint is applied to the membrane welding areas to check if they are defected by the change in color. Reference Leakage Point Inspection of Color Change When there is no change in color to the parts where the response paint was applied, it is accepted. Next Energy, With KOGAS 12

15 3-3. Inspection 1. Helium Test 2. NH 3 Test 3. PT 4. VBT 5. ATT After the steel roof and membrane are repaired, PT is used to check if the base metal and welding areas have defects on their surface or not. Penetration Test When there are no defects found on them, it is accepted. Next Energy, With KOGAS 13

16 3-3. Inspection 1. Helium Test 2. NH 3 Test 3. PT 4. VBT 5. ATT It is a test to find the defected parts by applying bubble solution on the surface of the inspected specimen. The inspector attaches it to the vacuum box, form the negative pressure and find the forming bubbles through the leakage part. Vacuum Box Test When there is no leakage indicated by the bubble solution, it is accepted. Next Energy, With KOGAS 14

17 3-3. Inspection 1. Helium Test 2. NH 3 Test 3. PT 4. VBT 5. ATT In order to maintain air tightness against the steel roof reinforced parts, air is supplied to the inside of the reinforcement welding area to apply bubble test solution to the welding areas in a pressurized state to find the leakage position. Injection of Air Bubble Test to Welding Area When there is no leakage indicated by the bubble solution, it is accepted. Next Energy, With KOGAS 15

18 3-4. Repair & Reinforcement Repair & Reinforcement for Steel Roof The disparate space between the steel roof main beam including stiffener beam and the steel roof plate is reinforced as welded with the same material. Reinforcement Welding Reinforcement Plate Roof Plate Roof Plate Reinforcement Plate Existing Welding Main Beam Welding Main Beam & Roof Plate Welding Stiffener Beam & Roof Plate The defects of the steel roof which are founded by visual inspection and non-destructive test such as He, NH3, PT, VBT, ATT are repaired. Next Energy, With KOGAS 16

19 3-4. Repair & Reinforcement Painting for Steel Roof Metal Silicon Application : The metal silicon on the irregular welding surface of the steel roof repair welding and original welding parts is strengthened Rust Grip Application : The rust grip is to prevent the steel roof reinforcement welding parts and original steel plate welding ones from corrosion. Next Energy, With KOGAS 17

20 3-4. Repair & Reinforcement Repair for Membrane The repair welding is performed on the membrane defects founded through the visual test and non-destructive test. Order of Repair Welding Division Object 1 st Defect parts by visual/helium/ammonia test 2 nd Insulation sampling areas and defect parts of RLP, 2 nd ammonia test 3 rd Defect occurred area after the 2 nd ammonia test completion Defect parts of RLP and 2 nd ammonia test Repair Method Damage Type Judgment Standard Repair Method Surface Dent Round Type(under 150µm) Spot Hole type (over 150µm) No Repair Flat Patch Welding Surface Scratch When performed Power Brush, Sand Paper Next Energy, With KOGAS 18

21 3-5. Test After Repair & Reinforcement Acoustic Emission Test : Final inspection for soundness of roof Global Test : Final inspection for soundness of membrane Acoustic Emission Test a. Sensor attachment & cable monitor connection b. Background noise is measured before pressurization c. AE Signal Collection at 20kPa d. Acceptable when signal related to leakage is not detected Global Test a. Nitrogen sweeping in IBS b. Tank inner pressure is pressurized from 0 to 20kPa c. Trend of O 2 concentration in IBS is recorded & analyzed d. Acceptable when O2 concentration averaged value difference between reference & actual test is lower than 1,500ppm Next Energy, With KOGAS 19

22 3-6. Restoration Temp. Equipment Disassembly a. Scaffolding boards for inspection b. Gondola, safety equipment for repair c. Protective plywood & corrugated sheets d. Structure & winch for entry of material e. Exhaust fan & temp. material storage f. Crane & temp. electric equipment Reinstallation of Insulation a. Transportation of new glass wool inside tank (approximately 50% of total quantity) b. Installation of plywood & box type of glass wool at outer deck c. Installation of aluminum coating glass wool at work aisle, middle area & nozzle area on deck Next Energy, With KOGAS 20

23 4. Commissioning N2 & FG Purge N2 Purge : Decreasing oxygen concentration & dew point until the acceptance criteria FG Purge : Filling with methane into tank(40vol%) Pipe Normalization Normalization of pipes Disassembly of blanks & BL flanges Cool-down& LNG Filling LP Pump Test dddddddd & Operation Cooling of internal tank with spray nozzle Filling level : 5m or more, Temp. at bottom : -155 마감처리개선 (Glass cloth 단은 Glass Wool) Checking discharge pressure, flow rate, vibration Normal operation resumption Next Energy, With KOGAS 21

24 5. Conclusion Internal Tank & Steel Roof Without Maintenance New Developed Maintenance [ Diagnosis & Overhaul Technique ] Extension of Usable Lifetime The highest Safety Level Deterioration Occurrence to internal tank & steel roof during long operation Potential hazardous factors such as gas leakage, BOG increase, etc. Extended construction of storage tanks due to shorten lifetime Cost increase Saving Cons. Cost Removal of Hazards Next Energy, With KOGAS 22

25 Next Energy, With KOGAS