TFC KAOHSIUNG FACTORY 30 KMT AMMONIA STORAGE TANK INSPECTION REPORT. By: Jackson Yang (TFC R&D Department) 01 Oct 2016

Transcription

1 TFC KAOHSIUNG FACTORY 30 KMT AMMONIA STORAGE TANK INSPECTION REPORT By: Jackson Yang (TFC R&D Department) 01 Oct

2 CONTENT 1. Introduction 2. Internal Inspection Planning 3. Applied Inspection Technique 4. Inspection Findings 1) External & internal visual inspection 2) Bottom plates corrosion test & UT measurement 3) Bottom plates weld WFMP test 4) Bottom plates & shell plates joint weld WFMP test 5) Shell plates weld WFMP test 6) Accessories weld WFMP test 7) Mechanical properties test 5. Summary 2

3 1. Introduction

4 Description of Ammonia Storage Tank T-101 T-101 is a flat bed, double wall & double roof anhydrous liquid ammonia storage tank. The internal wall is constructed with low temperature resistant steel plate and outer wall is constructed by steel covered with reinforced concrete wall. Inside of external wall has 6m/m layer of low temperature resistant steel and a layer of insulation cotton. The internal tank dimension is 48 meter diameter and 38 meter height with 60,000 cubic meter volume. The design storage capacity is 30,000 MT anhydrous liquid ammonia. All the tank nozzles and transfer pump connections are located at the tank roof, there is no any nozzle connection at the side or bottom of the tank. The tank was designed and constructed in 1987 by Mitsubishi Heavy Industries & Chiyoda Tank Engineering Corporation, Japan. For 27 years ( ), this tank was well maintained and successfully operated without incurring any incident related to safety or environmental issues.

5 Ammonia Tank T-101 Outline 5

6 Ammonia Tank T-101 General Assembly 6

7 T-101 Equipment Name Plate (Design Specification)

8 Ammonia Tank T-101 Annular space 8

9 2. INTERNAL INSPECTION PLANNING

10 Inspection Planning 1. Inspection Party: Taiwan Metal Quality Control Co., LTD (TMQC) 2. Inspection Date: Inspectors got entry permit to start T-101 internal inspection on 7 Jun The field inspection, testing & data collecting were completed on 17 Jun Inspection Program: Refer to the inspection methodology & scope in the next slides. 10

11 T-101 Inspection Program-1 Inspection area Technique Description 1. Tank internal and external structure 2a. Corrosion test of bottom plates on both soil side & chemical side 2b. Corrosion test of Annual Ring Plate on both soil side & chemical side 2c. bottom plates ultrasonic thickness measurement 2d. bottom plates welds 3. Bottom and wall joint welds Visual Inspection Floor Mapping test (Magnetic Flux Leakage test, MFL) Hand Type Floor Mapping test Ultrasonic thickness monitoring (UT) Wet fluorescent magnetic particle test (WFMP) Wet fluorescent magnetic particle test (WFMP) Visual inspecting bottom plates, wall plates, ceiling plates, fittings, nozzles for any deformation, bulging, dents, corrosion, cracking and localized corrosion. Keep the photographic record. Apply Floor Mapping to test all bottom plates for any corrosion on both soil side & chemical side. Against the corrosion parts, apply Ultrasonic thickness test to measure the plate thickness. Apply Hand Type Floor Mapping to test annular ring plates and the area that Floor Mapping cannot reach. Against the abnormal parts, apply Ultrasonic thickness test to measure the plate thickness. Take 6 samples of each selected plate ( 30 cm from 4 corners and 2 at center region) to do UT measurement for observing corrosion rate and trend. Bottom plates are the most loaded and stressed area. Apply WFMP test to samples of 30 cm from left & right each for all T and Y welds. To do WFMP test for 100% bottom and wall joint welds. 11

12 T-101 Inspection Program-2 Inspection area Technique Description 4. Shell plates welds Wet fluorescent magnetic particle test (WFMP) 4a Shell plates thickness measurement Ultrasonic thickness monitoring (UT) 5. Accessories welds Wet fluorescent magnetic particle test (WFMP) 6. Pseudo installation welds 7. Against crack or corrosion on welds 8. Mechanical properties test Wet fluorescent magnetic particle test (WFMP) ultrasonic phased-array detector test 1. Apply WFMP to vertical welds (50 cm above bottom plate) in course Apply WFMP to 100% horizontal and vertical welds in course 1 and 2 (50 cm left & right and 50 cm up & down). Take 6 samples of each shell plate from course 1 & 2 (30 cm from 4 corners and 2 at center region) to do UT measurement. 1. Apply WFMP to all manhole welds and fitting welds. 2. Apply WFMP to pump seat casing welds. 3. Apply UT to 2 samples of pump seat casing plates. Apply WFMP to 10% samples. When observing weld cracks or corrosion, apply advanced ultrasonic phased-array detector for further 3- D imaging detection. 1. Take 2 samples each of bottom plates from center, half radius and near wall to do pull test. 2. Take 2 samples each of wall plates from course 1 & 2 to do pull test.. 12

13 3. APPLIED INSPECTION TECHNIQUE

14 Applied Inspection Technique Technique Inspection Area Remarks Visual Testing Tank bottom/shell/roof View deformation, bulging, dents, corrosion, cracking, localized corrosion. Magnetic Flux Leakage test (MFL) Ultrasonic gauging (UT) Wet Fluorescent Magnetic Particle Testing (WFMP) Mechanical Properties Testing Tank bottom plates/annual Ring Plate Bottom/shell plate (including vaporliquid phase interface)/roof (A) the base plate bead comprising an annular plate, (B) the bottom wall bead, (C) wall weld: horizontal and vertical bead, (D) the top wall groove weld, (E ) tank top bead, (F) on the tank nozzle (or cannula) bead Sampling: chassis / shell plate / roof of the weld and the base material, each three pieces Corrosion test of bottom plates on both soil side & chemical side Measure steel plates thickness Inspect orientation: Vertical & horizontal bead, wall covering at least a gas and liquid phase region. Refer to the next slide for sampling location. Test items: (A) Tensile test: room temp. (B) Impact test: -33 (C) Hardness test: room temp. 14

15 WFMP Sampling Area & Location Course n+1 Course n Course 2 Course 1

16 Scope of Internal Inspection Step 1: Initial inspection Step 2: The 2 nd inspection if any defect found during initial inspection. Step 3: The 3 rd inspection if any defect found during the 2 nd inspection.

17 4. INSPECTION FINDINGS

18 1A: External visual inspection findings Tank external ladder was corroded at some parts and tank top platform and handrail were found corroded and deformed. Roof handrail corroded and deformed Roof platform corroded 18

19 1B: Internal visual inspection findings During visual inspection, found 2 bolts of internal pipe flange connection were missing and an impact dent of 1.5 mm depth at bottom plate. No other abnormality was observed at internal tank. 2 bolts missing Impact dent (A16) 19

20 2A: Bottom plates corrosion test and UT measurement Applied UT to measure the corrosion rate. The design bottom edge plate thickness was 19.0 mm, UT test result was 19.2~19.6 mm, no soil side corrosion found. The design other bottom plate thickness was 4.8 mm, UT test result was 4.9~5.2 mm, no soil side corrosion found. Bottom plates MFL test Bottom plates UT measurement 20

21 2B: Bottom plates corrosion test and UT measurement The bottom plates were numbered from A1to A139. Applied MFL(Magnetic Flux Leakage test) to do floor mapping, found 6 defects. After visual confirmation, 1 defect at ring plate was impact dent (A1) and the other 5 defects were chemical side corrosion. Impact dent (A1) Bottom plates numbering (A1~A139) 21

22 2C: Bottom plates corrosion test and UT measurement Applied MFL to do floor mapping, found 6 defects. After visual confirmation, 1 defect at ring plate was impact dent and the other 5 defects were chemical side corrosion (A20*2/A22/A30/A68). corrosion defect (A20) corrosion defect (A22) corrosion defect (A30) corrosion defect (A68) 22

23 3: Bottom plates T & Y welds WFMP test For T & Y welds of bottom plates, applied WFMP test at 30 cm left and right areas. No crack at first or second layer was found. Bottom plates T welds WFMP test Bottom plates Y welds WFMP test 23

24 4: Bottom and shell plates joint welds WFMP test The joint welds of bottom and shell plates are the most loaded and stressed area, applied WFMP to do 100% test, no crack at first or second layer was found. Bottom & shell plates joint welds WFMP test Bottom & shell plates joint welds WFMP test 24

25 5A: Shell plates welds WFMP test and UT measurement Apply WFMP to vertical welds at 50 cm above bottom plate in course 1 and horizontal and vertical welds in course 1 and 2 at 50 cm left & right and 50 cm up & down for 100% test. No crack at first or second layer was found. Shell plates welds WFMP test Shell plates welds WFMP test 25

26 5B: Shell plates welds WFMP test and UT measurement Take 6 samples for each shell plate from course 1 & 2 (30 cm from 4 corners and 2 at center region) to do UT measurement. The design plate thickness of course 1 was 30.3 mm, the UT test result was 29.9~30.2 mm, no shell plate corrosion in course 1 found. The design plate thickness of course 2 was 27.4 mm, the UT test result was 27.2 mm, no shell plate corrosion in course 2 found. Shell plates UT measurement Shell plates numbering (S1 & S2) 26

27 6: Accessories welds WFMP test Apply WFMP to 2 sets of manhole welds and submerged transfer pump fitting welds. No crack at first or second layer was found. Northern manhole WFMP test Southern manhole WFMP test 27

28 7: Mechanical properties test The sample tank plate pieces were subjected to three kinds of mechanical properties tests: the tensile test, positive bending & back bending test, low temperature impact test. Photo of sample tank plate test pieces 28

29 7A: The tensile test result: Compared with the ASTM standard values, all test pieces are in line with the standard, only No. 8 bottom plate yield strength less than the standard value 1N /mm 2. Observed 3 groups of test pieces, the fracture points are also fall in the base metal, showing the bead strength is higher than the base metal required strength. S# Test Pieces Description Cross area (mm 2 ) Ultimate strength (N/mm 2 ) Yield strength (N/mm 2 ) Elongation % (G.L= 200mm) STD ASTM A537-CL Fracture point No.1 Sidewall bead test piece 1S Base metal No.2 Sidewall bead test piece 2S Base metal No.3 Outer ring plate bead A Base metal No.4 Sidewall metal test piece 1S No.5 Outer ring plate metal A No.6 Sidewall metal test piece 2S No.7 Bottom plate metal A No.8 Bottom plate metal A

30 7B: Positive & back bending test result: The presence of crack of No.4 ~ No.8 test pieces in the positive bending and back bending test are not found, indicating that the material anti-bending ability is still quite adequate after 29 years of use. S# Test Pieces Description Positive bending test Back bending test No.4 Sidewall metal test piece 1S-12 No crack No crack No.5 Outer ring plate metal A11 No crack No crack No.6 Sidewall metal test piece 2S-10 No crack No crack No.7 Bottom plate metal A76 No crack No crack No.8 Bottom plate metal A81 No crack No crack 30

31 7C: Low temperature impact test result: No.4 to 6 test pieces were made to a V-notch of 10x10x55 size. The three test pieces had high absorption energy of 260J, 112J &182J. It indicates that the side wall and bottom plates in the lowtemperature area still has a very good toughness, did not change into brittle material and still meet the standard requirements after long-term service. S# Test Pieces Description V-notch (mm) No.4 Sidewall metal test piece 1S-12 No.5 Outer ring plate metal A11 No.6 Sidewall metal test piece 2S-10 Test Temp. ( o C) Absorption Energy (J) 10*10* *10* *10*

32 5. SUMMARY

33 T-101 Inspection report summary The UT measurement had been done for T-101 shell plates in course 1 & 2 (S1 & S2) and bottom plates: The design and actual thickness difference for shell plates S1 is 0.1~0.4 mm and for S2 is 0.1~0.3 mm. The bottom plates thickness measurement showing the actual is higher than design value. T-101 was operating in the condition of -33 o C and there was no corrosion mechanism available. Therefore, it is reasonable to conclude that the thickness difference between design and actual is resulting from manufacturing tolerances of the plates during construction. 33

34 T-101 corrosion rate & remaining life assessment Based on thickness measurement data, the corrosion rate and the tank remaining life are calculated: T-101 corrosion rate is mm/year. T-101 remaining life is 43.5 years at minimum. 34

35 Conclusion of T-101 inspection report The factors that will affect the integrity of ammonia storage tank are: construction defect, corrosion, SCC crack and fatigue. Taking the opportunity of T-101 decommission, this ammonia storage tank had gone through thorough internal inspection by non-destructive technique. There is only minor corrosion spots observed on bottom plates and no defect found on all shell plates and welds. All welds were inspected without SCC cracking as observed. Based on this inspection result, we can conclude that ammonia storage tank under cryogenic operating condition, there is no sign of corrosion or SCC crack/fatigue even after near 30 years of service. Therefore, it is concluded that if we are able to strictly control the construction quality, eliminate construction defects, follow proper commission procedure and normal operating procedure, the risk of tank failure can be considered as zero. 35

36 End of Presentation & Thank You! 36