1、1996 API Coke Drum Survey Final Report NOVEMBER 2003 1996 API Coke Drum Survey Final Report NOVEMBER 2003 FOR AMERICAN PETROLEUM INSTITUTE Subcommittee on Inspection Coke Drum Task Group By Capstone Engineering Services, Inc. Houston, TX i Contents Page Summary v Background .vii 1.0 General Informat
2、ion 1 2.0 Design . 2 3.0 Coke Drum Operation . 2 4.0 Inspection Practices 4 5.0 Deterioration Experience. 5 5.1 Skirt Deterioration. 5 5.2 Shell Bulging 7 5.3 Shell Cracking 7 5.4 Cladding and Cracking. 8 6.0 Repair Procedures 8 6.1 Skirt Attachment. 8 6.2 Shell Repairs 9 6.3 Cladding Repairs 9 7.0
3、Trends and Correlations 9 7.1 Material Design Trends 9 7.2 Dimensions Trends 15 8.0 Materials and Design Compared to Drum Cracking Experience 19 8.1 Shell Materials 19 8.2 Drum Design Dimensions vs. Cracking . 23 9.0 Material and Design Compared to Drum Bulging Experience. 28 9.1 Drum Design Dimensi
4、ons vs. Bulging 29 9.2 Cladding Performance . 29 10.0 Skirt Deterioration Versus Materials and Design 38 11.0 Operating Parameters Versus Cracking Experience 42 12.0 Bulging Versus Operating Parameters 53 13.0 Future Survey Recommendations. 53 Figures 3.01 3 3.02 3 3.03 Current Fill Cycle Times. 4 5
5、.1 6 7.01 Trend of Material Selection (Skirt) (Combined Chrome Moly) . 11 7.02 Trends of Material Selection (Skirt Material) 11 7.03a Trend of Material Selection (Shell and Cone) 12 7.03b Trends of Material Selection (Shell/Cone Material) . 12 7.04a Trend of Material Selection (Shell and Cone) 13 7.
6、04b Trends of Material Selection (Shell/Cone Material) . 13 7.05 Trend of Material Selection (Shell/Cone Cladding) 14 7.06 Trends of Material Selection (Shell/Cone Cladding) 14 7.07 Trends of Material Selection (Weld used to join Cladding) 15 7.08 Skirt Wall Thickness vs. Installation Year 16 7.09 S
7、hell Thickness (Bottom Course) vs. Installation Year 16 7.10 Drum Diameter vs. Installation Year 17 7.11 Diameter Wall Thickness (Bottom Course) vs. Installation Year . 17 7.12 Drum Height (T-T) vs. Installation Year . 18 7.13 Drum Capacity vs. Installation Year . 18 8.01a Number of Surveys Reportin
8、g First Through Wall Crack 20 8.01b Percent of Surveys Reporting First Through Wall Shell Crack 20 8.01c Number of Drums Reporting First Through Wall Crack. 21 8.01d Percent of Drums Reporting First Through Wall Shell Crack 21 8.01e Shell Materials vs. Cycles to First Through Wall Crack . 22 8.01f M
9、aterials vs. Cycles to First Through Wall Crack 22 ii Page 8.02 Diameter vs. Cycles to First Through Wall Crack 24 8.03 Drum Wall Thickness vs. Cycles to First Through Wall Crack.24 8.04 Diameter/Thickness vs. Cycles to First Through Wall Crack .25 8.05 Total Number of Cracks vs. Operating Cycles .2
10、5 8.06 Total Number of Cracks vs. Operating Cycles and Materials.26 8.07 Number of Through Wall Cracks vs. Operating Cycles26 8.08 Number of Through Wall Cracks vs. Operating Cycles and Materials.27 9.01a Number of Surveys Reporting First Shell Bulge.30 9.01b Percent of Surveys Reporting First Shell
11、 Bulge .30 9.01c Number of Drums Reporting First Shell Bulge .31 9.01d Percent of Drums Reporting First Shell Bulge31 9.01e Material vs. Cycles to First Bulge .32 9.01f Material vs. Cycles to First Bulge .32 9.02 Diameter vs. Cycles to First Bulge .33 9.03 Wall Thickness vs. Cycles to First Bulge33
12、9.04 Diameter/Thickness vs. Cycles to First Bulge34 9.05 Number of Bulges vs. Total Cycles 34 9.06 Number of Bulges vs. Operating Cycles.35 9.07 Number of Bulges vs. Diameter .35 9.08 Number of Bulges vs. Diameter/Thickness36 9.09 Histogram of Bulge and Crack Distribution 36 9.10 Histogram of Bulgin
13、g Depth37 9.11 Occurrence of Disbonding37 10.01 Skirt Bulging Status vs. Material and Operating Cycles .39 10.02 Material vs. Cycles to First Skirt Crack.39 10.03 Skirt Cracking Status vs. Material and Operating Cycles.40 10.04 Skirt Cracking Status vs. Cycles and Skirt Thickness40 10.05 Skirt Compr
14、essive Stress vs. Cycles to First Skirt Crack.41 11.01a Cycles to First Through Wall Crack vs. Initial Quench Rate 43 11.01b Cycles to First Through Wall Crack vs. Initial Quench Rate/Diameter.43 11.01c Cycles to First Through Wall Crack vs. Initial Quench Flux .44 11.02 Number of Cracks vs. Initial
15、 Quench Flux44 11.03 Number of Cracks vs. Initial Quench Rater over Diameter 45 11.04 Cycles to First Through Wall Crack vs. Proofing Rate .45 11.05 Number of Cracks vs. Proofing Rate46 11.06 Total Number of Cracks vs. Total Cycles.46 11.07 Cycles to First Through Wall Crack vs. Final Quench Rate .4
16、7 11.08 Number of Cracks vs. Final Quench Rate47 11.09 Cycles to First Through Wall Crack vs. Furnace Outlet Temperature .48 11.10 Number of Cracks vs. Furnace Outlet Temperature 48 11.11 Cycles to First Through Wall Crack vs. Sulfur Content 49 11.12 Number of Cracks vs. Sulfur Content.49 11.13 Cycl
17、es to First Through Wall Crack vs. Quench Overhead Pressure 50 11.14 Number of Cracks vs. Quench Overhead Pressure.50 11.15 Current Fill Time vs. Cycles to First Through Wall Crack 51 11.16 Steam Strip Time vs. Cycles to First Through Wall Crack .51 11.17 Hydrocarbon Vapor Preheat Time vs. Cycles to
18、 First Through Wall Crack .52 12.01a Cycles to First Bulge vs. Initial Quench Rate .54 12.01b Cycles to First Bulge vs. Initial Quench Rate Over Diameter.54 12.01c Cycles to First Bulge vs. Initial Quench Rate .55 12.02a Number of Bulges vs. Initial Quench Rate .55 12.02b Number of Bulges vs. Initia
19、l Quench Rate Over Diameter.56 12.02c Number of Bulges vs. Initial Quench Flux 56 12.03 Cycles to First Bulge vs. Proofing Rate 57 12.04 Number of Bulges vs. Proofing Rate 57 12.05 Number of Bulges vs. Total Cycles 58 12.06a Cycles to First Bulge vs. Final Quench Flux.58 12.06b Cycles to First Bulge
20、 vs. Final Quench Flux.59 iii Page 12.07a Number of Bulges vs. Final Quench Rate 59 12.07b Number of Bulges vs. Final Quench Rate 60 12.08 Cycles to First Bulge vs. Furnace Outlet Temperature 60 12.09 Number of Bulges vs. Furnace Outlet Temperature 61 Tables 2.01 Frequency of Material Selection for
21、Shell and Cone Materials 1 2.02 Frequency of Material Selection for Cladding Materials. 2 2.03 Frequency of material Selection for Welding Clad Materials . 2 5.1.1 Skirt Cracking Results 6 5.2 Maximum and Average Bulge Results. 7 5.3 Drums with Either Cracking or Bulging Only 8 8.01 Cycles to First
22、Through Wall Crack . 19 9.01 Cycles to First Bulge 28 9.02 Occurrence of Disbonding . 29 v Summary In 1996 a survey was sent by the API Subcommittee on Inspection; Coke Drum Task Group, to companies operating coke drums in the United States and abroad. This was the third survey of similar nature con
23、ducted by the API. Fifty-four surveys were returned representing 17 different operating companies and a total of 145 drums. The purpose of this survey was to collect data covering a broad range of issues including: 1. General information 2. Design 3. Operating Information 4. Inspection Practices 5.
24、Deterioration Experience 6. Repair Procedures Three of the six areas, Operation Information, Inspection Practices and Deterioration Experience were not covered in the first two surveys. Additionally, this third survey asked more information in the other three areas as compared to the first two surve
25、ys. Capstone Engineering Services, Inc. was contracted by the American Petroleum Institute (API) to collect, tabulate and develop correlations with the data in an effort to increase safety and reliability of coke drum operation. Findings (per Survey): General: 1) 20% of the surveys (12% of the drums
26、) (41% of Companies) reported that they had experienced a fire 2) Not all through wall cracks resulted in fires 3) There were no reported incidents of a drum crack causing a fire that damaged adjacent equipment 4) 94% indicated a desire to have an API Recommended Practice Design: 5) New drum materia
27、l selection has been towards increasing Chrome Moly alloy content 6) As observed in the 1968 Survey, no correlation between drum life and drum material was apparent 7) 40% indicated they had removable insulation around the skirt to aid in inspection of these locations Operation: 8) No correlation be
28、tween drum cracking and fill cycle time was found 9) Drum operating parameters such as initial quench rate and proofing quench practice rather than metallurgy appears to have a greater influence on drum cracking Skirt Deterioration Experience: 10) Skirt cracking was reported by 78% of the surveys 11
29、) 43% of these reported cracks propagated into the shell 12) 89% of the skirts with slots experienced cracking 13) Only 22% of the skirts without slots experienced cracking 14) In-line skirts accounted for 83% of the skirts that did not experience cracking vi 15) 75% of the skirts without cracking w
30、ere skirts that had flush ground welds 16) 67% of the skirts without cracking were both in-line design and had flush ground welds 17) Skirts were replaced by 23% 18) Of the 23% that replaced skirts, recracking eventually occurred 43% of the time Shell Deterioration Experience: 19) First bulge appear
31、ed sooner than first through wall cracks 20) Shell bulging was reported by 57% 21) Shell cracking was reported by 57% 22) Of the drums that bulged, 87% also experienced cracks 23) Cracking without bulging was reported only by 6% 24) Circumferential cracking was found 97% of the time 25) Most cracks
32、and bulges were located in courses 3, 4, and 5 (course 1 is at the bottom) 26) Roll bond cladding was used the most and had a slightly better success rate, however the data set for explosion bond and plug weld cladding was small Repair Procedures: 27) Shell repairs were performed from the OD by 26%
33、28) Of the 26% that performed OD repairs of ID cracking, 88% experienced recracking 29) Shell repairs were performed from the ID by 55% 30) Of the 55% that performed ID repairs, only 21% experienced recracking Inspection Procedures: 31) The most common method of mapping bulges was manually as report
34、ed by 26 surveys. Responses from 14 surveys reported using laser mapping techniques 32) Considering drums four years and older: 100% of the surveys indicated that some form of inspection was performed during shutdowns 40% indicated that they performed some inspection during operation Frequency of in
35、ternal inspection varied from one year intervals to 10 year intervals with an average of 4 years Future Survey Recommendations: 34)Given the complexity of the design and operation of coke drums, it is anticipated that there would be minimal value in performing another industry wide coke drum survey
36、in 10 years 35)If a survey was performed in the future, it is recommended to selectively survey younger drums made of similar materials and experienced fewer variations in cycle time and operation vii Background This survey was the third performed by the American Petroleum Institute. Previous survey
37、s were conducted in 1968 and in 1980. The conclusions of these two reports as they appeared in the 1980 report are as follows: 1968 Survey: a) Carbon steel drums bulged far more extensively than C-Mo drums before giving Through Wall Cracks. b) Through Wall Cracks were circumferential. They occurred
38、during quenching, steam cooling, or start up. Although cracks were extensive, no failures were catastrophic. c) It appeared that thinner vessels had shorter life. d) The report showed clearly that both C-Mo and Carbon Steel drums increasingly embrittled with time. Carbon Moly drums appeared to be mo
39、re sensitive to embrittlement and cracking. 1980 Survey Summary: A. Most of the reporting was on drums not included in the 1968 API report. Apparently many of these drums have been retired. B. Review of service experience shows much less through wall cracking of drums than previously reported. C. Te
40、n companies reported on sixty coke drums. D. Most of the more recent drums are primarily constructed of Chrome Moly rather than Carbon Steel and Carbon Moly. E. No advantage of Chrome Moly over C-Mo is apparent except it appears that Chrome Moly in Graphite Coke service gives better service. Review
41、of both surveys showed that the 1968 survey did not conclude that Carbon Moly drums were more sensitive to cracking, rather, it was both the 1968 and 1980 authors opinion that increased embrittlement would likely result in increased cracking. The 1980 Survey conclusions state that there was no obser
42、ved advantage in terms of service life for Chrome Moly over Carbon Moly drums. 1996 Survey Data The line by line detailed data from the surveys is provided in Appendix 1. The results were reformatted with the question across the top. The next row refers to the question number from the original surve
43、y. The 54 survey responses are given in the following rows. At the bottom of the survey, three rows provide the number of “yes” responses to “yes/no” questions along with the percentage of “yes” responses compared to total number of responses for that question. Since not all questions were answered
44、by all surveys, results are given as a fraction and a percentage, based on specific answers over the total number of answers to that question. For data indicating a numerical value, minimum, maximum and average values are given in the last three rows of the tables. viii The identification number giv
45、en in the second column of the General Information section is for reference only. The first two digits of the identification number indicates physical surveys that were returned. Some surveys had multiple units or refineries on one survey, therefore the number after the dash indicates the column of
46、data from the original survey. Therefore, when the first two numbers are the same for multiple surveys, the same company was responding. However, when multiple survey forms were submitted by one company, the groups of forms were split up to promote anonymity of the respondent. In the 1996 survey it
47、was found that a returned survey represented several different groups. When all the drums within a plant were the same design, age, and operation, they were all grouped together. As many as six drums were represented by one survey. When a plant had two or more sets of drums with each set having a di
48、fferent age or material of construction, one survey per set was used. Much of the survey results are presented in terms of “percent of surveys”. As a part of the follow-up, the number of drums per survey was gathered and used to evaluate answers in terms of “percent of drums”. The results of the two
49、 methods were found to be very similar indicating minimal value in trying to recalculate any other results based on “percent of drums.” Care should be taken when using raw statistics presented in this report. Due to the wide range of drum ages, there could be considerable “age bias” in the results. Much of this age bias is due to the limited nature of any survey. Not every possible question was asked (even though the survey covered 18 pages and asked 250 questions). 1 1996 API Coke Drum Survey Report 1.0 General Information The year of installation for coke drums varied from 1950 to 1
