DILLINGER PRESSURE VESSEL COLLOQUIUM. Fabrication of heavy wall reactors made in CrMo(V) plates

Transcription

1 DILLINGER PRESSURE VESSEL COLLOQUIUM DILLINGER HÜTTE GTS September 2009 Fabrication of heavy wall reactors made in CrMo(V) plates Giacomo Fossataro (Walter Tosto SpA)

2 Walter Tosto SpA was founded in 1960 by Mr. Walter Tosto First steps of company activities Nowdays, Company awarded with INNOVATION PRIZE 2009 by The President Of the Italian Republic G. Napolitano

3 Walter Tosto SpA is located in the central part of Italy with shops in Chieti Scalo and in the port of Ortona

4 Production range covers the most critical components of a petrochemical plant such as Reactors, HP heat exchangers and Process Columns using the most advanced and sophisticated steels

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7 Case Study: fabrication of a CrMoV reactor REACTOR DATA INTERNAL DESIGN PRESSURE DESIGN TEMPERATURE MINIMUM DESIGN METAL TEMPERATURE INTERNAL DIAMETER SHELL THICKNESS DESIGN CODES TOTAL WEIGHT 92 barg 450 C -25,2 C 4500 mm 150 mm ASME VIII div.1/ped 500 MT

8 Courtesy of Axens

9 Adopded materials: - Shell by plate in SA 542 D Cl 4a - Heads by plate in SA 542 D Cl 4a - Shell course with catalyst grid support ring by forging in SA 336 Gr F22V -All materials (including consumables) are procured in compliance with the most stringent market requirements, including both API 934 A and Axens Specification for chemistry limitation (ultra clean steel with very low level of tramp elements) Requested Actual Values J-factor <=100 42,14 X-bar <= 15 10

10 Adopted welding process with some test results Welding Process Tensile Test PWHT min (710 C x 8h) [At +20 C] Tensile Test PWHT max (710 C x 26h) [At +20 C] Impact test PWHT min (710 C x 8h) [At -30 C] Impact test PWHT max (710 C x 26h) [At -30 C] Hardness Test PWHT min (710 C x 8h) Hardness Test PWHT max (710 C x 26h) Required Obtaine Required Obtaine Required Obtained Required Obtained Required Obtained Required Obtained SAW (Tandem) at 1/2 thk. (A.W.M.) Y.S. > 415 N/mm Y.S. > 415 N/mm Min > 48J Avg > 55J HAZ J Min > 48J Avg > 55J HAZ J < 248 HV10 HAZ H V10 < 248 HV10 HAZ HV10 SAW (Tandem) at 1/2 thk. T.S T.S Min > 48J Avg > 55J NW J Min > 48J Avg > 55J NW J < 248 HV10 NW H V10 < 248 HV10 NW HV10 SAW (Tandem) HOT Tensile at 1/2 thk. [At +454 C] Y.S. > SAW (Tandem) HOT Tensile at 1/2 thk. [At +454 C] T.S. > SAW (Tandem) Step CoolingTest at 1/2 thk. WM V Tr (V Tr55- VTr55) < 10 C C

11 Adopted welding process with some test results Welding Process Tensile Test PWHT min (710 C x 8h) [At +20 C] Tensile Test PWHT max (710 C x 26h) [At +20 C] Impact test PWHT min (710 C x 8h) [At -30 C] Impact test PWHT max (710 C x 26h) [At -30 C] Hardness Test PWHT min (710 C x 8h) Hardness Test PWHT max (710 C x 26h) Required Obtained Required Obtained Required Obtained Required Obtained Required Obtained Required Obtained SMAW at 1/2 thk. (A.W.M.) Y.S. > Y.S. > Min > 48J Avg > 55J HAZ J Min > 48J Avg > 55J HAZ J < 248 HV10 HAZ H V10 < 248 HV10 HAZ HV10 SMAW at 1/2 thk. T.S T.S Min > 48J Avg > 55J NW J Min > 48J Avg > 55J NW J < 248 HV10 NW H V10 < 248 HV10 NW HV10 SMAW HOT Tensile at 1/2 thk. [At +454 C] Y.S. > SMAW HOT Tensile at 1/2 thk. [At +454 C] T.S. > SMAW Step CoolingTest at 1/2 thk. WM V Tr (V Tr55- VTr55) < 10 C C

12 Summary of adopted heat treatments DHT ISR PWHT 350 C 650 C 710 C (±5 ) x 6h x 6h x 8h Typical Heat Treatment Sequence A) Longitudinal welds B) Nozzles and heads welds C) Circumferential

13 HEADS FABRICATION - Hot forming of petals at 950 C - Quenching & tempering of petals according to mill recommendation - Warm calibration of petals (at C) - Fit-up and SAW welding followed by ISR - Machining of circumferential bevel - Fit-up and welding of nozzles followed by ISR

14 SHELL COURSES FABRICATION - Warm rolling of plates (at C) - Fit-up & SAW welding of longitudinal seam followed by ISR - Machining of circumferential bevel - Fit-up and welding of nozzles followed by ISR

15 FABRICATION OF SECTIONS (3 courser or 2 courses + head) - Circumferential fit-up and SAW welding followed by DHT - Weld overlay by double heads ESW process type 347

16 Automatic system of pre-heat/interpass management

17 Drying and feeding flux system designed and manufactured in-house.

18 REACTOR COMPLETION - Assembly and circular welding of main sections, followed by DHT - Assembly and welding of external & internal appurtenances

19 Main Non Destructive Tests BEFORE PWHT AFTER PWHT AFTER HYDRO TEST Longitudinal welding MT - TOFD - MANUAL U.T. MT - TOFD - MANUAL U.T. MT - TOFD - MANUAL U.T. Circumferential welding MT - TOFD - MANUAL U.T. MT - TOFD - MANUAL U.T. MT - TOFD - MANUAL U.T. Nozzles welding MT TOFD - PHASED ARRAY MT TOFD - PHASED ARRAY MT TOFD - PHASED ARRAY Overlay PT UT - FERRITE PT - UT

20 Manual Shear Wave Procedure for Identifying Transverse Reheat Cracks Recommendation Comments Surface Condition of Welded Joint Probe Frequency Probe Angles Calibration Reference Scanning Sensitivity Scanning Location Scanning Direction Flaw Characterization Rejection Criteria Flush Ground 2 to 4 MHz (focused if necessary to achieve adequate resolution at maximum depths) 70 (primary detection angle), 60 and possibly 45 degrees 3 mm side drilled holes (DAC setup) + 14 db above reference level Along ground weld Both directions along weld Based on EN1713 (except no minimum amplitude and no echodynamic evaluation) 1) Greater than 20% DAC - Reject 2) 10-20% DAC - Investigate and Characterize Transducer frequency should be 4 MHz for near side examination and 2 MHz for depths greater than 100 mm. Multiple probes are used to cover the near and far zones: 70 degrees covers about mm, 60 degrees covers about , and 45 degrees covers the deeper areas. Holes at multiple depths and some EDM notches are typically included. Scanning for transverse flaws or A-scan, however this terminology is not consistent worldwide. Primary objective is to determine if indication is planar and transverse. Look for >9 db difference between the 70 and 60 degree scans (45 and 60 degree for depths greater than 120 mm). If > 9db (Hdmax-Hdmin) then classify as planar. Compare maximum signal obtained from transverse and parallel directions with the same probe that produced the maximum signal (Figure 4) if the difference is >9 db, the defect can be considered transverse. Rejected except if classified as another type of defect and passing ASME Code requirements.

21 POST WELD HEAT TREATMENT The whole reactor has been treated in furnace with target 710 C +/- 5 C. During the soaking time the temperature range was between 707 C and 714 C Furnace Dimension 10x11x28,5 mt.

22 FINAL ACTIVITIES - Assembling and welding of bottom nozzles and skirt + local PWHT - NDTs after PWHT - Hydrotest - NDTs after Hydrotest - Painting, cleaning, blanketing etc.

23 Conclusion Some of the winning factors for a safe reactor fabrication - Intensive training of all involved personnel - Special care in consumable management system - Reliable automatism in preheat/interpass continuous control - Development of appropriate welding procedures - Locked welding parameters in production and automatic continuous record of them - ISR furnace located inside the shop - Severity in NDTs (Specific training and qualification for the operators) - Reliable PWHT procedure, furnace & skilled personnel to guarantee precise temperature (+/-5 C)

24 Thank you for your attention