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Cracking Furnace Tube Metallurgy Part 1 A
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Transcript of Cracking Furnace Tube Metallurgy Part 1 A
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Ethylene Furnace TrainingEthylene Furnace Training
PEQUIVENPEQUIVEN OlefinasOlefinas IIII
23 rd to 27th March 200923 rd to 27th March 2009
Cracking Furnace Tube MetallurgyCracking Furnace Tube Metallurgy
Part I: Materials and Failure MechanismsPart I: Materials and Failure Mechanisms
LE TAW Pullach
Dr. Hubert Kpf
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Cracking Furnace Tube Metallurgy
Agenda:
Part I:
Materials and Failure Mechanisms
Part II:
Inspection and Evaluation/Failure analysis
Part III:
Troubleshooting and Repair Methods
Window rupture
of a Catalyst
Tube
Cracked CatalystTube
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1. Tube Materials
Cracking Furnace Tube Metallurgy
Part I: Materials and Failure Mechanisms
Ceramics / GraphiteGraphite
C / C
Refractory MetalsODS-Superalloys
PM 1000 / PM 2000
Adv anced
Titanium Allo ys
Temperature [C]
500 1000 1500
Oxidation Stability Oxidation Protective Coatings Required
Directionally Solidified Eutectics
Rapid Quenched MetalsTitanium
Composites
Alumin ium All oysAlumin ium
Composites
Conventional
TitaniumAll oys
Single
Crystals
Superalloys
-Titanium
Aluminide
based Alloys
Usablestrength
2000
In Ethylene Cracking metal surface temperatures up to 1100C in combination with
carburization and oxidation stability have to be managed by the tube materials. The
materials shall be weldable and economic. This requirements are fulfilled by high Ni,Cr austenics (superalloys).
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1. Tube Materials
Centrifugally cast tubes of these alloys are selected due to their enhanced high
temperature strength compared to wrought alloys
Cracking Furnace Tube Metallurgy
Part I: Materials and Failure Mechanismus
However, the ductility properties of the cast materials at ambient
temperatures are reduced compared to the wrought alloys.
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1. Tube Materials
The table below shows typical cast alloys used by LINDE in Ethylene Cracking Furnaces
Cracking Furnace Tube Metallurgy
Part I: Materials and Failure Mechanisms
Its important that Si is high to improve the carburization resistance.
Impurities such as As, Sn, Zn, Sb and Pb shall be low; these elements
are indications for the amount of scrap used in the tube production
process
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1. Tube Materials
The design of Tubes follows the general rules for all equipment in high temperature
service (example for power stations acc. to VGB)
Cracking Furnace Tube Metallurgy
Part I: Materials and Failure Mechanisms
Operation in creep rangeOperation in range of yield strength
at elevated temperature
stress
= stress
Rp0.2/ = yield strength at temperature
Rm/time/ = rupture strength at time and temperature
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1. Tube Materials
Cracking Furnace Tube Metallurgy
Part I: Materials and Failure Mechanisms
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2. Failure Mechanisms for Radiant Tubes
Cracking Furnace Tube Metallurgy
Part I: Materials and Failure Mechanisms
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2. Failure Mechanisms for Radiant Tubes
Cracking Furnace Tube Metallurgy
Part I: Materials and Failure Mechanisms
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2. Failure Mechanisms for Radiant Tubes
Cracking Furnace Tube Metallurgy
Part I: Materials and Failure Mechanisms
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2. Failure Mechanisms for Radiant Tubes
Cracking Furnace Tube Metallurgy
Part I: Materials and Failure Mechanisms
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2. Failure Mechanisms for Radiant Tubes
Cracking Furnace Tube Metallurgy
Part I: Materials and Failure Mechanisms
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2. Failure Mechanisms for Radiant Tubes
Cracking Furnace Tube Metallurgy
Part I: Materials and Failure Mechanisms
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2. Failure Mechanisms for Radiant Tubes
Creep damage: Time-dependent strain occurring under stress. The creep strain
occurring at a diminishing rate is called primary creep; that occurring at a minimum
and almost constant rate, secondary creep; and that occurring at an acceleratingrate, tertiary creep. Below please find a principle Master curve for creep damage.
Cracking Furnace Tube Metallurgy
Part I: Materials and Failure Mechanisms
= Elongation
Au= Creep elongation at fracture
t= time
tm= time to fracture
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2. Failure Mechanisms for Radiant Tubes
At temperatures above approximately 50% of the reformer tube alloy melting
(approx. 1350 C) creep is determined by relocation of micropores and lattice
defects (dislocations) towards the grain boundary.
Cracking Furnace Tube Metallurgy
Part I: Materials and Failure Mechanisms
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2. Failure Mechanisms for Radiant Tubes
Cracks resulting from this mechanism are intergranular / interdendrit ic
(Example: X5NiCrTi 26-15, 1.4980)
Cracking Furnace Tube Metallurgy
Part I: Materials and Failure Mechanisms
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2. Failure Mechanisms for Radiant Tubes
Cracking Furnace Tube Metallurgy
Part I: Materials and Failure Mechanisms
Stage 2(Magnification X 200)
Stage 3 - 4(Magnification X 200)
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2. Failure Mechanisms for Radiant Tubes
Cracking Furnace Tube Metallurgy
Part I: Materials and Failure Mechanisms
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2. Failure Mechanisms for Radiant Tubes
Cracking Furnace Tube Metallurgy
Part I: Materials and Failure Mechanisms
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2. Failure Mechanisms for Radiant Tubes
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Part I: Materials and Failure Mechanisms
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2. Failure Mechanisms for Radiant Tubes
Cracking Furnace Tube Metallurgy
Part I: Materials and Failure Mechanisms