This document provides an overview of various damage mechanisms that can affect fixed equipment in refineries. It discusses types of corrosion, cracking, and other material degradation processes. Some key points covered include temper embrittlement in low alloy steels, brittle fracture risks during startup and shutdown, and methods for preventing issues like thermal fatigue and caustic stress corrosion cracking. A variety of inspection techniques are also outlined for evaluating different damage mechanisms in plant equipment.
Analysis of Interfacial Microsstructure of Post Weld Heat Treated Dissimilar ...IOSR Journals
In Prototype Fast Breeder Reactor (PFBR), the main vessel which contains the primary sodium and supports the
core is suspended from the roof slab. The materials for construction for main vessel and roof slab are type 316LN austenitic
stainless steel and Carbon steel of grade A48P2, respectively. As the materials of construction are different, a transition joint
between austenitic stainless steel and C-steel is necessary. In this investigation the effect of post-weld heat treatment (PWHT) on the interfacial microstructure of as-welded and PWHTed type 316LN/C-steel joint welded with Inconel 182 was investigated. These joints were PWHTed to various temperatures between 898 to 973K for 1h and results were evaluated. From the above results, different methods to temper the martensitic structure or to change to an equilibrium structure without PWHT are also presented.
Analysis of Interfacial Microsstructure of Post Weld Heat Treated Dissimilar ...IOSR Journals
In Prototype Fast Breeder Reactor (PFBR), the main vessel which contains the primary sodium and supports the
core is suspended from the roof slab. The materials for construction for main vessel and roof slab are type 316LN austenitic
stainless steel and Carbon steel of grade A48P2, respectively. As the materials of construction are different, a transition joint
between austenitic stainless steel and C-steel is necessary. In this investigation the effect of post-weld heat treatment (PWHT) on the interfacial microstructure of as-welded and PWHTed type 316LN/C-steel joint welded with Inconel 182 was investigated. These joints were PWHTed to various temperatures between 898 to 973K for 1h and results were evaluated. From the above results, different methods to temper the martensitic structure or to change to an equilibrium structure without PWHT are also presented.
Weld Purging ~ Corrosion Problems in Stainless Steel by WeldingRon Sewell
Abstract
Corrosion is not uncommon in stainless steels, despite their name. Salt water environments in particular can give rise to corrosion and this is even noticeable at domestic level where cutlery discolours in mild salt solutions during dishwashing cycles. Loss of corrosion resistance during welding takes place when oxygen levels in shield and purge gases are high enough to deplete the chromium content.
Weld Purging ~ Corrosion Problems in Stainless Steel by WeldingRon Sewell
Abstract
Corrosion is not uncommon in stainless steels, despite their name. Salt water environments in particular can give rise to corrosion and this is even noticeable at domestic level where cutlery discolours in mild salt solutions during dishwashing cycles. Loss of corrosion resistance during welding takes place when oxygen levels in shield and purge gases are high enough to deplete the chromium content.
ENGR 1210: FA 2016; HW 8
1
Homework 8 on chapters 8, 9 & 11; (Total points: 100)
Reading assignments: Chapters 8, 9 & 11 from textbook and slides
Student Name: _______________________________ MTSU ID: ____________________
Honor pledge: I _______________________________ acknowledge that I have neither received
nor given any unauthorized help/aid during this assignment.
Part 1 Key Engineering Terms: fill in the blanks – 30 points
1. Phase: a _____________________________________ homogeneous and distinct portion
of material system.
2. Degrees of freedom: number of variables that can be changed
___________________________________________ without changing phases of the
system.
3. Eutectoid: a steel with ____________________________ percent C.
4. Austenite has ____________________________________ crystal structure and
maximum carbon solubility of 2%.
5. Martensite: a ______________________________________ interstitial solid solution of
carbon in __________________________________________ iron.
6. Tempering: the process of _____________________________________________ a
quenched steel to increase its toughness and ductility.
7. Spherodite: a mixture of particles of _________________________ in α iron matrix.
8. Hardenability: the ease of forming _________________________________________ in
a steel upon quenching from austenitic condition.
9. White cast irons: contains large amounts of
_____________________________________ which make them hard and brittle.
2
10. Gray cast iron: contain large amount of _______________________________ flakes.
11. Ductile cast iron: contain large amount of carbon in form of
___________________________________________.
12. Malleable cast iron: __________________________________ is added to composition
other than iron and carbon.
13. Intermetallics: ___________________________________ compounds of metallic
elements with high hardness and high temperature strength but brittle.
14. Shape memory alloys: metal alloys that recover previously defined shape when subjected
to an appropriate _______________________________________.
15. Amorphous metal: metals with a ___________________________________ structure
also called glassy metal.
16. Octahedral interstitial site: has coordination umber of ____________________________.
17. Tetrahedral site: has coordination number of _______________________________.
18. Ceramic materials: __________________________________ nonmetallic materials that
consist of metallic and nonmetallic elements bonded together by ionic or covalent bonds.
19. Buckyball: is a soccer shaped molecule of _____________________________________
carbon atoms.
20. Firing: heating a ceramic material to high temperature to cause
______________________________________________ to form between particles.
21. Dry pressing: ______________________________________ uniaxial compaction and
shaping of ceramic granular particles in a ...
The main objective of this paper is to
determine casting defects generally happening in an
aluminium die casting process and efforts have been
taken to identify the tools which eliminate the casting
defects. In global prospective this study briefs the
application of the various tools that are used in the
industries for improvement of quality in foundry
industry. In our national prospective these tools are not
so popular, hence this study will help us to utilise the
available technology through which the productivity is
enhanced with safe and economical means. The QC
tools were used to analyse the casting condition of the
given pattern with three dimensional simulations for the
result preparation. This work has been carried out to
improve the quality of the pattern which is made with
gravity die casting process and this was achieved
through continuous quality control operation with QC
tools, then it was taken to test in some simulation
software. The latest trend available in casting and
foundry shops are the scientific approach in
optimization of all kind of fields including optimization
of defects in castings. These trends are incorporated in
the analysis of aluminium die casting.
Numerical simulation of friction stir butt welding processes for az91 magnesi...eSAT Journals
Abstract Friction Stir Welding (FSW) is a solid state welding process. In particular, it can be used to join high-strength aerospace magnesium and other metallic alloys that are hard to weld by conventional fusion welding. It was performed on 4 mm thickness AZ91 Magnesium alloy. Magnesium alloy have more advantage than aluminum such as light weight, softer, tendency to bend easily, cost effective in terms of energy requirements so magnesium alloy has selected in this FSW technique. In friction stir welding (FSW), a momentous residual stress is present in weld due to complex nature of fixturing system compared to fusion welding. These residual stresses can affect properties of welded components during service. Therefore, for estimating magnitude of welding residual stresses and their nature of distribution along with thermal history, a three dimensional non- linear thermo-mechanical finite element (NLTMFE) model using ABAQUS/ CAE package was developed for butt welded magnesium alloy AZ91. The objective of this work is to predict the temperature distribution in both materials and evaluate the mechanical properties during the friction stir welding on magnesium alloy. Keywords: Fsw, Nltmfe, Abaqus, Cae, Az91.
Numerical simulation of friction stir butt welding processes for az91 magnesi...eSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Study Of Mechanical Properties On Al 6061 Hybrid Composite by Stir Casting Me...
571 exercises, rev2
1. API 571 Damage Mechanisms Affecting Fixed Equipment in the Refining Industry
Rev. 2 10/06 DTM Enterprises Technical Training Division Page 1 of 11
281-330-9542 – www.DTM-Enterprises.org
1
4.2.3 Temper Embrittlement
1. Temper Embrittlement is a ________ in toughness that can occur in some low alloy
steels.
A. increase
B. decrease
2. Equipment subject to Temper Embrittlement is normally those that operate at
___________.
A. higher temperatures
B. lower temperatures
3. Temper Embrittlement can be readily found by Visual and other NDE methods.
A. True
B. False
4. A common method of monitoring for Temper Embrittlement is to _____________
inside the reactor. Samples are periodically removed from these blocks for impact
testing to monitor progress of temper embrittlement or until a major repair issue
arises.
A. install blocks of the original heats of the alloy steel
B. install a block of a similar heat of the alloy steel
C. install Temper Embrittlement probes
4.2.7 Brittle Fracture
5. Brittle fracture is characterized by ________________________________.
A. a slow cracking that develops over an extended period of time
B. a high strain rate that leads to a sudden failure
C. a sudden rapid failure under stress
6. The main concern for brittle fracture is ______________________.
A. during shutdown
B. during startup
C. during startup and shutdown
2. API 571 Damage Mechanisms Affecting Fixed Equipment in the Refining Industry
Rev. 2 10/06 DTM Enterprises Technical Training Division Page 2 of 11
281-330-9542 – www.DTM-Enterprises.org
2
7. Brittle fracture cracks will typically be straight, non-branching, and largely devoid of
any associated plastic deformation.
A. True
B. False
8. Inspection for brittle fracture is______________________________.
A. dependent on accessibility to internal surfaces
B. dependent on expensive NDE methods such as Acoustic Emissions
C. not normally done
4.2.9 Thermal Fatigue
9. The materials subject to thermal fatigue are __________________________.
A. high chrome alloys
B. all materials of construction
C. austenitic stainless steels
10. Thermal fatigue cracks usually initiate _______________of the component.
A. on the surface
B. in the through thickness
C. on the interior
11. Thermal fatigue is best prevented through design and operation to minimize thermal
stresses and thermal cycling. Some methods to help prevent thermal fatigue include
____________________________________________.
A. blend grinding the weld profile of components to remove stress raisers
B. controlled rates of heat during startup and shutdown
C. designs that incorporate sufficient flexibility
D. All of the above
12. External ________inspection can be used for non-intrusive inspection for internal
thermal fatigue cracking and where reinforcing pads prevent nozzle examination.
A. Dye penetrant
B. Shear Wave UT
C. Visual
3. API 571 Damage Mechanisms Affecting Fixed Equipment in the Refining Industry
Rev. 2 10/06 DTM Enterprises Technical Training Division Page 3 of 11
281-330-9542 – www.DTM-Enterprises.org
3
4.2.14 Erosion / Erosion-Corrosion
13. Erosion - Corrosion is ______________________________.
A. the accelerated mechanical removal of surface material as a result of relative
movement between, or impact from solids, liquids, vapor or any combination
thereof
B. removing protective films or scales by exposing the metal surface to further
corrosion
14. Increasing the hardness of the metal substrate is _____________________.
A. always a good method to prevent erosion from occurring
B. not always a good method to prevent erosion from occurring
15. Visual examination of suspected or troublesome areas, as well as UT checks or RT
can be used to detect the extent of metal loss.
A. True
B. False
16. Which of the following is not a form of erosion or erosion - corrosion?
A. cavitation
B. fretting
C. carburization
4.2.16 Mechanical Failure
17. One of the properties of mechanical fatigue is that it typically happens
___________.
A. well below yield strength of the material
B. well above yield strength of the material
C. at the yield strength of the material
18. Fatigue cracks usually initiate on the surface _______________under cyclic
loading.
A. at openings only
B. at notches or stress raisers
C. underneath reinforcement pads only
4. API 571 Damage Mechanisms Affecting Fixed Equipment in the Refining Industry
Rev. 2 10/06 DTM Enterprises Technical Training Division Page 4 of 11
281-330-9542 – www.DTM-Enterprises.org
4
19. Heat treatment can have a significant effect on the toughness and hence fatigue
resistance of a metal. In general ___________tend to perform better
than___________.
A. coarse grained microstructures - finer grained
B. medium grained microstructures - coarse grained
C. finer grained microstructures - coarse grained
20. An example of a component that might exhibit mechanical fatigue due to thermal
cycling is a ______________________________________.
A. large bore piping systems
B. coker drum
C. high pressure drop control valves
21. NDE monitoring for mechanical fatigue might include _______________________.
A. SWUT, RT and MT
B. PT, MT and SWUT
C. RT, PT and MT
4.3.2 Atmospheric Corrosion
22. Materials that might be affected by atmospheric corrosion include ______________.
A. Carbon steel, low alloy steels and copper alloyed aluminum
B. Carbon steel, low alloy steels and alloyed brasses
C. Carbon steel, low alloy steels and the 400 series stainless steels
23. Piping on supports are often very prone to atmospheric corrosion due to ________.
A. long horizontal runs
B. being located next over sprays and leaks
C. water entrapment between the pipe and the supports
24. The method(s) that can be used for inspection to find atmospheric corrosion
are_________________.
A. Visual and RT
B. UT and Visual
5. API 571 Damage Mechanisms Affecting Fixed Equipment in the Refining Industry
Rev. 2 10/06 DTM Enterprises Technical Training Division Page 5 of 11
281-330-9542 – www.DTM-Enterprises.org
5
4.3.3 Corrosion Under Insulation (CUI)
25. Materials that might be affected by CUI include_______________________.
A. Carbon steel, low alloy steels 300 and 600 Series SS
B. Carbon steel, low alloy steels 500 Series SS and duplex stainless steels
C. Carbon steel, low alloy steels 300 Series SS and duplex stainless steels
26. It is known that 300 Series SS, 400 Series SS and duplex SS are subject to pitting
and localized corrosion. The 300 series are also subject to what form of attack if
chlorides are present?
A. ________________________________________
27. Preventing CUI calls for careful selection of insulating materials. Therefore
__________ materials will hold less water against the vessel/pipe wall than
___________and, are potentially be less corrosive.
A. closed-cell foam glass - mineral wool
B. mineral wool - closed-cell foam glass
C. asbestos - closed-cell foam glass
28. The recommended technique for identifying wet insulation and potential CUI is
____________.
A. Profile radiography
B, Neutron backscatter
C. Insulation removal
4.3.4 Cooling Water Corrosion
29. Cooling water corrosion is a general or localized corrosion of carbon steels and
other metals caused by _______________________________________.
A. dissolved salts, gases, organic compounds or microbiological activity
B. Low pH, inert gases, inorganic compounds or microbiological activity
C. High pH, gases, organic compounds or microbiological activity
30. ________cooling water outlet temperatures and or process side inlet temperatures
tend to increase corrosion rates as well as fouling tendency.
A. Decreasing
B. Increasing
6. API 571 Damage Mechanisms Affecting Fixed Equipment in the Refining Industry
Rev. 2 10/06 DTM Enterprises Technical Training Division Page 6 of 11
281-330-9542 – www.DTM-Enterprises.org
6
31. Cooling water corrosion ________areas will appear as grooving along the weld
fusion lines.
A. at GTAW welds
B. at ERW welds
C. at nozzle welds
32. Cooling water should be monitored for variables that affect corrosion and fouling.
Below list the main variables that affect cooling water corrosion.
A. _______________________________
B. _______________________________
C. _______________________________
D. _______________________________
E. _______________________________
F. _______________________________
G. _______________________________
4.3.5 Boiler Water Condensate Corrosion
33. Corrosion in boiler feed water and condensate return system is usually the result of
dissolved gases, such as____________________________.
A. oxygen and sulfur phosphates
B. carbon dioxide and low pH amine
C. oxygen and carbon dioxide
34. Corrosion from oxygen tends to be pitting type damage and can show up any where
in the system, but is most aggressive in __________________________.
A. equipment such as closed heaters and economizers
B. boiler tubes in the radiant section
C. boiler tubes in the convection section
35. _______________is the common monitoring tool used to assure that the various
treatment systems are performing in a satisfactory manner.
A. pH measurement alone
B. complete water analysis
C. oxygen content
7. API 571 Damage Mechanisms Affecting Fixed Equipment in the Refining Industry
Rev. 2 10/06 DTM Enterprises Technical Training Division Page 7 of 11
281-330-9542 – www.DTM-Enterprises.org
7
4.4.2 Sulfidation
36. Which of the following alloys form sulfides at a lower temperature than carbon
steel?
A. copper alloys
B. nickel alloys
C. aluminum alloys
37. Generally the resistance to Sulfidation in iron and nickel base alloys increases as
the _____________ content increases.
A. nickel
B. molybdenum
C. chromium
38. Inspection methods to determine thinning by Sulfidation include ___and ___.
A. UT thickness and VT
B. UT thickness and Profile RT
C. EC and Profile RT
39. Sulfidation is also known as __________________.
A. Sulfurous Oxide Attack (SOA)
B. High Temperature Sulfide Attack (HTSA)
C. Sulfidic Corrosion (SC)
4.5.1 Chloride Stress Corrosion Cracking (Caustic Embrittlement)
40. The description of Chloride Stress Corrosion Cracking is surface initiated cracks
caused by environmental cracking of 300 Series SS and some nickel base alloys
under the combined action of tensile stress, temperature and an aqueous chloride
environment. This condition is accelerated by__________.
A. increasing temperature
B. decreasing temperature
C. decreasing chloride
41. Which of the following alloys is highly susceptible to CLSCC?
A. nickel
B. duplex stainless steel
C. 300 series stainless steel
8. API 571 Damage Mechanisms Affecting Fixed Equipment in the Refining Industry
Rev. 2 10/06 DTM Enterprises Technical Training Division Page 8 of 11
281-330-9542 – www.DTM-Enterprises.org
8
42. SCC usually occurs at pH values_____. At lower pH values, uniform corrosion
generally predominates. SCC tendency decreases toward the alkaline pH region.
A. above 2
B. below 2
C. above 4
43. Inspection for CL SCC can be detected by using which of the following NDE
methods?
A. VT
B. PT
C. Both methods above
4.5.2 Corrosion Fatigue
44. Corrosion fatigue can affect __________________ materials.
A. Carbon Steel
B. Austenitic Stainless Steel
C. All metals and alloys
45. The fatigue fracture is brittle and the cracks are most often _________, as in stress-
corrosion cracking, but not branched, and often results in propagation of
____________cracks.
A. transgranular - multiple parallel
B. intergranular - multiple parallel
C. transgranular - multiple radial
46. Corrosion fatigue is usually found in Deaerators by using __________ NDE.
A. VT
B. MT
C. WFMT
9. API 571 Damage Mechanisms Affecting Fixed Equipment in the Refining Industry
Rev. 2 10/06 DTM Enterprises Technical Training Division Page 9 of 11
281-330-9542 – www.DTM-Enterprises.org
9
4.5.3 Caustic Stress Corrosion Cracking (Caustic Embrittlement)
47. Caustic embrittlement is a form of stress corrosion cracking characterized by
surface-initiated cracks that occur in piping and equipment exposed to caustic,
primarily adjacent to___________.
A. non-PWHT welds
B. PWHT welds
C. nozzles and other openings
48. Crack propagation rates increase dramatically with temperature and can sometimes
grow through wall in ____________________________.
A. a matter of a few weeks
B. a matter of hours or days
C. a matter of a few months
49. Caustic embrittlement is often found in piping and equipment that handles caustic.
It may also be found in a process unit that______________________.
A. removes naphtha
B. mercaptans
C. Light Gas Oil
50. Prevention of cracking in carbon steels can be achieved by PWHT to a temperature
of __________________.
A. 1250 o
F
B. 1150 o
F
C. 1300 o
F
5.1.2.3 Wet H2S Damage (Blistering/HIC/SOHIC/SCC)
51. Name the four types of Wet H2S Damage.
A. ________________________________________________________
B. ________________________________________________________
C. ________________________________________________________
D. ________________________________________________________
10. API 571 Damage Mechanisms Affecting Fixed Equipment in the Refining Industry
Rev. 2 10/06 DTM Enterprises Technical Training Division Page 10 of 11
281-330-9542 – www.DTM-Enterprises.org
10
52. Blistering, HIC, and SOHIC damage have been found to occur between ambient
and _______________.
A. 300o
F or higher
B. 400o
F or higher
C. 500o
F or higher
53. Typical low-strength carbon steels used in refinery applications should be controlled
to produce weld hardness <200 HB. These steels are not usually subject to SCC at
hardness below ___________________.
A. 200 HB
B. 237 HB
C. 190 HB
53. Blistering and HIC damage _________ prevented with PWHT.
A. cannot be
B. can be
C. may be
5.1.3.1 High Temperature Hydrogen Attack (HTHA)
54. HTHA occurs when hydrogen reacts with ______in steel to form ______which
cannot diffuse through the steel.
A. iron - iron oxide
B. carbon - carbon dioxide
C. carbides - methane
55. Internal visual inspection for blisters ______________ HTHA.
A. will always indicate
B. may not indicate
C. does not indicate
56. Acoustic Emission Testing is a proven method for finding HTHA.
A. True
B. False
11. API 571 Damage Mechanisms Affecting Fixed Equipment in the Refining Industry
Rev. 2 10/06 DTM Enterprises Technical Training Division Page 11 of 11
281-330-9542 – www.DTM-Enterprises.org
11
Answer Key API RP 571 Damage Mechanisms
1. B 36. A
2. A 37. C
3. B 38. B
4. A 39. C
5. C 40. A
6. C 41. C
7. A 42. A
8. C 43. C
9. B 44. C
10. A 45. A
11. D 46. C
12. B 47. A
13. B 48. B
14. B 49. B
15. A 50. B
16. C 51. A. Hydrogen Blistering
17. A B. Hydrogen Induced Cracking
18. B C. Sulfide Stress Corrosion Cracking
19. C D. Stress Oriented Hydrogen Induced Cracking
20. B 52. A
21. B 53. B
22. A 54. C
23. C 55. B
24. B 56. B
25. C
26. A. Stress Corrosion Cracking
27. A
28. B
29. A
30. B
31. B
32. A. pH
B. Oxygen Content
C. Cycles of Concentration
D. Biocide Residual
E. Biological Activity
F. Cooling Water Outlet Temperature
G. Hydrocarbon Contamination& Process Leaks
33. C
34. A
35. B