Module 3 Alkalies and Amine Treating Flashcards
(58 cards)
1
Q
Amine SCC (ACSCC) found where?
A
HAZ (non PwHT)
2
Q
Amine SCC (ACSCC) affected material?
A
CS/Low alloy
3
Q
Amine SCC (ACSCC) critical factors
A
a. type of amine
b. stress
c. temperature
4
Q
Amine SCC (ACSCC) is often associate with what type of amine? and at what %?
A
Lean / >2%
5
Q
Amine SCC (ACSCC) pure amine is \_\_\_\_\_ corrosion
A
not
6
Q
Amine SCC (ACSCC)
appearance?
a. Amine SCC initiates on _______side (welds)
b. cracking typically ____to the weld (longitudinal or transverse)
c. could occur process side opposite external ________
A
a. process
b. parallel
c. attachment welds
7
Q
Amine SCC (ACSCC) c. thoroughly \_\_\_\_\_\_ non-PWHT
A
water wash
8
Q
Amine SCC (ACSCC) \_\_\_\_\_\_\_\_ effective for surface breaking cracks
A
a. WFMT/ACFM/ECT
9
Q
Amine SCC (ACSCC) \_\_\_\_\_\_ effect to detect size cracks
A
b. Angle beam (SWUT/PAUT)
10
Q
Amine SCC (ACSCC) \_\_(2)\_\_ may not be used/effective
A
PT/ RT
11
Q
Carbonate SCC (ACSCC) affected material?
A
CS / low alloy steels affected
12
Q
Carbonate SCC (ACSCC) critical factor? (3)
A
a.WATER/carbonate/stress
13
Q
Carbonate SCC (ACSCC) what pH >\_\_\_ is an issue and what level failure typically occurs?
A
7.5
8-10
14
Q
Carbonate SCC (ACSCC) ammonia (NH3) does what to the pH
A
increase
15
Q
Carbonate SCC (ACSCC) carbon concertation?
A
> 100 ppm BUT no specific threshold
16
Q
Carbonate SCC (ACSCC) does Cyanide have any effect
A
NO
17
Q
Carbonate SCC (ACSCC) increase N2 feed does what to pH
A
increase PH
18
Q
Carbonate SCC (ACSCC) H2S concentration?
A
d. H2S - no specific level of concentration
19
Q
Carbonate SCC (ACSCC) where does it occur most often location? (3)
A
Carbonate cracking has been most prevalent in FCC unit main fractionator OVERHEAD condensing and reflux systems,
regenerator cold wall shell
PWHT
20
Q
Carbonate SCC (ACSCC)
appearance?
propagate ____to the weld in the HAZ OR adjacent base metal within___”
A
a. parallel / 2 in.
21
Q
Carbonate SCC (ACSCC) found \_\_\_\_\_away from the toe of the weld than cracks resulting from SSC or SOHIC.
A
further
22
Q
Carbonate SCC (ACSCC)
prevention?
PWHT to what temp?
A
1200-1225F
23
Q
Carbonate SCC (ACSCC) best mitigation?
A
monitor pH of SW most practical and cost-effective method
24
Q
Carbonate SCC (ACSCC) NDE?
A
WFMT/ACFM/ECT effective for surface breaking cracks
25
```
Caustic SCC (ACSCC)
affected material?
```
Cs/ low alloys/ SS
26
```
Caustic SCC (ACSCC)
description
```
caustic SCC due to elevated temp
27
```
Caustic SCC (ACSCC)
critical factor? (3)
```
strength, temp, stress
28
```
Caustic SCC (ACSCC)
concentration of caustic needed?
```
50-100ppm
29
```
Caustic SCC (ACSCC)
affected equipment? (4)
```
a. non-PWHT
b. h2S and mercaptan removal units, caustic for neutralization in alkylation units
c. failures occurred in heat traced piping or equipment
d. occur in equipment as the result of steam cleaning after being in caustic service
30
```
Caustic SCC (ACSCC)
a. propagate _____ in HAZ
```
parallel
31
```
Caustic SCC (ACSCC)
a. propagate _____ in HAZ
```
parallel
32
```
Caustic SCC (ACSCC)
PWHT to ____min with 1 hour min for CS
```
1150F
33
```
Caustic SCC (ACSCC)
300 SS offer resistance to cracking? alloy 400
```
No and Yes to alloy 400 will offer resistance
34
```
Caustic SCC (ACSCC)
type of NDE
```
a. WFMT/ACFM/ECT effective for surface breaking cracks
| b. Angle beam (SWUT/PAUT) effect to detect size cracks
35
Amine Corrosion
description?
a. localized corrosion (at high velocity) / general (low velocity)
b. corrosion is not from amine but from ____and______and _______
dissolved acid gases (CO2 and
H2s) / heat stable amine salts (HSAS)
anime degradation products (bicines, oxalate, salt)
36
Amine Corrosion
| material affected?
CS
37
Amine Corrosion
| critical factor? 4
corrosion depend on type of amine, contaminants, temperature, velocity
38
Amine Corrosion
| Most problem can be traced to ____&_____or solution contamination
faulty design, poor operating practices
39
Amine Corrosion
| Type of amine from most to least corrosion -->
MEA, DGA, DIPA, DEA, MDEA.
40
Amine Corrosion
| Lean amine not corrosion , unless salts above ___% lean amine is (2) _____
2%
low conductivity/high pH)
41
Amine Corrosion
| what happen at >220F?
can result in acid gas flashing
42
Amine Corrosion
| velocity limit for rich amine / lean amine
3 to 6 fps for rich amine, and
20fps for lean amine
43
Amine Corrosion
| affected units?
amine units
44
Amine Corrosion
| appearance
uniform thinning (localized)
45
Amine Corrosion
| what happens to weld when flashing occurs
preferentially attacked
46
Amine Corrosion
prevention?
a. Proper operation to the ____ system
b. control local pressure drop to minimize ____
c. upgrade to 300 SS or other materials.
D. avoid ____ to prevent formation of corrosive heat stable salts
a. amine
b. flashing
d. air ingress
47
Amine Corrosion
| NDE ? (3)
VT/ Rt/ UT
48
Caustic Corrosion
| affect material
a. CS / low alloy steels / 400SS are affected / 300SS
49
Caustic Corrosion
| when is 300SS good till ?
300 SS is good until passitivity is damage which occurs at 160F to 210F (depends on concentration)
50
Caustic Corrosion
| critical factor? (2)
High solution caustic, temp >170F in CARBON STEEL
51
Caustic Corrosion
| temp limit >___F for CS?
170F
52
Caustic Corrosion
| localized _____due to a concentration mechanism must exist (DNB, evaporation, deposition of salts)
gouging
53
Caustic Corrosion
| Caustic gouging typically in boiler tube that may appear as ____
grooves
54
Caustic Corrosion
| steam generating equipment is BEST prevented through ______
proper design
55
Caustic Corrosion
| Cs/SS have serious problem at high -__-(2)___
high concentration / temp
56
Caustic Corrosion
| best material?
alloy 400 or nickel
57
The regenerator reboiler and the regenerator are areas where the temperature and __________ of the amine stream are the highest
turbulence
58
While the amine does remove other contaminants, the targeted material for removal is which of the following?
Mercaptans, CO2 and H2S
