Simplified process flow diagrams for several process units commonly found in many refineries are shown in this section. The P FD’s are highlighted to to show show some of the areas within within the unit where many many of the primary primary damage damage mechanisms mechanisms can be found. The reader should s hould be advised that this is not intended to to be an all inclusive list of the damage mechanisms but should serve as a starting point for some of the major considerations. The The proces ocess s flow flow diag iagram rams incl inclu uded in this sect sectio ion n are are list listed ed below elow. A key to the Dam Damage age Me Mech chan anis ism ms The The numberin ering g syst system em for for damage age mech echani anisms sms use used d on the PFD’ PF D’s s is show shown n in Table able 5-4. -4. 5.2.1
Crud e Unit / Vacuu m: See Figure 5-65.
5.2.2
Delayed Coker : See Figure 5-66.
5.2.3 5.2.3
Fluid Catalyti Catalyti c Cracking : See Figure 5-67.
5.2.4 5.2.4
FCC Lig ht Ends Recovery: See Figure 5-68.
5.2.5 5.2.5
Catalyti Catalyti c Reformin g – CCR: CCR: See Figure 5-69.
5.2.6 5.2.6
Catalytic Catalytic Reformin g – Fixed Bed: See Figure 5-70.
5.2. 5.2.7 7
Hydroprocessing Units – Hydrotreating, Hydrocracking: See Figure 5-71.
5.2. 5.2.8 8
Sulfuric Acid Alkylation: See Figure 5-72.
5.2.9 5.2.9
HF Alky lation : See Figure 5-73.
5.2.10 5.2.10 Ami ne Treatin g: See Figure 5-74. 5.2.11 5.2.11 Sulfur Recovery: See Figure 5-75. 5.2.12 5.2.12 Sour Water Water Stripper: See Figure 5-76. 5.2.13 Isomerization: See Figure 5-77. 5.2.14 5.2.14 Hydrog en Reforming : See Figure 5-78 5.2.15 Visbreaker: See Figure 5-79. 5.2.16 5.2.16 Causti c Treating : See Figure 5-80.
5-90 API Recommended Practice 571 - Ballot November 2009 ___ ___ _____ _________ ___ _______ _________ _______ ___________ _________ _____ _________ ___ _______ ______
Table 5-4 – Key to Damage Mechanis ms DM#
Damage Mechani sm
DM#
Damage Mechani sm
1
Sulfidation
34
Softening (Spheroidization)
2
Wet H2S Damage (Blistering/HIC/SOHIC/SSC)
35
Reheat Cracking
3
Creep / Stress Rupture
36
Sulfuric Acid Corrosion
4
High temp H2/H2S Corrosion
37
Hydrofluoric Acid Corrosion
5
Polythionic Acid Cracking
38
Flue Gas Dew Point Corrosion
6
Naphthenic Acid Corrosion
39
Dissimilar Metal Weld (DMW) Cracking
7
Ammonium Bisulfide Corrosion
40
Hydrogen Stress Cracking in HF
8
Ammonium Chloride Corrosion
41
Dealloying (Dezincification/ Denickelification)
9
HCl Corrosion
42
CO 2 Corrosion
10
High Temperature Hydrogen Attack
43
Corrosion Fatigue
11
Oxidation
44
Fuel Ash Corrosion
12
Thermal Fatigue
45
Amine Corrosion
13 14
Sour Water Corrosion (acidic) Refractory Degradation
46 47
Corrosion Under Insulation (CUI) Atmospheric Corrosion
15 16
Graphitization Temper Embrittlement
48 49
Ammonia Stress Corrosion Cracking Cooling Water Corrosion
17
Decarburization
50
Boiler Water / Condensate Corrosion
18 19
Caustic Cracking Caustic Corrosion
51 52
Microbiologically Induced Corrosion (MIC) Liquid Metal Embrittlement
20
Erosion / Erosion-Corrosion
53
Galvanic Corrosion
21
Carbonate SCC
54
Mechanical Fatigue
22
Amine Cracking
55
Nitriding
23
Chloride Stress Corrosion Cracking
56
Vibration-Induced Fatigue
24
Carburization
57
Titanium Hydriding
25
Hydrogen Embrittlement
58
Soil Corrosion
26
Steam Blanketing
59
Metal Dusting
27
Thermal Shock
60
Strain Aging
28
Cavitation
61
Sulfate Stress Corrosion Cracking
29
Graphitic Corrosion (see Dealloying)
62
Phosphoric Acid Corrosion
30
Short term Overheating – Stress Rupture
63
Phenol (carbolic acid) Corrosion
31
Brittle Fracture
64
Ethanol Stress Corrosion Cracking
32
Sigma Phase/ Chi Embrittlement
65
33
885 F (475 C) Embrittlement
Oxygen-enhanced Ignition and Combustion Organic Acid Corrosion Of Distillation Tower Overhead Systems
o
o
66
September 2010 API Recommended Practice 571 5-91 ___ ___ _____ _________ ___ _______ _________ _______ ___________ _________ _____ _________ ___ _______ _____
Figure 5-65 – Crude Unit / Vacuum
5-92 API Recommended Practice 571 - Ballot November 2009 ___ ___ _____ _________ ___ _______ _________ _______ ___________ _________ _____ _________ ___ _______ ______
Figure 5-66 – Delayed Coker
September 2010 API Recommended Practice 571 5-93 ___ ___ _____ _________ ___ _______ _________ _______ ___________ _________ _____ _________ ___ _______ _____
Figure 5-67 – Fluid Catalytic Cracking
5-94 API Recommended Practice 571 - Ballot November 2009 ___ ___ _____ _________ ___ _______ _________ _______ ___________ _________ _____ _________ ___ _______ ______
Figure 5-68 – FCC Ligh t Ends Recov ery
September 2010 API Recommended Practice 571 5-95 ___ ___ _____ _________ ___ _______ _________ _______ ___________ _________ _____ _________ ___ _______ _____
Figure 5-69 – Catalytic Reform ing – CCR
5-96 API Recommended Practice 571 - Ballot November 2009 ___ ___ _____ _________ ___ _______ _________ _______ ___________ _________ _____ _________ ___ _______ ______
Figure 5-70 – Catalytic Reformin g – Fixed Bed
September 2010 API Recommended Practice 57 5-97 ___ ___ _____ ___ _________ _______ _________ _________ ___ ___ ___ _________ _____ ___ _________ _______ _____
Figure 5-71 – Hydropro cessing - Hydrotreating, Hydrocrackin g
5-98 API Recommended Practice 571 - Ballot November 2009 ___ ___ _____ _________ ___ _______ _________ _______ ___________ _________ _____ _________ ___ _______ ______
Figure 5-72 - Sulfuric A cid Alk ylation
September 2010 API Recommended Practice 571 5-99 ___ ___ _____ _________ ___ _______ _________ _______ ___________ _________ _____ _________ ___ _______ _____
Figure 5-73 – HF Alkylatio n
5-100 API Recommended Practice 571 - Ballot November 2009 ___ _________ ___ ___ ___ _________ _____ ___ _________ _______ _________ ___ _____ _______ ___ _________ _____ _
Figure 5-74 – Amin e Treating
September 2010 API Recommended Practice 571 5-101 ___ ___ _____ ___ _________ _______ _________ _________ ___ ___ ___ _________ _____ ___ _________ _______ _____
Figure 5-75 – Sulfur Recover y
5-102 API Recommended Practice 571 - Ballot November 2009 ___ _________ ___ ___ ___ _________ _____ ___ _________ _______ _________ ___ _____ _______ ___ _________ _____ _
Figure 5-76 – Sour Water Stripper
September 2010 API Recommended Practice 571 5-103 ___ ___ _____ ___ _________ _______ _________ _________ ___ ___ ___ _________ _____ ___ _________ _______ _____
Figure 5-77 – Isomeri zation
5-104 API Recommended Practice 571 - Ballot November 2009 ___ _________ ___ ___ ___ _________ _____ ___ _________ _______ _________ ___ _____ _______ ___ _________ _____ _
Figure 5-78 – Hydrogen Reform ing
September 2010 API Recommended Practice 571 5-105 ___ ___ _____ ___ _________ _______ _________ _________ ___ ___ ___ _________ _____ ___ _________ _______ _____
Figure 5-79 – Visbreaker
5-106 API Recommended Practice 571 - Ballot November 2009 ___ _________ ___ ___ ___ _________ _____ ___ _________ _______ _________ ___ _____ _______ ___ _________ _____ _
