Eun2020_Chapter_DesignEngineering

1.3 Advanced Design 101 r r = the radius reached by the plastic deformation Plastic Deformation Field Crack Tip Figure 1.43 Stresses at crack tip 1.3.4.3 Linear Elastic Fracture Mechanics (LEFM) and Elastic Plastic Fracture Mechanics (EPFM) Fracture mechanics models, such as linear elastic fracture mechanics (LEFM) or elastic-plastic frac- ture mechanics (EPFM), provide mathematical relationships for critical combinations of stress, crack size, and fracture toughness that lead to Figure 1.44 Several stress-strain modes crack propagation. (a) LEFM approaches apply to cases where crack propagation occurs during predominately elastic loading with negligible plasticity. LEFM applies when the nonlinear deformation of the material is confined to a small region near the crack tip. For brittle materials, it accurately establishes the criteria for catastrophic failure. However, severe limitations arise when large regions of the material are subject to plastic deformation before a crack propagates (Fig. 1.44). (b) EPFM methods are suitable for materials that undergo significant plastic deformation during crack propagation. EPFM is normally proposed to analyze the relatively large plastic zones. EPFM assumes isotropic and elastic-plastic materials. Based on the assumption, the strain energy fields or opening displacement near the crack tips are calculated. When the energy or opening exceeds the critical value, the crack will grow (Fig. 1.44). Note that although the term elastic-plastic is used in this approach, the material is merely nonlinear-elastic. In others words, the unloading curve of the so-called elastic-plastic material in EPFM follows the original loading curve, instead of a parallel line to the linear loading part which is normally the case for true plastic-plastic materials. Ã Fracture Analysis Using EPFM There are two major branches in EPFM: Crack Tip Opening Displacement (CTOD) suggested by Wells, popular in Europe, and the J Integral proposed by Rice, widely used in the USA. However, Shih provided evidence that a unique relationship between J and CTOD exists for a given material. Thus, these two parameters are both valid in characterizing crack tip toughness for elastic-plastic materials. The basic EPFM analysis can be summarized as follows: 1 Calculate the J integral or crack tip opening displacement (CTOD), δ, as a function of the loading and the geometry 2 The critical J integral Jc or the critical CTOD, δc, can be determined empirically 3 The J integral J should NOT exceed Jc, or, the CTOD δ should not exceed the critical CTOD, δc (CrackThickness) 1.3.4.4 Stress Intensity Factor in Practice (Crack Width) Engineers are interested in the maximum stress near the crack tip and whether it exceeds the Figure 1.45 Stress intensity factor at crack fracture toughness. Thus, the stress intensity factor K is commonly expressed in terms of the applied stresses, σ, at r ! 0 and θ ¼ 0. For example, for a through crack in an infinite plate under uniform tension σ, the stress intensity factor is where a is one half of the width of the through crack. The dimension of K is KI ¼ σ√πα. (Fig. 1.45). I ¼ mode I, c ¼ critical. In the last few decades, many closed-form solutions of the stress intensity factor K for simple configurations were derived. Some of the common ones are listed in the following three categories: classic, specimen, and structure.

102 1 Design Engineering 1.3.4.5 Stress Intensity Factor and Fracture Toughness Based on the linear theory, the stresses at the crack tip are infinite, but in reality there is always a plastic zone at the values. It is very difficult to model and calculate the actual stresses in the plastic zone and compare them to the maximum allowable stresses of the material to determine whether a crack is going to grow or not. (a) Plane Strain Fracture Toughness-Critical Stress Intensity Factor, KIC/Critical J Value (J Integrity, Jcrit) The fracture toughness (K1C) of a material measures its ability to resist crack growth initiation and propagation. The critical J value (J Integrity, Jcrit) characterizes energy release rate during a small crack extension, which may also be valid in the presence of significant crack tip plasticity. The subscript Ic denotes mode I crack opening under a normal tensile stress perpendicular to the crack, since the material can be made deep enough to stand shear (mode II) or tear (mode III) as shown in Fig. 1.42. Finally it is denoted KIc and has the units of Pa (m)1/2 or psi (inch)1/2. An engineering approach is to perform a series of experiments and reach a critical stress intensity factor Kc for each material, called the fracture toughness of the material. One can then determine the crack stability by comparing K and Kc directly. Kc’s for a number of common engineering materials are listed in this page. (b) Definition of J Integral – Fig. 1.46 To consider a nonlinear elastic body containing a crack, the J integral is defined as ð ∂Ui ∂x J¼ wdy‐T i ds r ð εij where w ¼ σijdεij is the strain energy density, Ti ¼ σijnj is the traction vector, Γ is an arbitrary contour around the tip of the crack, 0 n is the unit vector normal to Γ, and σ, ε, and u are the stress, strain, and displacement field, respectively. Rice, J.R. showed that the J integral is a path-independent line integral and it represents the strain energy release rate of nonlinear elastic materials: J % ÀdM=dA where M ¼ U – W is the potential energy, the strain energy U stored in the body minus the work W done by external forces, and A is the crack area. The dimension of J is Dim½JŠ ¼ F Á L=L2 ¼ Energy=Area Plastic-elastic fracture toughness is denoted by JIc, with the unit of J/cm2 or lbf-in/in2, and is a measurement of the energy required to grow a thin crack (Fig. 1.46). (c) Relationship Between ( j) and K For linear elastic materials, the integral J is in fact the strain energy release rate, , and both are related to the stress intensity factor K in the following fashion: The dimension of is: KIC ¼ [JCRITÃE/ (1-ν2)]1/2 E ¼ Young’s modulus, MPa or ksi KIC ¼ ksi (in)1/2 or MPa (m)1/2 ν ¼ Poisson’s ratio JCRIT ¼ MPa-m or ksi-in L ¼ πα [α ¼ 1/2 of crack length] 1.3.4.6 Fracture Toughness Estimation from Charpy V-Notch Data The V-notch Charpy test provides an indication of fracture toughness rather than a direct measurement. Many correlations between V-notch Charpy energy and fracture toughness have been published over decades. The majority of these correlations were developed with limited data and materials. In some cases, correlations developed in the 1970s, when fracture toughness testing was in its infancy, have been shown to be unreliable when applied to the large amount of toughness data that is available today. See API 579-1/ASME FFS-1, 9F.3.4, for more details. Figure 1.46 Mode of definition of J integral

1.3 Advanced Design 103 1.3.4.7 Test Methods for Failure Assessment and ASTM Standards a. State-of-the-art facilities and software for performing: – K1C – J1C – R-curve determinations – CTOD – Drop weight tear tests (DWTT) – Dynamic tear testing – Nil ductility transition temperature – Notched bar impact (Charpy and Izod) b. References • ASTM E399 Linear Plastic Plane Strain Fracture Toughness (K1C) of Metallic Materials • NTIS AD-773 673 Plane Strain Fracture Toughness (KIC) Data Handbook for Metals (1973) • ASTM E813 JIC Testing – withdrawn. Now go to ASTM E1820 Measurement of Fracture Toughness • ASTM E1820 Measurement of Fracture Toughness • ASTM E561 KR-Curve Determination • ASTM E1290 Crack Tip Opening Displacement (CTOD) Fracture Toughness – withdrawn. Now go to ASTM E1820 Measurement of Fracture Toughness • ASTM E208 Drop Weight Test to Determine Nil Ductility Transition Temperature • ASTM E604 Dynamic Tear Testing of Metallic Materials • ASTM E23 Notched Bar Impact Testing of Metallic Materials • API 579-1/ASME FFS-1 See Sect. 5.2.3 for detailed information for several test methods of fracture toughness. 1.3.5 Minimum Allowable Temperature (MAT) and Lowest Metal Temperature (LMT) 1.3.5.1 Minimum Allowable Temperature (MAT) The MAT is the lowest (coldest) permissible metal temperature for a given material and thickness based on its resistance to brittle fracture. It may be a single temperature or an envelope of allowable operating temperatures as a function of pressure. The MAT is derived from mechanical design information and material specification. See API 579-1/ASME FFS-1, 3.1.6, for more details. MAT at design pressure is MDMT. The permissible MAT during depressurization and blowdown may be able to be lower than MDMT. 1.3.5.2 Lowest Metal Temperature (LMT) LMT defined and used in this book is the lowest metal skin temperature at the process side due to the operating condition (mostly during depressurization and blowdown) and minimum ambient temperature. The LMT may be a single temperature at an operating pressure or an envelope of temperatures and coincident pressures. In this case, the LMT is calculated by the inner wall skin temperature calculated due to the contained process fluid temperature and also the minimum ambient temperature. The LMTs of the vessels coincident with final pressures (after depressurization and blowdown) are shown in Fig. 1.47. Figure 1.47 MAT and LMT (a sample calculation). 1.3.6 MPT (Minimum Pressurizing Temperature) (Source: Khazai, F. Avoid brittle fracture in pressure ves- sels, hydrocarbon processing, 2011 modified) 1.3.6.1 What Is MPT? Normally pressure shows slow strain of the material. However, the pressuriz- ing at low temperature may be able to be a root cause of brittle failure. Especially the precipitations of Cr-Mo steel during operation create temper embrittlement of the metal and then a gradual increase of the ductile-to-brittle transition temperature. As a result, the vessel may be exposed to brittle failure on starting up and hydrostatic test unless the pressurizing is controlled by the certain temperature and pressuring rate. Therefore, MPT is for the threshold minimum temperature before pressur- izing to avoid the brittle failure. API RP934F committee has been developing the standard (MPT requirements for Cr-Mo reactors) to issue in the near future. Figure 1.48 shows a result of brittle failure during start-up.

104 1 Design Engineering 1.3.6.2 Key Considerations for MPT Decision (a) Fast Brittle Fracture Considerations (a-1) Temper Embrittlement on Fast Brittle Fracture (a-2) Determining the Effect of Temper Embrittlement on Fast Fracture (a-3) Dissolved Hydrogen on Fast Brittle Fracture (b) Slow Stable Crack Growth Considerations (b-1) Hydrogen-Assisted Crack Growth in Cr-Mo Steels (b-2) Laboratory KIH (slow-rising-displacement threshold stress Intensity) Test- ing and MPT Estimation for Internal Hydrogen-Assisted Cracking (IHAC) of 2¼-1Mo Figure 1.48 Failure due to pressuring under limita- (b-3) Modeling Stable Crack Growth in Cr-Mo Steels tion of low temperature during startup. (Source: CLG (b-4) Establishing Tcrit (Threshold Temperature) for Hydrogen-Assisted Crack report 2011) Growth (b-5) Laboratory KIH Testing and MPT Estimation for IHAC and HEAC (Hydro- gen Environment-Assisted Cracking) of 2¼Cr-1Mo-V (c) Hydrogen Embrittlement (c-1) Hydrogen Solubility, Diffusivity, and Trapping in V-modified Cr-Mo Steel (c-2) Hydrogen Embrittlement of Cr-Mo and Cr-Mo-V Steels in hydrogen containing service 1.3.6.3 Requirements of MPT Curve MPT is not a material requirement, but a requirement for operation due to embrittlement at low temperature in Cr-Mo steel with heavy wall. The heavy wall Cr-Mo vessels in hydrocracking units have MPT limits that must be adhered to during the startup process or field hydrotesting. These MPT limits require unit operations to achieve certain reactor wall temperature thresholds before the pressure can be raised. In addition, the recycle compressor has a minimum pressure at which it can safely operate outside the pressure surge ranges when liquid is added to the unit. When required, the vessel fabricator shall define MPT requirement based on this document and in accordance with sound industry practice to avoid brittle fracture of the base material and welds during vessel operation including startup and shutdown. The requirements of this document shall be included in the operating manual of the unit that specify startup and shutdown procedures. All mechanical and metallurgical properties for new pressure vessel shall comply with this document, process requirements, and purchase requisition of the equipment. 1.3.6.4 Vendor Data Requirements (a) Test Reports from Mill Manufacturer The manufacturer shall prepare a report where the minimum requirement noted in this document, process specification, and purchase requisition are verified through calculation and testing. The reports shall be made of each heat-number of the shell and head materials. Following reports are required, as a minimum: 1. Report showing the details of “step cooling” heat treatment. The step cooling test is required for the base metals. The test procedure and acceptance criteria shall be in accordance with API RP934-A, if applicable. 2. Details of all heat treatments used to simulate and accelerate embrittlement of test specimens for the purpose of evaluating the potential of temper embrittlement of alloy steel in high temperature service. (b) Additional Deliverables by Vendor 1. The vessel fabricator shall define MPT considering the requirements noted in this document and also taking into account the following, as a minimum: – The FATT (Fracture Appearance Transition Temperature-ASTM A370) of material and welds considering any possible embrittlement due to in-service metallurgical degradation – Effect of hydrogen absorbed to material during operation – A safety margin 2. The vendor shall provide the following additional reports: – All reports shall consider the effects of wall thickness (base metal and clad) and the material damage (due to high temperature creep and hydrogen embrittlement) on fracture toughness, in order to predict the minimum pressurization temperature. – Report showing the safe curve (pressure  temperature) to the reactor’s operation, in startup and shutdown, to prevent brittle fracture and to permit sufficient time for hydrogen degassing (that were trapped in the matrix of the base metal). The maximum rate in temperature increasing or decreasing and in pressure increasing or decreasing shall be indicated. – Using “REACT” program or other acceptable technique, the vessel fabricator shall submit a report which shall include the curve with threshold hydrogen partial pressure (up to design pressure) vs. temperature (up to design temperature) to sustain the hydrogen levels at the cladding interface below 2.0 ppm. – If the dissolved hydrogen level in the clad bond layer is above 2 ppm, the vendor shall perform analysis to determine hydrogen levels after cool down and advise the results of an outgassing evaluation. Also, the vendor shall advise the impact on MPT and recommend controls to permit outgassing of the hydrogen to ensure dissolved hydrogen levels is less than 2 ppm to avoid hydrogen-assisted cracking.

1.4 Standardization and Documentations 105 1.3.6.5 General Guidelines for Application of MPT Curves in Operations It is a normal practice during unit startup and shutdown of heavy wall alloy vessels to maintain pressure at a low level until vessel wall temperature exceeds the minimum pressurizing temperature (MPT). The following general guidelines shall be incorporated in operating manual: (a) The MPT curves which specify the temperature and pressure limit shall be applied for vessel operation during startup and shutdown. (b) Typical guidelines for pressurizing vessel require the pressure during startup be limited to 25% of design pressure for temperature below MPT. (c) Pressure vessel fabricator’s recommendations for MPT and operating (P/T) transient/pressurizing rates, etc. shall be considered in finalizing the operating guidelines of heavy wall Cr-Mo pressure vessels. References (a) API TR934-F, Part 1 through 4 (Reports regarding MPT): see Table 2.37 in this book for more details. (b) API RP934-A Materials and Fabrication of 2 1/4Cr-1Mo, 2 1/4Cr-1Mo-1/4V, 3Cr-1Mo, and 3Cr-1Mo-1/4V Steel Heavy Wall Pressure Vessels for High temperature and High Pressure Hydrogen Service (c) API RP579/ ASME FFS-1 Fitness-For-Service (d) WRC 562 Recommendations for Establishing the Minimum Pressurization Temperature (MPT) for Equipment (d) J. Mclaughlin, Establishing MPT for Heavy Wall Reactors in Hydroprocessing Units, ASME PVP2006-ICPVT-11-93243 (e) A. Seijas and T. Munsterman, MPT and Pressure-Temperature Envelope of A 1 1/4Cr-1/2Mo Steel Heavy Wall Vessel, ASME PVP2006-ICPVT-11-93310 (f) Y. Wada et al., Hydrogen Embrittlement Testing of Aging Pressure Vessel Steels Using Large Thick Specimen, Processing ICPVT-10 (Jul. 7-10, Vienna, Austria) (g) Y. Wada et al., Hydrogen Embrittlement Testing of 2.25Cr-1Mo Steel Using Large Thick Specimen, PVP2002 (h) T. Iwadata, MPT for Pressure Vessels made of Cr-Mo Steels, ASME PVP-Vol. 288 (1994) (i) API 934 committee meeting minutes email (2008) prepared by J. Mclaughlin (j) S. Pillot et al., Effect of Hydrogen of Mechanical Behavior for 2.25Cr-0.5Mo Steel Grades (Standard and Vanadium Added), NACE paper 08559 (k) Iwadate, T. and Tahara, T., “Minimum Pressurization Temperature of Pressure Vessels made of Cr-Mo Steels”, Pressure Vessels and Piping Conference/ High Pressure Technology PVP vol. 297, ASME 1995 1.4 Standardization and Documentations 1.4.1 Principal Engineering Execution Documents (PEED) for Facilities in PDP, FEED, EPC, and Operation Normally PEED may include the following documents at the initial stage of the project: 1. Basic Engineering Design Data (BEDD) (see Sect. 1.1.2.1 for more details) 2. HAZID and/or HAZOP Study Reports 3. Adequate Reports for Existing Facilities in Revamping Projects 4. DPDT (design pressure and design temperature-minimum and maximum) (see Sect. 1.1.2.2 for more details) 5. PFD, Heat and Materials Balance, UFD, P&ID, Datasheets for Facilities 6. Process Design Basis and Process Safety Design Basis 7. Scopes (service, materials, guarantee, etc.) and Schedule 8. List of Specifications and Design Manuals including Applicable Codes, Standards, and Regulations 9. List of Approved Vendors 10. List of Equipment 11. Organization Chart for Project Execution 1.4.2 Basic Documents for Materials and Corrosion 1.4.2.1 Design Stage Normally the following documents are prepared at the beginning stage for project execution. – Adequate report, list of MOC (materials of construction) – MSD (materials selection diagrams) – CII (corrosion inhibition injection) – MSG (materials selection guideline) – CMR (corrosion monitoring report) – MSP (materials selection philosophy)

106 1 Design Engineering – CP DWG (cathodic protection drawing) – MSR (materials selection report) – CRAS (corrosion risk assessment study) report – MST (materials selection table) – List of MOC (materials of construction) – TML (thickness measurement location) including CUI inspection window – MCA (material-corrosion audit) report 1.4.2.2 Operation and Maintenance Stage On-stream inspection reports (for remained thickness, internal local corrosion, cracks including NDE reports) should be prepared periodically. In addition, various documentations in Sect. 1.5 are also used for sound fitness-for-service system. 1.4.3 Piping Materials Classes See Sect. 1.2.12 for continuous development and responsibility of piping materials classes. The grouping of piping materials classes has the following key factors for the project execution: 1. Material (CS, LTCS, SS, Nickel Alloy, Copper Alloy, Aluminum Alloys, etc.) 2. Services (hydrocarbon (HC), HC + wet H2S (sour), HC + amine, HC + HF, HC + hydrogen, hydrogen, caustic, water-untreated/treated/ seawater/steam/condensate/air/etc. 3. Corrosion allowance (0 mm, 0.5 mm, 1 mm, 1.5 mm, 3 mm, 4.5 mm, 6 mm, etc.) 4. Pressure rating (normally using psi., e.g., #150, 300, 600, 900, 1500, 2500, etc.) 5. Heat treatment (PWHT, normalizing, Q-T, etc.) 6. Design temperature range 7. Valve trim material and hardfacing 8. Specific requirements (part’s materials, design, fabrication, test and inspection, etc.) 1.4.4 Units of Dimension and Measurement Table 1.74 shows the types of most common units in oil and gas industries. Table 1.75 indicates the conversion factors of several units. Tables 1.76, 1.77, 1.78, and 1.79 show the typical conversion standards used in ASME Section VIII for the convenience of users. 1.4.5 Description and Locations of Major Activities in ASME Table 1.80 shows the standard description with templates in ASME. Table 1.74 Principal units US customary SI (ISO standard) Metric Inch, foot Units lb. mm Length Weight (mass) psig kg, g, ton kg, g, ton Weight, % psia Pressure, gauge Psi or ksi wt%, ppmw Pressure, absolute F Stress Pag Kgf/cm2g Temperature, T Ft.lbs Inch3, ft3 Kgf/cm2a T conversion ΔT conversion KPa or MPa Kgf/cm2, Kgf/mm2 Energy Volume C C Volume % C ¼ 5/9 (F – 32), F ¼ 9/5(C) + 32 C ¼ 5/9 (F), F ¼ 9/5(C) J (joule) Kgf.m m3 m3 vol.%, mol%, ppmv, baume (caustic)

1.4 Standardization and Documentations 107 Table 1.75 Conversion factors (ASME Section VIII) From US Customary To SI Conversion Factor Notes – in. mm 25.4 – ft 0.3048 – in2 m 645.16 – ft2 mm2 0.09290304 – in3 m2 16,387.064 – ft3 mm3 0.02831685 – US Gal. m3 0.003785412 psi m3 0.0068948 Used exclusively in equations psi 6.894757 Used only in text and for nameplate ft-lb MPa 1.355818 F 5/9(F–32) – F kPa 5/9(F) Not for temperature difference R For temperature differences only lbm J 5/9 lbf C 0.4535924 Absolute temperature in.-lb C 4.448222 – ft-lb 112.98484 – ksi(in.)1/2 K 1.3558181 Btu/hr 1.0988434 Use exclusively in equations lb/ft3 kg 0.2930711 Use only in text 16.018463 – N N Á mm Use for boiler rating and heat transfer NÁm – MPa(m)1/2 W kg/m3 Table 1.76 Typical conversion of length and thickness used in ASME Section VIII US Customary, inch to SI, mm Difference (%) US Customary, inch to SI, mm Difference (%) 1/32 0.8 À0.8 2 1/2 64 À0.8 3/64 1.2 À0.8 3 75 +1.6 1/16 1.5 +5.5 3–1/2 89 À0.1 3/32 2.5 À5.0 4 100 +1.6 1/8 3 +5.5 4–1/2 114 +0.3 5/32 4 À0.8 5 125 +1.6 3/16 5 À5.0 6 150 +1.6 7/32 5.5 +1.0 8 200 +1.6 1/4 6 +5.5 10 250 +1.6 5/16 8 À0.8 12 300 +1.6 3/8 10 À5.0 14 350 +1.6 7/16 11 +1.0 16 400 +1.6 1/2 13 À2.4 18 450 +1.6 9/16 14 +2.0 20 500 +1.6 5/8 16 À0.8 24 600 +1.6 11/16 17 +2.6 26 650 +1.6 3/4 19 +0.3 28 700 +1.6 7/8 22 +1.0 32 800 +1.6 1 25 +1.6 36 900 +1.6 1 1/8 29 À1.5 40 1000 +1.6 1¼ 32 À0.8 54 1350 +1.6 1½ 38 +0.2 60 1500 +1.6 2 50 +1.6 72 1800 +1.6 2 1/4 57 +0.3

108 1 Design Engineering Table 1.77 Typical conversion of pressure used in ASME Section VIII US Customary SI US Customary SI US Customary SI US Customary SI 0.5 psi 3 kPa 30 psi 200 kPa 300 psi 2 MPa 1500 psi 10 MPa 2 psi 15 kPa 50 psi 350 kPa 350 psi 2.5 MPa 30,000 psi 205 MPa 3 psi 20 kPa 100 psi 700 kPa 400 psi 3 MPa 38,000 psi 260 MPa 10 psi 70 kPa 150 psi 1 MPa 500 psi 3.5 MPa 60,000 psi 415 MPa 14.7 psi 101 kPa 200 psi 1.5 MPa 600 psi 4 MPa 70,000 psi 480 MPa 15 psi 100 kPa 250 psi 1.7 MPa 1200 psi 8 MPa 95,000 psi 655 MPa Table 1.78 Typical conversion of NPS and DN used in ASME Section VIII NPS (nominal pipe size) and DN (diameter nominal) US Customary SI US Customary SI US Customary SI US Customary SI NPS 1/8 DN 6 NPS 3 1/2 DN 90 NPS 22 DN 550 NPS 44 DN 1100 NPS 1/4 DN 8 NPS 4 DN 100 NPS 24 DN 600 NPS 46 DN 1150 NPS 3/8 DN 10 NPS 5 DN 125 NPS 26 DN 650 NPS 48 DN 1200 NPS 1/2 DN 15 NPS 6 DN 150 NPS 28 DN 700 NPS 50 DN 1250 NPS 3/4 DN 20 NPS 8 DN 200 NPS 30 DN 750 NPS 52 DN 1300 NPS 1 DN 25 NPS 10 DN 250 NPS 32 DN 800 NPS 54 DN 1350 NPS 1 1/4 DN 32 NPS 12 DN 300 NPS 34 DN 850 NPS 56 DN 1400 NPS 1 1/2 DN 40 NPS 14 DN 350 NPS 36 DN 900 NPS 58 DN 1450 NPS 2 DN 50 NPS 16 DN 400 NPS 38 DN 950 NPS 60 DN 1500 NPS 2 1/2 DN 65 NPS 18 DN 450 NPS 40 DN 1000 NPS 3 DN 80 NPS 20 DN 500 NPS 42 DN 1050 Table 1.79 Typical temperature conversion used in ASME Section VIII (see Appendix A.1 in this book for detailed design) Temperature, F Temperature, C Temperature, F Temperature, C Temperature, F Temperature, C 510 À320 À196 350 175 950 540 À275 À171 400 205 1000 565 À155 À104 450 230 1050 595 À55 À48 500 260 1100 620 À50 À46 550 290 1150 650 À20 À29 600 315 1200 675 À18 650 345 1250 980 0 1040 1095 70 20 700 370 1800 1120 100 38 750 400 1900 120 50 800 425 2000 150 65 850 455 2050 200 95 900 480 250 120 925 495 1.5 Maintenance, Reliability, and Integrity OSHA, MIL, NASA, ASME, API, and several companies have developed standards, regulations, certifications, programs, reports, guidance, and commercial software for practical application of effective maintenance, reliability, fitness-for-service, and integrity of the facilities. Here is a brief summary of the terms and characteristics of several tools and terms. The Omega & Alfa of scale reliability are not summarized in this book. Commercial Programs (Prog), Software (S/W), Certification (Cert), Standards/Regulations (Reg), Guidance (Guide), and Organizations (Org) CCDs (Corrosion Control Documents-Prog): CCDs are a valuable addition to an effective Mechanical Integrity Program that help identify the damage mechanism susceptibilities of pressure-containing equipment, their related corrosion-causing components, and recommended actions to be implemented to mitigate the risk of loss of containment or unplanned outages. They serve the basis for tracking their development, implementation, and maintenance in order to maintain consistency and to integrate the CCD work process with other plant integrity programs, such as MOC, PHA, HazOps, RCM, and RBI. See API RP970 for more details.

1.5 Maintenance, Reliability, and Integrity 109 Table 1.80 Standard description with templates in ASME Items Parts Paragraphs of Codes User’s design Single Chamber & Multi-chamber Sec. VIII, Div. 1: Form U-DR-1&2 requirements Sec. VIII, Div. 2: Table 2-A.1 Marking for ASME stamp U, UM, PRT, etc. Sec. VIII, Div. 1: Figure UG-116, 129.1&2, Sec. VIII, Div. 2: Figure 2-F.1 Marking for types of W (arc or gas welded), P (pressure fusion welded), Sec. VIII, Div. 1: UG-116 construction B (brazed), RES (resistance welded), G (graphite) Marking for service L (lethal service), UB (unfired steam boiler), DF Sec. VIII, Div. 1: UG-116 (direct firing) Nameplate (stamping Stamping form Sec. VIII, Div. 1: UG-119 form) Welding Joint categories Div. 1: UW-3 Joints details Div. 2: Table AF-241.1 Impregnated graphite Sec. VIII, Div. 1 vessel Forms WPS and PQR Data report forms & supplementary sheet, ASME Sec. IX Final data report for manufacturer’s certificate of compliance forms Sec. VIII, Div. 1, Form U-1, U-1A, U-1B, U-1P, U-2, U-2A, U-3, vessels and pressure relief U-3A, U-3P, U-4, U-5, Fig. W-3.1 & 3.2, Table W-3.1, Form UV-1, valves Certificate of authorization UD-1 Sec. VIII, Div. 1, Table 2-B.1, Form A-1/ A-1P/ A-2/ A-3/ A-3L/ A-4/ Company certification H_EX tube bundles including tube-to-Tubesheet Sec. VIII, Div. 1, Fig. DD-1 Sec. VIII, Div. 2, Fig. 2-H.1 Tube expansion procedure Technical data sheet Sec. VIII, Div. 1, Form QEXP-1&2, Table QEXP-1 specification (TEPS) Forms and contents Sec. VIII, Div. 2, Form TEXP-1&2 PMI report Sec. VIII, Div. 2, Table 6-A, 9.2-1 Marking and reports Div. 1: UG-115 to 120 CMMS (Computerized Maintenance Management System-Prog): It is also known as computerized maintenance management information system (CMMIS). A CMMS software package maintains a computer database of information about an organization’s maintenance operations, i.e., CMMIS. This information is intended to help maintenance workers do their jobs more effectively (e.g., determining which machines require maintenance and which storerooms contain the spare parts they need) and to help management make informed decisions (e.g., calculating the cost of machine breakdown repair versus preventive maintenance for each machine, possibly leading to better allocation of resources). CMMS data may also be used to verify regulatory compliance. CMMS packages can produce status reports and documents giving details or summaries of maintenance activities. The more sophisticated the package, the more analysis facilities are available. CMMS packages are closely related to computer-aided facility management packages (also called facility management software). CMRP (Certified Maintenance & Reliability Professional-Prog & Cert): The leading credentialing program for certifying the knowledge, skills, and abilities of maintenance and reliability professionals. It is accredited by the American National Standards Institute (ANSI), which follows ISO standards for its accreditation and processes. Examining more than just textbook information, the CMRP is a thorough examination of a broader scope of expertise measured against a universal standard. It was developed to assess professionals’ aptitude within the following five pillars: – Maintenance and Reliability Body of Knowledge – Business Management – Equipment Reliability – Manufacturing Process Reliability – Organization and Leadership and Work Management The CMRP Program has the following three components: – Eligibility requirements that are a blend of education and healthcare-specific experience and profile of the individual who is likely to be successful on the Certification Examination. – A 110-item multiple-choice Certification Examination that tests tasks that are performed regularly in practice and are considered important to competent practice. 100 items are scored; 10 are pretest items used to collect data. – A renewal requirement. Certification is valid for 3 years at which time it must be renewed through retaking and passing the Certification Examination or documenting 45 contact hours of continuing professional education. Meanwhile the CMRT is for Certified Maintenance and Reliability Technician (Prog). CPI (Center for Public Integrity-Org): This is an American nonprofit investigative journalism organization whose stated mission is “to reveal abuses of power, corruption and dereliction of duty by powerful public and private institutions in order to cause them to operate with honesty, integrity, accountability and to put the public interest first.”

110 1 Design Engineering FME(C)A (Failure Mode and Effects (Criticality) Analysis-Guide): FMEA is a design tool used to systematically analyze postulated component failures and identify the resultant effects on system operations. The analysis is sometimes characterized as consisting of two sub-analyses, the first being the failure modes and effects analysis (FMEA) of a system reliability study and the second the criticality analysis (CA). It involves reviewing as many components, assemblies, and subsystems as possible to identify failure modes and their causes and effects. For each component, the failure modes and their resulting effects on the rest of the system are recorded in a specific FMEA worksheet. There are numerous variations of such worksheets. An FMEA can be a qualitative analysis but may be put on a quantitative basis when mathematical failure rate models are combined with a statistical failure mode ratio database. A successful FMEA activity helps to identify potential failure modes based on experience with similar products and processes or based on common physics of failure logic. It is widely used in development and manufacturing industries in various phases of the product life cycle. FMEA can be performed at the system, subsystem, assembly, subassembly, or part level. IOW (Integrity Operating Windows): Program to avoid unexpected process facilities degradation that could lead to loss of containment. A vital component of corrosion management (materials degradation control) and inspection planning, including RBI. Other PSM systems may be affected by or involved with the IOW program, including Management of Change (MOC), Process Safety Information (PSI), and Training. See API RP584 for more details. Meridium (Mechanical Integrity-S/W): Meridium provides tools with sufficient database for problem-solving related to recurring equipment failures, including unplanned downtime; the inability to maintain planned production rates; high costs of fixing problems that result from equipment failures, and threats to employee and environmental safety. After the data exists in Meridium, it can be analyzed to determine the state of the equipment and the reliability, trends, potential risks, and probability of failures associated with that equipment. Based on the gathered data and associated analyses, you can map out the impact of projected changes and then make recommendations and suggest strategies for future equipment maintenance. MI (Mechanical Integrity-Reg): MI is just the 14 elements included in Process Safety Management (PSM), driven by the OSHA 1910.119 standard, but it is significant in terms of the asset coverage involved. For example, MI includes any and all equipment/assets used to produce products made from specific quantities of defined hazardous materials on the list covered by the PSM standard. System examples include fixed equipment such as pressure vessels and storage tanks, piping systems and associated hardware (valves, fittings, etc.), relief devices, vent hardware, and emergency shutdown/control systems. Rotating equipment/assets, such as pumps, blowers, fans, and compressors that may be used to move hazardous materials within these systems are also included. In many cases, this means that all equipment within the boundaries of a facility are subject to the PSM standard. MI encompasses the activities necessary to ensure that equipment/assets are designed, fabricated, installed, operated and maintained in such a way that they provide the desired performance in a safe, environmentally protected, and reliable fashion. In short, it is the Life Cycle Asset Management (LCAM) process, including the above plus procurement, testing, commissioning, and disposal of the assets. MI is a part of an effective reliability program and overall asset management, specific to equipment types, and more tactical in nature including the evaluation of condition requirements through regular monitoring and inspection of the condition of these assets. The key phases of MI program development, shown in Table 1.81, include management responsibility, equipment selection, and implementation through inspection, testing, and application of proactive maintenance strategies. Properly trained and certified personnel conducting these activities are also a key part of an effective MI program. MTBF (Mean Time Before Failure) or MTTF (Mean Time To Failure): The average time that the units in the population are expected to operate before failure. This metric is often referred to as MTBF or MTTF. The results show the comparison of the failure rate per the design condition with future, current, and past process conditions. MTTR (Mean Time To Repair): MTBF consists of MTTF (Mean Time To Failure) and MTTR (Mean Time To Repair). MTTF is the difference of time between two consecutive failures, and MTTR is the time required to fix the failure. Reliability for good software is a number between 0 and 1. Table 1.81 Key phases of work necessary for effective mechanical integrity (MI) requirements Phase 1 Phase 2 Phase 3 (Management Responsibility) (Equipment Selection)(1) (Inspection, Testing and Proactive Maintenance)(1) – Roles and responsibility for facility leadership and – Selection criteria per priority and organization consequence For targeted task: – Planning – Reporting – Level of detail to be addressed – Selection – Auditing – Documentation required – Scheduling – Execution and monitoring Source: LCE report 2017 Note: (1)Personnel Qualification for MI Execution (Staff, Contractors, and 3rd parties) – Shill/Knowledge for Assessment – Training Required and the Verified Certifications and Documentation – Continuous and Refresher Training

1.5 Maintenance, Reliability, and Integrity 111 OEE (Overall Equipment Effectiveness): Availability  Performance  Quality Availability ¼ Actual Run Time=Total Operative Mode Time ½Time Losses deductedŠ Performance ¼ Actual Speed=Normal Speed ½Speed Losses deductedŠ Quality ¼ Actual Good Product=Product Output ½Rework=Defects=Waste deductedŠ Pareto Diagram (Guide): A Pareto diagram (Fig. 1.49) (source: http:// Figure 1.49 Typical Pareto diagram in (Sample in Pizza House) www.discover6sigma.org/post/2005/11/pareto-chart/) is a simple bar chart that ranks related measures in decreasing order of occurrence. The purpose of a Pareto diagram is to separate the significant aspects of a problem from the trivial ones. By graphically separating the aspects of a problem, a team will know where to direct its improvement efforts. Reducing the largest bars identified in the diagram will do more for overall improvement than reducing the smaller ones. There are two ways to analyze Pareto data depending on what the user wants to know: – Counts Pareto: May use this type of Pareto analysis to learn which category occurs most often. The user will need to do a counts Pareto diagram. To create a counts Pareto, the user will need to know the categories and how often each occurred. – Cost Pareto: May use this type of Pareto analysis if the user wants to know which category of problem is the most expensive in terms of some cost. A cost Pareto provides more details about the impact of a specific category than a count Pareto can. For example, suppose the user have 50 occurrences of one problem and 3 occurrences of another. Based on a counts Pareto, the user would be likely to tackle the problem that occurred 50 times first. However, suppose the problem that occurred 50 times costs only $0.5 per occurrence ($25 total) and the problem that occurred 3 times costs $50 each time ($150 total). Based on the cost Pareto, the user may want to tackle the more expensive problem first. To create a cost Pareto, the user will need to know the categories, how often each occurred, and the cost for each category. Despite its simplicity, Pareto analysis is one of the most powerful problem-solving tools for system improvement. Getting the most from Pareto analysis includes making subdivisions, multi-perspective analyses, and repeat analyses. PCMS® (Plant Condition Management Software-S/W): PCMS (by MISTRAS Group) is a utilized software in many different energy industries for the management of inspection information on piping, pressure vessels, safety relief devices, valves, tanks, and other process equipment. PCMS offers tremendous benefits to any facility to budget and plan long-term maintenance strategies to identify problems before failures actually occur, thus reducing unplanned shutdown. The program provides a host of tools to organize, link, and synchronize information enabling the thorough evaluation of the results. PCMS is the only Mechanical Integrity software application on the market today that has 25+ plus years in asset, corrosion, and inspection data management. All program modules are seamlessly fed into the integrated RBI calculator, thus eliminating the need to manage multiple applications to perform total asset integrity analysis. PCMS is truly a “single-source” inspection management solution that provides an array of elements to achieve a company’s Mechanical Integrity initiatives including: • Complete Asset Tracking and Analysis • Integrated RBI • Comprehensive Inspection Tracking and Analysis • Inspection and Turnaround Planning • Corrosion Analysis and Trending • Safety Relief Valve Management PM (Preventive/Preventative Maintenance-Guide): PM is regularly performed on a piece of equipment to lessen the likelihood of its failing. Preventative maintenance is performed while the equipment is still working, so that it does not break down unexpectedly. Preventative maintenance is more complex to coordinate than run-to-failure maintenance because the maintenance schedule must be planned. Preventative maintenance is less complex to coordinate than predictive maintenance because monitoring strategies do not have to be planned nor the results interpreted. PSM (Process Safety Management-Reg.): It is a regulation, promulgated by the US Occupational Safety and Health Administration (OSHA). A process is any activity or combination of activities including any use, storage, manufacturing, handling, or the on-site movement of highly hazardous chemicals (HHCs) as defined by OSHA and the Environmental Protection Agency (EPA). The end-user should document that equipment complies with RAGAGEP. For existing equipment designed and constructed in accordance with codes, standards or practices that are no longer in general use, the end-user should determine and document that the equipment is designed, maintained, inspected, tested, and operated in a safe manner.

112 1 Design Engineering A process safety incident is the “Unexpected release of toxic, reactive, or flammable liquids and gases in processes involving highly hazardous chemicals.” Incidents continue to occur in various industries that use highly hazardous chemicals which exhibit toxic, reactive, flammable, or even explosive properties or may exhibit a combination of these properties. Regardless of the industry that uses these highly hazardous chemicals, there is a potential for an accidental release any time they are not properly controlled. OSHA has issued the Process Safety Management of Highly Hazardous Chemicals regulation (Title 29 of CFR Section 1910.119) which contains requirements for the management of hazards associated with processes using highly hazardous chemicals. RAGAGEP (Recognized and Generally Accepted Good Engineering Practices-Guide): The PSM standard does not define RAGAGEP. This RAGAGEP (memorandum) provides guidance on the enforcement of the PSM (Process Safety Management) Standard’s recognized and generally accepted good engineering practices (RAGAGEP) requirements, including how to interpret “shall” and “should” language in published codes, standards, published technical reports, recommended practices (RP) or similar documents, and on the use of internal employer documents as RAGAGEP. Enforcement activity, including the Petroleum Refinery Process Safety Management National Emphasis Program, and requests for assistance from the field revealed the need for guidance on the PSM standard’s RAGAGEP provisions. RAM (Reliability, Availability, and Maintainability-Prog): An asset management program developed by PinnacleART for optimization of costs through a combination of increased asset availability and reliability and optimized maintenance strategies. – Reliability is defined as the probability that an item will perform its intended function for a specified period of time. – Availability refers to the total time a system is in an operative state. – Maintainability describes the ability of an item to be retained or restored to specified conditions when maintenance is performed by qualified personnel. RAT (Bundle Retube Analysis Tool-Company’s Prog.): Developed by LyondellBasell. Traditionally the top failure mechanisms of tubes of H/EXs in oil and gas industries, listed below, resulted in 90% of the failures: • Corrosion by corrosive process fluids • Under deposit corrosion of carbon steel tubes • SCC of stainless steel tubes • Steam/condensate corrosion • Erosion by vibration of tubes • Galvanic corrosion • Crevice corrosion • SRB corrosion of cooling water in carbon steel or copper alloy tubes A Weibull analysis of cooling water exchanger failures was performed for each production unit in this plant. The range of MTTF (mean time to failure) was found to be between 7.2 and 13.2 years. The team identified three main areas for improvement to minimize future in-service tube failures. These areas were: 1. Tube testing 2. Retubing strategy during turnarounds 3. Design improvements (tube material, velocity, no tubes in window (NTIW), tube arrangement, impingement plate, tube-to-tubesheet design, etc.) Currently, the following four techniques are being used to test ferromagnetic tubes: 1. Remote field eddy current testing (RFEC) 2. Partial saturation eddy current testing (PSET) 3. Magnetic flux leakage (MFL) 4. Internal rotating inspection system (IRIS) The retube-analysis matrix is based on a point system. The following four risk factors are used in the matrix: 1. Tube-age factor 2. Remaining life factor 3. Production-criticality factor 4. Service factor [Background] The tube age factor compares the current age of the tube bundle to the historic average age of the tube bundle. The remaining life factor is based on the current tube wall loss and the corrosion rate. The production criticality factor takes into consideration the business and/or safety/environmental consequences of a tube leak. The service factor primarily covers the variables associated with reboilers, cooling water exchangers, and the mechanical design. A maximum of 4 points can be obtained for each factor. The inspection and retube priorities are determined based on the total number of points. The following are the three risk categories: 1. Retube, 11–16 points 2. Priority inspection, 8–10 points 3. Normal inspection, 1–7 points

1.5 Maintenance, Reliability, and Integrity 113 Retube-category exchangers are high-risk exchangers and are planned for retube during the turnaround. Exchangers in the “priority inspection” category are scheduled for testing early in the turnaround so that if required, there is sufficient time during the turnaround for retube. The turnaround team must evaluate whether mate- rial is required or shop space must be reserved for these exchangers. “Normal inspection” cate- gory exchangers are not expected to have prob- lems and are inspected after the priority exchangers. The retube-analysis matrix was val- Figure 1.50 Fishbone cause mapping by Kaoru Ishikawa idated and fine-tuned against past in-service tube failures (reliability hits) and past turnaround scopes. Of the exchangers that failed in service resulting in production loss of this plant, 77% would have been retubed during the turnaround if the retube-analysis matrix had been used. The remaining 23% of the exchangers fell in the “priority inspection” category. RC(F)A (Root Cause (Failure) Analysis-Guide): Root cause analysis is an approach for identifying the underlying causes of why an incident occurred so that the most effective solutions can be identified and implemented. It is typically used when something goes badly but can also be used when something goes well. Within an organization, problem-solving, incident investigation, and root cause analysis are all fundamentally connected by three basic questions: What’s the problem? Why did it happen? What should be done to prevent it? Figure 1.50 shows the fishbone diagram that builds from right to left. The Cause Mapping method actually uses Ishikawa’s convention by asking why questions in the direction we read. For the chronic failures, the following data should be collected and analyzed: – Preserving Failure Data – Ordering the Analysis – Analyzing the Data – Communicating Findings and Recommendations – Tracking for Success RCM (Reliability-Centered Maintenance-Prog): It is a process of determining the most effective maintenance approach. The final result of an RCM program is the implementation of a specific maintenance strategy on each of the assets of the facility. It is generally used to achieve improvements in fields such as the establishment of safe minimum levels of maintenance. Successful implementation philosophy of RCM employs Preventive Maintenance (PM), Predictive Maintenance (PdM), Real-Time Monitoring (RTM), Run-to-Failure (RTF), and Proactive Maintenance techniques in an integrated manner to increase the probability that a machine or component will function in the required manner over its design life cycle with a minimum of maintenance. The goal of the philosophy is to provide the stated function of the facility, with the required reliability and availability at the lowest cost. RCM requires that maintenance decisions be based on maintenance requirements supported by sound technical and economic justification. Currently RCM is defined in the standard SAE JA1011 (Evaluation Criteria for RCM Processes). This sets out the minimum criteria for what is, and for what is not, able to be defined as RCM. There are several different methods for implementing reliability-centered maintenance that are recommended, summarized in the following seven steps: – Step 1: Select an equipment for RCM analysis – Step 2: Define the boundaries and function of the systems that contain the selected equipment – Step 3: Define the ways that the system can fail (failure modes) – Step 4: Identify the root causes of the failure modes – Step 5: Assess the effects of failure – Step 6: Select a maintenance tactic for each failure mode – Step 7: Implement and then regularly review the maintenance tactic selected RMP (Risk Management Plan): It is used for facilities which are under extremely hazardous substances. These plans provide valuable information to local fire, police, and emergency response personnel to prepare for and respond to chemical emergencies in their community. The following identifications are to be prepared for the Risk Management Plan: – Identifies the potential effects of a chemical accident – Identifies the steps the facility is taking to prevent an accident – Spells out emergency response procedures should an accident occur

114 1 Design Engineering SagePlus® (FFS Assessment Software-S/W): SagePlus (by E2G) is a software for FFS (API 579/ASME FFS-1, Level 1 & 2), equipment design codes, materials tools, fluid and heat transfer, specialty in-service evaluation, safety, and stress analysis of equipment in oil and gas industries. It is based on the API/ASME 579, API 520, ASME B31.3, and other relevant code and standard committees. It is continuously updated in accordance with the updates of the based industrial standards. SAP (Systems, Applications, and Productions for Process Industries-rog): It is an asset management program that manage physical assets sustainably, to maximize return on assets, manage risk, achieve superior asset performance, optimize assets and portfolios, solve issues quickly, and mitigate risk. It can be used for all industries, infrastructures, building, utilities, militaries, etc. SMRP (Society for Maintenance & Reliability Professionals-Cert): SMRP Certification Programs such as the edited Certified Maintenance and Reliability Professional (CMRP), the Certified Maintenance and Reliability Technician (CMRT), and the Certified Asset Manage- ment Assessor (CAMA) are the No. 1 credentialing programs for validating the knowledge, skills, and abilities of M&R and asset management professionals and technicians. SPC (Statistical Process Control-Guide): It is an application of the same 14 tools to control process inputs (independent variables). SQC (Statistical Quality Control-Guide): It is an application of the 14 statistical and analytical tools (7-QC and 7-SUPP) to monitor process outputs (dependent variables). 7-QC 7-Supplemental • Cause-and-effect analysis • Data stratification • Check sheets/tally sheets • Defect maps • Control charts • Events logs • Histograms • Process flowcharts/maps • Pareto analysis • Progress centers • Scatter analysis • Randomization • Sample size determination TPM (Total Productive Maintenance-Guide): It is a system of maintaining and improving the integrity of production and quality systems through the machines, equipment, processes, and employees that add business value to an organization. TPM focuses on keeping all equipment in top working condition to avoid breakdowns and delays in manufacturing processes. One of the main objectives of TPM is to increase the productivity of plant and equipment with a modest investment in maintenance. Total quality management (TQM) and total productive maintenance (TPM) are considered as the key operational activities of the quality management system. The main objective of TPM is to increase the Overall Equipment Effectiveness (OEE) of plant equipment. TPM addresses the causes for accelerated deterioration while creating the correct environment between operators and equipment to create ownership. OEE has three factors below which are multiplied to give one measure called OEE. Performance  Availability  Quality ¼ OEE Each factor has two associated losses making six in total, these six losses are as follows: Performance ¼ (1) running at reduced speed – (2) minor stops Availability ¼ (3) breakdowns – (4) product changeover Quality ¼ (5) startup rejects – (6) running rejects The objective finally is to identify then prioritize and eliminate the causes of the losses. This is done by self-managing teams that problem solve. Employing consultants to create this culture is common practice. Weibull Analysis (Life Data Analysis-Guide): In Weibull analysis (life data analysis), the practitioner attempts to make predictions about the life of all products in the population by fitting a statistical distribution to life data from a representative sample of units. The parameterized distribution for the data set can then be used to estimate important life characteristics of the product such as reliability or probability of failure at a specific time, the mean life, and the failure rate. Life data analysis requires the practitioner to: • Gather life data for the product • Select a life time distribution that will fit the data and model the life of the product • Estimate the parameters that will fit the distribution to the data • Generate plots and results that estimate the life characteristics of product, such as the reliability or mean life Once the user has calculated the parameters to fit a life distribution to a particular data set, the user can obtain a variety of plots and calculated results from the analysis, including: • Reliability Given Time: The probability that a unit will operate successfully at a particular point in time. For example, there is an 88% chance that the product will operate successfully after 3 years of operation. • Probability of Failure Given Time: The probability that a unit will fail at a particular point in time. Probability of failure is also known as “unreliability,” and it is the reciprocal of reliability. For example, there is a 12% chance that the unit will fail after 3 years of operation (probability of failure or unreliability) and an 88% chance that it will operate successfully (reliability). • Mean Life: The average time that the units in the population are expected to operate before failure. This metric is often referred to as “mean time to failure” (MTTF) or “mean time before failure” (MTBF). • Failure Rate: The number of failures per unit time that can be expected to occur for the product.

1.6 Reiterative Engineering Mistakes 115 • Reliable Life (warranty time). The estimated time when the reliability will be equal to a specified goal. For example, the estimated time of operation is 4 years for a reliability of 90%. • B(X) Life: The estimated time when the probability of failure will reach a specified point (X%). For example, if 10% of the products are expected to fail by 4 years of operation, then the B(10) life is 4 years. (Note that this is equivalent to a reliable life of 4 years for a 90% reliability.) • Probability Plot: A plot of the probability of failure over time. (Note that probability plots are based on the linearization of a specific distribution. Consequently, the form of a probability plot for one distribution will be different from the form of another. For example, an exponential distribution probability plot has different axes than those of a normal distribution probability plot.) • Reliability vs. Time Plot: A plot of reliability over time. • pdf Plot: A plot of probability density function (pdf). • Failure Rate vs. Time Plot: A plot of the failure rate over time. • Contour Plot: A graphical representation of the possible solutions to the likelihood ratio equation. This is employed to make comparisons between two different data sets. References for Maintenance, Reliability, and Integrity API 579/ASME FFS-1, API RP580/581/584, API STD 689/ISO 14224, API STD2610, API RP2D/1107/1111, API 500 series for Inspection Standards, ISO/TC 67, IPMC (international property maintenance code), TWI Report 13,237 for CRIS (corrosion reliability inspection scheduling), PIP REEE002, NACE Conference Paper 04184, NACE MP Sep.2004 (p38), NACE Corrosion, Vol.60, No.5, p429, etc. 1.6 Reiterative Engineering Mistakes 1.6.1 Pressure psig: Internal Pressure (1 atm ¼ 1.013 bar ¼ 14.7 psig ¼ 29.4 psia, 0 psig ¼ 14.7 psia, 1 bar ¼ 14.5 psi) psia: Partial Pressure (H2, CO2, H2S, etc.) ¼ total absolute pressure x mole fraction Half/Full Vacuum: Internal Vacuum Ext. 15 psig (for design): Internal Vacuum Torr: Internal Vacuum (760 torr ¼ 14.7 psia ¼ 0 psig) ÃDifferential Pressure: psi 1.6.2 Temperature Conversion Formula C ¼ 5/9(F À 32) Ã1 F ¼ 9/5C + 32 Ã1 Several Mistakes of Conversion A Certain Temperature – Same as Above Differential Pressure: Δ C ¼ Δ 5/9 F Ã2 Δ F ¼ Δ 9/5 C Ã2 For example, PWHT: 1150 FÃ1 Æ 50 FÃ2 ! 621 CÃ1 Æ 28 CÃ2 621 (1150-32) Â 5/9 and 28 50 Â 5/9 For 50 F, Ã1 (Absolute value): C ¼ 5/9 (50À32) ¼ 10F – False Ã2 (Differential value): Δ C ¼ 5/9 (50) ¼ Δ 28F – True 1.6.3 Weight and Volume 1. Weight (liquid or solid): weight%, ppmw, ppbw, baume (caustic) 2. Volume (gas or vapor): sometimes used for partial pressure calculation : mole%, vol%, ppmv, ppbv

116 1 Design Engineering 1.6.4 Minimum, Maximum, and Average: ( ) for Example 1. Minimum: TS (tensile strength), YS (yield strength), Impact Test Absorbing Energy Value/Lateral Expansion, Elongation, Tolerance (machined parts of H/EX), Minimum Thickness, Chemical Composition, Hardness (wear resistance, hardfacing), Preheat, Postheat, Heat Treatment Temperature, Interpass Temperature, Fluid Velocity (to avoid MIC) 2. Maximum: TS, Ratio of YS/TS, Tolerance (most cases), Deflection (tower, structures), Hardness (stress corrosion cracking, sulfide stress corrosion, weld crack), Chemical Composition (carbon equivalent and carbon content for weldability), Noise (max. dB), Vibration, Heat Treatment Temperature, Interpass Temperature, Fluid Velocity (to avoid severe corrosion), etc. 3. Average or Range: Chemical Composition, Impact Test Absorbing Energy Value, etc. 1.6.5 Shall, Should, May, and Can “Shall” is “must be.” “Should” is “strongly recommend.” However, many project specifications may apply the “Should” in the applicable industrial codes/standards to “Shall” for the project execution for new construction and maintenance. These terminologies are the most important concern in RAGAGEP (Recognized and Generally Accepted Good Engineering Practices-Guide). Meanwhile, “May” indicates a permission and “Can” indicates a possibility or a capability. 1.6.6 Applicable Standards and Reference Standards Applicable Standards have the same authority with the code requirements. Reference Standards in the project specification are only for reference information unless the specification indicates to alloy the reference as project requirements.