ASME Boiler and Pressure Vessel Code (PDF)

Chapter 1 • Legislation and Codes for Power Engineers OBJECTIVE 8 Explain the scope of the ASME, and state the purpose and general content of the following sections oftheASME Boiler and Pressure Vessel Code: Sections I, II, IV, V, VI, VII, VIII (Divisions I and II), and IX. SCOPE OF THE ASME Origi...

Chapter 1 • Legislation and Codes for Power Engineers OBJECTIVE 8 Explain the scope of the ASME, and state the purpose and general content of the following sections oftheASME Boiler and Pressure Vessel Code: Sections I, II, IV, V, VI, VII, VIII (Divisions I and II), and IX. SCOPE OF THE ASME Originally founded in 1880 as a mechanical engineering society, the American Society of Mechanical Engineers (ASME) is a multidisciplinary engineering association with a membership of over 100,000. According to their website asme.org, ASME activities include the following: • Codes and standards: The ASME produces approximately 600 codes and standards covering many technical areas, including power plant systems and components. The most extensive standard is the ASME BPVC. • Certification: The ASME code stamp certifies that boilers and pressure vessels have been designed, manufactured, and inspected according to the ASME BPVC. • Training, education, and conferences: The society offers a range of online and on-site courses in areas such as boiler and pressure vessel design, gas turbines, and nuclear engineering. • Publications: The ASME publications include code books, engineering books, journals, and conference proceedings. • Engineering advocacy: The society provides advice to government officials on engineering and technology matters and policies affecting the public interest. The devastating boiler explosions of the nineteenth and early twentieth centuries resulted in a call for improved engineering standards. In response, the ASME set up a committee in 1911 for the purpose of formulating standard rules of safety" for the design, fabrication, and inspection during the construction of steam boilers and other pressure vessels. This committee was named the Boiler and Pressure Vessel Committee. The function of this committee is to establish rules of safety governing the design, fabrication, and inspection during construction of boilers and pressure vessels. It also interprets the rules when questions come up regarding their intent. The first edition of the BPVC was issued in 1914 and published in 1915. The BPVC provides rules for the design, fabrication, installation, inspection, care, and use of boilers, pressure vessels, and nuclear components. The code also includes standards on materials, welding and brazing procedures and qualifications, nondestructive examination, and nuclear inservice inspection. 36 3rd Class Edition 3 • Part A2 Legislation and Codes for Power Engineers • Chapter 1 ASME BOILER AND PRESSURE VESSEL CODE REFERENCES The ASME BPVC 2019 has 12 sections, several of which are divided into sub-sections called divisions or parts. This part of the chapter looks at sections relating to power boilers, heating boilers, and pressure vessels, as well as materials, non-destructive examination, and welding. It is particularly important to be aware of the date on the code, standard, act, or regulation that you are using. The paragraph numbers change as revisions and deletions occur in newer versions. Always try to ensure that you have the most up-to-date version available of the document. This course uses the following versions: 2018 PanGlobal ASME Academic Extract, containing extracts of the following: • ASME BPVC 1-2015 Rules for the Construction of Power Boilers • ASME BPVC 11 - Part D (Metric) - 2015 Materials • ASME BPVC IV - 2015 Rules for Construction of Heating Boilers • ASME BPVC VIII Div. 1-2015 Rules for Construction of Pressure Vessels • ASME BPVC IX - 2015 Welding, Brazing, and Fusing Qualifications • ASME B31.1 - 2014 Code for Power Piping • ASME B31.3 - 2014 Code for Process Piping ASME Code References Sections There are two ways to reference ASME code sections. As shown in Figure 3, sections may be separated with either decimals or hyphens. Both forms are used on the ASME website. You may also see references with spaces in between the words, such as ASME BPVC VIII Div. 1-2015. In all cases, a hyphen should precede the date and the date should be written out in full. The code reference in Figure 4, ASME BPVC.VIII.1-2015, contains the following information: • Name of organization: ASME (American Society of Mechanical Engineers) • Name of code: BPVC (Boiler and Pressure Vessel Code) • Section: VIII • Division: 1 • Date: 2015 Figure 3 - ASME Code Section References ASME BPVC.VIII.1-2015 ASMEBPVC-VIII-1-2015 ^7 Name of Name of Section Division Year organization code 3rd Class Edition 3 • Part A2 37 Chapter 1 • Legislation and Codes for Power Engineers Parts and Paragraphs Each section of the code has several parts. These parts are identified using a tsvo-letter code. The letters are selected to describe the content of the particular part. The first letter might be, for example, P (power boilers), H (heating boilers), or U (pressure vessels), depending on the equipment covered in the section. Some examples of second letters are G (general information), W (welding), FT (firetube), and WT (watertube). For example, the two-letter code PG means power boilers, general information. The two-letter code is followed by a hyphen and then the paragraph number. Decimals are used to indicate subdivisions within the paragraph. An alternate method is to notate sub-paragraphs with letters placed in brackets. Examples are shown in Figure 4. Figure 4 - ASME Code Paragraph References PG-67.2.1 UG-35.2(b)(8) ^~^ . -<^T Part Paragraph Part: Paragraph Sub-paragraphs SECTION 1: RULES FOR THE CONSTRUCTION OF POWER BOILERS As of 2019, the ASME BPVC, Section I is divided into fifteen parts with the main part being Part PG - General Requirements for all Methods of Construction. This part is pertinent to all power boilers, high-pressure and high-temperature water boilers, and liquid phase thermal fluid heaters, no matter their manner of construction. Other parts deal with requirements for boilers being constructed by different methods. For example. Part PW - Requirements for Boilers Fabricated by Welding. Still other parts deal with requirements for specific types of boilers. For example. Part PWT - Requirements for Watertube Boilers, or Part PFT - Requirements for Firetube Boilers. There are also parts for Alternative Rules, Optional Requirements, and Mandatory and Non-Mandatory Appendbces. An overview of Section I, Part PG follows with some information pertinent to the Third Class. The remaining Parts are similar. Following this overview are several self-tests based on the 2018 PanGlobal ASME Academic Extract. The full version ofASME BPVC Section I, 2015 can also be used. General Scope of Part PG, limitations, referenced standards, units of measure Materials The materials which can be used in boiler construction are listed including plate, forgings, pipe, and more Design The design requirements for boilers are included here. Highlights of this sub-part are: • Equations for calculations of maximum allowable pressure and minimum thickness of piping, tubing, drums, shells, and headers (PG-27) • Equations for the calculation of minimum thickness of dished heads (stayed or unstayed) and unstayed flat heads (PG-29,30,and31) Openings and • Required marking of valves and fittings (PG-42.2) Compensation . §^g of inspection openings (PG-44) 38 3rd Class Edition 3 • Part A2 Legislation and Codes for Power Engineers • Chapter 1 Boiler External Piping and Boiler Proper • The limits of boiler external piping and boiler proper piping is established in this sub-part (PG-58) Connections • Figures PG-58.2-1 to PG-58.2-6 graphically show the ^ transitions between boiler proper and boiler external piping and provide code references. • BlowofF requirements (PG-59.3) Design and Design and application requirements for miscellaneous pipe, valve, Application and fittings including: • Water level indicators, water columns, and connections (PG-60.1, 60.2, and 60.3) • Pressure gauges (PG-60.6) • Overpressure protection requirements (PG-67) Fabrication PG-75 states that the fabrication of boilers and parts must conform to the general fabrication requirements contained in part PG and to the specific requirements for fabrication in the parts of Section I that relate to the method of construction; for example, PW for boilers constructed by welding. Inspection and Test • This sub-part states that each boiler, superheater, waterwall, or economizer shall be inspected by an Authorized Inspector (AI) (PG-90.1) • It also states the requirements of a hydrostatic test (PG-99) Certification by Stamping and Data Reports • Stamping of a boiler, including nameplate data (PG-106) • Location of required stamping (PG- 111) • Manufacturers Data Report Forms (PG-112) and examples (Appendix A-350) Non-Mandatory Appendbc A • For estimating minimum pressure relief valve relieving capacity, Table A-44 Guide for Estimating Steaming Capacity Based on Heating Surface Self-Test 6 Design Formulas from ASME BPVC, Section 1-2015, PG-27 to PG-29 1) In the formulas given in PG-27.2.1 and PG-27.2.2, which variable is used for the minimum pipe wall thickness? 2) How does the manufacturing tolerance affect the minimum wall thickness "t" listed in PG-27.3? 3) What is the formula for calculating the thickness of a dished head? 4) Does the maximum allowable working pressure refer to gauge or absolute pressure? 3rd Class Edition 3 • Part A2 39 ^ Chapter 1 • Legislation and Codes for Power Engineers Self-Test 7 Valves and fittings from ASME BPVC, Section 1-2015, PG-59 and PG-60 1) In PG-59.2, why should the feedwater inlet through the drum be fitted with shields/ sleeves, or other suitable means to prevent direct discharge? 2) What is the minimum size for the pipe connections for gauge glasses connected directly to the boiler or to an intervening water column? Self-Test 8 Pressure relief valves from ASME BPVC, Section 1-2015, PG-67 to PG-73 1) The blowdown of a safety valve is the difference between the opening and closing pressures. What is the minimum blowdown requirement listed in Section I? 2) At what pressure must a safety valve attain full lift? 3) Which materials are not permitted for safety valve seats and disks? 4) What are the size requirements for body drains on a safety valve? 40 3rd Class Edition 3 • Part A2 Legislation and Codes for Power Engineers • Chapter 1 ^ Self-Test 9 Boiler Stamping and nameplates from ASME BPVC, Section 1-2015, PG-106 Refer to the Figure 5 and ASME BPVC 1-2015, PG-106 concerning power boiler stamping to answer the following questions: 1) What is the CRN for this boiler? 2) In which provinces has this boiler design been registered? 3) What is the name of the boiler manufacturer? 4) What is the maximum allowable working pressure? 5) What is the heating surface in square metres? 6) What is the stated steaming capacity of this boiler? 7) What type ofASME code stamp has been used? 8) What is the manufacturer's serial number? Figure 5 - Boiler Stamping CRN C.2767.5631 CERTIFIED BY POWERLINE BOILER MAWP150PSI 1002 SQ FT 3500 LB/H S/N155812 1970 3rd Class Edition 3 - Part A2 41 ^ Chapter 1 • Legislation and Codes for Power Engineers SECTION II: MATERIALS Note: The following paragraph refers to ASME-B31, Code for Pressure Piping. This code will be covered in detail in Section A2 Chapter 4: Piping Design, Connections, Support. The B31 code is divided into several sections, such as B31.1, Power Piping and B31.3, Process Piping. ASME Section II consists of four parts, three with material specifications and the fourth with the properties offerrous and non-ferrous materials that have been adopted by the code for the design of boiler and pressure vessel components. The material properties, such as allowable stress, are used in calculations found in the other sections of the ASME-BPVC and ASME-B31, Code for Pressure Piping. Within a given steel specification, the word grade refers to materials that have different carbon content or mechanical properties (tensile and yield strengths). Grade numbers for carbon steel pipe are A, B, and sometimes C. Grade A has the least carbon content and the greatest ductility. For calculations with tubing, piping drums, shells, and headers, the Power Engineer needs to be familiar with the following two parts of Section II: 1. Part A: Ferrous Material Specifications. Part A includes material specifications for steel pipe, flanges, plates, bolting materials, and castings, and wrought, cast, and malleable iron. Requirements such as heat treatment, chemical analysis, tensile requirements, and permissible variations in dimensions can also be found in this part. 2. Part D: Properties. Part D lists the properties, including the maximum allowable stress, of the materials approved for use in Sections I (Power Boilers), IV (Heating Boilers), and VIII (Pressure Vessels) of the ASME BPVC. How to Use Table 1A in ASME BPVC 11 - D (Metric) Table 1A is arranged in sets of four consecutive pages of data. Figure 5 shows only the first and fourth page. To find the maximum allowable stress (S) at a given temperature, follow the simple procedure outlined in the example below. Example: Find S for SA-213, TP304 (18 Cr-8 Ni) at temperature 550°C. Solution: Step 1. Find the spec number and type/grade by scrolling down the chart to SA-213, TP304. Step 2. Go left to locate the line number for the steel spec and grade, in this case, line 17. Step 3. Follow line 17 to the right, across two or three pages, to locate the column with 550°C. Step 4. Read the value for S (max allowable stress) in the 550°C column. 5 = 70.8 MPa. Answer For SA-213, TP304 at temperature 550°C, S = 70.8 MPa. 42 3rd Class Edition 3 - Part A2 Legislation and Codes for Power Engineers • Chapter 1 ^ Figure 6 - How to Use Table 1A Table 1A (Cont'd) Section I; Section III, Classes 2 and 3;*Section VIII, Division 1; and Section XII Maximum allowable stress values S for ferrous materials (*See maximum temperature limits for restrictions on class) Alloy Desig./ UNS Line Size/ Class/ Condition/ Thickness, mm Group Nominal composition Product form Spec No. Type/Grad( 14 16Cr-12Ni-2Mo Smls. tube SA-213 TP316H S31609 8 1 15 16Cr-12Ni-2Mo-N Smls. tube SA-213 TP316N S31651 8 1 16 18Cr-8Ni Smls. tube SA-213 TP304L S30403 8 1 1171 (8 18Cr-8Ni Smls. tube I SA-213 TP304 S30400 8 1 18Cr-8Ni Smls. tube SA-213 TP304HI S30409 8 1 19 18Cr-8Ni-N Smls. tube SA-213 TP304N S30451 8 1 20 18Cr-10Ni-Cb Smls. tube SA-213 TP347 S34700 8 1 No. No. Temper P-No. No. Step 1 Step 2 Maximum allowable stress, MPa (multiply by 1000 to obtain kPa), for metal temperature, °C, not exceeding Step3 Line No. 500 600 625 650 675 700 725 750 775 800 825 38.6 29.6 8.05 14 107 106 105 99.8 80.3 65.5 50.4 15 126 124 119 101 81.6 65.3 50.4 16 72.5 23.0 17.7 13.4 10.4 60.2 49.5 40.4 32.9 26.7 22.0 73.6 72.4 70.8 68.9 65.4 51.4 41.7 32.9 26.5 21.3 17.2 13.9 11.1 8.73 18 73.6 19 109 72.4 70.8 <68.9 65.4 51.4 41.7 32.9 26.5 21.3 17.2 13.9 11.1 8.73 106 98.3 7^ 64.3 51.4 41.6 20 115 113 99.8 77.2' 57.7 39.9 30.0 23.2 16.3 11.2 8.93 7.08 5.77 5.32 117 850 875 900 Step 4 3rd Class Edition 3 • Part A2 43 r5> Chapter 1 • Legislation and Codes for Power Engineers Self-TestlO Using Stress Table 1A in ASME BPVC II - D (Metric) - 2015 1) Find the maximum allowable stress value 5 in MPa for SA-213 Type 347 at 410°C. 2) Find the maximum allowable stress value 5 in MPa for the following materials and temperatures: a) Carbon steel, SA-210 Grade C, at temperature 120°C b) Low alloy steel, lCr-l/2Mo, SA-335 P12, at temperature 220°C c) Alloy steel 17Cr, SA-268 TP 430, at temperature 490°C SECTION IV: RULES FOR CONSTRUCTION OF HEATING BOILERS Section IV covers minimum safety requirements for the design, fabrication, installation, and inspection of steam heating, hot water heating, and hot water supply boilers intended for low-pressure service that are directly fired by oil, gas, electricity, or coal. This section contains the rules and general requirements for all methods of construction of power, electric, and miniature boilers and high-temperature water boilers used in stationary service. It also includes power boilers used in locomotive, portable, and traction service. The rules in this section are applicable to steam boilers operating at pressures not exceeding 100 kPa and high-temperature water boilers operating at pressures not exceeding 1100 kPa and temperatures not exceeding 120°C. The contents of the ASME BPVC, Section IV are outlined here. It is similar in layout to Section I. Part HG is titled General Requirements of All Materials of Construction. Subsequent parts deal with boilers fabricated using welding or brazing; boilers made of cast iron or cast aluminum; and potable water heaters (commercial or industrial size). Each part is broken down into articles with the two-letter designator followed by a number. The article is divided into headings with three digits beginning with the article number. For example, the material in article 2 will have heading numbers such as HG-201 and HG-202. Within each heading, the paragraphs are marked with decimals, such as HG-201.2. This numbering system makes it easy to find specific references in the code. The summary below covers only Part HG: General Requirements, which is the first part of the document. The information included for each article are highlights only and are not inclusive. Self-tests will follow. 44 3rd Class Edition 3 • Part A2 Legislation and Codes for Power Engineers • Chapter 1 ^ Part HG: General Requirements Article 1 Scope and Service Restrictions This article provides rules restricted to the following services: • Steam boilers operating at pressures not exceeding 15 psi (lOOkPa) • Hot water heating boilers and hot water supply boilers operating at pressures not exceeding 160 psi (1100 kPa) and temperatures not exceeding 250°F (120°C) Article 2 Materials Requirements for the materials used in the fabrication of heating boilers. Article 3 Design Requirements regarding the design of heating boilers is included in this article. • Calculations like those found in Section I, Part PG for design pressure, required wall thickness ofcylindrical shells, pipes, tubes, and headers • Calculations for pressure and thickness in heads Article 4 Pressure Relieving Devices The requirements for various types of pressure relieving devices is found in this article, including: • Safety and safety relief valve requirements for steam and hot water boilers • Temperature and pressure safety relief valves Article 5 Test, Inspection and Stamping Included in this article is information and requirements for: • Hydrostatic and pneumatic tests • Inspection tests, boiler certification • Stamping requirements for heating boilers based on service (steam/water), material (cast iron, cast aluminum, and other) Article 6 Instrumentation, Fittings, and Controls This section is divided according to steam or hot water boilers. It includes requirements for: • Steam gauges • Water gauge glasses • Pressure and temperature control • Automatic low-water fuel cutoff and/or water feeding devices Article 7 Installation Requirements This article includes requirements for: • The mounting of safety and safety relief valves • Provision for piping expansion • Provisions for thermal expansion in hot water systems 3rd Class Edition 3 • Part A2 45 ^ Chapter 1 • Legislation and Codes for Power Engineers Self-Test 11 Pressure relieving devices from ASME BPVC, Section IV-2015, HG-400 to HG-403 1) What is the maximum pressure rise permitted when safety valves are discharging on a steam heating boiler? 2) What is the ASME certification mark for a heating boiler safety valve? 3) Is heating surface calculated on the water side or the side receiving heat in the boiler circulating system? Self-Test 12 Heating boiler instruments, fittings, and controls ASME BPVC, Section IV - 2015, HG-602 to HG-611 1) What is the minimum size for gauge glass connections? 2) What is the minimum size for connections between the water column and boiler? 3) What is the setting of the safety limit control that cuts off the fuel to prevent over-pressure? 4) What is the scale range for a mechanical pressure (altitude) gauge? 46 3rd Class Edition 3 ' Part A2 Legislation and Codes for Power Engineers • Chapter 1 SECTION V: NON-DESTRUCTIVE EXAMINATION Section V includes requirements and methods for non-destructive examination, which are referenced and required by other code sections. It also includes manufacturers examination responsibilities, duties of authorized inspectors, and requirements for qualification of personnel during inspection and examination. Examination methods are intended to detect surface and internal imperfections in materials, welds, and fabricated components. A glossary of related terms is included. Each method of non-destructive examination is described in detail in Sub-section A. The main contents of this code include information on the following: • General requirements • Radiographic examination • Ultrasonic examination methods for welds • Ultrasonic examination methods for materials • Liquid dye penetrant examination • M.agnetic particle examination • Eddy current examination • Visual examination • Leak testing SECTION VI: RECOMMENDED RULES FOR THE CARE AND OPERATION OF HEATING BOILERS ASME Section VI deals with the recommended rules for caring for and operating heating boilers. This includes boilers that do not exceed 100 kPa or 120°C as defined in Section IV of the ASME BPVC, as well as the auxiliary equipment needed to run them. The amount of information in Section VI is quite extensive, from how to conduct a try-lever test of a safety valve to why a cold boiler sometimes looks like it is leaking when it is first fired, and from safety and housekeeping to how to prepare a boiler for inspection. It is for every learners benefit to access a copy of Section VI. 3rd Class Edition 3 • Part A2 47 ^ Chapter 1 • Legislation and Codes for Power Engineers The articles in this section and an overview of the information they contain is listed below. Article 1: Introduction Explains the scope of the section (the types of boilers to which Section VI applies). Article 2: Glossary Lists terms applicable to heating boilers, fuels, fuel-burning equipment, combustion, and water treatment. Article 3: Types of Boilers Classifies heating boilers according to their design, construction, and application. Article 4: Fuels and Provides information on the common fuels and how they are Fuel-burning Equipment burned including stoker firing. Article 5: Boiler Room Facilities and Installation Recommended procedures for the safe, economical operation and maintenance of automatically fired boilers. This article also lists boiler room facilities requirements, including ventilation, log books, and records. Article 6: Overpressure Protection Lists requirements for pressure relief devices including: • The number of pressure relief valves • Certification marks • Capacity Article 7: Accessories and Installation Discusses the requirements for major accessories including: • Steam traps • Circulating pumps • Expansion tanks Article 8: Controls and Instrumentation Information on: • Low water fuel cut-offs and water-feeders • Pressure controls • Temperature controls Article 9: Operation and Maintenance of Steam Boilers Covers procedures for steam boilers including: • Cleaning, filling, and firing new boilers • Boil out procedures • Starting a boiler after layup, condensation Article 10: Operation Similar to Article 9 but covers requirements for the care and and Maintenance of Hot-Water Boilers operation of hot-water supply boilers and hot-water heating boilers. Article 11: Inspection of Installed Boilers inspector should conduct an inspection. - Article 12: Boiler Repairs This article covers: Covers preparations for periodic inspections as well as how the • Authorization for repairs • Notification to inspectors • Welding requirements Article 13: Water This article contains information on the recommended Treatment procedures for treating water in steam and hot water boilers. Tliis includes factors to be considered when determining water treatment, common boiler water problems, etc. Article 14: Treatment Wet and dry lay-up procedures of Laid-up Boilers 48 3rd Class Edition 3 • Part A2 Legislation and Codes for Power Engineers • Chapter 1 SECTION VII: RECOMMENDED GUIDELINES FOR THE CARE OF POWER BOILERS ASME Section VII states the following: The purpose of Section VII, Recommended Guidelines for the Care of Power Boilers, is to promote safety in the use of power boilers. These guidelines are intended for use by those directly responsible for operating, maintaining, and examining power boilers. Guidelines are also provided for the operation of auxiliary equipment that affects the safe and reliable operation of power boilers. The boilers discussed in this section are limited to the operating ranges of power boilers, in which steam is generated at a pressure exceeding 15 psig or 100 kPa, as defined in Section I of the ASME BPVC, but not including high-temperature hot water boilers. The information in Section VII can be very useful to the Power Engineer, both while learning the basics and while working in the industry. Guidelines on how to start a boiler and its auxiliaries can be found here. Also found here are recommendations on instrumentation and controls, interlocks, inspections, water treatment, and prevention of boiler failures. It cannot be emphasized enough that this is a very valuable source of information for Power Engineers. As of the 2019 edition of the ASME BPVC, Section VII is divided into 5 sub-sections and articles within those sub-sections. The five sub-sections are as follows: Sub-section 1 Watertube Drum-Type Industrial Steam Boilers Sub-section 2 Pertaining to All Steam Boilers Sub-section 3 Other Boiler Types Sub-section 4 Coal-Fired and Other Solid-Fuel-Fired Boilers Sub-section 5 Glossary 3rd Class Edition 3 • Part A2 49 ^r Chapter 1 • Legislation and Codes for Power Engineers A short description of some of the Section VII articles are included below. Sub-section 1: Watertube Drum-Type Industrial Steam Boilers Article 101: Boiler Describes the guideline for routine boiler operation including: Operation • Start-up, normal operation, and shut-down • Training Article 102: Boiler Auxiliaries Guidelines for the normal and emergency operation of boiler auxiliaries including: • Airheaters • Boiler feed pumps • Draft fans and dampers Article 103: Boiler Guidelines and descriptions for frequently used appurtenances Appurtenances including: • Boiler pressure relief valves maintenance • Water column and gauge glass blowdown procedure • Boiler blowdown Article 104: Short description of the recommended instrumentation for boilers Instrumentation, Controls, and Interlocks and boiler operation including: • Water level • Furnace draft pressure • Steam flow • Air flow Article 105: The 2019 edition of ASME BPVC, Section VII differentiates Examinations between the terms inspection and examination. The term inspection is reserved for the activities of commissioned inspectors. Examinations refer to visual checks made by plant operating and maintenance personnel. This article includes guidelines for the examination of boilers to ensure their safe operation. Article 106: Repairs, Alterations, and Maintenance Information and guidelines for repairs, alterations, and maintenance of power boilers, including maintenance checks for steam boilers. Refers to Nonmandatory Appendix A, which contains, among other things, recommended checklists regarding maintenance of watertube boilers. Sub-section 2: Pertaining to all Steam Boilers Article 200: Protecting Information on the control of chemical conditions within steam Heat Transfer Surfaces boilers to promote safety in operation, including: • Internal cleaning of boilers • Deposits and internal corrosion • Corrosion cracking of boiler steel • Water analysis (sampling, testing, controlling, and reporting) Article 201: Preventing Boiler Failures 50 Information is included here that describes the main causes of boiler failure and the steps that can be taken to prevent failure. 3rd Class Edition 3 • Part A2 Legislation and Codes for Power Engineers • Chapter 1 Side Track In Canada, most sections of the ASME BPVC can be brought into a jurisdictional Power Engineering examination and used for reference during the exam. However, Sections VI (Recommended Rules for the Care and Operation of Heating (B Boilers) and Section VII (Recommended Guidelines for the Care of Power Boilers) are not allowed. Learners are expected to know the material in these two sections without looking it up. There is a wealth of information about looking after boilers in these two sections/ and a Power Engineer would be helped a lot during their examinations and careers if they read and study them. SECTION VIII: RULES FOR THE CONSTRUCTION OF PRESSURE VESSELS Pressure vessels are different from boilers in that they are not designed to be pressurized by the direct application of heat. Instead, pressure vessels are designed to store and contain an expansible fluid under pressure. This is an important distinction to remember. Section I (Power Boilers) of the ASME code cannot be used when dealing with pressure vessels. Section VIII must be consulted instead. Division 1 - Rules for the Construction of Pressure Vessels Division 1 covers the minimum safety requirements for the construction, design, fabrication, and certification of pressure vessels, whether under internal or external pressure. Pressure vessels may be fired or unfired. Specific requirements are given for several classes of material used in pressure vessel construction and fabrication methods, such as welded, forged, and brazed construction. Division 2 - Alternative Rules These rules provide an alternative to the minimum requirements provided in the scope of Division 1. Division 2 covers only vessels installed in a fixed location for a specific service where the vessel owner prepares the design specifications and retains control of the operation and maintenance of the vessel during its useful life. The difference between Division 1 and Division 2 is as follows: • Division 1 uses a design-by-rule approach. This means strict use of design equations and rules. This method is more conservative and incorporates a higher safety factor (also called design factor). The Division 1 safety factor was formerly 4, but the 2001 and later editions use a safety factor of 3.5. A higher safety factor means the pressure vessel tends to be more expensive overall. • Division 2 uses a design-by-analysis approach. This method uses complex numerical methods, typically finite element analysis. The calculations are much more rigorous than Division 1 but use a lower safety factor of 3. A lower safety factor means higher allowable stresses and thus smaller wall thicknesses. So, for large or complex vessels, the overall cost may be lower when using Division 2. Division 3 - Alternative Rules for the Construction of High-Pressure Vessels The rules of this division constitute requirements for the design, construction, inspection, and overpressure protection of pressure vessels with design pressures above 69 MPa. 3rd Class Edition 3 • Part A2 51 ^ Chapter 1 • Legislation and Codes for Power Engineers Self-Test13 Use ASME Section VIII, Division 1 to answer the following questions. 1) What is the difference between a U and a DM pressure vessel whose certification marks are shown in UG-116? 2) Refer to Figure UW-3 in Sub-section B, Part UW. What is the definition of a category? Which category (A, B, C, D) applies to the following weld locations? a) Circumferential joints within the main shell b) Longitudinal joints within the main shell c) A welded joint connecting nozzles to the main shell d) A welded joint connecting flanges to the main shell SECTION IX: WELDING AND BRAZING QUALIFICATIONS PROCEDURES Section IX covers the rules for the qualification of welding and brazing procedures, as required by other code sections. It also covers rules for the qualification and re-qualification of welders, brazers, and welding and brazing operators in order that they may perform welding or brazing, as required by other code sections, in the manufacturing of boiler components. Part QG General In this section are the general requirements for all material-joining Requirements processes. This includes qualifications ofwelders, welding operators, and brazers. The purpose of Welding Procedure Specifications (WPS), Procedure Qualification Records (PQR), and Welder Performance Qualification (WPQ) are detailed. Also included is an extensive glossary with definitions of common welding and welding process terms. Part QW Welding This section contains separate articles on general welding requirements, WPS, PQR, and WPQ. The information includes details on types of tests required as well as acceptance criteria of those tests. Mandatory Appendix E lists acceptable Standard Welding Procedure Specifications (SWPs). 52 3rd Class Edition 3 • Part A2 Legislation and Codes for Power Engineers • Chapter 1 T® SUMMARY OF LEGISLATION AND CODES FOR POWER ENGINEERS This chapter presented an overview of the legislation and codes found in the boiler and pressure vessel industry, as well as the stakeholders involved. Governments enact legislation for boiler and pressure vessel safety in order to safeguard life and property. During the late 19th century, boiler explosions were a regular occurrence. The development of codes and standards was a response to this public safety issue. At that time, there was no uniformity in the design rules for the construction of pressure equipment. Design codes such as the ASME BPVC provide uniform design standards across jurisdictions and help protect life and property. Having a good working knowledge of legislation and codes helps Power Engineers safely and efficiently operate the equipment for which they are responsible. Safety must always be paramount for the Power Engineer. 3rd Class Edition 3 • Part A2 53