APPENDIX C
EXCERPTS FROM: ASME BOILER AND PRESSURE VESSEL CODE
SECTION VIII - RULES FOR CONSTRUCTION OF PRESSURE VESSELS
2010 EDITION
INTRODUCTION
SCOPE
U-1 SCOPE
U-1 (a)
U-1(a)(1) The Foreword provides the basis for the rules described in this Division.
U-1(a)(2) For the scope of this Division, pressure vessels are containers for the containment of pressure, either internal or external. This pressure may be obtained from an external source, or by the application of heat from a direct or indirect source, or any combination thereof.
U-1(a)(3) This Division contains mandatory requirements, specific prohibitions, and nonmandatory guidance for pressure vessel materials, design, fabrication, examination, inspection, testing, certification, and pressure relief. The Code does not address all aspects of these activities, and those aspects which are not specifically addressed should not be considered prohibited. Engineering judgment must be consistent with the philosophy of this Division, and such judgments must never be used to overrule mandatory requirements or specific prohibitions of this Division. See also informative and nonmandatory guidance regarding metallurgical phenomena in Appendix A of Section II, Part D.
U-1(b) This Division is divided into three Subsections, Mandatory Appendices, and Nonmandatory Appendices. Subsection A consists of Part UG, covering the general requirements applicable to all pressure vessels. Subsection B covers specific requirements that are applicable to the various methods used in the fabrication of pressure vessels. It consists of Parts UW, UF, and UB dealing with welded, forged, and brazed methods, respectively. Subsection C covers specific requirements applicable to the several classes of materials used in pressure vessel construction. It consists of Parts UCS, UNF, UHA, UCI, UCL, UCD, UHT, ULW, and ULT dealing with carbon and low alloy steels, nonferrous metals, high alloy steels, cast iron, clad and lined material, cast ductile iron, ferritic steels with properties enhanced by heat treatment, layered construction, and low temperature materials, respectively. Section II, Part D also contains tables of maximum allowable stress values for these classes of materials.
The Mandatory Appendices address specific subjects not covered elsewhere in this Division, and their requirements are mandatory when the subject covered is included in construction under this Division. The Nonmandatory Appendices provide information and suggested good practices.
U-1 (c)
U-1(c)(1) The scope of this Division has been established to identify the components and parameters considered in formulating the rules given in this Division. Laws or regulations issued by municipality, state, provincial, federal, or other enforcement or regulatory bodies having jurisdiction at the location of an installation establish the mandatory applicability of the Code rules, in whole or in part, within their jurisdiction. Those laws or regulations may require the use of this Division of the Code for vessels or components not considered to be within its Scope. These laws or regulations should be reviewed to determine size or service limitations of the coverage which may be different or more restrictive than those given here.
U-1(c)(2) Based on the Committee's consideration, the following classes of vessels are not included in the scope of this Division; however, any pressure vessel which meets all the applicable requirements of this Division may be stamped with the Code U Symbol:
(a) those within the scope of other Sections;
(b) fired process tubular heaters;
(c) pressure containers which are integral parts or components of rotating or reciprocating mechanical devices, such as pumps, compressors, turbines, generators, engines, and hydraulic or pneumatic cylinders where the primary design considerations and/or stresses are derived from the functional requirements of the device;
(d) except as covered in U-l(f), structures whose primary function is the transport of fluids from one location to another within a system of which it is an integral part, that is, piping systems;
(e) piping components, such as pipe, flanges, bolting, gaskets, valves, expansion joints, fittings, and the pressure containing parts of other components, such as strainers and devices which serve such purposes as mixing, separating, snubbing, distributing, and metering or controlling flow, provided that pressure containing parts of such components are generally recognized as piping components or accessories;
(f) a vessel for containing water
1 under pressure, including those containing air the compression of which serves only as a cushion, when none of the following limitations are exceeded:
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(1) a design pressure of 300 psi (2 MPa);
(2) a design temperature of 210°F (99°C);
(g) a hot water supply storage tank heated by steam or any other indirect means when none of the following limitations is exceeded:
(1) a heat input of 200,000 Btu/hr (58.6 kW);
(2) a water temperature of 210°F (99°C);
(3) a nominal water containing capacity of 120 gal (450 L);
(h) vessels not exceeding the design pressure, at the top of the vessel, (see 3.2) limitations below, with no limitation on size [see UG-28(f), 9-l(c)]:
(1) vessels having an internal or external pressure not exceeding 15 psi (100 kPa);
(2) combination units having an internal or external pressure in each chamber not exceeding 15 psi (100 kPa) and differential pressure on the common elements not exceeding 15 psi (100 kPa) [see UG-19(a)];
(i) vessels having an inside diameter, width, height, or cross section diagonal not exceeding 6 in. (152 mm), with no limitation on length of vessel or pressure;
U-1(d) The rules of this Division have been formulated on the basis of design principles and construction practices applicable to vessels designed for pressures not exceeding 3000 psi (20 MPa). For pressures above 3000 psi (20 MPa), deviations from and additions to these rules usually are necessary to meet the requirements of design principles and construction practices for these higher pressures. Only in the event that after having applied these additional design principles and construction practices the vessel still complies with all of the requirements of this Division may it be stamped with the applicable Code symbol.
U-1(e) In relation to the geometry of pressure containing parts, the scope of this Division shall include the following:
U-1(e)(1) where external piping; other pressure vessels including heat exchangers; or mechanical devices, such as pumps, mixers, or compressors, are to be connected to the vessel:
(a) the welding end connection for the first circumferential joint for welded connections [see UW-13(g)];
(b) the first threaded joint for screwed connections;
(c) the face of the first flange for bolted, flanged connections;
(d) the first sealing surface for proprietary connections or fittings;
U-1(e)(2) where nonpressure parts are welded directly to either the internal or external pressure retaining surface of a pressure vessel, this scope shall include the design, fabrication, testing, and material requirements established for nonpressure part attachments by the applicable paragraphs of this Division;
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U-1(e)(3) pressure retaining covers for vessel openings, such as manhole and handhole covers;
U-1(e)(4) the first sealing surface for proprietary fittings or components for which rules are not provided by this Division, such as gages, instruments, and nonmetallic components.
U-1(f) The scope of the Division includes provisions for pressure relief devices necessary to satisfy the requirements of UG-125 through UG-137 and Appendix 11.
U-1(g)(1) Unfired steam boilers shall be constructed in accordance with the rules of Section I or this Division [see UG- 125(b) and UW-2(c)].
U-1(g)(2) The following pressure vessels in which steam is generated shall not be considered as unfired steam boilers, and shall be constructed in accordance with the rules of this Division:
U-1(g)(2)(a) vessels known as evaporators or heat exchangers;
U-1(g)(2)(b) vessels in which steam is generated by the use of heat resulting from operation of a processing system containing a number of pressure vessels such as used in the manufacture of chemical and petroleum products;
U-1(g)(2)(c) vessels in which steam is generated but not withdrawn for external use.
U-1(h) Pressure vessels or parts subject to direct firing from the combustion of fuel (solid, liquid, or gaseous), which are not within the scope of Sections I, III, or IV may be constructed in accordance with the rules of this Division [see UW-2(d)].
U-1(i) Gas fired jacketed steam kettles with jacket operating pressures not exceeding 50 psi (345 kPa) may be constructed in accordance with the rules of this Division (see Appendix 19).
U-1(j) Pressure vessels exclusive of those covered in U-l(c), U-l(g), U-l(h), and U-l(i) that are not required by the rules of this Division to be fully radiographed, which are not provided with quick actuating closures (see UG-35), and that do not exceed the following volume and pressure limits may be exempted from inspection by Inspectors, as defined in UG-91, provided that they comply in all other respects with the requirements of this Division:
U-1(j)(1) 5 cu ft (0.14 m3) in volume and 250 psi (1.7 MPa) design pressure; or
U-1(j)(2) 3 cu ft (0.08 m3) in volume and 350 psi (2.4 MPa) design pressure;
U-1(j)(3) 1½ cu ft (0.04 m3) in volume and 600 psi (4.1 MPa) design pressure.
In an assembly of vessels, the limitations in (1) through (3) above apply to each vessel and not the assembly as a whole. Straight line interpolation for intermediate volumes and design pressures is permitted. Vessels fabricated in accordance with this rule shall be marked with the “UM" Symbol in Fig. UG-116 sketch (b) and with the data required in UG-116. Certificates of Compliance shall satisfy the requirements of UG-120(a).
U-1 (k) The degree of nondestructive examination(s) and the acceptance standards beyond the requirements of this Division shall be a matter of prior agreement between the Manufacturer and user or his designated agent.
GENERAL
U-2 GENERAL
(a) The user or his designated agent
4 shall establish the design requirements for pressure vessels, taking into consideration factors associated with normal operation, such other conditions as
startup and shutdown, and abnormal conditions which may become a governing design consideration (see UG-22).
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(1) the need for corrosion allowances;
(2) the definition of lethal services. For example, see UW-2(a).
(3) the need for postweld heat treatment beyond the requirements of this Division and dependent on service conditions;
(4) for pressure vessels in which steam is generated, or water is heated [see U-l(g) and (h)], the need for piping, valves, instruments, and fittings to perform the functions covered by PG-59 through PG-61 of Section I.
(1) The Manufacturer of any vessel or part to be marked with the Code Symbol has the responsibility of complying with all of the applicable requirements of this Division and, through proper certification, of assuring that all work done by others also complies. The vessel or part Manufacturer shall have available for the Inspector's review the applicable design calculations. See 10-5 and 10-15(d).
(2) Some types of work, such as forming, nondestructive examination, and heat treating, may be performed by others (for welding, see UW-26 and UW-31). It is the vessel or part Manufacturer's responsibility to ensure that all work so performed complies with all the applicable requirements of this Division. After ensuring Code compliance, the vessel or part may be Code stamped by the appropriate Code stamp holder after acceptance by the Inspector.
(c) A vessel may be designed and constructed using any combination of the methods of fabrication and the classes of materials covered by this Division provided the rules applying to each method and material are complied with and the vessel is marked as required by UG-116.
(d) When the strength of any part cannot be computed with a satisfactory assurance of safety, the rules provide procedures for establishing its maximum allowable working pressure.
(e) It is the duty of the Inspector to make all of the inspections specified by the rules of this Division, and of monitoring the quality control and the examinations made by the Manufacturer. He shall make such other inspections as in his judgment are necessary to permit him to certify that the vessel has been designed and constructed in accordance with the requirements. The Inspector has the duty of verifying that the applicable calculations have been made and are on file at Manufacturer's plant at the time the Data Report is signed. Any questions concerning the calculations raised by the Inspector must be resolved. See UG-90(c)(l).
(f) The rules of this Division shall serve as the basis for the Inspector to:
(1) perform the required duties;
(2) authorize the application of the Code Symbol;
(3) sign the Certificate of Shop (or Field Assembly) Inspection.
(g) This Division of Section VIII does not contain rules to cover all details of design and construction. Where complete details are not given, it is intended that the Manufacturer, subject to the acceptance of the Inspector, shall provide details of design and construction which will be as safe as those provided by the rules of this Division.
(h) Field assembly of vessels constructed to this Division may be performed as follows.
(1) The Manufacturer of the vessel completes the vessel in the field, completes the Form U-1 or U-1A Manufacturer's Data Report, and stamps the vessel.
(2) The Manufacturer of parts of a vessel to be completed in the field by some other party stamps these parts in accordance with Code rules and supplies the Form U-2 or U-2A Manufacturer's Partial Data Report to the other party. The other party, who must hold a valid U Certificate of Authorization, makes the final assembly, required NDE, final pressure test; completes the Form U-1 or U-1A Manufacturer's Data Report; and stamps the vessel.
(3) The field portion of the work is completed by a holder of a valid U Certificate of Authorization other than the vessel Manufacturer. The stamp holder performing the field work is required to supply a Form U-2 or U-2A Manufacturer's Partial Data Report covering the portion of the work completed by his organization (including data on the pressure test if conducted by the stamp holder performing the field work) to the Manufacturer responsible for the Code vessel. The vessel Manufacturer applies his U Stamp in the presence of a representative from his Inspection Agency and completes the Form U-1 or U-1A Manufacturer's Data Report with his Inspector.
In all three alternatives, the party completing and signing the Form U-1 or U-1A Manufacturer's Data Report assumes full Code responsibility for the vessel. In all three cases, each Manufacturer's Quality Control System shall describe the controls to assure compliance for each Code stamp holder.
(i) For some design analyses, both a chart or curve and a formula or tabular data are given. Use of the formula or tabular data may result in answers which are slightly different from the values obtained from the chart or curve. However, the difference, if any, is within practical accuracy and either method is acceptable.
