Training program on Code Awareness Awareness ASME Section VIII VIII div. 1 Introduction: This code is intended for the construction of new pressure vessels. The objective is to provide rules defining the minimum requirements for constructing boilers and pressure vessels that may be operated safely. It is not a purchase specification that defines all criteria required for special application. It is not a design handbook. It is a set of rules mandated by state law. Scope : (Para U-1) Definition of pressure vessel: Pressure vessels are containers for the containment of pressure, either internal or external. This pressure may be obtained form an external source, or by the application of heat from a direct or indirect source, or any combination thereof.
This division contains mandatory requirements , specific prohibitions, and non mandatory guidance for pressure vessel materials, design, fabrication, examination, inspection, testing, certification, and pressure relief. This division is divided into three subsections, mandatory Appendices, and non mandatory 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 Par UW, UF, and UB dealing with welded, forged and brazed methods. Subsection C covers specific requirements applicable to the several classes of materials used in pressure vessel construction. It consists of Part UCS, UNF, UHA, UCI, UCL, UCD, UHT, ULW, and ULT,UHX dealing with carbon and alloy steels, non ferrous, high alloy steels, cast iron, clad and lined material, cast ductile iron, ferritic steel with properties enhanced by heat treatment, layered construction, and low temperature materials.
Section II Part D also contains contains tables of maximum allowable stress stress values for these these classes of materials. The mandatory appendices addresses specific subjects not covered elsewhere in the division, and their requirements are mandatory when the subject covered is included in construction under this division. The non mandatory appendices provide information and suggested good practices.
Any pressure vessel which meets all the applicable requirements of this division may be stamped with Code U symbol Following class of vessels are not included in the scope of this division. a) those those withi within n the scope scope of other other divis division ions; s; b) fired fired proce process ss tubul tubular ar heate heaters rs
c) pressure containers containers which are integral part (or components) of rotating machinery piping systems( except pressure relieving device) c) pipe fittin fittings, gs, valves, valves, pipe components components(( eg. strainers strainers,, flow meters) meters) and other accessories; d) vessels vessels with water water capacity capacity of 120 gallons(545 gallons(545 litres) litres) or less, less, for containme containment nt of water; e)
hot water storage tanks with limitations; - heat input not exceeding 2,00,000 BTU/hr - water temperature not exceeding 210 deg F - nominal water capacity 120 gallons(545litres)
f) Vessels with loading of external or internal pressure of 15 psi and less; g) vessels having inside diameter or width/height/ cross section diagonal not exceeding six inches; h) vessels for pressure exceeding 3000 psi Battery Limits: a)For external connections 1) welding welding ends, ends, for welded external external connect connection ion 2) thread threaded ed joints joints for for screwed screwed connec connectio tions ns 3) flange flange face face for for bolte bolted d connect connection ionss 4) sealing sealing surface surface for proprietar proprietary y connecti connections ons
b) weld attachment of pressure part to non pressure part c) manhole covers/ handhole covers- for vessel openings d) sealing surface for instruments , gauges etc. Included in the Scope: Pressure relief devices Unfired steam boilers with pressure relief device as per section I Such as
a) b) c) d)
evapora evaporator torss and and heat heat excha exchanger ngers; s; proces processs heat gener generate ated d steam steam boilers boilers directly directly fired fired steam steam boilers boilers not covered covered under sectio section n I, IV gas fired fired jacketed jacketed steam kettles kettles with jacket pressure pressure 50 psi and and below. below. See appendix 14 clause 30
Vessels for human occupancy when made are subject to additional requirements requirements of the code Small vessels not exceeding 5cft volume and DP 250psig OR 1.5cft volume and DP 600psig , not requiring radiography and not provided with quick actuating closures. Responsibilities : Manufacturer: a) compliance compliance of all all requiremen requirements ts of code by himsel himself, f, and by all all others others (vendor) (vendor) b) providing providing proper proper certifica certification tion of materi materials als and construct construction ion c) provid providing ing applic applicabl ablee design design calculat calculation ionss d) establishi establishing ng a mandatory mandatory quality quality system. system.
Inspector’s: a) monit monitori oring ng quality quality contro controll b) verif verifica icatio tion n of design design calcula calculatio tion n c) conduct conducting ing speci specifie fied d inspec inspectio tions ns d) code code st stampi amping ng e) cert certif ific icat atio ion n
The purchaser of the vessel must define to the manufacturer, in sufficient detail, how the vessel is intended to be operated ope rated so that the vessel can be b e properly designed. Following specific considerations are listed: ( refer Para UG-22 ) 1) 2) 3) 4)
the need for corros corrosion ion allo allowan wance ce whether whether the vessel vessel is is in lethal lethal servic servicee ( defined defined in para para UW-2 UW-2 ) the need need for for PWHT PWHT on serv service ice condi conditio tions ns if the vessel vessel is to generate generate steam, steam, how the system system requirem requirement ent of Section Section I are are to be implemented. Reference Standards : Various standards related to the design as per this division is included in Table U-3. General Requirements: Part UG This section is applicable for all pressure vessels regardless of type of construction and type of material used. Rules of Part UG are to be supplemented as applicable by the rules relating to specific type type of construction and for specific type of material and applicable mandatory appendices.
Materials: Para UG 4 thru 15 define general requirements for material meeting ASME section II .
The material must also be listed in tables of o f permitted specification in the applicable part of subsection C. Allowable stress values are gien in Section II part D Non pressure attachment should be weldable quality. Allowable stress shall not exceed 80% of maximum allowable stress for a similar material incase material is not identified to a particular speceification.(UG-4b) Pipes and tubes include seamless and welded construction. Fusion welded pipes with filler metal require that it is done by authorized shop for code use where code stamping is required. ERW do not fall under this category. ( UG 8 ) Maximum allowable working pressure shall be based on minimum thickness at the root diameter of the finned section. For external pressure design for some alloys Appendix 23 allows the use of proof testing of finned tube to establish allowable working pressure . Finned tubes are required to be tested tested for code use. see para UG8. UG-10 deals with materials not fully identified with or produced to specification recognized by division 1. UG 12 deals with bolts and studs for use in pressure vessel. Table referenced in UG-23a gives the bolting specification allowed for code use.
Design:
Regardless of required thickness calculatedSection VIII div 1 specifies minimum thickness of shell and heads for pressure p ressure vessel. They are specified are in Para UG-16. To properly design a pressure vessel, the design condition must be established. Refer Para UG20, UG21, UG22.
Maximum and minimum temperature of design shall be established. MDMT (min design metal temperature) must be correctly determined. Material of Pno.1(Gr1,2) are exempted for impact upto minus 20deg F provided provided material under curve A of UCS-66 are not thicker than ½” or materials under curve B, C, D of UCS-66 are not thicker than 1”. UG-21 defines the considerations for establishing the design pressure of a vessel. UG-22 mentions the other loads to be considered for design. UG-23 defines maximum allowable stress for internal and external pressure to be used in design of vessels to Division 1. Values are tabulated in Section II Part D. UG-25 provides a general discussion related to corrosion, erosion, abrasion etc. which is to be added as allowance to the derived formulae. Internal Pressure Design : for cylindrical shells use para UG-27 External pressure design: para UG-28, appendix L
p ar UG-33 for external Formed heads: para UG-32 for internal pressure and par pressure.also refer appendix 1-4 Conical Heads and Sections: UG-32, Ug-33, appendix 1-5 Flat Heads and Cover : UG-34 Openings and Reinforcement : UG-36, UG-37, UG-45, appendix L Attachment to Pressure vessels : UG-54, UG-55, appendix G General Fabrication requirements : para UG-75 thru UG- 85 Impact test requirements : UG-20f, UCS-66 and UHA-51. provision of UG-84 shall be satisfied. Production coupon requirements to be taken into account for impact requirements to the code. Inspection and Tests :
UG-90 thru UG-103 provides general information for inspection and tests. Duties of manufacturer and Inspector are provided.
UG-98 provides a discussion about maximum allowable working pressure ( MAWP ). Refer Appendix 3 UG-99 and UG-100 provide information on pressure tests. Hydro test pressure is eauql to 1.3 times MAWP multiplied by ratio of stress at test temperature and stress at design temperature. Temperature of water should be 30deg F above MDMT but not to exceed 120deg F. Pneumatic test allowed for vessels where hydro test is not desirable. Test pressure shall be 1.1 times MAWP multiplied by ratio of stress at test temperature and stress at design temperature.
UG-101 allows proof test in certain cases. Marking and Reports:
UG-115 thru UG-120 gives stamping requirements requirements and preparation of MDR. Pressure Relief Devices : Requirements are covered in para UG-125 thru UG-137. Subsection – B Requirements pertaining to methods of fabrication of pressure vessels Part UW: Pressure vessel fabricated by welding
UW-2 defines requirements for specific services. Vessels in lethal shall have all butt welds fully radiographed. UW-3 defines categories of weld. Category A, B, C, D Refer to sketch UW-3 of division 1. UW-9 provides general requirements for the design design of welded joint. refer Table Table UW-12 of division 1. UW-11 provides requirements for three radiographic and ultrasonic e xamination category used for butt welds. Full radiography as per UW-51 and spot radiography as per UW-52. UT may be substituted for closure seam where radiography is difficult.
UW-13 provides rules for weld details of welds attaching heads and intermediate heads to shell, and flat plate to pressure part that form corner joints. Attachment details for connection and openings are covered in para UW-14, UW-15, UW-16, appendix L UW-18 provides general guidelines for the use of fillet welds. UW-20 provides mandatory requirements for tube to tubesheet welds. Refer to appendix A. UW-27 provides a listing of welding process and any restrictions that may be used in construction of pressure vessel. ( eg. Inertia welding, welding, lase, oxyfuel oxyfuel etc. ) UW-33 provides allowable alignment tolerance applicable for butt welds for different categories of weld. UW-35 provides requirements of finished butt welds for longitudinal and circ seam. UW-37 requires seam to be identified for welder and/or welding operators. UW-40 provides criteria and information related procedure for PWHT. PWHT requirements are given in UCS-56, 56.1, UHA-32, UHT-56. UW-42 refers to surface metal build up permitted by code. Inspection and tests are defined in UW-47, 48, 49 Subsection C: Requirements pertaining to classes of materials
UCS: Carbon and Low alloy steel UCS-5 thru UCS-15 provides information information relating relating to various material material forms. UCS-16 thru UCS-33 UCS-33 provides design related information information UCS-56 provides information related to PWHT UCS-57 provides information related to full radiography of joints mandatory for various groups of material wrt thickness. UCS 65 thru 68 gives rules rules for low temperature temperature application requirements and exceptions. UCS-75 thru 79 gives rules for fabrication inclusive of formed heads requirement to be met.
UCS-85 sets rule for heat treatment of specimens and exemptions permitted as per code. Inspection , tests , marking and stamping, pressure relief devices etc to be followed as per Part UG. List of mandatory appendices List of non mandatory appendices: Appendix A: Basis for establishing allowable loads for tube to tube sheet joints. C: Suggested methods for obtaining the operating temperature of vessel walls in service. D: Good practices regarding internal structures. E: Corrosion allowance F: Linings G: Piping reactions and design of supports and attachments H: Guidance to accommodate loadings produced deflagrations K: Sectioning of weld joints joints L: Examples illustrating illustrating the application of code formulae and rules M: Installation and operation P: Basis for determining allowable stress stress value R: Preheating S: Design considerations for bolted flange connection T: Temperature Protection W: guide for preparing manufacturer data reports Y: flat-face flanges with metal to metal contact outside the bolt circle AA: Rules for the design of tubesheets CC: Flanged and flued or flanged only expansion joints DD: Guide to information appearing in the certificate of authorization EE: Half Pipe jackets
