asme sec viii div 1_icb
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DESCRIPTIONAsme Sec Viii Div 1_icb
Welcome toTraining Program on ASME Sec. VIII Div. 1
P. S, JoshiConducted for ICB Technimont Mumbai.
Agenda - session 1This session will provide:An introduction to Codes and StandardsObjectives of Codes/ Standards.ASME Code System.Introduction To ASME Sec. VIII-1Approximate duration 1.5 hours
CODE CredibilityCollective Knowledge and Experience2 SSafety(Plant, Personnel, People) Standardization
WHY ADOPT CODES ?
Common pressure vessel codes
ASME Sec VIII Div 1 and Div 2
Ad Merk Blatter (German)
Issue freq. : New edition every 3 years, on 1st July latest edition was on 1st July 04.
Addenda : In-between revisions, issued yearly also on 1st July. Edn. & '04 add. --- 1st July '04 Addenda --- 1st July '052006 Addenda --- 1st July '06Again new edition - 2007 (1st July)Applicability : Edition & Addendas effective 6 months from date of issue (i.e. 1st Jan of next year)Issued by : American society of mechanical Engineers, New York.
ASME SEC. VIII DIV. 1 Pressure vessels within scope: Vessels having inside diameter above 6 in.Vessels designed for pressures above 15 psig and not exceeding 3000 psi. Unfired steam boilers, evaporators, Heat exchangers
ASME Sec. VIII div.1--Excluded from scope Piping system & components beyond battery limits. Vessels covered by other sections Vessels for human occupancy Pressure containers which are integral part of rotating machinery.
ASME Boiler & Pressure Vessel CodesASME Codes give stipulations and guidelines for the design, materials, manufacture and testing of pressure vessels. These are issued by the American Society of Mechanical Engineers, New York.
The codes were first issued in 1915. Since then, many changes have been made and new sections added to the code as need arose. It is a LIVE code and is revised and updated periodically. It keeps pace with time and is responsive to its users.
In its present from the ASME Code System is a follows
Section IPower Boilers. Section IIMaterial specifications.
Part AFerrous materials,Part BNon Ferrous MaterialsPart CWelding rods, electrodes, filler metals.Part DMaterial properties.CODE SYSTEM
CODE SYSTEM Section III Nuclear Power Plant Components. Section IV Heating Boilers. Section V Non destructive Examinations. Section VI Care and operation of Heating Boilers. Section VII Rules for care of Power Boilers. Section VIII Division 1 - Pressure Vessels Division 2 Alternative Rules ( Pr. Vessel) Division 3 Rules for constructive of High Pressure Vessels. Section IX Welding and Brazing Qualifications.
CODE SYSTEM, contd Section XFiber glass reinforced Plastic Pressure Vessels.Section XIRules for in service inspection of Nuclear Power Plant Components.
APPLICABILITY The editions and addenda become applicable after six months from date of issue. Thus, 1st Jan. 2000, the construction of Pressure Vessels shall be as per 1998 edition and 1999 addenda. However, for old contracts spilling over beyond 1st Jan 2000, the old applicable edition and addenda are valid.
CODE INTERPRETATION ASME issue written replies know as "Interpretations" to the inquiries concerning technical aspects of the code .These are issued twice in a year (July and December) and are sent to "Edition - subscribers" as up-date service.
CODE CASES Boiler and Pressure Vessels committee meets regularly to consider
Proposed additions and revisions to the code. At the same time it may formulate code cases to clarify ' Intent' of existing requirements. These are published as code Case books. It is published along with new editions and supplements are automatically sent to subscribers of code case book till new edition ispublished.
ASME Sec. VIII Div. 1 has five different partsPart 1 : UG General requirements (Design requirements)Part 2 : Material Specific RequirementsUCS Carbon steel & low alloy steelUHA High alloy steelsUNF Non ferrous metallurgyPart 3 : Fabrication method specific requirementsUW Welded constructionUF Forging constructionPart 4 : Mandatory Appendices &
Part 5 : Non mandatory Appendices
Types of vesselsCylindrical Horizontal or Vertical
Steps in design -1Find service conditions & metallurgy. Ensure ductility at service conditionsCalculate thickness required (TR).
Steps in design -2Design thickness = TR + Corr Allow Roundup to commercially available thickness to get nominal thicknessFind MAWP from nominal thickness
Solve a problem
Calculate the minimum thickness of a cylindrical shell of inside diameter 4000mm, tan to tan length of 8300mm and a design pr. of 100 Kg/sq cmg.
Design temperature of the vessel is 343 C
Material of construction ASTM A 516 Gr 70
Allowable stress of vessel at 343 C = 16500 psi
Corrosion allowance = 3.0 mm
Efficiency of the weld joint 1.0
UW 3 : WELD JOINTS CATEGORIES.
UW 3 : WELD JOINTS CATEGORIES. Category A :
Longitudinal weld joints in main shell or nozzles. Any welded joints in spherical shell.Any welded joints in Dished Head.Circumferential Seam , Hemisph. head to shell.
UW 3 : WELD JOINTS CATEGORIES. Category B :
Circumferential seam in main shell, or nozzle Circumferential seam connecting formed head (other than hemi-spherical head) to shell.
UW 3 : WELD JOINTS CATEGORIES. Contd.Category C :
Weld joints connecting flanges, tube sheets, flat head to main shell or Nozzles (Flange Welds)Category D:
Welds joining communicating chamber or nozzle to the main shell / heads. (Attachment Welds).
Types of endsFLAT HEADS : For low pressures up to 5 kg/sqcm
FORMED HEADS :TorisphericalGenerally used up to 15 kg/sqcmEllipsoidalGenerally used between 15 to 25 kg/sqcmHemisphericalGenerally used above 25 kg/sqcm.CONICAL HEADS : for Special purposes.
For spherical shells / head : t = P x R / (2SE - 0.2P) .for Thickness P = 2SEt / (R + 0.2t).for MAWP FORMED HEADSFor Torisph. Heads : (L = Crown Rad., r = 0.06 x L) t, = 0.885 x P x L / (SE - 0.1P) for Thickness P = SEt / ( 0.885L + 0.1 t ) for MAWPFor Ellipsoidal Heads : ( 2 : 1 type) t = P x D / (2SE - 0.2P) .for Thickness P = 2SEt / (D + 0.2t) .for MAWP
UW-11 :RT and UT EXAMINATIONS Full Radiography is required in following cases : All butt welds of vessels for lethal substances
If thickness exceeds given in table UCS-57, UHA - 33,
Butt welds of unfired boilers, with design pr. > 50 psi.
For all other vessels, All cat. A welds full radiography . Cat. B & C welds which intersect the Cat. A welds shall be spot radiographed.
Radiography is not required of category B and C butt welds in nozzles less than NPS 10 or 1 1/8 in. thick.
UW-11 :RT and UT EXAMINATIONScontd.
Spot Radiography : Spot RT of Butt joints if design efficiency is selected for spot radiography.2No Radiography : No RT of weld joints if design efficiency is selected for no radiography or vessel is designed for external pressure 3Ultrasonic examination : May be substituted for RT only for the final closure seam of a pressure vessel.
UW 12 :WELDED JOINT TYPES
UW 12 :WELDED JOINT EFFICIENCY RT 1 : Full Radiography ( E=1) : Full length radiography of all butt welds RT 2 : Full Radiography ( E=1): Cat A: Full length radiography Cat B: Spot RT per [UW 11 (a) 5 (b)]RT 3 : Spot radiography ( E= 0.85)RT 4 : No radiography ( E= 0.7)
Some key points:
Out of roundness of Shell
Difference between the maximum and minimum inside diameter measured at any cross section of the vessel shall not exceed 1% of the nominal diameter at that cross section under consideration. The diameter can be measured from either inside or outside. If measured from outside shall be corrected for the thickness at that cross section.
NOZZLE REINFORCEMENT Required area of Reinforcement = d X tr d= Diameter of finished opening tr = Required thickness of shell or head.
Reinforcement is waived off for single openings if:
finished opening size is 3 1/2" or less diameter in shell or head of thickness 3/8" or less; or
finished opening size 2 3/8" or less diameter in shell or head of thickness over 3/8";
UCS-66 : IMPACT TESTING MDMT - Thickness point falls on or above the relevant curve. Impact test is not required (Curve UCS 66 )
2Impact test is must, if MDMT < 120 deg F, and:Thickness Of welded part > 4Thickness for Non-welded part > 63Test normally required for MDMT < -55 deg. F