ASME VIII UG-ppt

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API 510 ICP Self study note

Transcript of ASME VIII UG-ppt

  • ASME VIII Div.1- Charlie Chong/ Fion Zhang/ He Jungang / Li Xueliang ASME VIII Div.1 API510 Training for 2013 June.
  • ASME VIII Div.1- Charlie Chong/ Fion Zhang/ He Jungang / Li Xueliang
  • Speaker: Fion Zhang 2013/April/15 ASME VIII Div.1- Charlie Chong/ Fion Zhang/ He Jungang / Li Xueliang
  • ASME VIII Div.1- Charlie Chong/ Fion Zhang/ He Jungang / Li Xueliang
  • ASME VIII Div.1- Charlie Chong/ Fion Zhang/ He Jungang / Li Xueliang Applicable sections; UG: the G denotes general requirements. UW: the W denotes welding. UCS: the CS denotes carbon steel. UHT: the HT denotes heat treatment. Appendix 1: supplementary design formulae. Appendix 3: definitions.
  • ASME VIII Div.1- Charlie Chong/ Fion Zhang/ He Jungang / Li Xueliang
  • ASME VIII Div.1- Charlie Chong/ Fion Zhang/ He Jungang / Li Xueliang SUBSECTION A GENERAL REQUIREMENTS
  • ASME VIII Div.1- Charlie Chong/ Fion Zhang/ He Jungang / Li Xueliang PART UG GENERAL REQUIREMENTS FOR ALL METHODS OF CONSTRUCTION AND ALL MATERIALS
  • ASME VIII Div.1- Charlie Chong/ Fion Zhang/ He Jungang / Li Xueliang Vessel design features
  • ASME VIII Div.1- Charlie Chong/ Fion Zhang/ He Jungang / Li Xueliang The main ASME VIII design topics required included in the API 510 syllabus are: Internal pressure in shells and heads (clauses UG-27 and UG-32) External pressure on shells (clause UG-28) Nozzle compensation (mainly figure UG-37.1) Nozzle weld sizing (mainly figure UW-16)
  • ASME VIII Div.1- Charlie Chong/ Fion Zhang/ He Jungang / Li Xueliang About rounding answers. In the ASME Code and for the exam you must round DOWN for pressure allowed. Even if our solution had been 1079.999 we cannot round to 1080, we still round down to 1079 psi. This is the conservative approach taken by the Codes in general and of course is different for the normal rules of rounding. When rounding thickness required we must round UP. The most conservative thing to do. So our example below would round to .230. Even it had been .2291 we would still round up to .230.
  • ASME VIII Div.1- Charlie Chong/ Fion Zhang/ He Jungang / Li Xueliang UG-20 DESIGN TEMPERATURE UG-20
  • ASME VIII Div.1- Charlie Chong/ Fion Zhang/ He Jungang / Li Xueliang UG-20 UG-20(f) lists an exemption from impact testing for materials that meet All of the following requirements. 1. Material is limited to P-No.1 Gr. No.1 or 2 and the thicknesses don't exceed the following: (a) 1/2 in. for materials listed in Curve A of Fig. UCS-66; (b) 1 in for materials from Curve B, C or D of Fig. UCS-66; 2. The completed vessel shall be hydrostatically tested 3. Design temperature is no warmer than 650F or colder than - 20F. 4. The thermal or mechanical shock loadings are not controlling design. 5. Cyclical loading is not a controlling design requirement.
  • ASME VIII Div.1- Charlie Chong/ Fion Zhang/ He Jungang / Li Xueliang UG-20 1. Material is limited to P-No.1 Gr. No.1 or 2 and the thicknesses don't exceed the following: (a) 1/2 in. for materials listed in Curve A of Fig. UCS-66; (b) 1 in for materials from Curve B, C or D of Fig. UCS-66; All of the conditions of UG-20(f) must be met to take this exemption from impact testing.
  • ASME VIII Div.1- Charlie Chong/ Fion Zhang/ He Jungang / Li Xueliang UG-27 THICKNESS OF SHELLS UNDER INTERNAL PRESSURE. UG-27
  • ASME VIII Div.1- Charlie Chong/ Fion Zhang/ He Jungang / Li Xueliang UG-27
  • ASME VIII Div.1- Charlie Chong/ Fion Zhang/ He Jungang / Li Xueliang c) Cylindrical Shells. The minimum thickness or maximum allowable working pressure of cylindrical shells shall be the greater thickness or lesser pressure as given by (1) or (2) below. (1) Circumferential Stress (Longitudinal Joints). When the thickness does not exceed one-half of the inside radius, or P does not exceed 0.385SE, the following formulas shall apply: (2) Longitudinal Stress (Circumferential Joints). When the thickness does not exceed one-half of the inside radius, or P does not exceed 1.25SE, the following formulas shall apply: UG-27
  • ASME VIII Div.1- Charlie Chong/ Fion Zhang/ He Jungang / Li Xueliang Shell calculations: internal pressure Shell calculations are fairly straightforward and are set out in UG-27. Figure below shows the two main stresses existing in a thin-walled vessel shell. Hoop (circumferential) stress This is the stress trying to split the vessel open along its length. Confusingly, this acts on the longitudinal weld seam (if there is one). For the purpose of the API 510 exam this is the governing stress in a shell cylinder. UG-27
  • ASME VIII Div.1- Charlie Chong/ Fion Zhang/ He Jungang / Li Xueliang The relevant UG-27 equations are: (used when you want to find t) or, rearranging the equation to find P when t is already known: Where: P = maximum design pressure (or MAWP). t = minimum required thickness to resist the stress. S = allowable stress of the material. E = joint efficiency. Ri = the internal radius of the vessel. UG-27
  • ASME VIII Div.1- Charlie Chong/ Fion Zhang/ He Jungang / Li Xueliang Remarks: S = allowable stress of the material. This is read from ASME II part D tables or, more commonly, given in the exam question (it has to be as ASME II part D is not in the syllabus). E = joint efficiency. This is a factor (between 0.65 and 1) used to allow for the fact that a welded joint may be weaker than the parent material. It is either read off tables (see UW-11 and UW-12 later) or given in the exam question. You can think of E as a safety factor if you wish. Ri = the internal radius of the vessel. Unlike some other design codes ASME VIII Div.I prefers to use the internal radius as its reference dimension, perhaps because it is easier to measure. UG-27
  • ASMEVIIIDiv.1-CharlieChong/FionZhang/HeJungang/LiXueliang Figure 9.4 Vessel stresses UG-27
  • ASME VIII Div.1- Charlie Chong/ Fion Zhang/ He Jungang / Li Xueliang UG-27
  • ASME VIII Div.1- Charlie Chong/ Fion Zhang/ He Jungang / Li Xueliang A key feature of Ri is that it is the radius in the corroded conditions (i.e. that anticipated at the next scheduled inspection). Dont get confused by this it is just worked out in this way. If a vessel has a current Ri of 10 in and has a corrosion rate (internal) of 0.1 in./years, with the next scheduled inspection in five years, then: Current Ri = 10 in. Ri in 5 years = 10 in. + (5 x 0.1 in) = 10.5 in corroded condition. Hence 10.5 in. is the Ri dimension to use in the UG-27 equation. UG-27
  • ASME VIII Div.1- Charlie Chong/ Fion Zhang/ He Jungang / Li Xueliang The thickness must not exceed one-half of the inside radius, i.e. it is not a thick cylinder. The pressure must not exceed 0.385SE, i.e. not be high pressure. In practice this is more than about 4000 psi for most carbon steel vessels. UG-27
  • ASME VIII Div.1- Charlie Chong/ Fion Zhang/ He Jungang / Li Xueliang UG-27 The pressure must not exceed 0.385SE, i.e. not be high pressure. In practice this is more than about 4000 psi for most carbon steel vessels. Example: for SA-515/Gr. 60 at 700F where S = 14,400 psi. P must not exceed 5544 psi.
  • ASME VIII Div.1- Charlie Chong/ Fion Zhang/ He Jungang / Li Xueliang Shell calculation example The following information is given in the question. Ri = inside radius of 30 in . P = pressure of 250 psi (MAWP). E = 0.85 (type 1 butt weld with spot examination as per UW-12). S = 15 800 psi. What minimum shell thickness is necessary to resist the internal MAWP? Using thickness (t) = PR/(SE0.6P) from UG-27 Thickness = 250x30 / [15800x0.85 (0.6x250)] t = 0.565 in ANSWER UG-27
  • ASME VIII Div.1- Charlie Chong/ Fion Zhang/ He Jungang / Li Xueliang Shell calculation example The following information is given in the question. Ri = inside radius of 30 in. t = 0.625 in. E = 0.85 (type 1 butt weld with spot examination as per UW-12). S = 15 800 psi. What is the MAWP? Using pressure (P) = SEt/(R + 0.6t) from UG-27 Pressure (P) = 15 800 x 0.85x 0.625 / [30 + (0.6 x 0.625)], MAWP = 276 psi ANSWER. UG-27
  • ASME VIII Div.1- Charlie Chong/ Fion Zhang/ He Jungang / Li Xueliang UG-27
  • ASME VIII Div.1- Charlie Chong/ Fion Zhang/ He Jungang / Li Xueliang UG-27 DESIGN INFORMATIO