MANDATORY APPENDIX 41 ELECTRIC IMMERSION HEATER ELEMENT SUPPORT PLATES

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Madeleine Freeman
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1 Page 1 of 5 No changes, age is included for reference. MANDATORY APPENDIX 41 ELECTRIC IMMERSION HEATER ELEMENT SUPPORT PLATES 41-1 SCOPE The rules in this Mandatory Aendix cover the design of electric immersion heater element suort lates, hereafter referred to as EIH suort lates. EIH suort lates are gasketed with a mating flange (Figure ). TERMINOLOGY The rules of UG-34 and UG-39 are not alicable to EIH suort lates constructed in accordance with this Mandatory Aendix. EIH Suort Plate: consists of an unstayed circular flat late that is attached by bolting to a mating flange. EIH suort lates are used as both a suort for electric immersion heater elements and a ressure retaining closure of a ressure vessel. The EIH suort late contains multile oenings in a uniform attern that subsequently will have tubular electric heating elements inserted and attached to the suort late as an assembly MATERIALS AND METHODS OF FABRICATION Materials and methods of fabrication for EIH suort lates shall be in accordance with Subsections A, B, and C. The EIH suort late shall be flat and circular. It shall be of uniform thickness, excet that the flanged extension may differ in thickness as determined in 41-7, Ste 1. The EIH suort late shall be uniformly erforated over a nominally circular area, in either radial triangular, equilateral triangular, or square atterns. [See Figure , illustration (a), (b), or (c).] Welding or brazing heater elements to the EIH suort late shall be in accordance with Part UW or Part UB NOMENCLATURE The symbols described below are used for the design of the EIH suort late. Figure EIH Suort Plate Gasketed With Mating Flange A outside diameter of EIH suort late C bolt circle diameter (see Mandatory Aendix 2) D o diameter of outer drilled element hole limit circle [see Figure , illustration (a), (b), or (c)] d diameter of holes in element attern E modulus of elasticity for EIH suort late material at design temerature. The modulus of elasticity shall be taken fm the alicable Table TM in Section II, Part D. When a material is not listed in the TM tables, the requirements of U-2(g) shall be alied. E * effective modulus of elasticity of EIH suort late in erforated region G diameter of gasket load reaction (see Mandatory Aendix 2) h thickness of the center of the EIH suort late, including raised face if resent. h g gasket moment arm, equal to the radial distance fm the center line of the bolts (bolt circle) to the line of the gasket reaction as shown in Mandatory Aendix 2, Table A C CONDITIONS OF APPLICABILITY FOR EIH SUPPORT PLATES P G h 546

2 Page 2 of 5 No changes, age is included for reference Figure Tyical EIH Suort Plate and Element Geometry (a) Radial Triangular Element Pattern [Note (1)] (b) Equilateral Triangular Element Pattern (c) Square Element Pattern NOTE: (1) minimum sacing 547

Page 3 of 5 41-5 41-7 temerature tables in ASME B16.5 and ASME 16.47 are h r minimum required thickness of the EIH suort not alicable when the EIH suort late is designed late flanged extension.

3 Page 3 of temerature tables in ASME B16.5 and ASME are h r minimum required thickness of the EIH suort not alicable when the EIH suort late is designed late flanged extension. See Figure to this Mandatory Aendix. P design ressure minimum itch of element holes in any direction design ressure. For internal vacuum, use a negative value for P. [Figure , illustration (a), (b), or (c)] r o radius to the center of the outermost drilled hole 41-7 CALCULATION PROCEDURE S allowable stress for EIH suort late material at Ste 1. Calculate EIH suort late flanged extension. design temerature (a) When the EIH suort late is goved for a erihs a allowable stress for the EIH suort late mateeral gasket, the net thickness of the EIH suort late unrial at atmosheric temerature der the gove shall not be less than the thickness, h r. W EIH suort late flanged extension bolt load for Figure deicts thickness h r for some reresentathe gasket seating condition. Use eq. 2-5(e)(5). tive flanged extension configurations. W m 1 EIH suort late flanged extension bolt load for oerating conditions. Use eq. 2-5(c)(1)(1). (b) Calculate the minimum required thickness of the μ ligament efficiency EIH suort late flanged extension, h r, as follows: ν* effective Poisson s ratio in erforated region of EIH suort late 41-6 DESIGN CONSIDERATIONS Ste 2. Calculate EIH suort late characteristics. Calculate ligament efficiency, μ: Electric heating elements are not considered to contribute to the strength of the EIH suort late As the calculation cedure is iterative, a value, h, shall be assumed for the EIH suort late thickness to calculate and check that the maximum stresses in the EIH suort late are within the maximum ermissible stress limits. Calculate h /. Determine the values of E*, E*/E, and ν * relative to h / using either Figure UHX-11.3 (equilateral triangular attern) or Figure UHX-11.4 (square attern) in Part UHX substituting μ for μ* When the electric heating element bundle is mounted horizontally, consideration should be given to erly suorting the electric heating element bundle to revent undue stress on the EIH suort late and the element-to-late attachments. NOTE: For radial triangular hole atterns [Figure , illustration (a)] use Figure UHX-11.3 for equilateral triangular atterns based on the minimum distance (itch) between any two holes. Ste 3. Calculate D o ASME B16.5 and ASME flanges may be used as EIH suort lates if designed in accordance with the rules of this Mandatory Aendix. The ressure Ste 4. Calculate diameter ratio ρ. Figure Some Reresentative Configurations Describing the Minimum Required Thickness of the EIH Suort Plate Flanged Extension, h r 548

4 Page 4 of P If τ 0.8S, the assumed EIH suort late thickness is accetable for shear. Otherwise, increase the assumed thickness, h, and return to Ste 2. Ste 5. Calculate moment, M T S, due to ressure, P, acting on the unerforated EIH suort late rim: 41-8 PRESSURE TEST REQUIREMENT The EIH suort late shall be subjected to a ressure test in accordance with UG-99 or UG-100. Ste 6. Calculate diameter ratio, K DATA REPORTS When all the requirements of this Mandatory Aendix have been met, the following notation shall be entered on the Manufacturer s Data Reort under Remarks: Construction in Conformance with Mandatory Aendix 41, Electric Immersion Heater Element Suort Plates. Ste 7. Calculate coefficient, F. Ste 8. Calculate moment, M *, acting on the unerforated EIH suort late rim EXAMPLE An examle illustrating the use of the design rules given in this Mandatory Aendix is shown as follows Ste 9. Calculate the maximum bending moments acting on the EIH suort late at the erihery, M, and at the center, M o. DATA SUMMARY The design ressure is 500 si at the design temerature of 500 F The mating flange is an ASME B16.5, NPS-8, CI 300 flange. Therefore, an ASME B16.5, NPS-8, CI 300 blind flange is chosen to construct the EIH suort late. The flange thickness according to the secification is 1.62 in. thick in the center and 1.56 in. thick in the extension. The flange outside diameter is in. with a bolt circle of 13.0 in. and (12) 7/8 in. SA-193-B7 bolts. The material of the flange is SA-350 Grade LF2 (K03011) with a in. corsion allowance. There are in. diameter element insertion holes drilled in an equilateral triangle attern with a minimum itch of in. The radius to the center of the outermost element hole center is in. Ste 10. Determine the maximum bending moment acting on the EIH suort late The gasket is 10.5 in. OD and 9 in. ID and has a gasket factor, m, of 2.0 and the minimum design seating stress, y, of 2,500 si. Ste 11. Calculate the EIH suort late bending stress, σ Data Summaries. The data summaries consist of those variables in the nomenclature, 41-5, that are alicable to this configuration. d in. E si at 500 F, Table TM-1 of Section II, Part D G in. h 1.62 in. h g in. If σ 2S, the assumed EIH suort late thickness is accetable for bending. Otherwise, increase the assumed thickness, h, and return to Ste 2. Ste 12. Calculate the average shear stress, τ, in the EIH suort late at the outer edge of the erforated region. 549 using the absolute value of ressure P.

5 P S Sa 500 si in in. 19,600 si at 500 F, Table 1A, Section II-D 20,000 si at atmosheric temerature, Table 1A, Section II-D W 91,537 lb [eq. 2-5(e)(5)] W m 1 57,377 lb [eq. 2-5(c)(1)(1)] Page 5 of 5 No changes, age is included for reference. Ste 6. Calculate diameter ratio, K, er 41-7, Ste 6. Ste 7. Calculate coefficient, F, er 41-7, Ste 7. Calculation Results. Ste 1. Calculate EIH suort late flanged extension. h r in. required for gasket seating h r in. required for design condition Ste 8. Calculate moment, M *, acting on the unerforated EIH suort late rim er 41-7, Ste 8. Actual h r in. The thickness of the flanged bolting extension is adequate. Ste 9. Calculate the maximum bending moments acting on the EIH suort late at the erihery, M. and at the center, M o. er 41-7, Ste 9. Ste 2. Calculate EIH Suort late characteristics. Calculate μ. Calculate h /. Ste 10. Determine the maximum bending moment er 41-7, Ste 10. Determine E *, E*/E, and ν * er 41-7, Ste 2. Ste 11. Calculate EIH suort late bending stress σ er 41-7, Ste 11. Ste 3. Calculate D o er 41-7, Ste 3. Ste 12. Calculate average shear τ in the EIH suort late at outer edge of erforated area er 41-7, Ste 12. Ste 4. Calculate diameter ratio ρ, er 41-7, Ste 4. Since the calculated EIH suort late stresses are within design stress limits, the assumed thickness is adequate. Ste 5. Calculate moment, M T S, due to ressure, P, er 41-7, Ste

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