la)

2011a SECTION VIlI - DIVISION 1

MANDATORY APPENDIX 41ELECTRIC IMMERSION HEATER ELEMENT SUPPORT

PLATES

41-1 SCOPE

41-1.1 The rulcs in this Mandatory Appendix coverthe design of electric immersion heater element supportplates, hereafter referred to as EIH support plates. EIBsupport plates are gasket cd with a mating flange(Fig. 41-1.1-1).

41-1.2 The rules of UG-34 and UG-39 are not applica­hie to EIH support plates constl1lcted in accordance withthis Mandatory Appendix.

41-3 TERMINOLOGY

EIH Support Plate: consists of an unstayed circular flatplate that is attached by bolting to a mating ftange. EIHsupport plates are llsed as both a support for electric immer­sion heater elements and a pressure retaining closure of apressure vessel. The EIH support plate contains multipleopenings in a uniform pattern that subsequently will havetubular electric heating elements inserted and attached tothe support plate as an assembly.

41-2

The EIH support plate shall be ftat and circular. It shallbe of uniform thickness, except that the flanged extensionmay differ in thickness as determined in 41-7, Step I. TheEIH support plate shall be uniformly perforated over anominally circular area, in either radial triangular, equilat­eraltriangular, or square patterns. [See Fig. 41-4-1, illustra­tion (a), (b), or (c).]

MATERIALS AND METHODS OFFABRICATION

41-2.1 Materials and methods of fabrication for EIBsupport plates shall be in accordance with Subsections A,B. and C.

41-2.2 Welding or brazing heater elements to the EIHsupport plate shall be in accordance with Part UW orPart un.

FIG.41-1.1-1 EIH SUPPORT PLATE GASI(ETEDWITH MATING FLANGE

41-4

41-5

CONDITIONS OF APPLICABILITYFOR EIH SUPPORT PLATES

NOMENCLATURE

r:- r--

--

- -

A- -- -

c Ep---- -+-h

---

---- ==

G

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The symbols described below are used for the designof the EIB support plate.

A = outside diameter of ElH support plateC = bolt circle diameter (see Mandatory Appendix 2)

Do = diameter of ollter drilled element hole limit circle[see Fig. 41-4-1, illustration (a), (b), or (c)]

d = diameter of holes in element patternE = modulus of elasticity for EIH support plate mate­

rial at design temperature. The modulus of elastic­ity shall be taken from the applicable Table TMin Section II, Part D. When a material is not listedin the TM tables, the requirements of U-2(g) shallbe applied.

E* = effective modulus of elasticity of EIH supportplate in perforated region

G = diameter of gasket load reaction (see MandatoryAppendix 2)

20lJ. SECTION VIII - DIVISION I

FIG.41-4-1 TYPICAL EIH SUPPORT PLATE AND ELEMENT GEOMETRY

o

Do

oo

o

oDo

o

o

o ii

° ~ °OO~OO~~P 0° O!OO~- - -9--QC------00 0g;'o 00

° '0°0:0°

° cD °Iii,o

(a) Radial Triangular Element Pattern (Noto (1)) (b) Equilatoral Triangular Element Pattern

o o

Do

o o(e) Square Element Pattern

NOTE:(}) p = minimum spacing

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2011. SECTION VIH - DIVISION 1

FIG.41-5-1 SOME REPRESENTATIVE CONFIGURATIONS DESCRIBING THE MINIMUM REQUIRED THICI(NESSOF THE EIH SUPPORT PLATE FLANGED EXTENSION, IJ,

·----t-----)'i-I I I II I I II I I II : I : ,___ I, , , , , ,!...._.J-- _1._, '- - ~ (

\ I

,1 i ~I(

h

(a) Raised Face (bl Grooved for Ring Gasket

properly supporting the electric healing element bundle toprevent undne stress on the EIH support plate and theelement-to-plate attachments.

41-6.4 ASME B16.5 and ASME 16.47 flanges may beused as EIH support plates if designed in accordance withthe rules of this Mandatory Appendix. The pressnre­temperature tables in ASME B 16.5 and ASME 16.47 arenot applicable when the EIH support plate is designed tothis Mandatory Appendix.

h = thickness of the center of the EIH support plate,including raised face if present.

118 = gasket moment arm, equal to the radial distmlcefrom the center line of the bolts (bolt circle) to theIinc of the gasket reaction as shown in MandatoryAppendix 2, Table 2-5.2

"r = minimum required thickness of the E1H supportplate flanged extension. See Fig. 41-5-1.

P = design pressurep = minimum pitch of element holes in any direction

[Fig. 41-4-1, illustration (a), (b), or (c)]1"0 = radius to the center of the olltermost drilled holeS = allowable stress for EIH support plate material at

design temperatureS. = allowable stress for the EIH sUPP0rl plate material

at atmospheric temperatureIV = EIH support plale flanged extension bolt load for

the gasket seating condition. Use Formula 5 ofMandatory Appendix 2, para. 2-5(e).

IV"" = EIH support plate flanged extension bolt load foroperating conditions. Use Formula I ofMandatory Appendix 2, para. 2-5(c).

/k = ligament efficiency11* = effective Poisson's ratio in perforated region of

EIH support plate

41·7

Step I:

CALCULATION PROCEDURE

Calculate EIH snpport plate flanged extension.(a) When the EIH support plate is grooved

for a peripheral gasket, the net thickness of theEIH support plate under the groove shall notbe less than the thickness, 11,. Figure 41-5-1depicts thickness hr for some representativeflanged extension configurations.

(b) Calculate the minimum reqnired thick­ness of the EIH support plate flanged extension,lin as follows:

1.9\Vmlll,]SG

41·6 DESIGN CONSIDERATIONS41·6,1 Electric heating elements are not considered to

contribute to the strength of the EIH support plate.

41-6.2 As thecalculation procedure is iterative, a value,h, shall be assumed for the EIH support plate thickness tocalculate and check that the maximum stresses in the EIHsupport plate are within the maximum permissible stresslimits.

41·6.3 When the electric heating element bundle ismounted horizontally, consideration should be given to

Step 2: Calculate EIH support plate characteristics.Calculate ligament efficiency, /k:

p-df.' = -­

pCalculate IIlp.Determjne the values of E*. E*/E, and v* rela­tive to hlp using either Fig. UHX-II.3 (equilat­eral triangular pattern) or Fig. UHX-IIA(square pattern) in Part UHX snbstituting /k

for /k*.

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20lla SECTION vln - DlVlsrON I

Step 3:

NOTE: For radial tri:lI1gular hole paltcnls [(Fig. 41·4·1,illustration (a)] usc Fig. UHX·ll.3 forcquilntcrallriangularpallems based on the lllinimum distance (pilCh) betweenany two holes.

Calculate Do.

increase the assumed thickness, II, and returnto Step 2.

Step 12: Calculate the average shear stress, T, in the EIHsupporl plate at the ouler edge of the perforatedregion.

Step 4:

Step 5:

Calculate dimneter ratio p.

Gp=­

Do

Calculate moment, Mrs. due to pressure, P,acting on the unperforated EIH support platerim: 41-8

If 7" 0.8S, Ihe assumed EIH support platethickness is acceptable for shear. Otherwise,increase the assumed thickness, h, and returnto Step 2.

PRESSURE TEST REQUIREMENT

The EIH support plate shall be subjected to a pressuretest iu accordauce with UG-99 or UG-I 00.

Step 6: Calculate diameter ratio, K.41-9 DATA REPORTS

Step 7:

AK =­

Do

Calculate coefficient, F.

I - v*F = ~(ElnK)

Wheu all the requirements of this Mandatory Appendixhave been met, the following notettion shall be entered onthe Manufacturer's Data Report under Remarks:"Construction in Conformance with MandatoryAppendix 41, Electric Immersion Heater Element SupportPlates."

Step 8: Calculate moment, M*. acting on the lluperfora­ted ElH support plate rim. 41-10 EXAMPLE

WIl,M* = Mrs +­

TIDo

Step 9: Calculate the maximum bending moments act­ing on the EIH support plate at the periphery.Mp• and at the center, Mo.

D'M* -~FP

32Mp = 1+ F

Step 10: Determine the maximum bending moment act­ing on the EIH support plate.

Step II: Calcnlate the EIB snpport plate bendingstress, U

If u " 2S, the assumed EIB support platethickness is acceptable for bending. Otherwise,

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An example illustrating the use of the design mles givenin this Mandatory Appendix is shown as follows.

41-10.1 Data Summary41-10.1.1 The design pressure is 500 psi at the design

temperature of 500°F.

41-10.1.2 The mating flauge is an ASME B 16.5.NPS-8. CI300 flange. Therefore. an ASME B 16.5. NPS-8.CI 300 blind flange is choseu to construct the EIB supportplate. The flange thickuess according to the specificationis 1.62 in. thick in the center and 1.56 in. thick in theextension. The nange outside diameter is 15.00 in. with abolt circle of 13.0 in. and (12) Js in. SA-193-B7 bolts. Thematerial oflhe flange is SA-350 Grade LF2 (K03011) witha 0.125 in. corrosion allowance. There are 48 - 0.500 in.diameter element insertion holes drilled in an equilateraltriangle pattern with a minimum pitch of 0.98425 in. Theradius to the center of the outermost element hole centeris 3.445 in.

41-10.1.3 The gasket is 10.5 in. OD and 9 in. JDand has a gasket factor, III, of 2.0 and the minimum designseating stress. Y. of 2,500 psi.

41-10.1.4 Data Summaries. The data summariesconsist of those variables in the nomenclature, 41-5 thatare applicable to this configuration.

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2011. SECfION VIII - DIVISION 1

d = 0.500 in.E = 27.3 X la' psi at 500°F, Table TM-I, Section H-DG = 9.888 in." = 1.62 in.

". = 1.556 in.P = 500 psip = 0.98425 in.

1'0 = 3.445 in.S = 19,600 psi at 500°F, Table IA, Section H-D

So = 20,000 psi at atmospheric temperature, Table lA,Section H-D

IV = 91,537 Ib [Formula 5, Mandatory Appendix 2,para. 2-5(e)]

IV"" = 57,377 Ib [Formula I, Mandatory Appendix 2,para. 2-5(c)]

41-10.1.5 Calculatiou ResultsStep I: Calculate EIH support plate flanged extension.

Ii r ;::: 1.170 in. required for gasket scatingIi, = 0.936 in. required for design condition

Actual ",= 1.557 in.The thickness of the flanged bolting extension isadequate.

Step 2: Calculate ElH Support plate characteristics.Calculate fJ-.

J1. = 0.492

Calculate Ii/po

hlp = 1.519

Determine E*, E*/E, and v* per 41-7, Step 2

E*/E = 0.554

Step 5: Calculate moment, MTS• due to pressure, P, per41-7, Step 5.

MTS := 1,609 in.-Ib/in.

Step 6: Calculate diameter ratio, K, per 41-7, Step 6.

K = 2.030

Stcp 7: Calculate coefficient, F, per 41-7, Step 7.

F = 0.904

SICp 8: Calculate moment, M*. acting on the unperfora­ted EIH support plate rim per 41-7, Step 8.

M* = 7,744 in.-Ib/in.

Step 9: Calculate the maximum bending moments act­ing on the Ell-I support plate at the periphery,Mp , and at the center, Mo. per 41-7, Step 9.

M, = 3,662 in.-Ib/in_

Mo := 5.067 in.-lb/in.

Step 10: Determine the maximum bending moment per41-7, Step 10.

M = 5,067 in.-Ib/in.

Step II: Calculate EIH support plate bending stress uper 41-7, Step II.

u = 27,647 psi (,; 2S [39,200 psi])

Step 3:

Step 4:

E* = 15.1 x 10' psi

1'* = 0.294

Calculate Do per 41-7 Step.3.

DQ = 7.390 in.

Calculate diameter ratio, p, per 41-7, Step 4.

p = 1.338

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Step 12: Calculate average shear T in the EIH supportplate at outer edge of perforated area per 41-7,Step 12.

T = 1,256 psi [';0_8S (15,680 psi)]

Since the calculated EIH support plate stressesare within design stress limits, the assumed thick­ness is adequate.