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(a) A patch is to be placed in the fire sheet of a horizontal return tubular boiler having a shell plate seven-sixteenths-inch (7/16,) thick, a longitudinal seam efficiency of seventy-four percent (74%), and a length of patch of thirty-six inches (36,). Find the width, W, of patch to be applied so that there will be no reduction in pressure, using a single-riveted seam of normal design.
Referring to Table 1, it is found that seven-sixteenths-inch (7/16") plate with fifteen-sixteenths-inch (15/16") diameter rivet holes, pitched two and one-fourth (2 1/4) gives a seam efficiency of fifty-six percent (56%).
Referring to Table 2, E= 0.74 and e= 0.56 gives a constant C= 1.75; then width W= Lx C = 36x 1.75= sixty-three inches (63").
(b) Pressure Allowed on an Existing Patch.
Divide the width of the patch, W = forty-eight inches (48") by the length, L= thirty inches (30") to find the constant, C= 48/30 = 1.60. Follow down column 0.57 of Table 2 until 1.60 is found. It will be noted that this is somewhere between 1.56 and 1.62 representing E somewhere between 0.72 and 0.73. As the difference between 1.56 and 1.62 is 6, and the difference between 1.56 and 1.60 is 4, Ewill be 0.72 plus 4/6 of 0.01 which is 0.7266. |
The maximum allowable working pressure varies directly as the seam efficiency. Accordingly, P= (0.7266/0.82) x 125 = 110#. If this pressure allowance interferes with the operation of the plant, the patch shall be replaced by a new one with the proper dimensions giving a diagonal efficiency of eighty-two percent (82%). |
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
CONSTANT "C" TRIANGLE OR CRESCENT SHAPE PATCHES C = W / L W = C X L L = W / C TABLE F-1 HEADS SUPPORTED DIAMOND OR OVAL SHAPE PATCHES C = 2W / L W = C X L / 2 L = 2W / C
"e" EFFICIENCY OF PATCH SEAMS | |||||||||||||||||
.50 |
.51 |
.52 |
.53 |
.54 |
.55 |
.56 |
.57 |
.58 |
.59 |
.60 |
.61 |
.62 |
.63 |
.64 |
.65 |
||
"E" | .65 |
1.68 |
1.60 |
1.51 |
1.43 |
1.36 |
1.28 |
1.20 |
1.13 |
- |
- |
- |
- |
- |
- |
- |
- |
E o l s o d e
|
.66 |
1.75 |
1.67 |
1.58 |
1.50 |
1.42 |
1.35 |
1.27 |
1.19 |
- |
- |
- |
- |
- |
- |
- |
- |
.67 |
1.82 |
1.73 |
1.65 |
1.57 |
1.49 |
1.41 |
1.33 |
1.26 |
1.18 |
- |
- |
- |
- |
- |
- |
- |
|
.68 |
1.88 |
1.79 |
1.70 |
1.63 |
1.55 |
1.47 |
1.40 |
1.32 |
1.24 |
1.16 |
- |
- |
- |
- |
- |
- |
|
.69 |
1.94 |
1.86 |
1.77 |
1.69 |
1.61 |
1.53 |
1.45 |
1.38 |
1.30 |
1.23 |
1.15 |
- |
- |
- |
- |
- |
|
.70 |
2.01 |
1.91 |
1.83 |
1.75 |
1.67 |
1.59 |
1.52 |
1.44 |
1.36 |
1.30 |
1.22 |
1.15 |
- |
- |
- |
- |
|
.71 |
2.06 |
1.97 |
1.89 |
1.81 |
1.73 |
1.65 |
1.57 |
1.50 |
1.43 |
1.35 |
1.28 |
1.21 |
1.15 |
- |
- |
- |
|
.72 |
2.12 |
2.03 |
1.95 |
1.86 |
1.79 |
1.71 |
1.63 |
1.56 |
1.48 |
1.41 |
1.34 |
1.27 |
1.20 |
1.14 |
- |
- |
|
.73 |
2.17 |
2.09 |
2.00 |
1.93 |
1.85 |
1.77 |
1.69 |
1.62 |
1.54 |
1.47 |
1.40 |
1.33 |
1.26 |
1.19 |
1.13 |
- |
|
.74 |
2.22 |
2.14 |
2.06 |
1.98 |
1.91 |
1.83 |
1.75 |
1.67 |
1.60 |
1.52 |
1.45 |
1.39 |
1.32 |
1.25 |
1.8 |
- |
|
.75 |
2.28 |
2.20 |
2.12 |
2.04 |
1.96 |
1.88 |
1.81 |
1.73 |
1.66 |
1.58 |
1.51 |
1.44 |
1.37 |
1.31 |
1.24 |
1.17 |
|
.76 |
2.34 |
2.25 |
2.17 |
2.09 |
2.02 |
1.93 |
1.86 |
1.79 |
1.71 |
1.64 |
1.57 |
1.50 |
1.43 |
1.36 |
1.30 |
1.23 |
|
.77 |
2.39 |
2.31 |
2.22 |
2.15 |
2.07 |
2.00 |
1.92 |
1.84 |
1.76 |
1.69 |
1.62 |
1.55 |
1.48 |
1.42 |
1.35 |
1.29 |
|
.78 |
2.44 |
2.36 |
2.28 |
2.20 |
2.13 |
2.05 |
1.97 |
1.89 |
1.82 |
1.75 |
1.67 |
1.61 |
1.54 |
1.47 |
1.41 |
1.35 |
|
.79 |
2.50 |
2.42 |
2.33 |
2.25 |
2.18 |
2.10 |
2.03 |
1.95 |
1.87 |
1.81 |
1.73 |
1.66 |
1.59 |
1.52 |
1.45 |
1.40 |
|
.80 |
2.55 |
2.46 |
2.39 |
2.30 |
2.23 |
2.15 |
2.06 |
2.00 |
1.93 |
1.86 |
1.79 |
1.72 |
1.64 |
1.58 |
1.48 |
1.45 |
|
.81 |
2.60 |
2.51 |
2.43 |
2.36 |
2.28 |
2.20 |
2.13 |
2.05 |
1.98 |
1.91 |
1.84 |
1.77 |
1.69 |
1.63 |
1.57 |
1.50 |
|
.82 |
2.65 |
2.56 |
2.48 |
2.40 |
2.33 |
2.25 |
2.18 |
2.11 |
2.03 |
1.97 |
1.89 |
1.82 |
1.75 |
1.68 |
1.62 |
1.55 |
|
.83 |
2.70 |
2.62 |
2.53 |
2.45 |
2.38 |
2.30 |
2.22 |
2.15 |
2.08 |
2.01 |
1.94 |
1.87 |
1.80 |
1.73 |
1.67 |
1.60 |
|
.84 |
2.75 |
2.66 |
2.59 |
2.51 |
2.43 |
2.35 |
2.27 |
2.20 |
2.13 |
2.05 |
1.99 |
1.92 |
1.85 |
1.78 |
1.72 |
1.65 |
|
.85 |
2.80 |
2.71 |
2.63 |
2.56 |
2.48 |
2.40 |
2.32 |
2.25 |
2.18 |
2.11 |
2.04 |
1.97 |
1.90 |
1.84 |
1.77 |
1.70 |
|
.86 |
2.85 |
2.77 |
2.68 |
2.60 |
2.52 |
2.45 |
2.37 |
2.30 |
2.23 |
2.16 |
2.09 |
2.02 |
1.95 |
1.89 |
1.82 |
1.75 |
|
.87 |
2.90 |
2.82 |
2.74 |
2.65 |
2.57 |
2.49 |
2.42 |
2.34 |
2.28 |
2.21 |
2.14 |
2.07 |
2.00 |
1.93 |
1.87 |
1.81 |
|
.88 |
2.96 |
2.87 |
2.78 |
2.71 |
2.62 |
2.54 |
2.47 |
2.40 |
2.32 |
2.25 |
2.19 |
2.12 |
2.05 |
1.98 |
1.92 |
1.85 |
|
.89 |
3.01 |
2.92 |
2.83 |
2.75 |
2.68 |
2.59 |
2.52 |
2.44 |
2.37 |
2.30 |
2.23 |
2.16 |
2.10 |
2.03 |
1.96 |
1.90 |
|
.90 |
- |
2.97 |
2.89 |
2.80 |
2.71 |
2.65 |
2.57 |
2.50 |
2.42 |
2.34 |
2.27 |
2.21 |
2.14 |
2.08 |
2.01 |
1.95 |
|
.91 |
- |
- |
2.94 |
2.86 |
2.77 |
2.69 |
2.62 |
2.54 |
2.47 |
2.39 |
2.32 |
2.25 |
2.19 |
2.12 |
2.05 |
2.00 |
|
.92 |
- |
- |
2.99 |
2.90 |
2.82 |
2.74 |
2.66 |
2.59 |
2.51 |
2.44 |
2.36 |
2.30 |
2.23 |
2.17 |
2.10 |
2.04 |
|
.93 |
- |
- |
- |
2.95 |
2.87 |
2.78 |
2.70 |
2.63 |
2.56 |
2.48 |
2.42 |
2.34 |
2.28 |
2.21 |
2.15 |
2.06 |
|
.94 |
- |
- |
- |
- |
2.91 |
2.83 |
2.75 |
2.67 |
2.60 |
2.53 |
2.45 |
2.39 |
2.32 |
2.25 |
2.19 |
2.13 |
|
.95 |
- |
- |
- |
- |
- |
2.87 |
2.79 |
2.72 |
2.64 |
2.57 |
2.50 |
2.43 |
2.36 |
2.29 |
2.23 |
2.17 |
CONSTANT "C" TRIANGLE OR CRESCENT SHAPE PATCHES C = W / L W = C X L L = W / C TABLE F-2 HEADS UNSUPPORTED DIAMOND OR OVAL SHAPE PATCHES C = 2W / L W = C X L / 2 L = 2W / C
"e" EFFICIENCY OF PATCH SEAMS | |||||||||||||||||
.50 | .51 | .52 | .53 | .54 | .55 | .56 | .57 | .58 | .59 | .60 | .61 | .62 | .63 | .64 | .65 | ||
"E" | .65 | 2.20 | 2.06 | 1.93 | 1.80 | 1.69 | 1.56 | 1.45 | 1.35 | 1.24 | 1.14 | - | - | - | - | - | - |
E o l s o d e
|
.66 | 2.30 | 2.16 | 2.03 | 1.90 | 1.78 | 1.65 | 1.55 | 1.45 | 1.34 | 1.22 | 1.12 | - | - | - | - | - |
.67 | 2.40 | 2.26 | 2.13 | 2.00 | 1.88 | 1.75 | 1.64 | 1.52 | 1.43 | 1.32 | 1.21 | - | - | - | - | - | |
.68 | 2.50 | 2.36 | 2.23 | 2.10 | 1.98 | 1.85 | 1.73 | 1.63 | 1.52 | 1.42 | 1.31 | 1.19 | - | - | - | - | |
.69 | 2.62 | 2.46 | 2.33 | 2.20 | 2.07 | 1.95 | 1.84 | 1.71 | 1.61 | 1.50 | 1.40 | 1.30 | 1.17 | - | - | - | |
.70 | 2.75 | 2.57 | 2.43 | 2.30 | 2.16 | 2.04 | 1.93 | 1.80 | 1.69 | 1.59 | 1.49 | 1.37 | 1.28 | 1.16 | - | - | |
.71 | 2.87 | 2.70 | 2.53 | 2.40 | 2.26 | 2.14 | 2.02 | 1.90 | 1.79 | 1.67 | 1.57 | 1.47 | 1.37 | 1.26 | 1.15 | - | |
.72 | 3.00 | 2.81 | 2.65 | 2.48 | 2.36 | 2.23 | 2.11 | 1.99 | 1.88 | 1.66 | 1.56 | 1.45 | 1.36 | 1.26 | 1.14 | ||
.73 | 3.14 | 2.93 | 2.76 | 2.60 | 2.46 | 2.33 | 2.20 | 2.09 | 1.97 | 1.75 | 1.64 | 1.54 | 1.44 | 1.35 | 1.24 | ||
.74 | 3.28 | 3.07 | 2.87 | 2.71 | 2.55 | 2.42 | 2.30 | 2.19 | 2.06 | 1.83 | 1.73 | 1.62 | 1.52 | 1.43 | 1.34 | ||
.75 | 3.38 | 3.19 | 3.00 | 2.83 | 2.66 | 2.52 | 2.40 | 2.27 | 2.15 | 1.92 | 1.81 | 1.71 | 1.61 | 1.51 | 1.42 | ||
.76 | 3.52 | 3.32 | 3.14 | 2.96 | 2.78 | 2.62 | 2.49 | 2.35 | 2.24 | 2.01 | 1.90 | 1.79 | 1.69 | 1.60 | 1.50 | ||
.77 | - | 3.46 | 3.28 | 3.07 | 2.90 | 2.74 | 2.58 | 2.45 | 2.32 | 2.10 | 1.98 | 1.88 | 1.77 | 1.67 | 1.56 | ||
.78 | - | - | 3.40 | 3.19 | 3.03 | 2.85 | 2.69 | 2.55 | 2.42 | 1.86 | 1.75 | 1.66 | |||||
.79 | - | - | - | 3.32 | 3.16 | 2.97 | 2.80 | 2.65 | 2.51 | 2.94 | 1.84 | 1.74 | |||||
.80 | - | - | - | 3.46 | 3.28 | 3.10 | 2.92 | 2.75 | 2.61 | 2.03 | 1.92 | 1.83 | |||||
.81 | - | - | - | - | 3.40 | 3.20 | 3.03 | 2.87 | 2.71 | 2.11 | 2.00 | 1.90 | |||||
.82 | - | - | - | - | - | 3.34 | 3.16 | 2.97 | 2.82 | 2.19 | 2.09 | 1.98 | |||||
.83 | - | - | - | - | - | 3.46 | 3.29 | 3.10 | 2.93 | 2.27 | 2.17 | 2.05 | |||||
.84 | - | - | - | - | - | - | 3.39 | 3.22 | 3.05 | 2.37 | 2.25 | 2.15 | |||||
.85 | - | - | - | - | - | - | - | 3.32 | 3.17 | 2.44 | 2.34 | 2.23 | |||||
.86 | - | - | - | - | - | - | - | 3.45 | 3.29 | 2.54 | 2.42 | 2.32 | |||||
.87 | - | - | - | - | - | - | - | - | 3.40 | 2.62 | 2.50 | 2.40 | |||||
.88 | - | - | - | - | - | - | - | - | - | 2.71 | 2.59 | 2.47 | |||||
.89 | - | - | - | - | - | - | - | - | - | 2.81 | 2.68 | 2.56 | |||||
.90 | - | - | - | - | - | - | - | - | - | - | 2.93 | 2.78 | 2.65 | ||||
.91 | - | - | - | - | - | - | - | - | - | - | 3.03 | 2.87 | 2.75 | ||||
.92 | - | - | - | - | - | - | - | - | - | - | 3.14 | 2.97 | 2.63 | ||||
.93 | - | - | - | - | - | - | - | - | - | - | 3.24 | 3.09 | 2.93 | ||||
.94 | - | - | - | - | - | - | - | - | - | - | 3.32 | 3.19 | 3.03 | ||||
.95 | - | - | - | - | - | - | - | - | - | - | 3.43 | 3.28 | 3.14 |
HISTORY
1. Repealer and new subsections (a) and (b) filed 8-12-76; effective thirtieth day thereafter (Register 76, No. 33).
2. Change without regulatory effect repealing and adopting new Figures 1-6 within subsection (b) filed 5-19-2008 pursuant to section 100, title 1,California Code of Regulations (Register 2008, No. 21).
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