Page 155 - Pipeline Rules of Thumb Handbook

142 Pipeline Rules of Thumb Handbook

F pt1 = 0.999781 Table 1
Fwt—Factor to correct for the thermal change in the
0 999217 (
F wt1 = . from Table1) specific volume of water from 60°F to the test water
temperature
F pwt1 = 0 999781 0 999217 1 000565
.
.
=
.
Temp. Temp.
(°F) Fwt (°F) Fwt
V tp1 = 111,888 ¥ 1.007454 ¥ 1.002796 ¥ 1.00565 (@ 2,422 psig
35 0.9990777 70 1.0010364
and 48° F)
36 0.9990590 71 1.0011696
37 0.9990458 72 1.0012832
V tp1 = 113,101 (Volume at reduced temperature—represents 38 0.9990375 73 1.0014229
39 0.9990340 74 1.0015420
volume that would be required to raise test pressure to orig-
40 0.9990357 75 1.0016883
inal value at 48°F) 41 0.9990421 76 1.0018130
42 0.9990536 77 1.0019657
43 0.9990694 78 1.0021222
V tp = 113,099 (Volume at initial test conditions)
44 0.9990903 79 1.0022552
45 0.9991150 80 1.0024178
To restore the pressure to the original test pressure, two 46 0.9991451 81 1.0025561
47 0.9991791 82 1.0027251
gallons of water could be added to the test section. If more
48 0.9992168 83 1.0028684
than two gallons is required to restore the test pressure, there 49 0.9992599 84 1.0030435
is the possibility that a leak exists. 50 0.9993061 85 1.0031919
51 0.9993615 86 1.0033730
52 0.9994112 87 1.0035573
When making these calculations, care must be exercised to 53 0.9994715 88 1.0037133
be sure that accurate temperature and pressure data is 54 0.9995322 89 1.0039034
55 0.9996046 90 1.0040642
available. Where test sections are long, it is very likely
56 0.9996683 91 1.0042601
that the temperature will not be uniform throughout the 57 0.9997488 92 1.0044357
test section and thus affect the accuracy of the calculated 58 0.9998191 93 1.0046271
59 0.9999074 94 1.0047972
results.
60 1.0000000 95 1.0050043
61 1.0000803 96 1.0052142
62 1.0001805 97 1.0053915
63 1.0002671 98 1.0056067
64 1.0003746 99 1.0057884
65 1.0004674 100 1.0060090
66 1.0005823 101 1.0061949
67 1.0006811 102 1.0064207
68 1.0008031 103 1.0066108
69 1.0009290 104 1.0068417
APPENDIX B

How to use charts for estimating the amount of pressure change for a change in test water
temperature

Example.

Pipe data 18≤OD ¥ 0.375≤wt where D = Pipe OD, in.
Water temp. at t = Pipe wall thickness, in.
beginning of test 70°F
Water temp. at time T 66°F Calculate
Test pressure 1,800psig
)
+
=
average temperature = (70 66 2 68 ∞ F
Calculate
Use the chart in Figure 3. Enter at 68°F and at the intersec-
Dt = 18 0 375 = 48 tion with D/t line representing 48, read 23psig/°F.
.