MIL-HDBK-1003/7
Pressure Vessel Plates, Carbon Steel, for Moderate and Lower Temperature Service, are
commonly used without preference of one type over the others. NEI standards require
1/32-inch corrosion allowance and 1/16-inch corrosion allowance is usually specified.
Tube Support Plates. Tube support plates are located at periodic intervals
7.3.2
along the length of the tubes to steady and prevent vibration of the tubes that could
otherwise result from impingement of high velocity steam or possibly from cooling water
flow. Carbon steel plate, either ASTM A283 Grade C or ASTM A285 Grade C material is
usually used. Tube support plates should not be less than 3/4 inch thick. The spacing
of the tube support plates shall be in accordance with HEI standards. The maximum
spacing for 1-inch, 22 gauge Type 304 stainless steel tubes shall not be greater than 48
inches.
Tubes. Recommended condenser tube gauge, water velocity, and application are
7.3.3
shown in Table 17. The relative resistance to various failure mechanisms of most widely
used materials is shown in Table 18. A final choice of tube material should not be made
without a thorough understanding of the effects and problems related to the following:
a)
Tube metal corrosion.
b)
Tube metal erosion.
c)
Tube water velocity.
d)
Cooling water scaling characteristics.
e)
Foreign body contamination, particularly seashells.
f)
Biofouling.
g)
Chemical attack.
h)
Galvanic corrosion and protection.
i)
Dealloying such as dezincification.
j)
Stress corrosion cracking.
k)
Tube impingement and vibration.
l) Cooling water characteristics such as freshwater, seawater,
brackish water, polluted water, concentrated cooling tower water, etc.
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