Cargo Tank Requirements and Specifications

MC-306 (DOT-406)

Non (low) pressure bulk liquid cargo tank
  • MC 306–Maximum operating pressure of up to 3 psi
  • DOT 406–Maximum operating pressure of up to 4 psi
  • Oval or “egg” shaped cross section
  • Flat or nearly flat ends
  • Aluminum—primary material of construction
  • Usually multi-compartmented
  • Separate manhole for each compartment
  • Emergency shutoff –drivers side front
  • Rollover protection to prevent manholes from opening up on rollover
  • Average maximum capacity–9,000 gallons

Contents:
NORMALLY—petroleum products, however, may be water or milk

MC-306 and DOT 406 tankers are elliptical when viewed from the rear. By far the most common product carried in them is gasoline or other flammable liquids. They usually have a heavy, built-up top that is hollowed out to contain small spills. These tankers have one or more domes and dome covers, generally one dome per compartment in the tank.

MC-307 (DOT-407)

Low-pressure bulk liquid cargo tank
  • Pressure—up to 40 psi @ 70ºF
  • Horse shaped” shaped cross section
  • Flat or slightly rounded ends
  • Stainless steel is primary material of construction
  • May be insulated. Insulation may hide tank shape—may not appear to be horseshoe shaped
  • Manway usually center (top) of tank
  • Discharge valves usually center (bottom) of tank
  • If multi-compartmented, will have a separate manhole for each compartment
  • Emergency shutoff –drivers side front
  • Rollover protection to prevent manholes from opening up on rollover, normally
  • center of tank top
  • Average maximum capacity–6,000 gallons

Contents:
NORMALLY—mild acids, however, may be water, milk, or combustible liquids

MC-307/DOT 407 tankers are a usually a horseshoe shape when viewed from the rear. They carry vegetable oils, syrups, and milk – and they also carry solvents, lubricants, mild corrosives, etc. The horseshoe shape tanks are insulated – the shape you see is the thin aluminum insulation shell cover. Some of these tankers are uninsulated, appear round with small ridges, and are usually unpainted aluminum if un-insulated. The domes in these tankers are usually in the center of the long axis of the tank, but can be multiples or in other locations.

MC-312 (DOT-412)

Corrosives Cargo Tank
  • Pressure—5 to 25 psi exterior strengthening (stiffener) rings often visible
  • Lined tank—usually lined with rubber or plastic
  • Round cross section
  • Stainless steel is primary material of construction
  • May be insulated, insulation may hide tank shape
  • Manway usually rear (top) of tank
  • Discharge valves usually rear (bottom) of tank
  • If multi-compartmented, will have a separate manhole for each compartment
  • Emergency shutoff –drivers side front
  • Cigar shaped tank—long, small diameter
  • Average maximum capacity—4,000 to 6,000 gallons

Contents:
Corrosives – High weight (specific gravity) liquids

Internal Pressure Specifications

CodeTest Pressure
MC 300, 301, 302, 303, 305, 30620.7 kPa (3 psig) or design pressure, whichever is greater
MC 304, 307275.8 kPa (40 psig) or 1.5 times the design pressure, whichever is greater
MC 330, 3311.5 times either the MAWP or the re-rated pressure, whichever is applicable
MC 3381.25 times either the MAWP or the re-rated pressure, whichever is applicable
DOT 40634.5 kPa (5 psig) or 1.5 times the MAWP, whichever is greater
DOT 407275.8 kPa (40 psig) or 1.5 times the MAWP, whichever is greater
DOT 4121.5 times the MAWP

MAWP (Maximum Allowable Operating Pressure)

In-Service Minimum Thickness for MC 300, MC 303, MC 304, MC 306, MC 307, MC 310, MC 311, and MC 312 Constructed of Steel

Minimum manufactured thickness (US gauge or inches)Nominal decimal equivalent for (inches)In-service minimum thickness reference (inches)
190.04180.038
180.04780.043
170.05380.048
160.05980.054
150.06730.061
140.07470.067
130.08970.081
120.10460.094
110.11960.108
100.13450.121
90.14950.135
80.16440.148
70.17930.161
3/160.18750.169
1/40.250.225
5/160.31250.281
3/80.3750.338

In-Service Minimum Thickness for MC 301, MC 302, MC 304, MC 305, MC 306, MC 307, MC 311, and MC 312 Constructed of Aluminum

Minimum manufactured thicknessIn-service minimum thickness (inches)
0.0780.07
0.0870.078
0.0960.086
0.1090.098
0.130.117
0.1410.127
0.1510.136
0.1720.155
0.1730.156
0.1940.175
0.2160.194
0.2370.213
0.270.243
0.360.324
0.450.405
0.540.486

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