The DOT MC-331 specifications are designed for high-pressure cargo tanks used to transport liquefied gases such as propane. These tanks are subject to stringent safety requirements due to the volatile nature of the materials they carry. Below are the key specifications and requirements for DOT MC-331 propane tanks:
### 1. **Tank Design and Construction**
- **Material**: MC-331 tanks are typically made from quenched and tempered steel to withstand high pressure. Some tanks may also be constructed from aluminum or other materials depending on the specific gas being transported.
- **Capacity**: These tanks have a capacity range of 10,600 to 11,600 US gallons.
- **Pressure Rating**: MC-331 tanks are designed to handle high pressures, often exceeding 250 psi.
### 2. **Safety Features**
- **Pressure Relief Devices**: Equipped with pressure relief valves to prevent over-pressurization.
- **Emergency Shut-off Valves**: Designed to minimize the risk of leaks or spills in case of accidents.
- **Recessed Skids and Protected Gauge Wells**: These features protect gauges and valves from damage during rollovers.
### 3. **Inspection and Testing Requirements**
- **External Visual Inspection**: Every 6 months for tanks loaded by vacuum with full opening rear heads; annually for all other tanks.
- **Internal Visual Inspection**: Every 10 years for MC-331 tanks with less than 3,500 gallons water capacity in dedicated propane service constructed of nonquenched and tempered NQT SA-612 steel.
- **Pressure Test**: Every 10 years for MC-331 tanks with less than 3,500 gallons water capacity in dedicated propane service constructed of nonquenched and tempered NQT SA-612 steel.
- **Leakage Test**: Annually for all tanks except those in chlorine service.
### 4. **Marking and Labeling**
- Tanks must be clearly marked with their capacity, pressure rating, and inspection dates.
- Propane tanks must display the UN identification number **1075** and be labeled as “Flammable Gas”.
### 5. **Transportation and Usage**
- MC-331 tanks are single-compartment designs, ensuring efficient loading and unloading of propane.
- Tanks must be equipped with specific loading and unloading facilities to ensure safe transfer of the gas.
### 6. **Additional Safety Measures**
- **Driver Qualifications**: Drivers transporting propane in MC-331 tanks must hold a Commercial Driver’s License (CDL) with a Hazardous Materials (H) endorsement.
- **Emergency Response Plans**: Transporters must have emergency response plans in place to handle leaks, spills, or accidents.
These regulations and specifications ensure that propane is transported safely and efficiently, minimizing risks to public safety and the environment.