What’s the difference between a DOT number and an MC number?

A DOT Number is required for carriers operating commercial vehicles in interstate commerce, especially those hauling hazardous materials. An MC (Motor Carrier) Number is required for carriers transporting regulated commodities, such as hazardous goods, across state lines. All commercial carriers need a DOT number; only those hauling regulated goods need an MC number.

What is a DOT 406 tanker?

Designed for transporting flammable liquids such as gasoline, diesel, and jet fuel. Features include aluminum construction, bottom loading/unloading, multiple compartments, emergency venting, shutoff and rollover protection, and typical capacity of 9,000–9,500 gallons.

What is a DOT 407 chemical trailer?

Built for non-corrosive chemical liquids and related products. Features include stainless steel construction, design pressure ~25–40 psi, top or bottom loading, pressure relief and emergency shutoffs, and typical capacity of 7,000–8,000 gallons.

What is a DOT 407 crude oil tanker?

A variant of DOT 407 adapted for crude oil transport. Typically aluminum or stainless tanks, single compartment, bottom loading, robust safety valves and overfill systems, and capacity range of ~8,000–13,000 gallons.

What is a DOT 412 tanker?

Designed for corrosive and acidic liquids like hydrochloric acid and sulfuric acid. Features include corrosion-resistant linings (rubber, FRP), stronger stainless or carbon steel, single compartment design, capacity ~3,500–5,500 gallons, and emergency venting and spill containment systems.

What is an MC‑331 tanker?

Used for compressed, pressurized gases such as propane, butane, ammonia, and LPGs. Features include quenched and tempered steel or aluminum, design pressures often >250 psi, single-compartment designs, pressure relief valves, emergency shutoffs, protected gauges, and typical capacity of 10,600–11,600 gallons.

How are DOT and FMCSA requirements enforced?

DOT and FMCSA enforce compliance through roadside inspections, safety audits, and review of carrier operating records. Cargo tank trailers must undergo routine checks; some inspections occur annually and certain hazardous material inspections occur every 6 months.

What are the consequences of non‑compliance?

Failing to meet DOT or MC standards can result in fines, penalties, suspension or revocation of operating authority, CDL repercussions, increased accident risk, and legal exposure. Staying compliant protects drivers, customers, and the public.

Why do these codes matter?

For companies hauling fuel, chemicals, corrosives, or pressurized gases, knowing these codes and specifications ensures regulatory compliance, safer operation, correct trailer selection, and reduced liability and risk.

Resources | CK Equipment | Norcross, GA

1. What Are DOT & MC Codes?

Purpose:

These codes are regulatory designations used in the United States to define the design, construction, and use of tanker trailers — especially those hauling hazardous materials.

Who Issues Them:

DOT (Department of Transportation): Oversees transportation safety nationwide.
FMCSA (Federal Motor Carrier Safety Administration): A division of the DOT that enforces safety rules for commercial carriers.

DOT vs. MC Numbers:

DOT Number: Required for carriers operating commercial vehicles in interstate commerce, especially those hauling hazardous materials.
MC (Motor Carrier) Number: Required for carriers transporting regulated commodities (like hazardous goods) across state lines.
- All carriers with commercial vehicles need a DOT number; only those hauling regulated goods need an MC number.

2. DOT / MC Specs for Tanker Trailers

DOT 406 – Non-Pressurized Tankers

Designed for transporting flammable liquids such as gasoline, diesel, and jet fuel.

Features & Uses:

Primarily aluminum construction.
Bottom loading/unloading.
Multiple compartments (commonly 3-4).
Emergency safety features (venting, shutoff, rollover protection).
Typically 9,000-9,500 gallon capacity.

Ideal For: Fuel delivery to gas stations, airports, and industrial sites.

DOT 407 - Low-Pressure Chemical Trailers

Built for non-corrosive chemical liquids and related products.

Features & Uses:

Stainless steel construction.
Design pressure typically ~25-40 psi.
Various loading/unloading options (top/bottom).
Safety systems: pressure relief, emergency shutoffs.
Capacity commonly 7,000-8,000 gallons.

Used In: Chemical manufacturing, petroleum transport, agriculture.

DOT 407 - Crude Oil Tankers

A variant of DOT 407 adapted for crude oil transport.

Features:

Aluminum or stainless tank.
Typically single compartment.
Bottom loading.
Robust safety valves and overfill systems.
Common capacity range ~8,000-13,000 gallons.

DOT 412 Corrosive Material Tanker Trailer

DOT 412 - Corrosive Material Tankers

Designed for corrosive and acidic liquids like hydrochloric acid and sulfuric acid.

Key Points:

Reinforced with corrosion-resistant linings (E.G., rubber, FRP).
Stronger materials (stainless/carbon steel).
Typically single compartment.
Capacity ~3,500-5,500 gallons.
Includes emergency venting and spill containment systems.

MC-331 - High-Pressure Gas Tankers

Used for compressed, pressurized gases such as propane, butane, ammonia, and LPGs.

Design & Safety:

Steel (often quenched & tempered) or sometimes aluminum.
High design pressures (often >250 psi).
Single compartment designs.
Safety devices: pressure relief valves, emergency shutoffs, protected gauges.
Typical hauling range ~10,600-11,600 gallons.

Resources CK Equipment

1. What Are DOT & MC Codes?

Purpose:

Who Issues Them:

DOT vs. MC Numbers:

2. DOT / MC Specs for Tanker Trailers

DOT 406 – Non-Pressurized Tankers

Features & Uses:

DOT 407 - Low-Pressure Chemical Trailers

Features & Uses:

DOT 407 - Crude Oil Tankers

Features:

DOT 412 - Corrosive Material Tankers

Key Points:

MC-331 - High-Pressure Gas Tankers

Design & Safety:

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