What 178.340-7(c) means in plain language
This regulation governs a specific component on certain hazardous materials tank vehicles: the double bulkhead drain system found on MC306, MC307, and MC312 tank trailers. These are the compartmentalized tanks commonly used to haul multiple loads of petroleum products, chemicals, or other regulated liquids.
The double bulkhead drain is a safety feature built into the internal structure of these tanks. It prevents contamination and ensures proper segregation of different cargo during loading, transport, and unloading. When this component is missing, damaged, or not functioning as designed, the tank itself becomes unsafe for hazardous materials transport.
A citation under 178.340-7(c) means an inspector found that your tank trailer's double bulkhead drain did not meet federal specifications for design, installation, or condition. This is a design and manufacturing compliance issue, not typically something a driver causes during normal operation—but it becomes your responsibility when you operate the vehicle.
What our enforcement data actually shows
Across our 13 million+ inspection records, this is one of the rarest citations on file. Our database shows only 1 citation issued all-time for this code. In the last 12 months and last 90 days, we recorded 0 citations.
The vehicle cited was not placed out of service, giving this code a 0.0% out-of-service rate—significantly lower than the 31.4% all-FMCSR average. This code ranks #2796 of 3,036 FMCSR codes by citation volume, placing it in the bottom tier of enforcement frequency.
The rarity of this citation reflects both the specificity of the requirement (only applies to three tank types) and the fact that most tank trailers meeting MC306/307/312 standards are manufactured with compliant bulkhead drains. However, when the issue does surface, it typically points to aging equipment or improper maintenance.
Who gets cited most
Our inspection records show only one carrier cited for this violation: Island Energy Inc (USDOT 2207996) with 1 citation. The vehicle makes involved were a Custom Tra and a Peterbilt, each with 1 citation. Because the enforcement volume is so low, no meaningful geographic or fleet pattern exists in our data.
How severe is this compared to similar codes
This code sits in the hazardous materials category alongside other tank design and loading requirements. For perspective, consider these peer violations from our dataset:
- 177.834A-HMC (General loading/unloading hazmat) has 3,954 citations with a 99.2% out-of-service rate—vastly more frequent and severe.
- 177.834(a) (General loading/unloading hazmat) has 3,839 citations with a 97.9% out-of-service rate—also far more common and subject to immediate removal from service.
- 172.602(c)(1) (Maintenance/accessibility of Emergency Response information) has 1,464 citations with a 0.0% out-of-service rate, similar to 178.340-7(c) in terms of not triggering immediate out-of-service action.
The lack of out-of-service placement for this code suggests inspectors view it as a defect requiring repair or equipment replacement rather than an immediate safety catastrophe on the road. That said, operating a tank with a non-compliant double bulkhead drain can compromise cargo segregation and create regulatory liability.
How to avoid it
Because this is a structural tank issue, your prevention strategy centers on equipment inspection and maintenance:
- Pre-trip tank inspection: Walk around your MC306/307/312 tank trailer before every trip. Look for visible damage, corrosion, or loose components on the external tank structure. If you see cracks, dents, or separation at internal bulkhead seams, do not operate the vehicle.
- Know your tank type: Confirm your trailer is actually MC306, MC307, or MC312 certified. This information is on your tank plate. If you're unsure, ask your fleet or equipment manager—misidentification of tank type can lead to compliance confusion.
- Report structural issues immediately: If you notice any damage, leaks, or unusual odors related to the tank structure during normal operation, report it to your dispatcher and maintenance department at once. Don't attempt temporary fixes.
- Partner with certified tank maintenance: Ensure your fleet uses DOT-certified repair facilities for any tank work. The double bulkhead drain system must be inspected and certified as part of annual or periodic tank maintenance.
- Cargo compatibility checks: Before loading, verify the previous cargo and confirm the tank compartments are properly segregated. Improper loading can mask underlying bulkhead drain problems.
- Routine maintenance records: Keep and review maintenance logs for your assigned trailer. If you notice repeated repairs or recurring issues with the tank's internal structure, flag it with management.