What 172.326(a) means in plain language
When you're hauling hazardous materials in a portable tank, federal regulations require that tank to display the correct shipping name and identification number on its exterior. These markings serve a critical safety function: they tell emergency responders, shippers, and inspectors exactly what's inside the tank and how to handle it in case of an accident or spill.
A citation under 172.326(a) means an inspector found that your portable tank was either missing these markings entirely, had markings that were illegible or faded, or displayed incorrect information. The shipping name must match the proper DOT shipping name for the material, and the ID number must correspond to the correct hazmat classification. Even a small error—wrong number, outdated placard, or weathered lettering—can trigger this violation.
This is fundamentally about communication. Emergency personnel depend on these markings to make split-second decisions. If a portable tank carrying corrosive material isn't properly marked, first responders might not know they need special equipment or evacuation procedures. That's why DOT takes marking requirements seriously.
What our enforcement data actually shows
Across our 13 million+ inspection records, 172.326(a) is cited extremely rarely. All-time, we see only 16 citations for this violation, with zero citations in the last 12 months and zero in the last 90 days. This ranks the code at #2026 out of 3,036 FMCSR violations tracked in our database—making it one of the least-cited hazmat infractions on the books.
None of the 16 all-time citations resulted in an out-of-service placement. The OOS rate is 0.0%, which stands in sharp contrast to the all-FMCSR average of 31.4%. This doesn't mean the violation is trivial; rather, it suggests that when inspectors cite this specific marking violation, they often allow the driver to correct it on the spot or at the next terminal, rather than immediately sidelining the vehicle.
The scarcity of citations over the past year indicates that most drivers and fleets hauling hazmat in portable tanks are getting the marking requirement right. When violations do occur, they're typically isolated incidents rather than systemic problems.
Who gets cited most
Our inspection records show carriers such as Imperative Chemical Partners Inc (USDOT 1796904) with 3 citations for this code, and Hoover Transportation Services LLC (USDOT 2424751) with 2 citations. The remaining citations are distributed across smaller operators, each with a single infraction. The low overall citation count means no single carrier dominates this violation category.
Because only 16 citations have been recorded all-time, we don't have meaningful geographic distribution data to report. The rarity of this citation means it's not concentrated in any particular state or region—it's a sporadic issue that affects a small fraction of hazmat operations.
How severe is this compared to similar codes
Hazmat marking and placarding violations exist on a spectrum of severity in the hazmat category. For perspective, consider these peer codes from the same family:
General loading and unloading hazmat violations (177.834A-HMC and 177.834(a)) generate thousands of citations annually—3,954 and 3,839 respectively—and are placed out of service at rates of 99.2% and 97.9%. These are high-severity, high-consequence violations that routinely ground vehicles.
Placarding violations (177.817(a)) account for 2,274 citations with a 75.1% OOS rate, reflecting DOT's serious stance on improper or missing placards. By contrast, our code—172.326(a)—sits at the far opposite end: rarely cited and never out-of-service.
Placard damage or deterioration (172.516(c)(6)) records 1,796 citations but only a 1.6% OOS rate, suggesting inspectors often see these as correctable issues rather than grounds for immediate removal from service. Your marking violation falls into a similar low-OOS-rate category.
How to avoid it
If you operate a portable tank, implement these practices before every trip:
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Pre-trip inspection of all markings. Walk around the tank before loading. Verify the shipping name and ID number are clearly visible, legible, and match your bills of lading. Use a flashlight if needed; faded or weathered markings are as problematic as missing ones.
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Replace or refresh markings regularly. Portable tanks are weather-exposed and take a beating on the road. Don't wait until an inspection to discover your markings have faded. If you see any deterioration, arrange for repainting or replacement stickers before your next haul.
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Cross-check documentation. Before departure, compare the physical markings on the tank against the hazmat shipping papers. A mismatch means you have a problem to solve before rolling—not at a weigh station.
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Maintain records of tank certification and updates. Keep photos or maintenance logs showing that your portable tanks are properly marked and inspected. This documentation protects you if a marking issue arises during transport.
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Work with your dispatcher and hazmat coordinator. If you're assigned a portable tank you haven't used before, ask your company's hazmat compliance team to certify the markings are current. Don't assume the tank is correct just because it was used last month.
The good news: this violation is rare, which means most drivers get it right. A little attention to detail during your pre-trip walk-around will keep you in the clear.