What 172.326C1 means in plain language
When you're transporting hazardous materials in a portable tank, the tank itself must display an identification number marking. This marking tells inspectors, emergency responders, and other drivers exactly what material is inside and where it's going. The ID# marking is a critical safety label that must be visible on the tank.
If an inspector finds that your portable tank lacks this marking—or the marking is illegible, missing, or not properly displayed—you'll be cited for 172.326C1. It's not about the placard on the cab or trailer door; it's specifically about the tank container itself having its own identification marking.
What our enforcement data actually shows
Across our 13 million+ inspection records, 172.326C1 is a relatively uncommon citation. We've recorded 8 all-time citations for this violation, with 7 in the last 12 months and 2 in the last 90 days. This ranks 172.326C1 at #2269 out of 3,036 FMCSR codes by citation volume—making it a low-frequency enforcement area overall.
However, the severity when cited is notable. Out of 8 all-time citations, 4 resulted in out-of-service placement, yielding a 50.0% OOS rate. This is significantly higher than the all-FMCSR average OOS rate of 31.4%, indicating that when inspectors write this citation, they often deem the vehicle unsafe to operate until the defect is corrected.
In the last 90 days, the citation pattern has remained steady but low-volume, showing that this isn't a widespread problem across the industry—yet when it occurs, enforcement is strict.
Who gets cited most
Our inspection records show Texas as the primary jurisdiction for this violation. In the last 180 days, Texas accounted for 4 citations with a 50.0% OOS rate (2 out-of-service placements). This matches the national OOS rate for this code, suggesting consistent enforcement intensity regardless of geography.
We don't see a dominant carrier pattern in the data. Citations are distributed across eight different carriers and independent operators, each with one citation on record, including HERC RENTALS INC, RIG RUNNERS LLC, LUXEMBORG TRADING LLC, LIVE OAK AG & RANCH SERVICES LLC, SKY RIDER INC, and several independent drivers. This spread indicates the violation is not concentrated among a specific fleet type or size.
How severe is this compared to similar codes
In the hazardous materials category, 172.326C1 sits between low-severity and moderate-severity violations. For context:
Placarding violation (177.817(a)) has been cited 2,274 times with a 75.1% OOS rate—significantly more frequent and more likely to result in out-of-service placement than 172.326C1.
General loading/unloading hazmat (177.834A-HMC) leads the category with 3,954 citations and a 99.2% OOS rate, representing the most severe enforcement focus.
Placard damaged/deteriorated (177.817(e)) has 2,038 citations but only a 5.2% OOS rate, showing that cosmetic placard issues are cited far more often but rarely deemed unsafe enough for removal.
Your 172.326C1 sits in the middle: low citation volume but high OOS probability when it does occur. This suggests inspectors view a missing portable tank ID# marking as a genuine safety gap, not a paperwork technicality.
How to avoid it
Prevention starts before you leave the terminal and continues through your pre-trip inspection:
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Inspect the portable tank itself during pre-trip. Walk around the entire tank exterior—top, sides, and bottom where applicable—and confirm the ID# marking is present, legible, and not obscured by dirt, damage, or wear. Use a clean rag to wipe the tank if needed to reveal any faded markings.
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Verify the marking matches your shipping papers. The ID# on the tank should match the hazmat description in your bill of lading or manifest. If there's a mismatch, stop and notify your dispatcher or the shipper before departing.
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Check for damage during your trip. Our co-occurring violation data shows that 172.504A (placarding issues) and 390.21(a) (vehicle marking requirements) frequently appear alongside 172.326C1. This suggests that tank damage, corrosion, or impact damage that affects the tank's overall condition can compromise the visibility of the ID# marking. If you notice impact damage, rust, or weathering on the tank surface, report it and request repair or replacement before the next load.
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Address emergency response information completeness. Our data shows 172.600C (emergency response information not available) co-occurred with 172.326C1 in one inspection. Ensure all hazmat documentation, including emergency contact info, is present and accessible. Missing or incomplete paperwork often travels with equipment maintenance issues.
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Don't assume markings survived the last trip. If your vehicle recently returned from a long-distance haul or sat in storage, re-inspect the tank marking. Weather, sun exposure, and vehicle contact can fade or damage ID# markings over time.
The 50.0% OOS rate makes this a high-stakes citation if you're caught unprepared. A few minutes of pre-trip verification will prevent an out-of-service order that can cost you hours and revenue.