What 172.328(e) means in plain language
Liquefied petroleum gas (LPG) comes in two forms when transported: odorized and non-odorized. Odorized LPG has a distinctive smell added for safety—so people can detect leaks. Non-odorized LPG has no such additive and requires explicit labeling so emergency responders and inspectors know immediately what's inside the tank.
FMCSR 172.328(e) requires you to clearly mark any cargo tank carrying non-odorized LPG. This isn't optional. The marking serves a critical safety function: if your tank is involved in an incident, firefighters, hazmat teams, and law enforcement need to know instantly whether they're dealing with a product that smells like gas or one that doesn't. Without that marking, responders can't make safe decisions about evacuation, ventilation, or containment.
If you were cited, it means an inspector found your cargo tank lacked the required marking for non-odorized LPG, or the marking was missing, illegible, or damaged beyond recognition.
What our enforcement data actually shows
Across our 13 million+ inspection records, we've documented 5 total citations for 172.328(e) since records began. In the last 12 months, there have been 0 citations, and in the last 90 days, 0 citations. This is an extremely rare violation in the field.
None of the 5 all-time citations resulted in an out-of-service order. The OOS rate for this code is 0.0%—meaning every driver cited was allowed to continue operating. By contrast, the all-FMCSR average OOS rate is 31.4%, so this violation sits well below the typical enforcement severity. Nationally, 172.328(e) ranks #2406 of 3,036 FMCSR codes by citation volume, placing it in the bottom tier of enforcement activity.
The rarity of this citation suggests one of two things: either most LPG carriers are compliant with marking requirements, or inspectors rarely encounter non-odorized LPG loads during roadside checks. Either way, if you've been cited, you're in an uncommon situation.
Who gets cited most
Our records show that citations for 172.328(e) have been distributed across five different carriers, each with exactly 1 citation: United Petroleum Transports Inc, Haigood & Campbell LLC, BDS Fluids Inc, Spirit Energy LLC, and Gigo Transport Inc. The data does not show a concentration at any single carrier, which indicates this violation is scattered across the industry rather than systematic at one or two fleets.
Because only 5 citations exist in our entire database and no specific state breakdown is available for this code, geographic patterns cannot be reliably identified. The violation appears episodic rather than endemic to any region.
How severe is this compared to similar codes
Within the hazardous materials category, 172.328(e) sits at the lenient end of the enforcement spectrum. Consider these peer codes:
General loading/unloading hazmat violations (177.834A-HMC and 177.834(a)) have generated 3,954 and 3,839 citations respectively, with OOS rates of 99.2% and 97.9%. Nearly every driver cited for those offenses is pulled out of service. By contrast, 172.328(e) has an OOS rate of 0.0%.
Placarding violations (177.817(a)) have 2,274 citations with a 75.1% OOS rate—still dramatically higher than 172.328(e). Even placard deterioration (177.817(e)) with 2,038 citations carries a 5.2% OOS rate, which is still five times higher than this code.
General placarding requirements (172.502(a)(1)) show 1,820 citations with an 18.5% OOS rate, and placard damage/obscuration (172.516(c)(6)) has 1,796 citations with a 1.6% OOS rate. This code's 0.0% OOS rate is comparable to the most permissive marking-related violations.
The difference: marking failures that affect emergency response (like missing non-odorized LPG notation) are treated as administrative defects rather than safety-critical violations at roadside. Inspectors cite them but don't typically halt the vehicle.
How to avoid it
If you haul non-odorized LPG, build these practices into your pre-trip and ongoing compliance routine:
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Verify marking before accepting the load. Walk the tank before you couple up. Look for the required non-odorized LPG marking or notation on the exterior. If you can't read it or it's absent, contact dispatch and the shipper. Do not haul a tank with unclear or missing hazmat markings.
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Check markings during every fuel stop or break. Road vibration, weather, and road debris can damage labels and stencils. Spend 30 seconds at each stop visually inspecting the tank for legibility. If a marking has faded, peeled, or been obscured by mud or damage, report it to your carrier and get it corrected before the next leg.
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Know what non-odorized LPG looks like when marked. Don't assume all LPG loads smell like gas. Ask your dispatcher if the load is odorized or non-odorized before you pick it up, and confirm the marking matches. Some drivers confuse product types because they're accustomed to smelly LPG.
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Document and photograph the tank at pickup. Use your phone to photograph the cargo tank and its markings before departure. If an inspector stops you and claims a marking is missing or illegible, you have evidence of the condition when you took the load. This protects you if damage occurred between pickup and inspection.
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Report damage immediately. If you notice a marking has been damaged (scraped, faded, or obscured) during your trip, call your dispatcher and the carrier's safety team right away. Request a repair or re-marking before the next inspection point. Proactive reporting shows due diligence and may limit liability if cited.
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Communicate with your shipper. If you consistently pick up non-odorized LPG from the same facility, ask the loading supervisor about their marking maintenance schedule. Work with them to ensure tanks are marked correctly before you take possession.
This is a low-frequency violation, but it's 100% preventable through pre-trip vigilance and clear communication with your dispatcher and shipper. The zero out-of-service rate means inspectors treat it as a documentation issue, not an emergency. But it's still a citation that can affect your CSA score and your carrier's compliance profile, so it's worth the 60 seconds of additional pre-trip inspection time.