What 172.203H2 means in plain language
When you're transporting liquefied petroleum gas (LPG), federal regulations require specific markings and labels on your tank to communicate hazard information to emergency responders and inspectors. Code 172.203H2 addresses a gap in that labeling system: either your tank is missing the required CORROSIVE or NONCORROSIVE designation for the contents, or your tank lacks the "NOT FOR Q AND T TANKS" marking where required.
In practical terms, this is about clarity. If your LPG cargo tank doesn't display whether its contents are corrosive or noncorrosive, or if a tank that shouldn't be used for certain service classes isn't marked accordingly, you're in violation. These markings exist so that anyone handling, servicing, or responding to an emergency involving your vehicle knows exactly what they're dealing with. Missing or incomplete labeling creates confusion and safety risk.
This is a hazardous materials compliance issue, not a mechanical or driver-conduct problem. The violation sits at the intersection of tank specification and documentation accuracy.
What our enforcement data actually shows
Across our 13 million+ inspection records, 172.203H2 is remarkably rare. Our database shows only 3 all-time citations for this code, with 1 citation in the last 12 months and 1 in the last 90 days. None of the 3 citations resulted in an out-of-service order—the OOS rate is 0.0%.
For context, the all-FMCSR average out-of-service rate sits at 31.4%. This code ranks #2551 out of 3,036 FMCSR codes by citation volume, placing it in the long tail of enforcement actions. The rarity of citations and zero OOS placement suggest that either compliance is widespread, inspectors encounter this violation infrequently, or both.
The single citation in the last 12 months occurred in March 2026. This sporadic enforcement pattern means you're unlikely to encounter a citation for this violation unless a detailed hazmat inspection specifically examines your tank labeling.
Who gets cited most
Our inspection records show enforcement concentrated in Texas, with 1 citation in the last 180 days and a 0.0% OOS rate in that state. The extremely limited volume—only one state with documented citations in recent months—reflects the overall rarity of this violation.
Among carriers, our all-time data indicates that Midstream Transportation Company (USDOT 2497677) has received 3 citations for this code. With only three total citations in our database, this carrier represents all documented cases. This does not imply systemic negligence; rather, it reflects the statistical reality that very few inspections surface this particular labeling deficiency.
How severe is this compared to similar codes
Other hazmat codes in the labeling and marking category show dramatically different enforcement profiles. Code 177.834A-HMC (general loading/unloading hazmat violations) has generated 3,954 citations with a 99.2% out-of-service rate. Code 177.817(a) (placarding violations) shows 2,274 citations at a 75.1% OOS rate. Even code 172.502(a)(1) (placarding general requirements) has 1,820 citations with an 18.5% OOS rate.
By comparison, 172.203H2's three citations and 0.0% OOS rate position it as extraordinarily low-enforcement and low-severity within hazmat compliance. This suggests the violation either occurs rarely or is caught infrequently relative to broader placarding and labeling infractions.
How to avoid it
If you operate an LPG cargo tank, protect yourself with these pre-trip and pre-shipment checks:
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Verify tank markings before departure. Walk your tank exterior and confirm that hazard class labels are present and legible. For LPG specifically, ensure the CORROSIVE or NONCORROSIVE marking is visible and matches your cargo specification.
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Check the "NOT FOR Q AND T TANKS" notation if required. If your tank is registered or certified for specific service classes, confirm the appropriate restriction marking is painted or affixed and not faded or damaged.
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Request a hazmat compliance inspection during routine maintenance. If you're unfamiliar with current marking requirements or unsure whether your tank is fully compliant, a certified hazmat inspector can review your placard and label system before you roll.
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Document your tank's certification class. Keep your tank registration and any inspection reports that confirm the service class your tank is authorized for. This proves what markings should be present and supports your defense if an inspector has questions.
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Don't assume old markings are sufficient. Weather, UV exposure, and wear fade labels. If markings look faded or unclear from a distance, repaint or re-apply them. Inspectors verify legibility, not just presence.
Because enforcement for this specific code is minimal, compliance is often achieved through standard hazmat tank maintenance and manufacturer documentation. If you're hauling LPG regularly, establish a visual checklist as part of your pre-trip routine.