Prevention FAQ — FMCSR 172.328C: MC330/MC331 Tank Marking

Inspectors verify that MC330 and MC331 cargo tanks display the required QT (Quenched and Tempered) or NQT (Non-Quenched and Tempered) marking. Across our inspection records, this violation appears in 10 citations all-time, with 3 citations in Texas over the last 180 days—the highest concentration in any state. Inspectors physically examine the tank exterior for a legible, permanent marking that identifies the steel type. The marking must be visible and not obscured by dirt, corrosion, or damage. Missing, faded, or illegible markings trigger the citation. Focus your pre-trip protocol on this specific visual check: have drivers photograph or verbally confirm the presence and readability of the QT or NQT designation before every load.

Add a dedicated MC tank marking section to your pre-trip form:

1. Visual confirmation: Driver inspects both sides and the rear of the cargo tank for QT or NQT marking.
2. Legibility test: Mark is readable from at least 3 feet away; not faded, peeling, or obscured.
3. Location check: Marking appears in the manufacturer's designated location (typically near the top rear or on the side).
4. Condition note: Record any dirt, corrosion, or surface damage affecting visibility.
5. Photo documentation: Driver takes a dated photo of the marking and uploads to your fleet management system.

Make this a hard stop—vehicle does not leave yard until the marking is confirmed readable. Given that 1 citation occurred in the last 90 days and 7 in the last 12 months, the issue remains active. Train drivers that this is a hazmat-specific requirement with no exceptions.

Drivers must carry the original tank certificate or manufacturer documentation confirming the MC330 or MC331 designation and the steel type (QT or NQT). Fleets should retain:

• Tank certification documents (issued at manufacture or last recertification).
• Pre-trip inspection logs showing the QT/NQT marking was verified before departure.
• Dated photographs of the marking taken at each pre-trip interval.
• Maintenance records documenting any repainting, re-marking, or resurfacing of the tank that could affect marking visibility.
• Inspector correspondence if a citation is issued, including photos the inspector took.

Organize these by vehicle VIN and tank serial number. In the event of a roadside citation, this documentation package is your evidence that preventive controls were in place. Our data shows 0 out-of-service placements for this code (0.0% OOS rate), meaning it rarely escalates to severity—but missing documentation can change that calculus.

Our inspection records show this code co-occurs with 172.519 (Placard does not meet specifications) in the same inspection, which indicates a broader pattern: incomplete hazmat compliance across multiple required markings on the same tank. This suggests two root causes:

1. Insufficient tank maintenance protocol: The QT/NQT marking degrades over time due to weather, UV exposure, and road grime. Fleets not scheduling regular tank inspections miss fading markings until roadside.
2. Incomplete driver training: Drivers unaware that this marking is separate from placards may overlook it during pre-trip checks. Co-occurrence with placard violations hints that some drivers treat all hazmat markings as a single unit rather than distinct regulatory requirements.

Target your prevention by separating the tank marking check from placard inspection in training. Require monthly tank surface condition reviews, especially for tanks in heavy use or stored outdoors. Pair this with retraining on the difference between QT/NQT designation (steel type) and hazard class placards.

If a marking is damaged, faded, or needs replacement, follow this verification workflow:

1. Engage a certified tank repair facility. Do not attempt to re-mark or repaint without manufacturer or DOT guidance.
2. Obtain written confirmation from the repair shop that the new marking meets the original tank specification (QT or NQT) and is applied per DOT standards.
3. Inspect the new marking for durability, legibility, and location before the tank leaves the shop.
4. Photograph the repaired marking from multiple angles and file with the tank maintenance record.
5. Run a secondary pre-trip by a second fleet safety person (not the repair tech) to confirm readability and compliance.
6. Update your maintenance log with the date, shop name, and type of marking work performed.

Given that our inspection records show 0 out-of-service placements for this code all-time, a repair error is unlikely to trigger immediate fleet removal—but it sets up a citation on the next roadside inspection. Invest in proper re-marking from the start.

If a driver is cited for 172.328C, conduct a structured debrief within 24 hours:

1. Obtain the inspection report: Get the inspector's photos and notes on why the marking was deemed illegible or missing.
2. Interview the driver: Ask whether they checked the marking on their pre-trip and why it was not flagged. Identify training gaps.
3. Physically inspect the tank at your facility. If the marking is genuinely unreadable, measure the distance and lighting conditions; if readable, consider challenging the citation via DataQs.
4. Review the driver's pre-trip logs for the 30 days prior. Did they document the check? If not, that's a compliance process failure, not a marking failure.
5. Check co-occurring citations: Our data shows this code appeared with placard specification violations. Audit the driver's other hazmat knowledge (placard placement, hazard class recognition).
6. Implement a corrective action plan: Retraining on tank marking checks, supervised pre-trip for the driver's next 10 loads, and a mandatory photo-documentation requirement for all MC tanks in the fleet for 90 days.

Document all findings and retain for your safety program file.

172.328C is ranked #2191 of 3,036 FMCSR codes by citation volume, placing it in the lower-frequency band. It does not trigger an out-of-service placement (0.0% OOS rate across 10 all-time citations), compared to the all-FMCSR average of 31.4%. This means it carries lower severity weight in the CSA system relative to, for example, placard or loading hazmat violations.

However, it still counts as a hazardous materials violation and will accumulate points in your Vehicle Maintenance BASIC if citations cluster over time. Our data shows 7 citations in the last 12 months and 1 in the last 90 days, indicating the issue is not epidemic but also not isolated. Monitor your fleet's citations for this code: if you see a second citation within 6 months, escalate the tank condition inspection program and retraining. A pattern of multiple citations on the same tank or repeated driver involvement will elevate your BASIC score more substantially than an isolated incident.

Design a hazmat marking-focused training module with these elements:

1. QT vs. NQT definition: Explain that these refer to steel temper type, not cargo hazard. QT (quenched and tempered) steel is stronger; NQT (non-quenched and tempered) is for lower-pressure applications. Drivers need to know this is a tank property, not a placard.
2. Visual identification: Show photos of properly marked tanks and degraded examples. Have drivers practice the "3-foot legibility test" on your own fleet tanks.
3. Pre-trip integration: Walk through your checklist step-by-step. QT/NQT check comes before placards; do them separately.
4. Reporting degradation: Train drivers to report fading, peeling, or corrosion immediately, not at the next scheduled maintenance.
5. Carrier-specific examples: Our top carrier with citations for this code is Midstream Transportation Company (2 citations all-time). Use anonymized case examples if you operate similar equipment.

Deliver training annually and at hire. Test comprehension with a short quiz on marking identification.

A DataQs challenge is appropriate if:

1. The marking is present and legible at your facility inspection, but the roadside inspector documented it as missing or illegible. Request the inspector's dated photograph; if unclear, that's grounds for a challenge.
2. Environmental conditions affected visibility: If the citation was issued during heavy rain, at dusk, or with glare, and the marking is clearly visible under normal lighting, document this.
3. The tank had recent re-marking: If the repair shop invoice and dated photos prove the marking was applied correctly after the citation date, challenge the citation.
4. Driver pre-trip documentation shows the check was performed: If your log or photo proves the driver verified the marking before dispatch and no intervening damage occurred, the inspector may have missed the marking.

Our inspection records show only 10 citations all-time for this code, so challenges are rare. However, if you have strong contradictory evidence (especially photos), filing a challenge protects your CSA profile. Consult your legal or compliance team on the specific evidence required for your DOT region.

Based on our inspection data, audit frequency should be tied to your citation history:

Baseline cadence: Monthly physical inspection of all MC330 and MC331 tanks in your fleet. Visual walk-around, legibility check, and photo documentation. Takes ~10 minutes per tank.

If no citations in the last 12 months: Continue monthly audits. Our data shows 7 citations in the last 12 months and only 1 in the last 90 days, indicating the violation is detected but not at epidemic rates. Monthly is a conservative baseline.

If you receive a citation: Intensify to weekly pre-trip audits for 90 days on all MC tanks, with mandatory driver photo submission and supervisor sign-off. After 90 days with zero issues, return to monthly.

If you operate tanks in high-citation states (Texas accounted for 3 of the last 180 days' citations), consider quarterly deep inspections plus monthly spot-checks.

Document all audits in your safety management system. This creates a defensible record of preventive controls and demonstrates due diligence if a citation occurs.