What 178.337-8A2 means in plain language
FMCSR 178.337-8A2 covers the outlets on MC331 cargo tanks—the connection points where hazardous materials enter or exit the tank during loading and unloading operations. These outlets must meet specific design and construction standards to prevent leaks, spillage, and exposure during transport and transfer of regulated hazmat.
If you're hauling hazardous materials in an MC331 tank, your outlets are a critical safety component. They include valves, caps, plugs, and fittings that secure the tank and prevent unintended discharge. A citation for this code typically means an inspector found an outlet that didn't meet the required specifications—whether in design, materials, installation, or condition.
What our enforcement data actually shows
Across our 13 million+ inspection records, FMCSR 178.337-8A2 has generated only 1 citation all-time and 0 citations in the last 12 months. This code ranks #2796 of 3,036 FMCSR codes by citation volume, making it extremely rare in roadside enforcement.
However, the data reveals a critical enforcement pattern: that single citation resulted in an out-of-service determination—a 100.0% OOS rate. This is significantly higher than the all-FMCSR average of 31.4%. When inspectors do cite 178.337-8A2, they see it as a defect serious enough to pull the vehicle from service. No citations occurred in the last 90 days, suggesting either strong industry compliance or low inspection focus on this specific outlet provision.
Who gets cited most
Our inspection database shows only one carrier with a documented citation for 178.337-8A2: Keith Morgan Trucking LLC (USDOT 291194), which received 1 citation. The extremely limited enforcement history means there is no meaningful state or carrier pattern to report. This should not be interpreted as low risk—rather, the rarity of citations combined with the 100.0% OOS rate when they do occur suggests that outlets typically pass inspection, or when they don't, inspectors treat the violation as serious enough for immediate removal from service.
How severe is this compared to similar codes
178.337-8A2 sits within the hazardous materials category alongside several peer codes with much higher citation volumes. For context:
- 177.834A-HMC (General loading/unloading hazmat) has 3,954 all-time citations with a 99.2% OOS rate—indicating that general hazmat loading/unloading violations are far more frequently cited and almost universally result in out-of-service determinations.
- 177.817(a) (Placarding violation) has 2,274 citations with a 75.1% OOS rate—roughly 2,000 times more common than 178.337-8A2, but with a lower OOS rate.
- 172.516(c)(6) (Placard damaged, deteriorated, or obscured) has 1,796 citations with only a 1.6% OOS rate—showing that not all hazmat code violations trigger immediate removal from service.
The contrast is stark: when 178.337-8A2 is cited, it almost always results in OOS status, whereas peer codes in placarding and general hazmat handling show much wider variation in enforcement outcomes.
How to avoid it
Because this code is extremely rarely cited, your best defense is a disciplined pre-trip inspection routine and understanding the MC331 tank specifications your employer requires:
- Inspect all tank outlets before each trip. Check that caps, plugs, and valve covers are intact, properly seated, and free of damage, corrosion, or deformation. A cracked cap or loose plug can trigger a citation.
- Verify outlet hardware matches your tank's design specifications. If your company has provided a diagram or parts list for your MC331, cross-check that the outlets, valves, and fittings on your unit match the approved configuration. Mismatched or aftermarket components are a red flag.
- Look for leaks or residue around outlets. Fresh spills, crystallized hazmat deposits, or wet spots near connection points indicate a defect. Report these to your dispatcher or maintenance immediately—do not attempt to load or transport.
- Ensure outlet caps and covers are secured and visible. Inspectors will verify that caps fit snugly and that no outlets are missing covers or caps entirely. A loose or missing cap is an easy citation.
- During loading and unloading, confirm that the person operating the transfer equipment uses the correct outlet connection. Wrong connections or forced fits can damage threads and valve seats, creating future compliance issues.
- Maintain communication with your carrier's maintenance team. If you notice any outlet repairs or replacement work, request written confirmation that the replacement parts meet DOT and your carrier's standards before returning to service.
Given the 100.0% OOS rate when this code is enforced, a single outlet defect found at roadside will likely take you out of service on the spot. Prevention through careful pre-trip inspection is far simpler than managing an OOS citation and the operational disruption that follows.