What 173.301G-HMGP means in plain language
When you transport certain hazardous materials in cylinders, the FMCSR requires those cylinders to meet specific packaging and securing standards during transport. Code 173.301G-HMGP focuses on manifolded cylinders—cylinders that are connected together or bundled as a unit—and ensures they comply with the rules for how hazmat must be packaged and secured in a vehicle.
A citation for this code means an inspector found that your cylinders didn't meet the required standards for manifolded transport. This could involve improper securing, incorrect valve protection, insufficient bracing, or failure to follow the approved packaging method for the specific material being shipped. The regulation isn't about whether you're allowed to carry manifolded cylinders; it's about how those cylinders must be prepared and positioned to prevent shifting, leaking, or damage during transit.
What our enforcement data actually shows
Across our 13 million+ inspection records, 173.301G-HMGP is a relatively uncommon citation. We've recorded only 5 all-time citations for this code, with all 5 occurring in the last 12 months and 1 in the last 90 days. This places it at rank #2406 out of 3,036 FMCSR codes by citation volume.
The out-of-service rate for this violation is 0.0%—none of the 5 citations resulted in a vehicle being placed out of service. This is significantly lower than the all-FMCSR average OOS rate of 31.4%. The low OOS rate suggests that when inspectors find manifolded cylinder issues, they typically treat them as correctable documentation or securing problems rather than immediate safety threats that prevent operation.
Citation activity has been sparse but consistent over the past 12 months. Our data shows 2 citations in May 2025, 1 in August 2025, 1 in September 2025, and 1 in January 2026. The infrequency of this violation indicates that most carriers and drivers hauling manifolded cylinders are handling them correctly.
Who gets cited most
Our inspection records show Wisconsin as the only state with a citation for this code in the last 180 days, with 1 citation and a 0.0% OOS rate. The limited geographic footprint reflects the overall rarity of this violation.
Among carriers, our data shows no single carrier with a pattern of repeated citations. The 5 all-time citations are distributed across five different operations: Monroe Tractor and Implement Co Inc, BFI Waste Services LLC, Don Oralls Garage LLC, Response Electric, and Outlaw Irrigation LLC, each with 1 citation on record.
How severe is this compared to similar codes
Hazardous materials packaging violations span a wide severity spectrum. By comparison, 177.834A-HMC (general loading/unloading hazmat violations) has been cited 3,954 times with a 99.2% OOS rate—far more frequent and enforcement-heavy. Similarly, 177.834(a) shows 3,839 citations at 97.9% OOS rate. Even placarding violations like 177.817(a) reach 2,274 citations with a 75.1% OOS rate.
Manifolded cylinder violations occupy the lower end of hazmat enforcement. Peer codes such as 172.602(c)(1) (maintenance and accessibility of emergency response information) have 1,464 citations but 0.0% OOS rate, matching the pattern we see with 173.301G-HMGP. Another peer, 172.516(c)(6) (damaged or obscured placards) shows 1,796 citations but only 1.6% OOS rate. This suggests manifolded cylinder issues are treated more as compliance corrections than as roadside violations warranting vehicle immobilization.
How to avoid it
Based on the violations co-occurring with manifolded cylinder citations in our database, here are concrete steps:
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Pre-trip cylinder inspection routine: Before loading, visually inspect all manifold connections for cracks, leaks, or loose fittings. Verify that valve caps are in place and undamaged. Check that all cylinders in the bundle are the same type and condition—mixing damaged and sound cylinders is a red flag.
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Secure manifolded bundles properly: Use approved bracing, strapping, or clamping methods to prevent any shifting during transport. Cylinders should not move relative to each other or the vehicle. Test by hand before departure—if you can shift a cylinder even slightly, it's not secure enough.
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Verify packaging documentation: Confirm that your bill of lading and hazmat paperwork match the actual cylinders in your load. Manifolded cylinders must be documented as a single unit, not as separate cylinders, if that's how they're configured.
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Know what you're hauling: Understand the material in your manifolded cylinders and whether special packaging rules apply. Different gases and liquids have different manifold standards. If you're unsure, contact your dispatcher or the shipper before accepting the load.
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Check vehicle condition: Our data shows citations issued to a variety of vehicle makes. Regardless of your truck's make or model, ensure tie-down points are secure, cargo floors aren't damaged, and there's no movement space in the cargo area that could allow cylinder shifting.
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Document your pre-trip: Take photos of the manifolded bundle after securing it. This protects you if an inspector questions the setup—you have proof of the condition at departure. It also helps identify if something shifted during the journey.
The rarity of this citation suggests most drivers are getting manifolded cylinders right. Consistent attention to physical security, proper documentation, and understanding the material you're transporting will keep you compliant and out of an inspector's citation book.