Cyanide on Top of Acid: Refusing a Pre-Built Load
You are loading a 53-foot dry van at a chemical repackager. The load plan on the dock wall shows four non-bulk products:
- 12 drums at 55 gal - UN1689, Sodium cyanide, 6.1, PG I
- 20 drums at 55 gal - UN1830, Sulfuric acid, 8, PG II
- 10 boxes - UN1479, Oxidizing solid, n.o.s., 5.1, PG II
- 6 drums at 55 gal - UN1263, Paint, 3, PG II
The loader has already built the load: cyanide and acid drums nose-to-tail down the left wall, oxidizer boxes stacked on top of the paint drums. Everything is strapped. The van has one bulkhead and no separate compartments. The loader says, "It's all secured, quit stalling." Your hours let you leave now; the customer's cutoff is 17:00.
1. Identify every loading problem in this configuration and state the rule each one violates.
Read the worked answer
Two prohibited combinations, not one.
1. Cyanide with acid - never in the same vehicle. The segregation rules in 49 CFR 177.848 include a specific prohibition on loading cyanides or cyanide mixtures with acids. This is not a paperwork nicety: acid plus cyanide salt liberates hydrogen cyanide gas. In a closed van, a single weeping drum of sulfuric acid contacting a cyanide drum creates a lethal atmosphere with no warning. Drums nose-to-tail down the same wall are still in the same vehicle.
2. Class 5.1 oxidizer with Class 3 flammable liquid - segregation table "X." The table marks oxidizer against flammable liquid as "X," meaning they may not be loaded in the same transport vehicle. Stacking the oxidizer boxes on top of the paint drums also creates a physical failure path: a dropped box or a leaking oxidizer lands directly on a flammable liquid drum.
3. Securement is not the issue. "It's all strapped" answers a different question. Straps do not cure a chemical incompatibility.
Bottom line: the load as built is not transportable. The driver has both the authority and the duty to refuse it until the plan is rebuilt.
2. The shipper offers to hold the acid off the load to save the trailer. Assuming that fix, what remains, and can you now depart?
Read the worked answer
Removing the acid fixes one conflict and leaves the other.
After the acid comes off, the trailer still holds oxidizer (5.1) and paint (3). That is still an "X" pair - they cannot ride together. So the answer is no, you still cannot depart.
The shipper must choose: hold the paint off or hold the oxidizer off. Do not accept "we'll put the bulkhead between them" - a bulkhead does not convert an "X" into an "O." Only "O" segregation can be satisfied by separation or a barrier.
Placarding for the corrected load (cyanide + oxidizer only):
- Sodium cyanide is Div. 6.1, PG I, which is a Table 1 material - a POISON placard is required for any quantity, and DANGEROUS may not substitute for it.
- Oxidizing solid is Table 2. Twelve cyanide drums at 55 gal alone will run the load over the 1,001-lb Table 2 aggregate, so an OXIDIZER placard is required.
Documentation: amend the bill of lading before you sign so the packages actually on the trailer match the paper. A shipping paper listing a drum that is not aboard is as much a violation as one missing a drum that is.
3. The loader argues the cyanide and acid could be "separated" - cyanide forward, acid on the rear tail, 40 feet apart with the bulkhead between. Does that work?
Read the worked answer
No. The segregation table uses two outcomes:
- "O" - must be separated in the vehicle (barrier, distance, or both).
- "X" - may not be loaded together in the same transport vehicle at all.
Cyanide/acid and oxidizer/flammable liquid fall in the "X" category. Distance, a bulkhead, and 40 feet of empty floor change nothing - the material is still in the same vehicle, and the same 40 feet of floor is what a spilled acid would run across toward the cyanide.
Practical script for the dock: "I can't take these together, and it isn't about securement. Show me the corrected plan or I take the trailer empty." Then get the corrected plan reflected on the bill of lading before you sign it.
Also check while you're there: drum condition and closure tightness on the acid, labels intact and correct on every package, and no residue or staining on the cyanide drums that suggests a prior leak.