The lowest-density freight on the scale
Rotationally molded polyethylene tanks, fiberglass-reinforced plastic (FRP) tanks, corrugated HDPE drainage pipe and molded containers are hollow by design. A vertical poly water tank is a shell about a quarter of an inch thick around hundreds of cubic feet of air. On the 13-tier scale that puts tanks below 1 PCF, class 400, and large corrugated pipe close behind at class 300.
Three more traits shape how this freight moves:
- Width. Many tanks are wider than a pallet and some are wider than a trailer door. A 90 in diameter tank takes a full row across a trailer by itself. Anything wider than 102 in is an oversize load that needs state permits.
- Length. HDPE pressure pipe ships in 20, 40 and 50 ft sticks; corrugated drain pipe commonly in 20 ft lengths. Long bundles fill linear feet even when they weigh almost nothing.
- Wind and strap pressure. An empty tank on an open deck behaves like a sail, and a ratchet strap cranked too hard deforms the wall. Securement is a skill here, not an afterthought.
The upshot is that tanks are poorly suited to LTL terminals. They cannot be stacked on, they take a whole trailer row, and their tariff cube is enormous relative to their weight. Most of our tank and pipe tenders go on a flatbed or Conestoga partial.
Typical tank, pipe and molded plastic units
| Unit | L × W × H (in) | Lbs | Cu ft | PCF | Class | Cubed to 96 in |
|---|---|---|---|---|---|---|
| 1,550 gal vertical poly tank | 90 × 90 × 73 | 310 | 342.2 | 0.91 | 400 | 0.69 PCF · 400 |
| 1,000 gal vertical poly tank | 64 × 64 × 82 | 210 | 194.4 | 1.08 | 300 | 0.92 PCF · 400 |
| FRP horizontal tank, 6 ft dia, in cradles | 120 × 72 × 72 | 650 | 360.0 | 1.81 | 300 | 1.35 PCF · 300 |
| HDPE pressure pipe, 20 ft bundle | 240 × 48 × 36 | 1,400 | 240.0 | 5.83 | 175 | 2.19 PCF · 250 |
| Corrugated HDPE drain pipe, 20 ft bundle | 240 × 48 × 48 | 420 | 320.0 | 1.31 | 300 | 0.66 PCF · 400 |
| FRP grating panels, 1 pallet | 96 × 48 × 36 | 1,900 | 96.0 | 19.79 | 70 | 7.42 PCF · 125 |
Tank dimensions are the overall footprint as a square (diameter × diameter), which is how a carrier dimensioner measures a round object. Weights are representative; wall thickness and fittings vary by manufacturer and specific gravity rating. The FRP grating line shows the other side of the plastics business: flat, dense product that rates well unless someone marks it non-stackable.
Run a poly tank load against Saia Item 111
- Safe — tariff cube, density and linear feet stay under the carrier's cube and linear-foot rules.
- Tier 1 — 350 cu ft or more under 3 PCF (XPO, Saia, ABF, Estes): synthetic weight of 6 lbs per tariff cubic foot.
- Re-bill — 750 cu ft or more under 6 PCF, or linear feet at the carrier's rule: book volume LTL or direct partial truckload.
Worked example: four poly tanks on Saia
A tank distributor ships two 1,550 gal tanks (90 × 90 × 73 in, 310 lbs) and two 1,000 gal tanks (64 × 64 × 82 in, 210 lbs) 520 miles. Nothing can ride on a tank. The quote request names Saia, whose SAIA 170 Item 111 uses 350 cu ft under 3 PCF and 750 cu ft under 6 PCF.
1,000 gal: 64 × 64 × 82 ÷ 1,728 = 194.4 cu ft × 2 = 388.7 cu ft
Actual cube = 1,073.1 cu ft · Weight = 620 + 420 = 1,040 lbs
Density = 1,040 ÷ 1,073.1 = 0.97 PCF → Sub 1, class 400
Imputed density = 1,040 ÷ 1,355.1 = 0.77 PCF → class 400
Synthetic weight at 6 PCF = 1,355.1 × 6 = 8,131 lbs
Linear feet = (2 × 90 + 2 × 64) ÷ 12 = 25.7 LF (one tank per row)
Both Item 111 tiers apply, and the carrier would rate 8,131 lbs against 1,040 real pounds. The tanks also take 25.7 LF, about half a 53 ft trailer, because a 90 in or 64 in tank cannot share a row with another tank.
| Option at 520 miles | Indicative linehaul |
|---|---|
| Class 400 LTL as booked | $530 |
| After Item 111 re-rate and W&I fee | $1,748 |
| Spot volume LTL on 25.7 LF | $691 |
| Direct partial truckload, 25.7 LF | $786 |
| Dedicated 53 ft truckload | $1,274 |
At about half a trailer, the direct partial costs roughly $488 less than a dedicated truck and less than half the re-rated LTL bill. For a single drop, the partial on an open deck is the tender we would make. If the distributor has enough tanks for a second customer on the same lane, filling the whole flatbed at about $1,274 brings the cost per tank down further.
Securement and loading guidance
- Load on an open deck where possible. Flatbeds and Conestogas let a forklift or two people place tanks from the side, and there is no door opening to clear. A 53 ft dry van works for tanks under about 96 in wide if the dock has the equipment to get them in.
- Use wide straps, not chains. Four-inch straps with edge protectors spread the load. Tighten until the tank is held, not until the wall dimples; polyethylene softens in summer heat and can take a permanent set.
- Strap over and through. Vertical tanks get at least two straps over the top in an X and a strap around the body, with manway lids secured or removed and boxed. An empty tank can lift off a deck at highway speed if it is only held at the base.
- Cradle horizontal tanks. Fiberglass tanks ride in the manufacturer's saddles or timber cradles, never directly on deck boards, and are strapped at the saddle points.
- Bundle pipe tightly with dunnage between tiers. Sticks should be banded at several points along the length so they do not telescope under braking, and loaded with the bell ends alternated where the pipe has bells.
- Nest where the design allows. Some open-top and cone-bottom tanks are made to nest; nesting two or three cuts the billed cube sharply. Confirm with the manufacturer before nesting finished tanks.
Equipment and accessorials
| Equipment | Deck or interior | Best for |
|---|---|---|
| 48 ft flatbed | 48 ft × 102 in, about 60 in deck height | Tanks up to about 8 ft tall, long pipe bundles |
| Conestoga (rolling tarp) | 48–53 ft, side loading under cover | FRP tanks and fittings that must stay clean and dry |
| Step deck | Lower deck around 38–40 in high | Tall vertical tanks that would exceed legal height on a flatbed |
| 53 ft dry van | About 98.5 in wide × 110 in high | Smaller tanks and molded parts, when dock forklifts are available |
Legal height in most states is 13 ft 6 in. On a flatbed with a deck around 5 ft, that leaves roughly 8 ft 6 in of freight height; a step deck adds about 22 in. Tanks over 102 in wide are oversize, which means permits, routing restrictions and sometimes pilot cars, all of which we quote up front. At delivery, farms, construction sites and plants usually unload with a telehandler; residential and small commercial sites may need a liftgate truck for the smaller tanks.
Which mode Cubic Transport tenders tanks and pipe on
One or two small tanks under 350 imputed cu ft can travel standard LTL if they are on a skid and boxed or wrapped, with exact dimensions on the bill. Past that, we tender tanks and pipe to open-deck carriers on a flatbed or Conestoga partial, priced on linear feet, or to a dedicated truckload when the load passes about 26 to 30 LF. Corrugated pipe and molded containers that are dock-to-dock and van-friendly can go on a volume LTL quote built on linear feet rather than class.
