The Snyder Industries 360 Gallon ASTM Black Double Wall Tank (SKU 5760102N51) is a self-contained double wall tank built for secondary containment without a separate dike or berm. The inner tank holds 360 gallons; the integral outer wall captures a leak from the primary, so you get containment in one footprint of 53.0 x 53.0 inches at a 63-inch overall height. It is molded in black High Density Linear Polyethylene and carries a 1.9 specific-gravity rating, meaning the inner wall is engineered for contents up to 1.9 times the density of water.
Will it work for your application
Start with weight, not just volume. Filled with water this tank runs about 3,002 lb, and at its full 1.9 specific-gravity rating it can carry a maximum contents load near 5,705 lb. Your pad, skid, or slab has to be rated for that number, not the water figure. Up top there are two distinct openings: an 18" PE threaded/vented fitting that serves as your vented closure and line connection, and a manway with 15" access that is your clean-out and inspection port. Note the PE (polyethylene) thread on the 18" fitting so you spec a matching vent or liquid line before ordering, and confirm the 53 x 53 footprint clears your containment area and any gate or door opening ahead of delivery. If you are matching gallons to a duty cycle, run the numbers through our Tank Sizing Calculator and the Tank Sizing Guide. For the reasoning behind usable volume and freeboard on Snyder double-wall units, the Snyder Captor freeboard sizing guide walks through ASTM D1998 in plain terms.
Containment and leak monitoring
The annular space between the inner and outer wall is where a primary-tank leak is captured, and it gives you a defined place to check for that leak rather than finding product on the ground. For buried or coated outer-wall installations, the cathodic disbondment testing guide covers how to protect that interstitial boundary over time. See the technical drawing on this page for exact fitting locations and dimensions.
The mistake to avoid
Do not read the 1.9 SG rating as a green light for any liquid. That number describes the wall's structural capacity for density, not chemical resistance. This is a water-service listing; the compatibility-limiting parts are not the HDLPE wall but the two elastomer and thread interfaces, so confirm both the PE thread of the 18" fitting and the gasket on the 15" manway against your intended liquid before putting it into anything other than water. And size your foundation to the loaded weight above, not the dry or water-only figure, so the double wall never sits on an under-rated base. If this is rural or remote water storage, the rural reservoir sizing guide is a useful planning read.
This double wall tank ships LTL freight from the Snyder plant in Marked Tree, Arkansas, quoted live to your ZIP. Get a freight rate with our Freight Cost Estimator or call 866-418-1777 to lock in freight and confirm fittings before you order.
