The Snyder Industries 405 Gallon ASTM XLPE Double Wall Tank is a containment-grade vessel built for sites that cannot tolerate a leak reaching the ground. It carries 405 gallons inside a primary tank, with a second outer wall surrounding it to capture the volume if the inner tank is ever compromised. Standing 73 inches tall on a 48 x 48 inch footprint and molded in Natural White crosslinked linear polyethylene (XLPE), it is rated to a 1.9 specific gravity - one of the highest density ratings available in a poly tank, which is what lets it hold dense liquids that would overstress a standard water tank.
Will it work for your liquid?
Two numbers decide this: weight and specific gravity. Filled with plain water this tank carries roughly 3,378 lb of contents; against its full 1.9 SG rating it is engineered to support up to 6,418 lb of liquid weight. Before you set it, confirm your slab or stand is rated for the loaded figure, not the water figure - heavier chemistry pushes you toward that 6,418 lb ceiling fast. Note that 405 gallons is nominal capacity, not your usable fill volume: ASTM D1998 freeboard means the working volume you can actually run is lower, so size for the liquid you need after that allowance. Run the numbers with our Tank Sizing Calculator and review the Tank Sizing Guide before you commit to a size.
Why a 1.9 SG double wall instead of a water tank
Choosing this 1.9 SG XLPE double-wall over a single-wall 1.0 SG water tank is the upgrade, not a compromise. It buys two things in one vessel: secondary containment from the second outer wall, and dense-liquid headroom up to that 6,418 lb rating. The crosslinked polyethylene wall resists stress-cracking and environmental fatigue better than single-wall HDPE in the vapor-saturated headspace where these tanks most often begin to fail - the wall-thickness-at-the-headspace guide explains exactly where that failure starts and why liquid-side inspection misses it.
Fittings, access, and interstitial monitoring
This double wall tank comes configured with an 18-inch polyethylene threaded/vented fitting and a manway with 15-inch access for entry, cleaning, and inspection of both the interstitial space and the primary tank. That access manway exists so the interstitial space between the walls can be inspected and monitored - the early-warning gap that tells you the inner wall has been breached before contents reach the ground; the interstitial-space testing guide covers that boundary condition in depth. One point buyers miss: the 18-inch threaded/vented fitting and the 15-inch-access manway gasket are wetted and vapor-exposed sealing surfaces, so their seal and gasket material must be specified for your liquid, not just the XLPE tank body. The exact port locations and elevations are shown on the technical drawing on this page - check it against your plumbing and fill arrangement before ordering, since relocating molded fittings in the field is not practical.
Freight and what to get right
This tank is molded by Snyder and ships LTL by freight truck from the Chowchilla, CA plant, quoted live to your ZIP code through our Freight Cost Estimator. The most common mistake on a 1.9 SG XLPE double-wall tank like this one is treating it as interchangeable with a single-wall water tank: it is built for secondary containment and dense-liquid duty, so size your foundation to the loaded contents weight and confirm both the XLPE resin and the fitting/gasket sealing materials suit your specific liquid before it goes into service. For freeboard and thermal-expansion sizing on Snyder double-wall tanks, the Snyder double-wall freeboard sizing guide walks through ASTM D1998 in plain terms. To confirm compatibility and the correct gasket and fitting material for your chemistry, or for help with configuration and freight, call 866-418-1777.
