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Each tank in the pressure test was completely filled with water and using a 5.5 horse power heavy duty trash pump, was pressurized until failure or rupture. The manway opening was completely sealed and the pump was connected to the tank through a standard 2 inch diameter pipe fitting. This technique simulates the normal filling characteristics of a tanker truck loading a bulk storage tank in the field. The pressure inside the tank was measured using a standard dial gauge. The linear tank catastrophically failed when it reached 9 psi. The failure of the tank was the result of multiple fracture lines, or cracks. The smooth fractured surfaces indicate a brittle failure.

 The cross linked polyethylene tank which failed after reaching internal pressure of 10 psi. Unlike the linear tank, only a 6 inch lesion was formed on the dome of the tank due to the pressurization. This clearly demonstrates the excellent resistance of cross linked polyethylene to crack propagation or un-zipping. Further analysis of this lesion revealed that it developed at one of the top corners of the stiffening gussets found on the dome, which is a stress riser location. Also, this lesion exhibited a ductile failure mode due to the presence of elongated plastic strands.

 

 

PPC Drop Test for Mobile Devices
 16.31 MB
 02-06-2018

The first test in this comparative study was the drop test. Each tank in the first set was filled with 7000 pounds of water, and lifted with a crane, one at a time, to a height of 15 feet. This height is comparable to that used in the testing of polyethylene drums used for fuel storage. Once the rotomolded tank reached the desired height it was released and allowed to free-fall onto the concrete surface below.  This catastrophic failure and its associated crack propagation appeared to be consistent with the un-zipping characteristic found in linear polyethylene resin grades. On the other hand, the cross linked polyethylene tank did not fail or develop any cracks.

We then filled the exact same Poly Processing Crosslinked Tank, the same tank that had just been dropped, but this time with 11000 pounds of water. That’s over 15 times the weight of an empty tank. We dropped it from the same height, to the same surface with the same results, no damage to the tank

To prove the tank was not damaged and to demonstrate the outstanding robustness of our Crosslinked Polyethylene Tanks, we dropped the same tank for a 3rd time. This time we went as high as the crane would go, 45 feet in the air which is 5 times the height of the tank. It held 11000 pounds of water which is 15 times the weight of the empty tank.  Again no damage to the tank after the 3rd drop