Is your water tank at risk of stress cracks?

Is your water tank at risk of premature stress cracking? If it’s not made from Alkatuff polyethylene, there’s a good chance it could be.

Stress cracking in a poly tank occurs as a result of slow crack growth caused by tensile stresses less than the material’s short-term mechanical strength.

Stress cracking can affect the life span of any product made from thermoplastic polymers that is not specifically designed to resist this form of deterioration. Experts estimate that as much as one quarter of all plastic part failures can be attributed to this condition.

However, while stress cracking is potentially a problem for poly water tanks, particularly in Australia’s harsh environment, strict standards ensure that an acceptable level of performance is achieved.

What are the rules governing stress crack resistance in water tanks?

In order to ensure all water tanks purchased in Australia are up to standard and fit for consumer purchase, an Australian/New Zealand Standard has been introduced which outlines best practice requirements for polyethylene storage tanks for water and chemicals.

AS/NZS 4766 contains specific rules and regulations regarding stress cracking in polyethylene water tanks. The Standard calls for tank materialss to be tested against ASTM D1693 Standard Test Method for Environmental Stress-Cracking of Ethylene Plastics.

This test requires that a notched sample of the material used in polyethylene water tanks sold in Australia be able to withstand up to 500 hours of exposure to an aggressive test reagent under different levels of strain and stress without demonstrating environmental stress cracking.

How do water tanks made from Alkatuff polyethylene stack up against these guidelines?

Alkatuff polyethylene is a strong and durable resin that is perfectly suited to use in one of the world’s more unforgiving environments – the Australian outback.

Because Alkatuff resin boasts a hexene (C6) comonomer, it offers significantly greater strength and crack resistance than the commonly used butene (C4) resin. As such, it far exceeds the minimum requirements set out in AS/NZS 4766.

In fact, Alkatuff polyethylene delivers stress crack resistance performance up to and exceeding 1,000 hours – twice that dictated by the Australian/New Zealand Standard. It is this sort of reliability and integrity that makes Alkatuff polyethylene the superior water tank solution.