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Rotationally Molded Polyethylene Tanks Offer These Advantages:
Difference in resin. The advantages our HDLPE resin has over other rotomolded linear resins
in tank applications? Over XLPE?
1. Over Linear, Medium and Low Density Polyethylene:
superior impact and stress-crack resistance
- Improved weatherability
- Broader chemical resistance
- Lower notch sensitivity
2. Crosslink versus Linear:
"The most important advantage that crosslinkable polyethylene (XLPE) tanks have over linear polyethylene (LLDPE)
tanks is that XLPE has a much higher molecular weight than LLDPE. In general, as the molecular weight of polyethylene
increases, the environmental stress cracking resistance (ESCR), part impact strength, elongation, weathering, toughness,
and tensile at elevated temperatures are improved."
This in fact is a true statement; however Snyder is using a TRUE HDLPE and not a LLDPE. In fact, during the molding
cycle the density of resins changes and testing has shown us that we end up with a higher density with our HDLPE
than with the CL200 XLPE.
We feel very confident that our studies and case histories can help us to determine the best resin for the application.
Sii has always taken pride in our ability to get the full development of the physical properties of the resins
which translate into chemical resistance and tank life.
Crosslinked vs. linear Advantages:
The most important advantage that crosslinkable polyethylene (XLPE) tanks have over linear polyethylene (LLDPE)
tanks is that XLPE has a much higher molecular weight than LLDPE. IN GENERAL, as the molecular weight of polyethylene
increases, the environmental stress cracking resistance (ESCR), part impact strength, elongation, weathering, toughness,
and tensile at elevated temperatures are improved.
Wall thickness is not the only factor relevant to determining the strength of the tank. Proper material cure is
more important than wall thickness in determining tank strength. Material cure is highly dependent upon the time
of exposure to heat conducting through the tooling and the plastic material. Excessive exposure to high temperature
will degrade the plastic material and cause a weak part. The ideal cure cycle is to reach the proper curing temperature
as fast as possible, maintain that temperature for the correct period of time, and to cool the part and tooling
at the proper rate of part temperature decrease. The superior Sii manufacturing process and oven capacity makes
it possible to reach the proper cure temperature quickly and avoid the material degradation caused by slow oven
temperature rise. Therefore, it is improper manufacturing technique to compensate for poor material cure with excessively
thick tank walls.
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The following chart will give you another comparison of XLPE and HDLPE that has
been developed by Exxon:
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ADVANTAGES
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Product
Attributes
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HDLPE
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XLPE
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ARM
RT Impact Strength
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X
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ARM-40
Impact Strength
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X
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Stiffness
(Flexural Modulus)
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X
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X
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Creep
Resistance
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X
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Tensile
Break Stress
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X
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Tensile
Break Elongation
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X
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Heat
Distortion Temp.
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Stress
Crack Resistance
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Color
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X
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X
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For Tank Standards Click Here
Quality, Service, Delivery, and Pricing. Sierra Sales will relate an "understanding"
to your process personnel and, if required, invite you to meet with the various manufacturers Sierra Sales represents.
We work with the manufacturers to give you exactly what your process requires. Polyethylene horizontal tanks, poly
cone bottom tanks, plastic ibcs, all plastic horizontal ibcs, polyethylene chemical processing tanks, industrial
strength bleach tanks, wastewater, and chemical bulk storage tanks. Read about all the plastic rotomolded poly tank materials.
Given the opportunity to quote engineering process supplies for your project, or day to day
maintenance, Sierra Sales can walk you through selection right up to delivery of your vessels, piping, valves,
and jacketing. If required, Sierra Sales's line of IBC's can move your finished product over the highways. Sierra
Sales's totes and plastic IBCs are UN Tagged. Ready to go! Including the worlds' largest all plastic horizontal
IBCs, Snyder's Megatainer!
Download the Sierra Sales Specification for Polyethylene Upright
Storage Tanks here. or view the Sierra Sales Specification here.
Browse our site, see the quality of the products, compare our services, then feel free to
call or contact us. Contact Sierra Sales's competition. Compare the quality of our products.
It is easy to see when selecting poly tanks or all plastic IBCs why
SIERRA SALES
215-258-5602
Fax 215-258-5606
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