Introduction: High-Density Polyethylene in Chemical Processing
High-Density Polyethylene (HDPE PE100) is widely utilized for industrial chemical storage due to its high impact resistance, chemical inertness, and light weight. However, how the HDPE vessel is fabricated directly determines its long-term resistance to hoop stress and catastrophic rupture.
1. Spiral Wound (Extrusion Wound) vs. Sheet Butt-Welded Tanks
- Spiral Wound HDPE: A continuous HDPE profile is extruded and wound around a heated rotating mandrel, fusing seamlessly along the helical seam. Wall thickness can be varied from bottom (thickest) to top (thinner) matching the hydrostatic pressure gradient.
- Sheet Butt-Welded Fabrication: High-grade HDPE sheets are rolled and welded using computerized hot-gas or extrusion welding equipment according to DVS 2205 standards. Ideal for custom rectangular tanks, pickling vats, and specialized process vessels.
2. Calculating Safe Wall Thickness (DVS 2205 Formula)
According to DVS 2205, required cylindrical shell wall thickness (s) is determined by:
s = (p * d) / (2 * σ_adm) + c
Where p is hydrostatic pressure, d is tank diameter, σ_adm is allowable design stress (accounting for temperature, creep factor, and chemical reduction coefficient), and c is the corrosion/wear allowance.
Conclusion
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