PetroChina Dushanzi HDPE DMDA6200 is processed as a blow-moulding resin with nominal density 0.953 g/cm³ and melt flow rate 0.20 g/10 min at 190°C/2.16 kg. Lot-release documents should reference ISO 1183-1:2019 for density and ISO 1133-1:2022 for melt flow rate confirmation. Tight-head drums of 200 L nominal capacity are blown on accumulator-head shuttle machines with a 90 mm grooved-feed extruder at 30:1 L/D. Barrel profiles are staged at 185–205°C and the accumulator head and die zones are set at 200–215°C to limit parison sag to below 8% over a 2.2 m drop length. A 10-point parison programmer thickens the top and bottom chime sections to 5.0–5.5 mm while holding the sidewall at 3.0–3.5 mm. Top-load resistance and drop impact requirements compete directly with material consumption, so wall-thickness programming is adjusted through the sidewall rather than the pinch-off zone. The die gap is maintained at 2.8–3.5 mm. The mould closer is operated at 0.35–0.50 m/s to prevent pinch-off fracture. Pre-blow is delayed 0.5–1.0 s after clamp-up, followed by blow air at 0.70–0.85 MPa through a calibrated needle. Cooling lasts 180–240 s before deflashing. Leak testing is performed at 30 kPa internal air pressure after reaming the filling bung.

Compliance for the 200 L tight-head container rests on UN 1H1/Y design type, with drop testing from 1.2 m for packing group II and hydraulic pressure testing at 250 kPa for 30 min. Stacking tests require no permanent deformation after 28 days under a load derived from 1.8 × the gross mass of the stacked configuration. High environmental stress crack resistance is required for diesel secondary containment and aqueous detergent concentrates. Lot-release certificates must include ASTM D1693-15 Method B F50 values in 10% Igepal CO-630 at 50°C. Closed-loop regrind from the same UN-certified drum production stream is limited to 20 wt% because higher ratios lower ESCR and increase parison melt-temperature variability. Pinch-off flash thickness above 600 µm indicates a parison programming offset or worn die ring. This condition correlates with sidewall thinning and should trigger mandrel and bushing replacement before further production.

Agricultural chemical containers in six-layer coextrusion

Coextrusion blow moulding of 5 L to 20 L agricultural chemical containers uses DMDA6200 as the outer and inner structural skins. The layer stack combines DMDA6200 skins with a polyamide barrier core and maleic anhydride–grafted polyolefin tie layers. A six-extruder line is configured with 40 mm skin extruders, a 25 mm polyamide extruder, and 20 mm tie extruders. Skin melt temperature is held at 205–215°C, barrier melt temperature at 230–240°C, and the coextrusion feedblock at 220°C. The outer skin is 25–35% of total wall thickness, the inner skin is 25–35%, the barrier is 3–5%, and each tie layer is 2–3%. The die gap is set at 2.5–3.0 mm. If the polyamide layer cools below 225°C inside the feedblock, viscosity mismatch with the DMDA6200 skins produces longitudinal weld lines in the bottle wall. The line must therefore run continuously during barrier-layer production and be purged with low-viscosity polyolefin during shutdown to prevent carbonised polyamide deposits.

Containers are tested for xylene and cyclohexanone weight loss under ASTM D2684. ESCR is verified by ASTM D1693-15 Method B in 10% Igepal CO-630 at 50°C. A failure before 100 h excludes the lot from emulsifiable concentrate packaging. Recycled HDPE from unknown amine-based antistatic drums must not be compounded into the skin layers because low-molecular-weight amides migrate to the tie interfaces and reduce interlayer adhesion. The terminal application is a tamper-evident, narrow-mouth container for organophosphate or pyrethroid formulations requiring barrier performance against aromatic solvent permeation.

In 20 L to 60 L jerrycans, the dominant processing limitation is low-temperature drop impact at the handle pinch-off zone. DMDA6200 is blown on reciprocating-screw machines with a 65 mm screw, 24:1 L/D, and shot capacity of 3.5–5.0 kg. Melt temperature is controlled at 195–210°C. The parison drop length is 700–900 mm; a die gap of 2.2–2.8 mm is used to control die swell at the handle bridge. Wall thickness at the handle bridge is programmed to 4.0–4.5 mm, sidewalls to 2.5–3.0 mm, and the bottom seam to 4.5–5.0 mm. Blow air at 0.65–0.80 MPa is applied 1.0 s after mould close. Cycle time is 60–80 s. The finished jerrycan is classified under UN 3H1/Y. Drop testing is conducted at 1.2 m for packing group II after conditioning at -18°C for 24 h. Fracture at the pinch-off seam below 1.2 m indicates excessive parison cooling or insufficient clamp pressure. Compression testing follows ISO 12048:1994, with the load determined by the purchaser’s warehouse stacking height.

What Stacking Load Governs 1,000 L Composite IBC Inner Bottle Moulding?

For 1,000 L composite intermediate bulk containers, the inner bottle is blow-moulded from DMDA6200 and then inserted into a steel grid cage. The governing stacking requirement for UN 31H1 design type is a superimposed load equal to 1.8 × the maximum permissible gross mass for 28 days at 40°C. This requirement imposes a creep-limited wall-thickness design rather than a short-term burst criterion. The bottle is produced on a large accumulator-head machine with a 120 mm extruder, 30:1 L/D, and a shot capacity of 25–35 kg. The parison length is 2,200 mm, and wall-thickness programming is set at 50 radial points. Top and bottom corner sections are 5.5–6.0 mm, the cylindrical sidewall is 3.5–4.0 mm, and the pinch-off tail is 6.0–7.0 mm. Melt temperature is 200–215°C. Mould cooling water is delivered at 10–18°C through drilled channels in the aluminium mould. Total cycle time is 360–480 s. The bottle is leak-tested at 20 kPa after cooling and before cage insertion.

In production, the main failure mode is sidewall buckling during stacking tests caused by parison sag in the lower cylinder. This is corrected by increasing lower-wall thickness by 0.5 mm and validating with a 24 h pre-conditioning at 40°C before the full stacking trial. The table below summarises the comparative processing envelope for three container classes produced from the same DMDA6200 feedstream.

Wheeled Waste Container Wall Thickness Programming and EN 840-1

For 120 L and 240 L wheeled waste containers under EN 840-1, DMDA6200 is processed on a single-station blow moulder with an 80 mm extruder and 25:1 L/D. Melt temperature is 200–215°C. The mould uses a five-point parison programmer: rim 4.0 mm, shoulder 3.5 mm, sidewall 2.8–3.2 mm, base 4.5 mm, and pinch-off 5.0 mm. Cycle time is 150–220 s depending on container volume and chilling water temperature of 12–18°C. UV stabilisation is achieved with 2.0 wt% carbon black masterbatch to meet outdoor service requirements, with weathering verification under ISO 4892-2 cycle 1. The main process defect is distortion at the axle bore after demoulding. This is controlled by extending mould-closed cooling by 15–20 s and maintaining a post-demoulding fixture until surface temperature drops below 55°C. Impact resistance is evaluated by a drop test from 1.0 m after conditioning at -20°C.

For marine buoyancy bodies, DMDA6200 is compounded with 2–4 wt% UV-stabilised carbon black masterbatch and extruded at 205–210°C on an accumulator-head machine with a 75 mm extruder. The part is a double-walled float with a nominal wall thickness of 3.5–5.0 mm. Blow air is supplied at 0.65–0.80 MPa. The critical weld line is the pinch-off seam around the mooring eye. This seam is compression-formed with a pinch land length of 8–10 mm to maintain tensile strength. Finished floats are tested for water absorption under ASTM D570-22 for 24 h and for impact after conditioning at -20°C. The design is limited to service temperatures above -30°C. Below this threshold, HDPE embrittlement can generate crack propagation from the eye weld. Published data for this specific Dushanzi configuration is limited, so lot-specific Charpy impact values at -30°C according to ISO 179-1 should be obtained before use in cold-climate installations.

When Aromatic Solvent Pack Resistance Demands ESCR Verification in Blow-Moulded Carboys

For laboratory and small-industrial solvent carboys of 10 L to 25 L, DMDA6200 is blown as a monolayer structure only when the contained aromatic solvent concentration is below the threshold established by chemical compatibility testing. The grade has typical density 0.953 g/cm³ and MFR 0.20 g/10 min. These values indicate a high-molecular-weight HDPE with the parison melt strength needed for consistent wall distribution in narrow-neck designs. The critical property is not MFR but ESCR. Solvent carboys require ASTM D1693-15 Method B F50 values above 100 h in 10% Igepal CO-630 at 50°C. Lot-specific certification is mandatory. If the F50 value falls below 80 h, the lot is unsuitable for xylene, toluene, and methyl ethyl ketone packaging. Processing is performed at 195–210°C with a 2.4–2.8 mm die gap. Wall thickness at the shoulder is programmed to 3.2–3.5 mm and the base chime to 4.0 mm. The carboy is classified under UN 3H1/Y for packing group II. Drop testing is performed at 1.2 m on the closure side. The pinch-off tail is trimmed to a residual height below 2 mm to prevent stress concentration at the base weld.