Large Diameter 3LPE Coating Line DN508 to 1220 mm

 

The anti-corrosion coating processing line includes:
-steel pipe transmission system
-Internal and external shot blasting system
-dust collection system
-pipe heating system
-electrostatic spraying system
-PE coating system
-water cooling system
-end cutting system
-hydraulic and pneumatic system
-testing system
-electronic control system

Pipe enters on the heavy conveyor and is centred before blasting so the wheel stream hits at the design angle. Abrasive is separated, screened and returned; spent fines go to the three-stage dust chain. After internal purging and end masking, an induction coil heats the wall through to the coating window. Epoxy powder, adhesive and polyethylene follow in sequence while the pipe rotates under its own drive. Water spray cooling, joint cutting and end bevelling complete the cycle, and a holiday detector inspects the full surface before the pipe is transferred to the finished rack. Two features matter more at this diameter than at smaller ones: the skew adjustment on the conveyor, which keeps the pipe from walking during a long blast, and the rotating drive speed, which the operator matches to extruder output rather than to conveyor speed.

1. Pipe diameter: 508-1220mm (20-48 Inch)
2. Processing capacity: ≥250m²/h
3. Cleaning level: ≥Sa2.5
4. Materials for production: epoxy powder, adhesive, polyethylene

Standards Compliance

Typical specifications met on this line include ISO 21809-1 for three-layer polyethylene and polypropylene coatings, DIN 30670 in Europe, and GB/T 23257 for domestic Chinese projects. For projects in Russian-speaking markets the same configuration is supplied in a GOST-adapted version. Surface condition is prepared to ISO 8501-1. We state plainly that we make no claim to being an approved supplier of any particular oil company; if your tender cites an operator specification, we confirm clause by clause during technical clarification and list the deviations in writing.

Applications

Long-distance oil and gas transmission pipe; large water conveyance pipe including internal and external coating combinations; city main gas headers; thermal power circulating water pipe; large port and industrial feed lines. Buyers at this diameter are usually supplying a named project, so the line is specified against the coating standard in the tender rather than against a catalogue. It is also common for the same plant to run this line for large diameters and a smaller line for branch pipe, which is why we keep the control platform and recipes compatible across the range.

Service & Support

Site supervision by 2 to 3 engineers across 15 to 30 days, including foundation verification before the modules are placed. Operators are trained to run the line and to diagnose the four fault classes we see most often on large diameter machines: blast wheel wear, coating eccentricity, cooling water temperature and holiday detection false positives. Documentation in English covers layout, foundation, electrical, P and ID and manuals. Wear parts by air freight within 72 hours. Main machine warranty 12 months, screw barrel and gearbox 24 months.

Why Choose Qingdao Huashida

Large diameter is where our reference list is deepest. A pipe mill in the Moscow region runs our line from DN530 to DN1620 mm; a plant in Volgograd runs DN1420 mm; and further south a coating plant has taken repeat orders in successive years as its project load grew from DN530 to DN1420 mm. We also delivered a complete large-diameter three-layer line to a South African pipe maker where the client asked us to hold the installed power down; the final design used a 1,600 kW drive group instead of the 2,400 kW originally quoted, and the line was delivered in 70 days.

--- FAQ ---
Q: Why does a large diameter line need a different conveyor?
A: At 23.5 t a pipe, a conventional chain conveyor lets the pipe skew and the blast pattern drifts off centre. The heavy lift-and-carry design with motorised skew adjustment keeps the pipe axis steady through the longest station on the line.

Q: Can it run both 3LPE and 3LPP?
A: Yes. Three-layer polypropylene uses the same mechanical platform with a different extruder temperature profile, die and cooling regime, so a plant that already runs 3LPE can add 3LPP capability without a second conveyor.

Q: How do you keep the coating concentric on a big pipe?
A: The pipe is rotated by its own drive rather than by the conveyor, so the surface speed under the die stays constant. Rotating drive speed, extruder output and die gap are stored together as a recipe per diameter.

Q: What clear height is required?
A: Nine metres for the 20 to 48 inch range. We verify the actual dimension from your building drawing before the layout is issued, because roof trusses and crane rails frequently reduce the usable height.

Q: What is the power requirement?
A: The total installed load depends on wall thickness and the induction heater rating chosen, which falls between 750 kW and 1000 kW. We recommend sizing your transformer at 120 percent of the total installed load, since the plant also runs cranes, lighting and auxiliaries.

Q: How much pipe can the line produce in a year?
A: Between 40 and 150 km of coated pipe a year depending on diameter, wall thickness, shift pattern and the number of diameter changes in the schedule.

Q: What happens if the holiday detector finds a fault?
A: The pipe is unloaded, the coating is stripped over the affected zone and the pipe re-enters the line. Detection therefore happens on your floor rather than after the pipe is buried, which is where the cost difference really sits.

Q: Is spare parts supply reliable during a long project?
A: Critical wear parts, spray nozzles, blast wheel liners and sealing elements are held in stock and despatched by air within 72 hours of a confirmed order. A two-year consumable package can also be shipped with the line.