Piling and Structural Steel Pipe 3LPE Coating Line DN406-1420 mm
Overview
Piling and structural pipe is coated for a different reason from line pipe, and that changes the machine. Nobody cares about internal roughness or hydraulic performance on a pile. What matters is whether the coating survives being lifted, stacked, driven and, in marine work, whether it survives the splash zone. Two consequences follow. First, the coating build is usually thicker than a pipeline coating, and the specification often varies along the length of the pipe because the buried section, the submerged section and the splash zone are exposed differently. Second, the pipe itself is long, commonly 12 to 40 m, and often heavy wall, so the conveying system rather than the coating station becomes the difficult part of the line. Several driven stations have to run at one speed, or the pipe skews and the coating is uneven. Handling into and out of the machine also matters: a yard with no long crane needs a side-loading transfer rather than an end lift. This configuration is arranged around those facts, with the coating build and the along-length specification split held as separate recipes.
Key Configuration
Blast chamber with two 75 kW wheels at 600 m2/h, abrasive recycling into three-stage dust collection, with the chamber length sized for the longest pipe the yard will run. Profile measurement after blasting, recorded per pipe rather than per batch. Long pipe conveyor with several driven stations synchronised through a common drive reference, soft-faced rollers, and skew detection that stops the line rather than letting the pipe walk. Induction heater in the 750 to 1000 kW band with liquid-cooled power unit and surface temperature measurement. Twin extruders with a dedicated adhesive head and a 1000 mm T-die, screw and barrel in 38CrMoAlA nitrided 0.4 to 0.7 mm above HV 740. Gun array with redundant positions and cartridge recovery. Water spray cooling with recycle and air pre-cooling for heavy wall. Well-known brand PLC with recipes per diameter and per along-length specification split.
| Item |
Parameter |
| Model / Type |
3LPE Coating Line for piling and structural steel pipe |
| Pipe Diameter Range |
DN406-1420 mm (16 to 56 inch) |
| Typical Specification |
external three-layer polyethylene or heavy duty coating for buried and driven service |
| Pipe Length |
12-40 m, handled in single lengths where the yard allows |
| Pipe Wall Thickness |
8 to 32 mm |
| Coating Capacity |
up to 500 m²/h |
| Design Emphasis |
mechanical damage resistance rather than flow performance |
| Surface Preparation |
shot blasting to Sa 2.5 or better, ISO 8501-1, with profile measured |
| Heating |
intermediate frequency induction, 750 kW to 1000 kW class |
| Extruder |
2 x 1,200 kg/h with dedicated adhesive head and 1000 mm T-die |
| Coating Build |
thickness set by the abrasion and driving damage allowance in the specification |
| Cooling |
water spray with recycle, with air cooling ahead of the spray on heavy wall |
| Conveyor |
long pipe conveying with multiple driven stations and synchronised speed |
| Handling |
side-loading transfer for long pipe, avoiding end lift where the yard has no long crane |
| Impact Handling |
protection of coated pipe during yard stacking is treated as part of the scope |
| PLC and HMI |
Well-known brand, recipe per diameter, batch records including blast profile |
| Operators per Shift |
5 |
| Yard Clear Height |
8 m minimum |
| Warranty |
12 months machine, 24 months drive train |
| Certification |
ISO 9001, Shandong First-Set Technical Equipment award |
Main Equipment List and specification
| No. |
Name |
Specification |
| A. Surface Cleaning Equipment |
| 1 |
Steel pipe conveyor |
Adjustable speed and angle, pipe uploading and unloading controlled by PLC |
| 2 |
Shot blasting machine |
|
| 3 |
Cyclone dust collector |
High efficient downwind cyclone dust removal |
| 4 |
Impulse cartridge dust collector |
|
| 5 |
Centrifugal fan |
|
| 6 |
PLC control system |
Automatic control of the line |
| B. Coating Equipment |
| 1 |
Spiral pipe conveyor |
Adjustable speed and angle |
| 2 |
Induction heating machine |
|
| 3 |
Powder spraying device |
Spraying thickness 80-800μm |
| 4 |
Automatic feeder&dryer |
|
| 5 |
SJ-PE Extruder |
|
| 6 |
SJ-AD Extruder |
|
| 7 |
Adhesive extruder die mould |
High quality die steel |
| 8 |
PE sheet extruder die mold |
High quality die stee |
| 9 |
Adhesive/PE sheet coating device |
Pressing roller with silicon coating and internal cooling |
| 10 |
Environmental Protection Ventilation equipment |
|
| 11 |
Cooling Spray equipment |
|
| C.Platform Equipment |
| 1 |
Steel pipe platform |
High quality |
| D.Groove Equipment |
| 1 |
PE Beveling Machine |
Steel brush disk, |
| 2 |
Hydraulic Lifting and Turning Machinery |
For lifting and turning the pipe |
| 3 |
Hydraulic Equipment |
|
A pile is not a pipeline. It is driven, it is handled roughly in a yard, and its coating is bought against mechanical damage rather than against flow performance.
Pile lengths of 12 to 40 m change the machine more than the diameter does: conveying has to be synchronised across several driven stations or the pipe walks sideways.
Marine piling adds a second requirement, because the same pipe sees soil, water and the splash zone, and the coating specification is often split by elevation along the pile.
Heavy wall pipe needs a slower pass and a controlled cool-down, so a pile line is usually rated lower than a pipeline of the same diameter.
Because the yard handles coated pipe with grabs and slings, damage during stacking is a real loss, and the line is designed with that in mind rather than treating coating as complete at the end of the machine.
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 is lifted from the rack and centred on the heavy conveyor, then advanced into the blast chamber where wheel units set below the pass line throw abrasive across the full circumference. Abrasive is separated and returned, dust passes the three-stage chain, and the pipe exits to inspection. After internal purging and end masking, the induction coil brings the wall to the coating window, epoxy powder is sprayed, the adhesive head extrudes the copolymer layer, and the side extruder lays polyethylene while the pipe turns on its own drive. Water spray cooling, joint cutting, end bevelling and a full circumference holiday scan follow before the pipe is transferred off line. On this size, cooling water consumption and the temperature gradient through a 25 mm wall are the two parameters the operator watches most closely.
1. Pipe diameter: 406-1420mm (20-48 Inch)
2. Processing capacity: ≥250m2/h (can be customized )
3. Cleaning level: ≥Sa2.5
4. Materials for production: epoxy powder, adhesive, polyethylene
Standards Compliance
External coating for piling is usually specified under ISO 21809-1 or a project-specific coating specification derived from it, with GB/T 23257 for Chinese domestic works and DIN 30670 where a European client specifies it. Surface preparation follows ISO 8501-1 on the coated length. Marine work frequently adds a separate abrasion and impact requirement along the splash zone, and where the specification is split by elevation we quote the sections separately so the split is visible in the offer rather than buried in a note.
Applications
Marine and harbour piling; bridge and viaduct foundation piles; building foundation piles in aggressive ground; sheet and tubular retaining structures; offshore jacket legs and bracing in the same diameter band; mooring and berthing structures; onshore structural tube in wet or saline ground. Buyers in this segment usually coat for a defined installation method, and the method determines how much uncoated length must be left and how much damage allowance the coating needs. We ask for the installation method before quoting the mask position and the coating build, because those two figures follow from it rather than from the diameter.
Service & Support
Site supervision by 2 to 3 engineers over 20 to 30 days, because a long pile line takes longer to align and commission than a short one. Training concentrates on skew control, profile measurement and the along-length specification split. Documentation is issued in English: layout, foundation, electrical, PID and manuals. Critical spares by air within 72 hours, and the recommended spares list carries the driven-station rollers and the profile measurement consumables, since those are what stop the line. Machine warranty 12 months, drive train 24 months.
Why Choose Qingdao Huashida
We build lines for heavy wall and long product, including three-layer anti-corrosion lines in this diameter band and large diameter coating equipment up to very heavy wall, and our own pipeline companies coat product of this kind. Our anti-corrosion machinery has been recognised on the Shandong Province First-Set Technical Equipment list, and the practical result for a pile yard is that the conveying and handling arrangements are drawn from machines that work in a real yard rather than from a layout that only works on a drawing.
---FAQ---
Q: Can the line coat pipe of 40 m in one pass?
A: Yes, subject to the yard's own handling arrangement. The conveyor is built with several synchronised driven stations and the blast chamber length is set by the longest pipe you intend to run. We ask for the handling method before quoting.
Q: Why is the line slower than a pipeline of the same diameter?
A: Because the wall is heavier and the coating is thicker. Heating a thick wall needs a longer dwell, and a thick coating has to cool at a controlled rate rather than be quenched.
Q: Can the coating specification change along the pipe length?
A: Yes. Where the buried, submerged and splash zones are specified differently, the line holds a position-based recipe sequence so the split is applied by pipe position rather than by timing.
Q: How is damage during yard handling addressed?
A: The release record states the uplift and stacking method the coating is designed for, because the coating is not finished when it leaves the machine; it is finished when it is installed undamaged.
Q: Is the surface profile measured?
A: Yes, after blasting and per pipe, not per batch. Profile is what the adhesive keys into, and it is the first property lost when the abrasive degrades, so it is recorded.
Q: What diameter range does this cover?
A: DN406 mm to DN1420 mm, which is 16 inch to 56 inch, with wall thickness from 8 to 32 mm.
Q: Which standards are usually applied to piling?
A: ISO 21809-1 or a project coating specification derived from it, GB/T 23257 for domestic Chinese works, DIN 30670 where a European client names it. Marine work often adds a separate splash zone requirement.
Q: How much uncoated length is left at each end?
A: That is set by the installation method and by the field joint material, so we ask for the method first and quote the mask position from it.
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