Oil Pipeline 3LPE Coating Line for Transmission DN323-1220 mm
Overview
Transmission pipe is not bought from a catalogue, it is bought against a project specification, and the coating line has to be arranged around how that specification is verified. The differences from a purely commercial line are less about the machine and more about the plant: where the inspection stations sit, how batch records are kept, and whether the production flow allows a third-party inspector to witness the stages the project names. This configuration covers 12 to 48 inch pipe and is laid out with those points decided before manufacture. The other practical difference is schedule. A transmission project's coating requirement arrives as a curve rather than a flat line, so the line has to be able to run hard and then idle without the coating quality drifting when it restarts.
Key Configuration
Blast chamber with 2 x 75 kW wheels rated 600 m2/h, abrasive recycling and three-stage dust collection, with an inspection station immediately downstream for profile measurement. Induction heater in the 750 to 1000 kW band with liquid-cooled power unit and surface temperature measurement at the booth entry. The extrusion group is two 1,800 kg/h units driving 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 of 16 to 20 with redundant units, cartridge recovery and rotary sieve with automatic pulse cleaning. Cooling is by water spray with recirculation. Holiday detection on the full circumference. Well-known brand PLC with batch records held against per-diameter recipes. Separate controllers for blasting, wrapping, bevelling and inspection.
Process Flow
Pipe is received, identified against the batch and loaded on the conveyor. Shot blasting to Sa 2.5 or Sa 3 is followed by anchor profile measurement and an inspection stop, because profile is a documented parameter on transmission coatings. Internal purging and end masking come next. An induction coil brings the wall to the coating window with surface temperature measured rather than inferred, and the pipe then passes through the coating sequence: epoxy powder applied electrostatically, copolymer adhesive extruded through its own head, polyethylene laid on by spiral wrap from the side extruder. Water spray cooling, joint cutting and bevelling follow, then a full circumference holiday detection before unloading and recording against the batch.
Applications
Long-distance oil transmission pipelines; gathering and trunk lines; gas transmission where three-layer polyethylene is the specified coating; pump station and terminal pipework; pipeline rehabilitation where coated pipe is replaced section by section. The buyer is usually a pipe mill holding a supply contract with the pipeline owner or the EPC contractor, which means the coating specification is fixed by someone else and the mill's task is to prove conformity rather than to choose a structure. In that situation the useful conversation is not about which coating to use but about which clauses are hard to hold and what the line needs in order to hold them.
| Item |
Specification |
| Model / Type |
3LPE External Coating Line configured for oil and gas transmission projects |
| Pipe Diameter Range |
DN323-1220 mm (12 to 48 inch) |
| Typical Specification |
three-layer polyethylene with layer thicknesses and test frequency named by the project owner |
| Pipe Length |
8-12 m, extendable to 15 m |
| Pipe Wall Thickness |
up to 25 mm |
| Coating Capacity |
up to 700 m²/h |
| Surface Preparation |
shot blasting to Sa 2.5 minimum, Sa 3 on request, profile measured |
| Heating |
intermediate frequency induction, 750 kW to 1000 kW with surface temperature measurement |
| Extruder |
2 x 1,800 kg/h, dedicated adhesive head, 1000 mm T-die |
| Spray Guns |
16 to 20 guns with four redundant units |
| Powder Recovery |
95 percent or above with automatic filter cleaning |
| Inspection |
holiday detection on the full circumference plus stations for the project test regime |
| Third-Party Inspection |
witness points planned into the layout at the design stage |
| PLC and HMI |
Well-known brand, with per-diameter recipe and batch record capability |
| Operators per Shift |
5 |
| Workshop Clear Height |
9 m minimum |
| Documentation |
mill test certificates, procedure qualification records, joint coating procedure sheets |
| Warranty |
12 months machine, 24 months drive train |
| Certification |
ISO 9001, Shandong First-Set Technical Equipment award |
| Delivery |
60 to 90 days from deposit, planned around the project coating schedule |
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 |
|
Built for pipe that runs above the polyethylene service ceiling, where a PE topcoat would soften and lose its bond.
Polypropylene runs on the same mechanical platform as our 3LPE line, so a plant that already coats PE can add PP capability without a second conveyor.
The cooling zone is split into stages with a controlled gradient, because polypropylene shrinks on a different curve from polyethylene and a single water spray leaves stress lines.
Separate recipe files for PP and for PE, stored per diameter, so switching structure is a selection on the screen rather than a re-tuning exercise.
Adhesive is metered through its own head, which is what keeps the bond between the epoxy primer and the polypropylene topcoat stable at working temperature.
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 blasted to Sa 2.5 or better and the surface profile checked, since adhesion on PP systems is less forgiving of a weak profile. Internal air purging and end masking follow. Induction heating brings the wall to the coating window, which for polypropylene sits higher than for polyethylene and is held more tightly. Epoxy powder is applied electrostatically, the copolymer adhesive is extruded through its own head, and the polypropylene topcoat is laid by spiral wrap from the side extruder. Cooling is deliberately staged: the pipe passes through successive water spray zones rather than a single drench, so that the temperature gradient through the coating stays inside the limit the material can tolerate. Joint cutting, end bevelling and holiday detection close the cycle.
1. Pipe diameter: DN323-1220 mm (12 to 48 inch)
2. Processing capacity: ≥250m2/h
3. Cleaning level: ≥Sa2.5
4. Materials for production: epoxy powder, adhesive, polyethylene
Standards Compliance
Three-layer polyethylene transmission coatings are normally specified under ISO 21809-1 or a project-specific derivative, with DIN 30670 used on European specifications and GB/T 23257 on Chinese domestic projects. Steel surface preparation follows ISO 8501-1. Field joint and cut-back requirements are covered separately, usually under ISO 21809-3. Where the project cites an owner specification, our quotation confirms the clauses we meet and lists any we do not, in writing, before the order, and we do not imply approval by any operator whose qualification process we have not completed.
Service & Support
Site supervision by 2 to 3 engineers over 15 to 30 days, timed so that commissioning is finished before the project's first commercial coating campaign. Training covers recipe selection, batch record keeping and the inspection routine, which is what makes the line auditable rather than only operable. Documentation in English covers layout, foundation, electrical, PID, manuals and the procedure sheets the project dossier expects. Spares ship by air within 72 hours of a confirmed order. Main machine warranty 12 months, drive train 24 months, with a two-year wear parts package available for projects with an extended schedule.
Why Choose Qingdao Huashida
We have delivered three-layer coating lines into projects where the buyer was supplying a named pipeline, including lines for export orders in Nigeria and for pipe mills in Russia, Kazakhstan and Thailand. For a South African pipe maker we redesigned the drive group down to 1,600 kW to match the customer's site power, and delivered the complete line in 70 days against a schedule that did not allow for a second attempt. Our anti-corrosion equipment carries Shandong Province First-Set Technical Equipment awards, and our documentation set is written for third-party inspection rather than for internal use.
---FAQ---
Q: Can the line be configured to a project specification rather than your standard?
A: Yes, and that is the normal case for transmission pipe. Send the specification and we will list the clauses the standard configuration meets and those that need a change, with the cost implication of each, before any order is placed.
Q: Does the line keep batch records?
A: Yes. Recipes are stored per diameter and the machine log is held against the production batch, so a query on a delivery can be answered from the record rather than from memory.
Q: Which tests can be carried out on the line?
A: Each pipe is checked by holiday detection. Coating thickness, adhesion and impact tests are carried out at the stations named in your contract, with third-party inspection at the witness points agreed at the layout stage.
Q: What happens if we need to hold a specific anchor profile?
A: Profile is measured immediately after blasting at a dedicated inspection stop, which is part of the standard layout for transmission work because profile is a documented parameter rather than an assumption.
Q: Can the line run intermittently as the project schedule requires?
A: Yes. Recipes are stored so restart is a selection rather than a re-tune, and where long stops are expected we recommend an acid pickling and phosphating unit to extend the oxidation-free window after blasting.
Q: What pipe range and clear height apply?
A: DN323 mm to DN1220 mm, which is 12 inch to 48 inch, with a 9 m clear height in the workshop and 8 m minimum for handling access.
Q: Are you approved by major oil companies?
A: We make no claim to being an approved supplier of any particular oil company. Where a project requires an operator specification we work through it clause by clause and record the outcome in writing, which is a more useful answer for your tender dossier than a general claim.
Q: How do you handle a project schedule that shifts?
A: The line is delivered against the coating schedule rather than a fixed date where possible, and we will quote a spare parts package sized for the project duration so a wear part failure does not become a schedule item.
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