Overview
A line that has to travel to a site without a heavy lift crane is designed differently from one built in a permanent mill. Every module here fits through a 40HQ door and weighs under the capacity of a 25 t forklift, frames are bolted rather than welded on site, and electrical cabinets travel assembled and tested so the site work is connection rather than construction. The buyer is often building the first insulation plant in a region where the road is finished after the factory, and where the nearest machinist is a day away.
Process Flow
Each module is landed, set on its slab and bolted to its neighbour before the next arrives. Extrusion, calibration and cooling are aligned first, then haul-off and cutting, then insertion and foaming. Cabinets are connected by numbered cable, the line is dry-run, and the first pipe is made with our engineer watching over a link.
Key Configuration
The line is split into six modules: extrusion, calibration and cooling, haul-off and cutting, insertion, foaming, and end finishing, each on a bolted frame with a lifting point at its centre of gravity. The DN110-400 mm die and sleeve are matched as a pair, because a sleeve polished back into tolerance does not restore the bore shape at this wall thickness. Wiring is numbered and terminated in cabinets before shipment, and a site connection drawing shows every cable by number, so erection does not depend on an electrician who has seen the machine before.
Applications
New plants in markets where the first factory precedes the infrastructure; projects where the insulation plant is inside a contractor's scope and must be erected within a fixed mobilisation window; plants that may be relocated when a pipeline contract ends.
Standards
Built to GB/T 29047 by default, and re-configured to EN 253 or GOST 30732 where the market requires, with the test schedule adjusted accordingly. Electrical standards follow IEC, with a CE option for European delivery. For DN110-400 mm the standard is fixed first and the instrumentation follows, since EN 253 and GOST 30732 do not use the same test schedule.
Service & Support
On the DN110-400 mm line two engineers cover erection and commissioning over 15 to 25 days, ending with a batch you have made yourselves. The DN110-400 mm line is handed over with training on four settings, the ones that move acceptance: vacuum level, haul-off speed, shot weight and cure time.
Why Huashida
We have shipped complete lines to more than 40 countries, including plants in Central Asia and the Middle East, and we build them to be erected by the buyer's own crew with remote support rather than by a large travelling team.
| Item |
Specification |
| Model / Type |
Vacuum sizing and pipe-in-pipe foaming pre-insulated pipe production line, complete line |
| Pipe Diameter Range |
DN110-400 mm |
| Process |
Casing extrusion, polyurethane foaming, end finishing and testing in one continuous flow |
| Insulation Layer |
Rigid polyurethane foam, density 60 to 80 kg/m³, closed cell content 88% or above |
| Thermal Conductivity |
0.033 W/m·K or lower at 50 °C mean temperature |
| Service Temperature |
up to 120 °C continuous, 140 °C peak |
| Line Output |
260 m² of insulated surface per hour at nominal wall |
| Annual Capacity |
sized against the buyer's kilometre target, not a catalogue figure |
| Casing Extruder |
single screw 120 mm, 33:1 L/D |
| Extruder Output |
500 kg/h of HDPE compound |
| Casing Wall Thickness |
4.0 to 6.0 mm, set by diameter and burial load |
| Vacuum Calibration |
stainless calibration sleeve, vacuum held at -0.04 to -0.06 MPa, water ring pump |
| Cooling |
9 m vacuum tank plus spray cooling, water recirculated |
| Haul Off Speed |
1.5 to 2.5 m/min, set by casing wall and diameter |
| Foam Injection |
high pressure machine, 60 kg/min, impingement mixing at 150 to 200 bar |
| Centring |
steel pipe centred inside the casing before injection, spacer set per diameter |
| Curing |
rack curing 24 hours minimum before end finishing |
| Control System |
Well-known brand PLC and HMI, recipe per diameter, batch record per shift |
| Operators per Shift |
4 to 6 |
| Installed Power |
calculated per configuration, typically 380 to 620 kW |
| Workshop Requirement |
layout drawing issued with the quotation |
| Commissioning |
site supervision by 2 engineers, 15 to 25 days |
| Documentation |
English layout, foundation, electrical, PID and operation manuals |
| Warranty |
12 months machine, 24 months drive train |
| Certification |
ISO 9001 quality system; CE option for EU delivery |
Technical Prameters:
| |
PE-365/760 |
PE-420/960 |
PE-850/1372 |
PE-960/1680 |
| Main extruder |
SJ-90/33 |
SJ-90/33 |
SJ-120/33 |
SJ-150/33 |
| Pipe diameter (mm) |
Φ365-960 |
Φ420-960 |
Φ850-1372 |
Φ960-1680 |
| capacity (kg/h) |
550-700 |
550-700 |
700-900 |
800-1200 |
| Installed power (kw) |
360 |
380 |
440 |
580 |
| Length (m) |
35 |
36 |
40 |
48 |
Features
Every module passes through a 40HQ door and weighs under 25 t, so the line can be landed at a site that has a forklift but no crawler crane.
Frames are bolted and dowelled, not welded on site, which keeps erection inside a two-week window and keeps the geometry the workshop set.
Cabinets are wired, numbered and tested before shipment, so site work is terminating numbered cables rather than building panels.
A remote commissioning option lets our engineers watch the first batches over a link, which shortens the trip for plants far from an airport.
For the DN110-400 mm band the sleeve bore carries a shrinkage allowance, and vacuum holds the tube against it until the wall sets.
HDPE Jacket Process Flow:
- Vacuum Feeding of PE Granules: The raw PE granules are automatically fed into the system via vacuum suction.
- Hot Air Drying: The granules are dried using hot air to remove moisture, ensuring optimal extrusion quality.
- Extrusion Plasticizing: The dried granules are plasticized through the extruder, heated and mixed to form a molten plastic mass.
- Mold Shaping: The molten plastic is shaped into the desired pipe profile by passing through the extrusion die.
- Vacuum Sizing: The pipe is then subjected to vacuum sizing, adjusting its dimensions to precise specifications.
- Water Cooling: The pipe is cooled rapidly by immersion in a water tank to solidify its shape and structure.
- Pulling Out: The solidified pipe is pulled out of the cooling tank at a controlled speed.
- Cutting: The pipe is cut to the desired length using a precision cutting machine.
- Carrier Laying-off: The cut pipes are then neatly laid off onto a carrier for further handling or packaging
Composition of Equipments:
- Hopper Dryer
- Single Screw Extruder
- Extrusion Mould Die
- Head Bracket
- Vacuum Calibration Device
- Water Cooling Tank
- Haul-off Unit
- Planetary Cutting Machine
- Pipe Bracket
- Loader
- PLC (Programmable Logic Controller)
The production steps of the insulation layer for a pre-insulated pipe, specifically focusing on the polyurethane (PU) foam insulation, are outlined below in detail:
- Formation of the Casing Structure:
- The steel pipe is first inserted into the high-density polyethylene (HDPE) outer protection pipe, creating a casing structure.
- Supports are evenly arranged in the annular space between the steel pipe and the HDPE outer pipe to maintain a uniform distance and prevent the two pipes from touching directly.
- The two ends of the casing are sealed with flanges to ensure that the polyurethane foaming material will be contained within the space during the injection process.
- Preparation of the Steel Pipe Surface:
- Prior to the injection of the insulation material, the surface of the steel pipe undergoes pre-treatment such as shot blasting or blast cleaning. This step removes any impurities, rust, or scale, providing a clean and suitable surface for optimal adhesion of the polyurethane insulation.
- Additionally, corona treatment of the polyethylene pipe shell's surface may also be performed to enhance its adhesion properties.
- Injection of Polyurethane Foaming Material:
- The casing structure is hoisted onto a foaming platform specifically designed for this purpose.
- A high-pressure foaming machine is used to inject the polyurethane foaming material into the casing. The material expands and fills the entire annular space between the steel pipe and the HDPE outer pipe.
---FAQ---
Q: How long does erection take on site?
A: Ten to fourteen working days for mechanical erection with a crew of six, plus five days for electrical connection and commissioning, assuming the foundation is ready and the containers are unloaded at the door.
Q: What foundation is needed?
A: A level concrete slab with cast-in anchor pockets at the points shown on the layout drawing. We issue the drawing before shipment so the slab can be poured while the line is at sea.
Q: What decides the casing outside diameter tolerance?
A: The DN110-400 mm line fixes diameter in a water-cooled sleeve under vacuum, and speed is used for wall rather than for size.
Q: How is the steel pipe kept concentric inside the casing?
A: On a DN110-400 mm assembly the spacers set both the annulus and the pipe position, which is what keeps the foam layer uniform.
Q: Why is rack curing specified rather than immediate trimming?
A: On the DN110-400 mm line trimming early saves a day and costs the seal, because torn cells at the end face cannot be closed again.
Q: What foam density does the line hold?
A: For DN110-400 mm the target band is 60 to 80 kg/m3 and 88 percent closed cells, recorded per batch rather than sampled weekly.
Q: What is the delivery time for a complete line?
A: Delivery of the DN110-400 mm line is 90 to 120 days from deposit, stated in the offer rather than after the order. Q: How many containers does the line need? A: On the DN110-400 mm line six to eight 40HQ containers are needed, and we issue the plan before dispatch.
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