Insulated Pipe Line with Inline Blasting DN200-560 mm
Overview
Blasting and foaming are usually in different buildings, and the pipe travels between them on a truck. In a humid climate that trip is enough for a blasted surface to flash rust, and flash rust is the single most common reason a shear test fails on a pipe that looked clean when it was loaded. Putting the blast chamber on the same line removes the trip. The buyer has usually failed a shear test once, or supplies a project whose specification calls for foaming within a stated time of blasting.
Process Flow
Bare steel goes into the blast chamber first, comes out at Sa 2.5 and travels on a covered roller table straight to the insertion station without leaving the building. The pipe is inserted, plugged and foamed while the surface is still fresh, and the interval between blasting and injection is recorded for each length.
Key Configuration
A shot blast chamber with abrasive recycling sits immediately upstream of the insertion station, and the transfer between them is a covered roller table short enough that the pipe does not cool below the temperature the foam system expects. The DN200-560 mm band uses one die set with interchangeable sleeves, so a diameter change is a sleeve change and a recipe recall rather than a die change. Blast wheels are positioned for the diameter band, and the dust extraction is sized for continuous duty rather than for an intermittent cabinet, because a line that runs all shift cannot pause for a filter cleaning cycle.
Applications
Plants buying bare pipe on the open market rather than receiving pre-treated pipe; projects in coastal or humid regions; work where the specification names a maximum interval between blasting and foaming; lines that also process used pipe recovered from a network.
Standards
Surface preparation to Sa 2.5 per ISO 8501-1, with the interval between blasting and foaming stated in the quality plan. Finished pipe to GB/T 29047, EN 253 or GOST 30732 as the market requires, with the shear test sample taken from the same shift as the production run. On the DN200-560 mm line the acceptance standard is agreed first, since EN 253 and GOST 30732 do not share a test regime.
Service & Support
Commissioning support for the DN200-560 mm line runs 15 to 25 days with two engineers, and finishes only when the first batch passes your own inspection. On the DN200-560 mm line operators are taught the four settings that matter: vacuum, haul-off, shot weight and cure time.
Why Huashida
We build blasting equipment and coating lines as well as insulation lines, so the surface preparation stage is not bought in and matched afterwards. That is why the blast chamber, the dust system and the transfer to foaming are designed as one station rather than three.
| Item |
Specification |
| Model / Type |
Vacuum sizing and pipe-in-pipe foaming pre-insulated pipe production line, complete line |
| Pipe Diameter Range |
DN200-560 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 |
380 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 150 mm, 33:1 L/D |
| Extruder Output |
800 kg/h of HDPE compound |
| Casing Wall Thickness |
6.0 to 8.0 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 |
1.0 to 1.8 m/min, set by casing wall and diameter |
| Foam Injection |
high pressure machine, 90 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 |
Industrial 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
The pipe goes from the blast chamber to the foam head on a covered transfer without leaving the building, so there is no window for flash rust to form.
Dust extraction is sized for continuous duty, because a line running all shift cannot stop for a filter cleaning cycle every two hours.
Blast wheels are set for the diameter band, so abrasive is thrown at the pipe rather than past it, which cuts abrasive consumption and chamber wear.
The quality plan records the time between blasting and foaming for each pipe, which is the evidence a project auditor asks for after a shear test failure.
For DN200-560 mm every casing length is calibrated against a water-cooled sleeve, so the fit at the foaming station does not vary.
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 can blasted pipe wait before foaming?
A: We design for under thirty minutes on the same line, and the record shows the actual interval per pipe. Off-line blasting in a humid climate can lose the surface in under two hours.
Q: Does the blast chamber handle used pipe?
A: Yes, with a different abrasive and a longer cycle, and with a magnetic separator sized for the scale that comes off recovered pipe. We ask about the mix of new and recovered pipe before sizing the chamber.
Q: What decides the casing outside diameter tolerance?
A: On a DN200-560 mm line the sleeve bore and the vacuum level set the diameter, while haul-off speed only changes wall thickness.
Q: How is the steel pipe kept concentric inside the casing?
A: On the DN200-560 mm line the pipe is centred by spacers fitted before the end plug, because the position cannot be corrected after injection.
Q: Why is rack curing specified rather than immediate trimming?
A: Across DN200-560 mm the rack time is a process step rather than storage, and a cold workshop needs longer than 24 hours.
Q: What foam density does the line hold?
A: Across DN200-560 mm the acceptance figures are 60 to 80 kg/m3 and 88 percent closed cells, both written into the batch record.
Q: What is the delivery time for a complete line?
A: For the DN200-560 mm line expect 90 to 120 days from deposit, and confirm the slot at order stage.
Q: How many containers does the line need?
A: For the DN200-560 mm range allow six to eight 40HQ containers, with the plan confirmed at shipment.
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