Core Technology of Composite Pipes: From Winding to Demolding, How to Accurately Match Harsh Working Conditions?

From winding to demoulding, how do you precisely match the harsh working conditions?

In extreme environments such as deep-sea oilfields, LNG storage and transportation, and ship engine rooms, glass fiber reinforced resin-based (GRE/GRP) pipelines have become key equipment due to their lightweight, high strength and corrosion resistance. The foundation of its performance lies in the three core processes - filament winding structure design, internal curing heat transfer control, and automatic demoulding accuracy. This article will unravel the technical logic of these processes and reveal how they are targeted to respond to the extreme demands of specific operating conditions.

 

Filament winding process

Structural customization enables scene loads

 

 

The winding method and parameters directly determine the hoop strength, axial stiffness and compressive resistance level of the pipe. Different application scenarios put forward completely different requirements for the process:

 

Oilfield high-pressure pipelines ✦

The dry winding process is dominant

 

The ultra-high-strength pipe wall (> 300MPa) was constructed with a prepreg epoxy yarn tape (resin content 32±2%) at a circumferential winding angle of ≥89°. Extreme resin uniformity resists cyclic pressure shocks, and tension control > 80N/bundle to avoid high-pressure permeation delamination.

 

LNG Cryogenic Pipeline (-162°C)

Dry winding + low temperature epoxy system

 

The prepreg avoids the risk of wet bubbles, and with the modified amine-cured epoxy resin, the stepped heating curing process ensures interlayer toughness (impact toughness >15kJ/m²) at -162°C.

 

Internal curing process

Thermal field control solves the problem of scene solidification

 

 

The internal curing technology realizes the synchronous curing from the inside to the outside through the internal steam circulation of the mandrel mold, and its parameters need to be precisely matched to the chemical characteristics of the material and the service environment.

 

Desulfurization flue pipe (160°C wet SO₂ corrosion)

High-temperature long-term curing strategy

 

The vinyl ester resin matrix is used to cure at a constant temperature of 130°C driven by 1.2MPa high-pressure steam for 4 hours, so that the resin is completely cross-linked to form a dense network and resist the erosion of acid condensate.

 

Offshore engineering refractory pipes

Silicone matrix stepped temperature control

 

After the solvent is removed by the semi-dry process, the temperature is raised in stages with a vapor pressure of 0.8MPa to avoid the sedimentation of the refractory filler and the refractory aging > 120 minutes (UL1709 standard).

 

Oilfield water injection pipe (30MPa burst pressure)

High-pressure rapid curing program

 

The high cross-linking density epoxy resin is rapidly heated to 150°C under 1.5MPa steam, and the curing reaction is completed within 30 minutes, forming a rigid network to resist high-pressure penetration.

 

Automated demoulding

Precise control ensures scenario compliance

 

 

The demoulding accuracy directly affects the quality and dimensional tolerance of the inner wall of the pipeline, which is directly related to the compulsory certification of the industry.

 

Ship ballast water pipes (IMO smoothness standard)

Servo constant force demoulding system

 

The demoulding speed is ≤2mm/s, and the tensile force fluctuation is controlled within ±5% (force sensor feedback) to ensure that the scratch depth of the inner wall is ≤0.05mm, which meets the DNV-CP-0416 detection specification.

 

Chemical high-purity media pipeline (zero metal pollution)

All-non-metallic contact demoulding

 

Ceramic-coated friction tongs and oil-free lubricated cylinders form a non-metallic demoulding system to eliminate iron ion contamination and meet the requirements of FDA/EC1935 food contact materials.

 

LNG cryogenic pipeline (ovality≤0.2%)

Real-time compensation technology for deformation

 

The double back-up roller is equipped with a laser rangefinder, which dynamically adjusts the lifting height to compensate for the deflection of the mandrel, and the ovality is stable within 0.15% after demoulding.