Method Statement for Bituseal Enamel application

The Bituseal Enamel is based on a specially selected bitumen, modified with high performance engineering polymers.

This polymer modification ensures improvements of a number of the product’s qualities, e.g. flexibility, adhesion and durability.

Bituseal Enamel is supplied in different types/grades, depending on the varying requirements for corrosion protection materials for pipelines.

The key factor in the application process is the design and operation of the extruder head which is capable of delivering a constant and uniform mass of Bituseal Enamel.

The length and width of the slot in the extrusion head can be adjusted depending on outer wrap width and coating speed.

The process variables can be accurately monitored and controlled by inputting the following parameters on to the computer:

• Pipe forward/rotation speed
• Pipe diameter
• Required coating thickness
• Wrap width

The precise material requirements are computed on the basis of the process variables entered. Unlike conventional flood coated enamel systems where the thickness is mainly controlled by flow, pipe speed and temperature, the extrusion system for Bituseal is independent of temperature.

As enamel temperature no longer a variable factor, one of the major elements of uncertainty in the coating process has been eliminated, resulting in a high level of process control and additional quality assurance.

Bituseal process flow diagram

Main components

• Melting tank
• Storage Tank
• Filling Pump for Storage Tank
• Supply Pump
• Application Head for Bituseal Enamel
• Heating unit
• PLC control unit

Melting tank

A melting tank is required if the Bituseal Enamel is supplied in 50 kg solid blocks.

Size of tank depends on rate of Bituseal® Enamel consumption.

Storage tank

The application temperature will normally be between 210–215ºC, and it is important that the tank are able to heat the Bituseal Enamel to the exact temperature and keep it within a temperature difference of ± 1ºC.

Size of tank depends on rate of Bituseal Enamel

Filling pump for storage tank: The pump transfers Bituseal from melting tank to storage tank when needed.

Supply pump

The pump for the Bituseal Enamel application and weld seam application run continuously and are delivering the Bituseal Enamel into circulation pipelines.

When the coating process is carried out, the revolutions of the pump will be regulated to give the exact amount of Bituseal Enamel needed for the applications, and the material will be led through the application head to the pipes.

When the process is off Bituseal Enamel will flow through the circulation lines and return to the supply tank.

Application head

The application heads for weld seam coating and for pipe coating are integrated in the same extruder head. The weld seaming extrusion has an adjustable opening width of 50 to 100 mm. The pipe application extruder has an adjustable opening width of app. 200 to 750 mm.

The weld seam and pipe application works differentiated, respectively weld seam and then the pipe application.
The two extruder heads have three built-in functions:

1. Opening for application: By activating, the orifice of the head is opened and the Bituseal Enamel is extruded from the head as a “carpet”.

2. Cleaning: In case a particle in the Bituseal Enamel should give a split in the extruded Bituseal carpet, the extrusion opening of the head can momentarily be wider opened by activating the cleaning function.

3. Valve for closing the return line: When the coating process is on, a valve closes the return line for Bituseal Enamel to the supply tank. When the process is off, the Bituseal Enamel flows through the head back to the supply tank.

All functions are operated by three electric/pneumatic valves inside each head.

Main function of weld seam coating

The Weld Seaming is done to ensure that the minimum required thickness of Bituseal coating above the weld seams is obtained. The pipes can either be longitudinally or spirally welded.

When the weld seam application is carried out, the pipe has to be placed exactly with its weld seam 5 to 7 cm vertically under the application head. By activating the application start button, the Bituseal begins to flow from the
head and the pipe starts to move keeping its weld seam in the correct position to the application head.

The flow of Bituseal Enamel and the movement of the pipe is automatically calculated and regulated from the electrical control.

The weld seaming process has to be checked by an employee who will also take care of minor adjustments during the process.

Main function of pipe coating

The pipe coating on the plant is done continuously.

From the electric control panel the specifications are set:

• Width of wrap
• Overlay of wrap
• Application thickness
• Application speed
• Pipe diameter

On the conveyor the angle of the support rollers for the pipes has to be adjusted manually to give the exact pitch per pipe revolution.

The correct pitch is the width of the wrap minus the overlay of the wrap.

From the electric control the flow of Bituseal Enamel will be regulated automatically, according to the pipe rotation speed, to give the specified coating.

The application head has to be positioned 8 to 12 cm above the pipe in the coating pan. By activating the start button the Bituseal Enamel will flow out of the head to the pipe.

The flow has to be manually checked continuously to ensure that splits in the Bituseal do not arise.

In case of a split in the Bituseal flow, the clean head button has to be activated immediately.

Heating unit

The unit supplies and controls the heating oil into tracing and tanks. Oil burner is heating the oil up to set point (maximum 270°C.).