Multi-Component Liquid (MCL)
As a result of the need to produce repeatable, high quality and reliable field joint coating systems, Multi-Component Liquid coatings (MCL) have gradually become more widely used as the coating system of choice, in the international onshore pipeline construction industry for multi-layer and fusion bonded epoxy coated pipelines.
MCL field joint coating system offers:
- Compatibility with the factory applied coating
- Excellent adhesive bond to the factory coating overlap areas
- Repeatable and consistent on-site application
- Short application cycle time
- Fast cure allowing for reduced period before lowering in of the pipeline
- Simple non-destructive on-site testing
One other advantage of the liquid system is that the cathodic protection system will not be compromised, hence ensuring a continuous flow of current to any defect. Many other field joint coating systems shield the CP system and hence defects may go undetected leading to serious failure in the anti-corrosion coating system.
There are many different urethane and epoxy based MCL coatings which offer particular properties appropriate to the pipeline parameters. Material selection will be based on a number of factors ; parent coating, climatic conditions, operating temperature and pipeline handling conditions during construction.
In order to make the most of the technical benefits of the Multi-Component Liquid coatings available in the market, PIH has designed and developed a family of automatic coating application machines. Not only does the equipment meter the individual liquid components to the spray head in the correct ratio, but the on-pipe rotating spray ring applies the material in a consistently even and repeatable manner to the specified thickness and band width. In this design the consumption of the liquid is reduced to the absolute minimum since over spray and wastage is virtually eliminated with obvious HSE benefits.
Since the application thickness is directly related to the number of rotations of the machine, once the procedure is proven by pre-production testing, the machine will be pre-programmed for the project and can then be operated by personnel who are trained and supervised by our technicians. Relatively small coating crews will be required consisting mainly of locally supplied labour, making the use of MCL field joint coating systems very commercially attractive. The equipment can be insulated and trace heated to assist with application in low ambient temperature conditions.
Our automated spray equipment has been refined over many years and offers very high daily production rates applying the liquid coating to a typical dft of 1,000 micron thickness and an overlap onto the factory coating of 50 mm - 75 mm.