Bitumen–enamels and suited primers to be used in combination therewith are described in Specification for Bitumen based Hot-applied Coating Materials for Protecting Iron and Steel, Including Suitable Primers Where Required”, BS 4147: 1980 by British Standards Institution, said matter hereby being incorporated in the present specification. The same applies to examples of tar enamels and suited primers described in “Specification for Coal-Tar-Based Hot-applied Coating Materials for Protecting Iron and Steel, Including Suitable Primers Where Required\”, BS 4164; 1980, also by British Standards Institution.
Coal tar enamels, a traditional pipe coating, boast effective corrosion protection. Yet, environmental concerns and challenges in sourcing quality raw materials contribute to its gradual obsolescence. Moreover, the production process faces drawbacks, including potential property changes. Repeated return pumpings, reheating, and flood coatings can lead to enamel ingredient evaporation, further complicating the process.
A typical tar enamel used for corrosion protection contains tar of quality 105/15, 105/8, or 120/5 according to BS 4164: 1980, comprising 65 to 75% by weight, along with filler in the range of 25 to 35% by weight.
Enamel pipe coat
Bitumen enamels are well-known and appreciated as pipe coating materials, increasingly replacing coal tar enamel. Furthermore, many oil and gas pipelines in the North Sea heavily rely on bitumen enamels. However, despite frequent endorsements, the material has faced criticism, particularly during the 1972-1973 oil crisis, citing significant concerns about subpar bitumen quality. Therefore, prioritizing the use of the correct bitumen quality, such as oxidized bitumen 115/15, is imperative to ensure a consistently reliable supply. Additionally, proactive measures must be taken to address challenges arising from potential variations in bitumen properties during production processes. In addition, optimizing production methods and ensuring stringent quality control are vital for overcoming these challenges and maintaining the effectiveness of bitumen enamel coatings. In conclusion, a strategic and thorough approach to bitumen enamel usage is essential for the longevity and reliability of oil and gas pipeline coatings in the North Sea.
A typical bitumen enamel used for corrosion protection contains 115/15 quality bitumen according to BS 4147:1980. It comprises 65-75% bitumen and 25-35% filler, with a common ratio of approximately 70% bitumen to 30% filler. The filler amount is typically based on the bitumen’s melting point. The application involves heating the conventional bitumen enamel to 220-230°C, stirring, and applying a 5-7 mm thick layer.
In GB-PS No. 1538267, a coating process is disclosed, using a bituminous composition with 80-99% bitumen and 1-20% block polymer. The polymer has A-B-(-B-A) n configuration, where A is a thermoplastic polymer block, and B is an elastomeric polymer block. However, despite ongoing advancements, this coating process has not yet gained acceptance for industrial use. The primary obstacle remains the insufficient bonding of the bituminous composition to the pipe. Consequently, additional research and development efforts are essential to address these limitations and enhance the suitability of the coating for widespread industrial applications.