Due to its good waterproofing properties, bitumen was first used as a material for the external coating of steel pipes intended for underground water transport pipelines.
Preparation of the pipe surface is carried out by pickling in sulfuric and hydrochloric acid, followed by neutralization and treatment with trisodium phosphate, which allows for better adhesion of the base layer and several days of protection against corrosion.
The coating consists of the following two layers:
- Base coat of cold bitumen coating applied with brushes
- Bitumen mass reinforced with glass wool in one or more layers. Slaked lime is applied over the bitumen coating.
Pipe outer diameter (D): 88.9mm to 1620mm
Coating manufacturing standard: DIN 30673
Coating thickness:
- 3.5mm– normal thickness according to DIN 30673
- 5.5mm– reinforced thickness according to DIN 30673
Porosity test – test voltage 25kV
Uninsulated ends: approx. 100mm
Pipe length: 6m to 12m
Each pipe is marked on the outside with paint using a template with data that includes the company name, pipe dimension, material, and standard to which the pipe is manufactured.
