External Bitumen Coating

Because of the good hydro-isolation properties of bitumen, it, firstly, began to be applied as a material for external coating of the steel pipes for buried pipelines for water transportation.

Preparation of the surface of the pipe is performed by decaping with sulfuric and hydrochloric acid, then is performed neutralization and treatment with trisodium phosphate that enable better acceptance of the base layer and several days of anti-corrosion protection.

Coating consists of two layers:

  • Primary layer of cold bitumen coating applied with brushes.
  • Bitumen enhanced with glass wool in one or more layers. Slaked lime is applied on the bitumen coating.

Outside diameter of pipe (D): 88,9 mm to 1620mm

Standard for coating application: DIN 30673

Coating thickness:

  • min. 3.5 mm – normal thickness according to DIN 30673
  • min. 5.5 mm – enhanced thickness according to DIN 30673

Porosity Test – test voltage 25 kV

Cut back: cca. 100mm

Length of pipe: 6m to 12m

Each tube is marked externally by the color pattern data containing the name of the company, pipe size, material and the standard by which the pipe is made.