Heavy corrosion resistance
In the sewer environment, H2S formation is very prominent due to biological decomposition of sulphur containing organic and inorganic matter (proteins, sulphates). H2S will undergo oxidation by bacteria to form H2SO4 (sulphuric acid), which will react with the lime content of cement-bound pipe materials. This is the main cause of corrosion, which would affect pipeline structural integrity and water tightness adversely. On the other hand, vitrified clay pipe is immune to corrosion by H2SO4.
The vitrified clay pipes joints are tested in accordance with EN 295, which means that they are guaranteed to be leak-tight at 0.5 bar, including the angular deflections and radial loads specified in the standard.
Excellent resistance to high-pressure cleaning
The requirement included in the EN 295 standard is met (resistance regarding a standardized maintenance cleaning test at 120 bar and an deblocking test at 340 bar). Here again, vitrified clay scores considerably better than many other types of material.
High abrasion resistance
Vitrified clay has very high abrasion resistance, which is equally true for the glaze and the rest of the wall. Abrasion values encountered in the tests are approximately 0.08 mm, which is much lower than the typical abrasion values of 0.2 to 0.5 mm after 100,000 load cycles measured using the Darmstadt test as specified in the EN 295 standard.
Excellent hydraulic roughness
Vitrified clay pipes have extremely smooth inner surface (wall roughness between 0,02 and 0,05 mm). Especially in the case of limited slopes, this offers quite some advantages. Because of the high erosion resistance, vitrified clay can even be used for slopes up to 10 m/sec., without any danger of material deterioration (for concrete e.g. the maximum slope is only 3 m/sec).
The vitrified life cycle is calculated to be 80 up to 100 years (LAWA directive A 250), even in the harshest conditions. Furthermore, vitrified clay is the only material that resists regular rinsing and unclogging by means of high water pressure techniques. This means that vitrified clay pipe sewer lines can be written down over a longer period and that maintenance, renovation and replacement costs can be limited to a much lower level. Excellent corrosion resistance also means no extra investment for early rehabilitation or replacements.
High mechanical strength
Vitrified clay pipes have a very high crushing strength. Under normal application, i.e. class 160 vitrified clay pipe vs class H reinforced concrete pipe, the crushing strength of vitrified clay pipes are much higher than reinforced concrete pipe, as according to EN 295 and SS 183. They are also able to withstand high static and dynamic loads.
The raw materials for manufacturing vitrified clay pipe are clay and recycled materials from the ceramic industry. Mining of the raw materials and subsequent restoration of a natural environment take place in an environmentally friendly manner. In addition to this, the environmental impact of manufacturing of vitrified clay is relatively negligible compared with most other types of sewer materials. The long service life of vitrified clay is an additional decisive factor in this regard. No polluting products are generated at the end of the life cycle.