Frequently Asked Questions

1. Is STOPAQ Wrappingband CZ or CZH a good insulator?

STOPAQ is an excellent electrical insulator thanks to its nonpolar structure.

The table below shows the values of the electrical resistance:

2. Can STOPAQ Wrappingband only be used as a corrosion prevention pipeline material?

STOPAQ can be used to insulate cables and wires, under the plastic insulation wire, this is also a very effective corrosion protector. STOPAQ is used over telephone cables, high voltage cables or subsea buoyancy applications, where the cables need to be additionaly protected from water as the wire can be infiltrated by capillary action and provoke breakdowns.

3. What does self-healing mean exactly?

STOPAQ as a coating, has the ability to heal cracks and scratches as it flows very easily at ambient temperature. The cold flow of a material is its ability to level out at ambient temperature and become flat, form a smooth uniform film.

The benefit of such a property is that :

  • scratches/pores of the substrate are filled without any external influence (temperature, pressure, etc.),
  • the material has good adhesion to surfaces with small defects or welds etc.
  • scratches in mechanical protective materials for examples shrink sleeves are repaired automatically.

4. How important is surface cleaning for STOPAQ applications?

A common process for coating application is to clean the surface of the substrate. It usually improves the wetting and therefore the adhesion between the coating film and the substrate.
With STOPAQ, there is no strict need for pre-cleaning the substrate such as SA2,5 including specific roughness profiles. STOPAQ absorbs traces of dust, thanks to high affinity to fillers.

5. Is STOPAQ impermeable?

STOPAQ CZH creates a barrier to gas and moisture:

  • Gas trapped inside cannot get out
  • No external moisture can penetrate.

Because STOPAQ shows an extremely low permeability to moisture, it is used as a moisture barrier.

6. How does STOPAQ flow?

Below is an illustration of the cold flow mechanism of STOPAQ CZH in a transparant version:

7. Is STOPAQ CZH harmless?

STOPAQ CZH is virtually tasteless and odor free. The raw materials are compliant with FDA and EU regulations. The STOPAQ CZH polymer is extremely nonpolar and does not show any interaction with the polar skin. This is why STOPAQ CZH is not skin irritating. STOPAQ CZH IS NSF/ANSI 61 APPROVED.

8. What is the difference between FN2100 and FN4100?

STOPAQ FN 2100 is specifically designed for sealing underground cable and pipeline penetration and can be applied in a wet environment. It can NOT be used to protect steel against corrosion.
STOPAQ FN 4100 is an anti corrosion compound which can be used underground to seal manway covers, valves, flanges, etc. STOPAQ FN 4100 has to be applied on a dry surface.

9. What is the difference between FN4100 and FN4200?

STOPAQ FN 4100 is only used as an anti corrosion compound for underground objects up to ca. 25 degrees celsius ambient temperatures.
STOPAQ FN 4200 is an anti corrosion filler to be used at surface to fill the space between above ground flanges or tank bottom chime areas.

10. What is viscosity?

Viscosity is a measure of the resistance of a fluid to being deformed by either shear stress or extensional stress. It is commonly perceived as "thickness", or resistance to flow. Viscosity describes a fluid's internal resistance to flow and may be thought of as a measure of fluid friction. Thus, water is "thin", having a lower viscosity, while vegetable oil is "thick" having a higher viscosity. All real fluids (except superfluids) have some resistance to stress, but a fluid which has no resistance to shear stress is known as an ideal fluid or inviscid fluid.The study of viscosity is known as rheology.

11. Why Metals corrode?

Hereby have fun reading this paper from Watson

12. Corrosion Forms and Rates

Typical forms of corrosion found in outdoor environments

General attack corrosion: 0.1-0.3mm/year
Crevice corrosion: 0.2-6.0 mm/year
Galvanic corrosion: 0.3-5.0mm/year

Corrosion rates, in most cases, are unpredictable, with a relatively wide range, for example, of 0-10mm/year

13. Structure of our Batchnumbers

Our Batch system is composed of following details:

Batch / Week / Year
xx / xx / xx

We use this structure since 23/05/2008.

Before the structure was composed as follows:

Batch / Day / Month / Year
xx / xx / xx / xx

Is STOPAQ CZH Paste the same as STOPAQ Wrappingband CZH?

Answer: the STOPAQ CZH Paste is slightly different. The Wrappingband CZH is reinforced by special elastic fabrics. This creates a balance between adhesion and cohesion. However, the CZH Paste is pure compound in sheets. The CZH Paste does not contain special elastic fabrics inside; for balance improvement it is reinforced by special other ingredients.

1. Facts about corrosion?

At normal temperatures iron will not corrode appreciably in the absence of moisture.

The presence of oxygen is also essential for corrosion to take place in ordinary water. Oxygen alone will cause considerable corrosion in acid, neutral, or slightly alkaline water. In natural waters, the rate of corrosion is almost directly proportional to oxygen concentration, if other factors do not change. Oxygen also accelerates the corrosion of iron in non-oxidizing acid solutions of moderate strength.

source: www.corrosiondoctors.com

Corrosion in acid solutions is much more rapid than in neutral solutions, and the latter is more rapid than in alkaline solutions.

Hydrogen gas is usually evolved from the surface of the metal during corrosion in acid solutions and in concentrated solutions of alkalies; in nearly neutral solutions the evolution is usually very much less and may not be appreciable.

The products of corrosion consist, mainly, of black or green ferrous hydroxide next to the metal, and reddish-brown ferric hydroxide (rust) which forms the outer layer, with graded mixtures of the two in between. When iron corrodes in the atmosphere the amount of ferrous rust produced is small, but when formed under water the corrosion products often contain a large proportion of ferrous iron.

In natural water, the precipitated rust usually carries down some compounds containing lime,, magnesia, and silica, together with other insoluble material from the water. These substances have considerable influence on the structure and density of the rust coating on the metal surface.' A loose, nonadherent coating under ordinary conditions may accelerate locally the rate of corrosion; a uniformly dense and adherent coating may cut down this rate very considerably.

Surface films, sometimes invisible, often play an important part in controlling the rate and distribution of corrosion. These films have been made visible by separation from some metals and have been shown to raise the potential of these metals making them more resistant in certain environments. In fact the superior resistance of metals like chromium and aluminum, for example, is undoubtedly due largely to the formation of such films.

In most cases the initial rate of corrosion is much greater than the rate after a short period of time. This is particularly noticeable in film-forming solutions, such as the alkalies or chromates. It should be noted, however, that the initial rate of corrosion of a highly polished metal surface is abnormally low.

Corrosion at normal temperature increases with increase of concentration in dilute solutions of many neutral salts, particularly chlorides, but decreases again in more concentrated solutions, other things being equal.

In natural waters the rate of corrosion generally tends to increase with increase in the velocity of motion of the water over the metal surface, with some exceptions where the film-forming tendency predominates (page 156).

Dissimilarity in the chemical composition of metals in contact with each other in an electrically conducting solution sets up a difference in potential (precisely as in the galvanic cell) and thus accelerates corrosion locally. In corroding metals these variations in potential are found between a metal and other reactive materials, or between different metals in contact. This action is accompanied by an electric current which flows through the solution from anode to cathode, i.e. from the more corrodible to the less corrodible metal in this particular solution.

Composition of ordinary iron or steel, within the common variations found commercially, has little effect on corrosion underwater or underground, but sometimes it has a marked effect in atmospheric and acid corrosion. From the standpoint of corrosion, homogeneity of a metal is not usually so important as external conditions.

The condition of the metal surface in submerged corrosion may not affect the total corrosion, although it may have a marked tendency to localize the action. Corrosion of iron is rarely uniform over its entire surface.

Variation in the composition or concentration of a solution in contact with a metal tends to localize corrosion at certain areas and retard the action at other areas of the surface. A portion of the metal surface which is protected from diffusion of oxygen inward becomes anodic to other areas which are in contact with a solution richer in oxygen, i.e., corrosion is more active at such protected areas.

The smaller the anodic areas in relation to the associated cathodic areas, the greater is the rate of penetration of corrosion at the anodic points. The polarity of a certain area often reverses during the progress of natural corrosion.