Quality standards

Quality standard of AH Hardt sp.j.

AH Hardt sp.j. regularly examines the resistance of its items to corrosion.
The test for the corrosion speed of the lightning protection system was performed in a salt chamber in neutral salt spray according to PN-76 H-04603 and PN-EN 60068-2-11 standards, and it was continued until red rust occurred. The test checked the time until white rust and the time between the appearance of white rust (the % of the item’s surface) and the appearance of red rust, which ended the test. White rust – oxidation of the outer layer – disqualifies an item if it occurs earlier than after 66 hours (Standard 62305).

At the beginning of 2009, we sent our typical items, items with different insulation and items according to a modified galvanising and coat-protection technology to a galvanisation laboratory. The test results are provided below. Each time we achieved resistance until red rust of over 500 h for all elements, over 600 h for other insulation, and almost 900 h for modified galvanising and layer protection technology. We must add that we zinc-coat screws and caps by ourselves since those available on the market are of very poor quality.  We have also decided to analyse the items manufactured by our competition.
The result of 48 h until red rust for the competitors’ items speaks for itself. The resistance of our items is over 500 h. This lets us provide 3- and 5-year anti-corrosion warranties for our products, zinc-coated in our galvanising shop.

Half a year later we decided to repeat the tests using more items made by various manufacturers. We purchased similar items from four Polish manufacturers and one from
a German company. We also added our standard items to the test.

For two Polish companies, item resistance until red rust did not exceed 48 h, for the third one – 72 h, while the fourth one had the best result of 144 h. Our items tested at the same time once again achieved more than 500 h. Measurement of the competition’s zinc layer thickness points to galvanisation in slightly acid baths. Such baths result in considerable fluctuations in zinc layer thickness. Hence the thickness value ranging from 3 to 11 µm
or 5 to 11 µm. Such fluctuations makes an item corrode almost immediately in places where the coating is too thin. The manufacturer also saves on coating insulation. Hence the poor results.

These companies are also fighting for the market using price as their only tool. The quality is to be sufficient until the Customer purchases the item.
A longer durability period is obtained through application of grease or another easily available lubricant. And this is basically the only means of protecting an item long term. Screws and caps are galvanised in a standard way, and the layer thickness is usually 4-6 µm. Chinese items offer even lower values but they are cheaper. The use of metal sheets thinner than 2 mm by certain manufacturers results in item deformation during bending being significant enough to cause the thin zinc layer to break, uncovering a steel core. Which is why red rust appears after ten plus days.

A properly made galvanic layer gives the items extended resistance to corrosion, which – when accompanied by proper installation and lack of mechanical damage to the surface – results in the durability of items on the roof exceeding the warranty period.

The resistance of German elements lasted 240 h and 420 h. In the latter case, stainless steel screws and caps were used. For small hot-dip galvanised items, the manufacturer does not use passivation or any insulation agent. Hence the immediate oxidation (white rust). Only the thickness of the zinc layer makes the item more durable. This standard hot-dip galvanising of small items (where the excess zinc is centrifuged away) is achievable for screws of greater diameter and not achievable for caps – the thread is made for the latter after the hot-dip process. In one of the items, the screw and the cap were hot-dip galvanised, but the result (240 h) was twice worse than for our galvanised items. AH Hardt sp.j. has had its own galvanising plant since 2003.
We are learning the durability of our items just now because we have not had a single complaint about the anti-corrosion coatings made by our company.

Considering the recommendations of standard 62305, having regard to the conditions of standards 50164-1 and 60068-2-52, we must stress that the items for which white rust has occurred before 66 h do not meet the corrosion resistance criterion specified by standard 62305 and they cannot have a certificate of conformity with the standard.

We have also checked the time of copper- and zinc-coated earth electrodes for very harsh conditions of use.
Since we believe that it is hard to insert an earth electrode into the ground without this affecting the copper or zinc layer, the protection layer of the earth electrodes was damaged before the tests. For tests results and the comparative table see below.

The results show nothing new. According to the galvanic series, copper and steel are far from each other and on the opposite sides of zero, so if the environment is humid, electrochemical corrosion will occur quickly, with the core (iron) being the first one to corrode. In the second case, steel and copper are close to each other in the galvanic series, and on the same side of zero, which is why zinc will be the first one to corrode, followed by the core. The fundamental issue is the difference between corrosion times,
and the corrosion time for the iron-copper pair is over ten times shorter than that for the iron-zinc pair.

After tens of hours of the test, the damaged places are covered by corrosion products.
It can be noticed that the copper-coated electrode each time corrodes a few times faster than the zinc-coated one. Only one question remains: can we insert an earth electrode into the ground without damaging it? If not, then no tests are needed, our secondary school chemistry lessons are enough.

We encourage all of you who are interested to carry out similar tests. Our earth electrodes are available at various distributors in Poland. It is best to perform tests using items bought from an agent rather than the manufacturer as the latter may always improve a particular batch and then spread the news of the sensational corrosion resistance of their products. AH Hardt sp.j. is the only business to offer a 2-year anti-corrosion warranty for its earth electrodes.

Top