ANCHORS

El Stress corrosion cracking is a type of corrosion suffered by stainless steels that generates internal cracks, which can be as well the result of a sudden breakage of the material when a force load is applied and usually generated by the high concentration of chlorides and the presence of stress on the material as such as: residual from manufacturing or generated by installation or its use, with following aspects:

– In worst cases, anchors can break under only a few tens of kilograms – less than the climber weight.

– Usually along sea sides but can be some kilometers away from the coast.

– Corrosion is not always visible. Could be invisible cracks.

– Stress corrosion cracking, which is the most virulent, could initiate cracks very rapidly after anchor installation. Within some weeks maybe, a few months for sure.

– All stainless steels, even the 316L grade, are concerned.

– The most critical factors are:

> “Moderate” relative humidity location (very dry is OK, and very humid also, in between is a problem).

> Area NOT washed by rain (even washed by the sea can be OK!!).

> Temperature is not critical, SCC can occur at 20°C, but higher temperatures are worse.

> Rock types: limestone/dolomite is generally worse than sandstone or granite (Karst is the worst case).

Only destructive testing can confirm the presence/absence of SCC on installed anchors. It is not possible to visually assess or even to casually test (like to pull on them) the effective strength of the anchors in place. Even anchors that have been installed in recent months and/or look brand new could be compromised by SCC or some forms of corrosion.stress corrosion cracking es un modo de corrosión padecido por los aceros inoxidables que genera grietas internas, pudiendo resultar en una rotura repentina del material al aplicarse una carga de fuerza, generalmente generado por la alta concentración de cloruros y la presencia de estrés en el material (residual de fabricación o generado por la instalación o el uso) con las siguientes características:

– En el peor de los casos, los anclajes pueden romperse con solo unas pocas decenas de kilogramos –menos que el peso del mismo escalador.

– Generalmente a orillas del mar, pero puede pasar incluso a algunos kilómetros de la costa.

– La corrosión no siempre es visible. Puede aparecer en forma de grietas invisibles.

– El agrietamiento por corrosión bajo tensión, que es el más virulento, podría de manera muy rápida mostrar muestras de agrietamiento después de haber llevado a cabo la instalación del anclaje. Tal vez, dentro de unas pocas semanas pero seguro dentro de algunos meses.

– En referencia a todos los aceros inoxidables, incluso también 316L.

– Los factores más críticos son:

> Lugar de humedad relativa “moderada” (lugar seco: bien / muy húmedo también, entremedio de los dos: es un problema).

> Área NO rociada  por la lluvia (es posible) e incluso estando rociada por influencia marítima).

> La temperatura no es algo crítico. Sin embargo, el SCC puede ocurrir a 20 ° C , es decir, a temperaturas más altas las consecuencias son peores.

> Tipos de rocas: piedra caliza / dolomita es generalmente peor que la arenisca o el granito (el karst a evitar).

Solo las pruebas de destrucción  pueden confirmar la presencia y / o ausencia de SCC en anclajes ya instalados. No es posible evaluar visualmente o incluso probar casualmente (tirar de ellos) la resistencia efectiva de los anclajes en su colocación. Incluso los anclajes que se han instalado en los últimos meses y / o parecen nuevos podrían verse perjudicados por la SCC u otras formas de corrosión.

Ecotri zinc steel anchors are designed and approved to be installed in indoor environments (indoor closed spaces), such as climbing walls, gyms, pavilions, etc.;  without any potential corrosion and with an expected ambient temperature of 0 to 35ºC. Climbing walls located near industrial areas, such as swimming pools or near the sea are going to need definitely stainless steel or titanium anchors.

Moreover this type of anchor is used in the industry sector for non-permanent installations, where the material will not remain permanently in the wall.

Inox 316L anchors are designed and approved to be installed in the vast majority of outdoor environments that are not aggressive enough to create SCC. These are usually outdoors and basically in natural areas with temperatures between 70 and -30ºC. It is important to remark that 316L stainless steel is not recommended for highly corrosive environments. For these kind of environments, Fixe, following the latest updates to the CE959 Standard, offers the material that provides the highest resistance on the market: the titanium.

In some ravines, the microbiology or chemicals contained in the water can be a potential source of high corrosion. And because of that, special attention is advised in the regular reviews of the anchors installed in this kind of environments.

Titanium anchors are designed and approved to be installed in potentially corrosive and / or corrosive environments. They may be areas with high industrial or automotive pollution, acid rain, sulfurous waters, salty roads, interiors with swimming pools or in a very common case: such as marine environments, among others.

By default, it is considered a marine environment from 0 to 30km from the coast, but it should be noted that there is no clear limit; winds from the sea with significant salt concentration can travel hundreds of km inland

In 2016, the PLX family (duplex stainless steel) was presented since the main concern was to offer a solution to the cases of SCC fracture that occurred; resistance to SCC is a characteristic of the structure of duplex steels. Drafts of the UIAA anchor standard published at the time supported the decision, tabulating 5 degrees of corrosion resistance and placing the duplex at grade 2 between titanium (grade 1) and 316 (grade 3).

In the latest publication of the EN959 anchor standard, the table of anchor features and according to the “type of material and installation environment” was introduced as a novelty compared to previous versions and it simplified the tables that had inspired it (drafts and studies UIAA), offering three anchor types depending on the material used and three corresponding groups of installation environments. In order to simplify the choice for the installer and in order to work with the maximum of best praxis, the results were:

– Grade 1: for environments with aggressive SCC. Using Grade 2 titanium as an example.

– Grade 2: for outdoor environments generally. With Inox 316 as an example.

– Grade 3: for indoor locations without corrosive potentials. With galvanized steel as an example.

Given that the duplex then went through and according to the standard, to share main features with the Inox 316L, and in addition the fact that duplex presented additional difficulties such as: lack of knowledge according to the type of material by above all non-technical public; Difficulty finding other components (like for example: Allen screws) of the same material to avoid galvanic corrosion and with a greater difficulty in forming and welding, it was decided to launch a new family with Inox 316L.

There is no problem or contraindication. As in any installation, periodic review protocols appropriate to the frequency of use and corrosive potential must be followed.

The answer is no. For example, it would be bad practice to install the new Fixe1 316-Hanger with an expansion bolt made of PLX (duplex) material or merely common steel.

If a rock anchor has two or more components made from different materials there is the possibility of galvanic corrosion when the rock anchor is wetted by rain or, much more seriously, if it is wetted by seawater. Galvanic corrosion can be avoided if all parts of the rock anchor are made of the same material, or of material with the same electrolytic potential. If a rock anchor has a removable or replaceable part, such as a hanger, the user needs to know the construction material and be aware that a hanger or replaceable part made from a compatible material shall be used

It is just impossible to quantify it outside of a controlled laboratory environment in as much as the different environments where it has been installed (climate, geology and biology) and its external incidents (installation and use praxis). Nevertheless it’s impossible to test in its multitude of variants.

The lifespan of an anchor under normal conditions (that is to say, without corrosion and  / or wear enhancers) could be up to 25 years or even more. In case of being exposed to corrosion enhancers or a high frequency of use, its lifespan could be significantly reduced, even up to a few weeks and  in cases of choosing bad material or a bad installation practice, it might even suddenly  break due to the SCC (Stress Corrosion Cracking). And because of that is the periodic review of anchors essential.

A periodic review must be carried out by competent staff. As a matter of fact, technically qualified staff with experience in use and installation and accredited training in installation and anchor control courses is in this case understood.

It is also recommended to check accurately installed anchors every 12 months. Increased frequency of use or installation in highly corrosive environments (such as polluted or coastal areas) force to increase the frequency of control. If it is a mobile product, it must be verified before each use. For this reason remove and replace the anchors that show: section loss due to rope friction or other cause, or thereby after a major fall showing signs of deformation or corrosion.

In case of doubt according to the safety or effectiveness conditions of an already installed product, this has to be replaced as soon as possible.

If you have more questions about or problems with the products and material or with the understanding of these instructions, please contact Fixe immediately.

The main features of this type of Belay Station is that, when properly installed, it distributes the mechanical strain equally between its two anchor points. This reduces the stress that each anchor point and rock section that supports it receives.

It is the most reliable option on medium-strength or uneven rocks, as well as in climbing schools or high-frequented sport climbing areas, where fatigue or stress can be high.

The main feature of this type of Belay Station is that, when properly installed, only the lower anchor point works, the upper anchor serving as a redundant safety point in the event that the lower anchor fails. The mechanical strain and fatigue would fall on the lower point, keeping the upper anchor without any fatigue. In hard rock and in areas without high fatigue load, that would be for example the best option