When most parts of the Northern Hemisphere enter winter, many people tend to go climbing in tropical regions such as Thailand, Vietnam, the Dominican Republic, etc. But before you entrust your life to these protection points—attention, attention!! Based on several recent accidents,UIAAa risk warning has been issued regarding the failure of (stainless steel) protection points in tropical marine environments.
According toUIAAsampling, samples of bolts taken from certain tropical maritime regions indicate that in similar environments,10%up to20%protection points have strengths of only1KN-5KN! Yet typically, the impact forces of most falls range between1KN-5KN.UIAAStandards require that fixed protection points must have a strength of at least22KN.
Protection points with visible cracks:
The UIAA website states: “Some protection points broke simply under the climber’s body weight. All the protection points were made of stainless steel, met UIAA safety standards, and were claimed to have good corrosion resistance. It is estimated that the warm marine environment accelerates the corrosion process.”
Some protection point cracks can be seen with the naked eye, but some are very difficult to detect. The image below shows protection points with no visible surface cracks, yet tests revealed their strength to be between 1–5 kN.
Here are the UIAA’s recommendations for climbers in humid marine environments:
l Before every climb, it is strongly recommended that you ask local climbers or route developers about the condition of the protection points.
l In some areas, protection points are frequently replaced. Generally speaking, experience tells us that protection points used for no more than three years are unlikely to have reduced strength. However, based on known cases, even protection points used for just nine months can fail.
l If you notice signs of corrosion on a protection point during a climb, it may indicate serious damage. Do not apply force to such points and end the climb immediately (tests have shown that some protection points break under just the climber’s body weight). Warn local climbers and route developers so they can replace the damaged protection points. You can also replace them yourself with more corrosion-resistant ones.
l As a precaution, we strongly advise against climbing on tropical marine cliffs where the condition of the protection points (corrosion status, usage time, who maintains them, etc.) is unknown.
l In the absence of reliable safety information (such as corrosion status, usage time, who maintains the protection points, etc.), climbers should assume that all protection points in the area are compromised, similar to the approach taken in alpine climbing.
l Climbers must take full responsibility for their own judgments and actions regarding the condition of protection points.
Additionally, someone asked me about the safety of other alloy bolts, such as titanium. Theoretically, titanium bolts are indeed more durable than steel ones. Although titanium forms a dense oxide layer on the surface that prevents corrosion, this layer can be worn off during use. Coupled with wave impact, weather, and other factors, it may corrode again. No matter what material the bolts are made of, their condition must be checked before every climb. Expansion bolts and the condition of the rock itself must also be inspected.
http://www.petzl.com/en/outdoor/news-1/2009/12/16/planning-tropical-climbing-vacation-winter-beware-those-anchors
http://www.theuiaa.org/news_199_Extreme-caution-advised-for-anchors-in-tropical-marine-areas
http://www.theuiaa.org/upload_area/files/1/risks_of_anchor_failure_in_marine_environments_oct_22_09 (2).pdf
Information related to seawater corrosion:
Metals deteriorate and degrade through electrochemical reactions with seawater. The electrochemical corrosion of metals in seawater is caused by electrochemical non-uniformity on the metal surface. This non-uniformity can result from the metal itself (e.g., grain boundaries, inclusions, etc.) or changes in the surrounding medium at different surface locations (e.g., oxygen concentration differences, etc.). Carbon steel is the most widely used structural material in marine resource development facilities. Extensive research has been conducted on the corrosion behavior of carbon steel in seawater. Widespread bolt testing shows that the average corrosion rate of carbon steel in seawater is 0.05–0.13 mm/year, while pitting corrosion rates can reach up to 10 times the average annual corrosion rate. The main factors affecting the corrosion rate of steel in seawater include the supply rate of oxygen to the steel surface, as well as temperature, flow rate, fouling organisms, lime scale, pollution, and factors such as welding and stress in the steel structure, all of which also influence corrosion rates.
Corrosion of metal components in marine environments. The marine environment is a complex corrosive setting. In this environment, seawater itself is a highly corrosive medium, while waves, tides, and currents subject metal components to low-frequency cyclic stresses and impacts. In addition, marine microorganisms, biofouling, and their metabolic byproducts all directly or indirectly accelerate the corrosion process. Marine corrosion is mainly localized, meaning it begins on the component surface within a small area—such as galvanic corrosion, pitting corrosion, and crevice corrosion. There are also issues like low-frequency corrosion fatigue, stress corrosion, and microbiologically influenced corrosion. Typically, metal components experience the highest overall corrosion rates in the marine splash zone (the area reached by splashing waves and sea spray caused by wind and tides).
Compared to other metal materials, titanium alloys have the following advantages: ① High specific strength (tensile strength/density), with tensile strength reaching 100–140 kgf/mm², while density is only 60% that of steel. ② Good strength at medium temperatures, usable at several hundred degrees higher than aluminum alloys, maintaining required strength even at moderate temperatures, and capable of long-term operation at 450–500°C. ③ Excellent corrosion resistance; titanium surfaces quickly form a uniform and dense oxide film in the atmosphere, offering resistance to various media. Titanium generally has good corrosion resistance in oxidizing and neutral environments, and performs exceptionally well in seawater, wet chlorine, and chloride solutions. However, it shows poorer resistance in reducing media, such as hydrochloric acid. ④ Good performance at low temperatures; titanium alloys with very low interstitial elements, such as TA7, can retain certain plasticity even at -253°C. ⑤ Low elastic modulus, low thermal conductivity, and non-magnetic properties.
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