Thread protectors are essential for preventing damage to pipes used in mines and oil rigs, and are usually made of steel or plastic. Plastic thread protectors are often the first choice, as they are extremely lightweight and cost-effective. However, to ensure they remain fit for purpose, it is necessary to protect them from the effects of damaging UV sunlight.
This protection is required because many synthetic and natural polymers, or plastics, are susceptible to damage from the action of UV radiation. The UV rays are absorbed by some chromophoric groups in the structure of the plastic, causing breakdown of the polymer chain, which in turn leads to degradation. The immediate effects include discoloration and a chalky appearance on the surface layer, but if left unchecked, the degradation can result in cracking, or even complete disintegration of the product.
This is important because pipes for mines and oil rigs can often be left exposed to sunlight for long periods of time while being transported, so if they are fitted with plastic thread protectors, these must be protected from UV degradation. If the protectors were to crack or disintegrate, it could result in catastrophic failure of the piping system for the mine or rig. Either polymers with high resistance to UV rays, such as HDPE, must be used in their manufacture, or ways must be found of protecting the plastics from UV radiation effects.
This protection can be achieved by adding chemicals to the ingredients during manufacture, prior to shaping the products by injection molding. One effective solution is to add carbon black particles, at a level of between 2.5% and 4.5%, or other pigments such as titanium dioxide. Other solutions include adding UV absorbers such as benzophenone compounds, or UV stabilizers, such as a HALS — Hindered Amine Light Stabilizer.
Even with high resistance or additives, however, it is still possible, albeit remotely, for cracking and brittleness to occur, alongside color changes. It is therefore absolutely essential to carry out rigorous testing, to determine the ability of the plastic thread protectors to withstand prolonged exposure to sunlight. The test methods used have been refined over several years, to provide a total guarantee of safety.
An important part of the testing process is accelerated exposure testing, which uses solar concentration technologies to simulate several decades of UV radiation from the sun, within a single year. This is necessary to ensure the long service life of the product, and to predict its UV stability. In addition, the effect of UV rays on the material can be determined by employing UV spectroscopy or electron microscopy, and by using EPR (Electron Paramagnetic Resonance) to detect free radicals.
The use of plastic thread protectors undoubtedly brings many benefits to the oil and mining industries, in terms of increased safety and productivity. However, any plastic product that will be subject to prolonged exposure to direct sunlight must be formulated in a way that ensures adequate UV resistance, by using additives if necessary. Even when this is established, appropriate testing standards must be in place, so that any possibility of failure can be totally eliminated.
That’s why we test our products for UV resistance here at Essentra, among several other quality screenings, ensuring that all our pipe protection products are made to withstand extensive exposure to the elements. Contact us today, and take a look at our plastic thread protectors here.