Their explanation

No safety layer is given to the steel, as throughout driving, this would be scratched away by the soil. Engineers Helpful site and contractors rely upon opportunity helical stacks to provide the right-sized foundation remedy based on website dirt problems, called for ability, as well as setup room considerations. In some cases, pipeline stacks are full of concrete to provide extra moment ability or rust resistance. In the UK, this is generally refrained in order to reduce the expense. In these situations corrosion security is supplied by permitting a sacrificial density of steel or by embracing a greater grade of steel.