Older pipelines are usually made from steels that fall under the definition of St 35 and St 37. For pipelines, this is not very common anymore. For new pipeline projects, the API ranges are the most relevant standard framework. For example, the API 5LX X70 is one of the more recent types of steel being used. Amongst engineers it is common to refer to (only) the last part of the API code. With this example it would by word of mouth be referred to as “X70”.
St 35 and St 37 are considered to be steel qualities with a relatively low tensile strength in comparison to the high tensile strength steels on the top of the API range. Nevertheless, the surface characteristics of these steel, for example after grit blasting, are more or less the same; this means that for the application of external coatings, the used steel sort as such has no significant influence on the physical properties of the steel <–> coating interface.
A list with the most common type of pipeline steels:
| St 35 |
| St 37 |
| API 5LX Grade A |
| API 5LX Grade B |
| API 5LX X42 |
| API 5LX X46 |
| API 5LX X52 |
| API 5LX X56 |
| API 5LX X60 |
| API 5LX X65 |
| API 5LX X70 |
