Friday, July 31, 2009
As a high temperature fluid transporter, piping shall be insulated. It can be a mineral fiber insulation, or ceramic fiber insulation, depend on the temperature characteristic. There are two type of pipe insulation, blanket type and preformed type. Each type has strenghtness and weakness. In this article, i'd like to explain about how the insulations attached on the pipe, regarding with their strenghtness and weakness.
The first type of pipe insulation is blanket type. Actually, this type can be directly attached to the pipe as long as the pipe orientation is horizontal. But, if the pipe orientation is vertical, then the pipe should be completed with insulation support lug to avoid the insulation will shagging.
It shall shop welded with the same material of the pipe. The thickness is around 1/16", so while the material is alloy, it is allowed to ignore the PWHT. Insulation support lug is needed only for a 6" NPS or larger and attached at every 6' elevation. The width is 2" and the length shall extend to reach 1" penetrating the 2nd layer of insulation. In every elevation, insulation support lug quantity are four at each quadrant of the pipe.
The alternative for this insulation lug is called Marman clamp that can be attached in field, without any welding work. This clamp will be discussed in the next article.
The second type of insulation is preformed type, while insulation support lug is not required.