Pump seals are a frequent source of leaks in process and energy facilities. Moreover, the discharged liquid will normally be at high pressure, so it can travel a long distance and/or form a spray. Therefore, when laying out a facility it is important to make sure that pumps are located at a safe distance from other equipment and piping. (If the facility is already constructed and in operation it is still useful to consider spacing and layout guidelines.
This article provides guidance to do with the launching and retrieving of pipeline pigs (also known as scrapers or tools).
Below is a schematic of a launcher.
Positive isolation methods are those which remain effective even if there is equipment failure or operator error. These techniques apply not only to vessels, piping and tanks but also to pneumatic and hydraulic equipment.
The sketch shows some of the various isolation techniques that can be used to protect workers in the process industries. The process containing toxic or flammable chemicals under pressure is on the left; the open system, where the workers are present, is on the right. The order is from the least to the most secure.