There are few things we need to know about our pipeline and our plant process. Pipelines are very important to transfer fluid (eg. oil and water), gas (natural gas and steam), or solid (bleaching earth and other powder form solid). Selecting the right pipeline material, right sizing, right schedule is imperative in ensuring smooth and perfect production operation. Sometimes, we have to be very careful, because, though we have selected the correct material, size and schedule, but unfortunately the supplier cheated and supplied defective pipeline unrealized by us. As a result, the pipeline does not last long as expected. Crack appears and progressively developed into a bigger crack and hole. If oil is moving with some pressure in the pipeline, we can immediately detect the leaking oil when it dropped. It is very clear and if the leak is big, it will be very messy and dirty situation. What if the pipeline is a vacuum line? We can't see anything. We can only detect pressure vacuum dropped in the in the control system via the pressure transmitter installed in the line.
This 12" pipeline has some very small leak that affected the vacuum pressure. The leaking points were covered by another piece of metal to block the holes. However, it still leak (indicated by the yellow sign). Why we cannot weld this line? Explanation can be found below.
Similarly, this 12" SS316 line also has some tiny pin hole which is very hard to see by naked eye. It's impossible to weld the hole because the pipeline is running under vacuum. Any spark will be sucked into the system and will create fire and explosion.