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Air Test Before Plant Start-Up

The excruciating plant shutdown was finally over on Saturday. We started-up the plant on Saturday 2200 hrs. Hopefully everything will run silky smooth. We conducted both air and steam tests twice in two different sections in the plant. From the first air test (at the bleaching section), we hold the air pressure inside the vessels and pipelines at 1.5 bar (it took about 1 hour ++ to build the pressure up to 1.5 bar). The pressure dropped to 1.0 bar in 1.5 hours. This indicates that there were some leakages in the system and we need to search for it. Supervisors and plant operators hunted for the leaking points, equipped with alkaline solution to detect leaking air by spraying them on the vessels and pipelines. It's like finding a needle in a haystack, the leak could be anywhere on the pipe surface. After numerous sprays and long search for it, we acquired quite a number of tiny bubbles. Leak can simply be detected when bubble appeared from the leaking points. They were marked and maintenance fitters attended and welded them after we released the air.

Releasing air process does not take a short time. That's why we need to coordinate the shutdown properly and effectively. After detecting the leaking points, air was released from the vessels and pipelines. This took about 2 hours. After air pressure is lesser, maintenance fitters welded the leaking points. Upon completion and satisfied with the workmanship of the maintenance team, we repeated the air test, hold it at 1.2 bar. We targeted the previous leaking points, sprayed them and they were all ok except for one point beneath a retention vessel. We released the steam again, called the fitters and asked them to re-weld the point. Confident that the welding work is good, I instructed my supervisor to release the air. There goes another hour, waiting for the air to escape. At that point, bleaching section is ready for plant start-up.

I'll share about the steam test tomorrow.

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posted by zaki yamani @ 7:57 PM,

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The Author

zyz

I’m Zaki. I used to be a project, process and chemical engineer. Few years ago I successfully became a Chartered Engineer (IChemE) and Professional Engineer (BEM). I'm now employed as a chemical engineering educator/researcher/consultant. Hope you like reading my blog. I welcome any feedback from you. My email: zaki.yz[alias]gmail.com. TQ!


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