Brenntag Oil & Gas cleans Total pipeline with compressed air and achieves a lower explosion level of 0%

30-Jul-2007 - Netherlands

Brenntag Oil & gas Europe recently cleaned a 140 km / 60.96 cm crude transport line at Total Refinery in Vlissingen, The Netherlands, with N-SPEC® cleaning chemicals. Compressed air was applied as a propelling agent to transport the pigs through the pipeline, a technique hardly ever seen before in Europe due to the higher risks involved. Thanks to N-SPEC®'s patented cleaning properties, Brenntag was able to remove all hydrocarbons from the pipeline and as such bring the lower explosion level (LEL) down to a unique 0%.

The first phase involved the pre-cleaning part of the operation. Lab tests indicated that N-SPEC 50, a special wax and paraffin dispersant, and N-SPEC 120, a multi-purpose cleaner, would be most effective for this type of contamination and for the total removal of hydrocarbons. Brenntag carried out the pre-cleaning online to avoid having downtime and production losses.

The second phase of the project involved the removal of the crude and all remaining wax, paraffin and heavy carbons inside the line, totaling a volume of 40,000 cubic meters.

After the line was taken out of service and depressurized, Brenntag established a pig train, comprising four designated pigs interspersed with a column of the required chemicals and water. "Compressed air" was applied as a propelling agent. The advantage of compressed air is less waste disposal and time needed. Compared to nitrogen, it has the advantage of no issues with cold temperatures.

At the receiving site in Vlissingen, Brenntag created a steel dump line from the receiver to a temporary knockout vessel connected to containers. After all pigs were received, the line had to be depressurized again. During the depressurization, the LEL of the out-flowing air was measured by an independent company named Marsac at three sites: the launching site, the receiving site and the block valve station S3. The results turned out to be outstanding: all sites measured 0% LEL.

After completing all required reconstruction and necessary maintenance actions, the line had to be filled up again with crude from the MOT in Rotterdam to Total's refinery in Vlissingen. This was achieved by using two bidi separation pigs interspersed by a column of water, approx. 24 cubic meters. For this filling procedure, the knockout vessel with demister was used again; all out-coming air was blown into the environment without any spray while the LEL of this air remained at 0%.

Cleaning and emptying a large crude line using compressed air can be done in a safe and economical manner with N-SPEC® cleaning chemicals. The specific properties of N-SPEC® chemicals enable the line to become totally hydrocarbon-free, which can result in a 0% LEL of the air inside the line. The correct application of the product and the right safety precautions are crucial for a successful cleaning operation.

https://www.chemeurope.com/en/news/66652/brenntag-oil-gas-cleans-total-pipeline-with-compressed-air-and-achieves-a-lower-explosion-level-of-0.html