There are ways of cleaning the internally reduced bore pipeline, and among the commonly used which is economical and practical is mechanical pigging in combination with chemical cleaning.
Prior to determining which way you should be chosing is to study the physical and chemical properties of the scale buildup within your pipeline.
However, pigging may require you to do some modifications to existing pipeline such as installation of a temporary pig trap for launching & retrieving purposes. Your pipeline profile shall also be taken into consideration prior to pigging activity (bends/reducer/other limitations)
Mechanical pigging may be applicable if you utilize mechanical pig with brush or descaling capability. For the long pipeline transporting oil & gas, descaling pigs has been utilized over the years to rejuvenate the internal condition of those pipeline which have reduced bore.
However, mechanical pigging alone will not make it to the hard scale which has built up in years. Utilizing a chemical slug batched in two different pigs are one of the ways to treat the internal scale with the chemical used. These are just one of the many ways which has been used in the industry.
Regards,
Halda
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