Isolate a single 4” pipeline servicing many systems inside the refinery and unofficially labeled “Slop Header”. The pipe contained assorted hydrocarbons and the associated contaminants of each system. The pipe needed to be isolated and purged for the installation of a blind flange. The feeder systems to this common header were to remain live during this operation. The operating pressure was 100psi and the temperature was 225F.
Based on the temperature, pressure, and contents of the pipeline; it was determined that a #300 class pivot head linestop would provide an effective isolation with the necessary safety margin. RJ Stacey with the collaboration of the plant engineering and safety departments determined the appropriate polymer for the pivot head stopping element. Then we provided the appropriate B31.3 Split -t, and performed the required size on size hot-tap. The pivot head was inserted into the pipeline and the downstream piping was purged with nitrogen.
The resulting linestop achieved an effective seal and provided a safe isolation for the downstream work to take place. The safety of all crew members was ensured based on adherence to written procedures, documented equipment maintenance, and properly trained experienced technicians.