The key to success: Friction – Bypass - Velocity

In 2014 Reinhart Hydrocleaning SA (RHC SA) was asked to clean a 16” fuel pipeline. Based on pipeline geometry, such as a 10,500 m total length, 3D bends, two 16” tee pieces, no significant diameter changes and a height difference of app. 50m, the Mechanical Cleaning Tool (MCT) evaluation and construction seemed to be straight forward.

It quickly turned out that the solution to the pipeline integrity problem demanded innovation. The pipeline had been damaged at approximately the mid-point where it ran through a riverbed. Damage was such that unknown to the operator a significant volume of stones and gravel washed into the pipeline.

The pipeline damage was repaired with the stones still inside the pipeline. The problem was not identified until the operator started an ILI campaign. An initial BiDi pig got stuck and was reverse pigged out. Evidence about amount and sizes of stones could not be given and remained unknown.

RHC was required to remove all remaining stones out of the pipeline to guarantee the subsequent ILI inspection to be successful.

Key MCT parameters for a successful operation would require a 100% effective sealing during the cleaning run in combination with not just a high bypass but with a high velocity flushing effect in front of the MCT with the right size and angle of jets. The sealing disc arrangement used for propulsion was invented by RHC SA to provide 100% sealing in the line but requires a low “flip” pressure in the event of being reversed pigged.

Furthermore, as a crucial element of the MCT, the front nose of the tool is designed to bulldoze and prevent the tool riding over stones. The intention in combination with the jetting effect was to mitigate any risk of getting the tool stuck by a stone built-up. The evaluation had to be executed for a worst-case scenario.

After completing the MCT body set-up and propulsion disc configuration, the 3D model was tested with the in-house computer program in terms of bypass velocity.

After the flushing set-up was fine-tuned and completed, the individual 3D model pieces were converted to the in-house production machines to be constructed.

As a next step, the mechanical cleaning tool was assembled ready for testing. A 16” test pipe was built which consisted of an 18” one meter launching spool and a reducer piece 18”/16”, three straight 16” spool pieces of each 3 meter length, divided by a 3D bend, a 16” Tee connected approx. 3.5 m upstream to an open ended and 1 meter end spool piece.

Bypass water was collected in a 10m² water tank and was pumped into the test facility system. In total 7 runs were executed and compared to each other.

A launching pressure of approximately 3 bar and a run pressure of approximately 2 bar, across the opened test pipe, resulted in a high velocity bypass flushing action which can be seen on the pictures.

The tests resulted in positive feedback results and a planned start date for the operations was agreed with the client.

The infield flushing operation included two runs. The aim of the initial run was to transport all remaining stones and any other potential debris out of the pipeline. The execution of the second run was to ensure that the pipeline is free of any stones.

The MCT was equipped with a transmitter set to a 22Hz pulsing frequency in order to locate it at certain checkpoints along the 10,500 m pipeline route. The MCT needed an approximately pressure of 6.5 bar to be launched and was pushed with an average of approximately 5.5 bar which led to an average velocity of 0.8m/s throughout the run. MCT location and flowrate was monitored constantly with the control room operator.

Whilst tracking the MCT on the first run, as the tool approached specified tracking points significant rattling and rumbling noise could be heard with increasing loudness on approach to the checkpoint up to seven minutes before it passed. The tool velocity was 0.8m/s indicating that we were pushing stone debris up to 340 m in front of the MCT.

The average bypass was recorded to be approximately 20%.

During tool tracking of the second run, no abnormal or significant noise was heard. This indicted that the first MCT run had been successful in removing the debris and there were no remaining stones inside the pipeline.

All debris brought out by MCT were diverted into the internal system. Debris which could be seen upon retrieval was a minor amount of black sand in front the tool on 6 o’clock position. The MCT was in good condition with minimal wear on the discs.

Thereafter, the ILI vendor was brought back on site to run another ILI pig. This inspection operation was executed with success.

Despite the fact that RHC SA is known for challenging operations such as the above described, one has to keep in mind that maintaining pipeline condition by utilizing specialized mechanical cleaning tools on a regular basis as part of an operators ongoing production pigging and integrity management strategy keeps the pipeline in a clean condition throughout its operational life maximizing pipeline performance and corrosion management.

The use of high-quality mechanical cleaning tools will reduce the frequency of regular production pig runs required to maintain a higher level of internal cleanliness when compared to running off the shelf utility pigs. RHC SA focus on achieving the highest standard of internal cleanliness by using the best technology for the application.

The provision of specialized high-quality RHC mechanical cleaning tools designed and manufactured to suit the pipelines operational conditions are used initially to clean the line to the required level and thereafter when used as part of the regular production pigging strategy, they will maintain operating performance of the pipeline.

Due to its flexibility, RHC SA is a company that is able to adapt its cleaning technology to support and maintain long-term pipeline cleaning and integrity management on a regular basis throughout its operational lifetime.