In Nov 2012, discussions with ROSEN began for possible support services for a pre-commissioning pigging project at Singapore LNG (SLNG). 2 x 28” pipelines, 6km & 10km respectively, were to be cleaned, gauged & inspected (with an MFL pig) for baseline data, before commissioning.
As these pipelines were not operational, providing a suitable pigging propellant was a concern to ROSEN & the client. In view of ROSEN’s long standing relationship with PNS, in continental Europe, contact was established with PNS in Singapore. After scrutinizing the pipeline data, and taking into account various other factors, it was decided that N2 was the best option as propellant.
Equipment & personnel were mobilized in mid-January 2013.
The cleaning and gauging was completed with nary a problem, with N2 being pumped in at ≈ 2000-4000m3/hr, for a velocity of 0.5-1.0m/s. Providing a good velocity for the MFL pig was a challenge, considering the volume of the pipeline(s) and the high pressure required for the MFL pig. In order to ensure that the MFL pig moved with a constant velocity, for optimum data quality, the entire pipeline(s) was packed with N2 to 25barg, which is the minimum pressure required for the intelligent pig. A total of 2 pumps (180K & 360K), capable of pumping a maximum of 15000m3/hr were utilized, to provide a N2 velocity of ≈ 0.3-0.4m/s. A fine balance was achieved at the receiving end, by controlling the N2 blowdown rate, to ensure that the ΔP between the launcher and receiver was maintained at ≈1.5barg. The entire pigging program was successfully completed within 6 days, and kept with the promised timeline, ensuring that client’s schedule for pipeline commissioning was not affected.
All in all, the client was very pleased with the quality of the MFL pig data, and also with the timely completion of the project.
Let’s hope for more such projects in the future !