Safety is paramount in the gas industry. We talk to engineer Yeow Teck Sing on how SP PowerGrid (SPPG) inspects and maintains our gas pipelines, with the help of intelligent devices also known as Pipeline Inspection Gauges (PIGs).
What is the total (estimated) length of Singapore’s gas pipelines? Are there any differences in the pipelines within the system?
Singapore has about 3,320 km of underground gas pipelines which transport natural gas to local industries and town gas to home users daily. Gas pipelines are classified into two categories, namely transmission and distribution. Transmission pipelines, made of high-strength steel with anti-corrosion coating, are thicker and operate at a higher pressure. They are further protected by concrete slabs. Distribution pipelines are made of polyethylene or ductile iron and operate at a lower pressure.
Given the vast lengths of pipelines that lie beneath us, we understand SPPG inspects and ensures our gas pipelines stay in tip-top condition through the use of PIGs. Can you tell us more about this?
A PIG is typically used within large transmission pipelines where the gas pressure helps it to travel the length of the pipeline. Its in-built sensors will intelligently detect any signs of defects or anomalies in terms of metal loss or corrosion.
This PIG weighs about a tonne and is launched through a specially-designed launch pad. Given the weight of the device, one of the key challenges is to control its movement at an optimum speed of 1 to 3 metres/second. Any speed faster than 3 m/s will cause the sensors to miss out data points. Speeds lower than 1 m/s may cause the device to stall in the pipeline.
Besides the PIG, are there any other types of devices used to ensure the gas network remains in good working condition?
SPPG also deploys the Cleaning, Geometry and Gauging PIGs. The Cleaning PIG removes any trapped debris within the pipes with its attached foam, plastic or rubber cups. Any dents or deformities in pipelines can be detected using the Geometry PIG. Lastly, the Gauging PIG is used to check for any obstruction along the pipeline that will obstruct the PIG from flowing smoothly. Hence, the Gauging PIG is typically deployed just before the launch of the Intelligent PIG.
How has the use of PIGs helped to achieve a faster, more reliable inspection/maintenance operation for Singapore’s gas pipelines?
The use of the PIG is an important part of SPPG’s gas pipeline inspection and maintenance regime. Inspections and maintenance for gas pipelines have become more efficient. Checks can be swept across the entire length of the pipelines at a faster rate and at a higher precision. As technology improves, SPPG will continue to explore the use of smarter and more intelligent devices. This will help provide reliable and efficient energy utility services and ensure the safety of our gas pipelines at all times.