Inspection of on site buried natural gas pipeline
Inspection of on site buried natural gas pipeline
(OP)
Hi,
We operate and maintain a new gas fueled power station in the UK. We have a short section, approx 800 metres, of buried 450mm (18") natural gas pipeline. The gas is at 40 Bar. The line is internally and externally coated and has a sacrificial anode cathodic protectiom (CP) system.
What I want to know is what inspection techniques can be used to ensure the integrity of this pipeline? What would be the minimum accepted from the authorities?
The piping arrangement does not allow for intelligent pigging, or if necessary we would have to install temporary pigging facilities. Also the cost to carry out a pigging run would be expensive in relation to the relatvely short length of line.
Another option to pigging would be to excavate around sections of the line and carry out some ultrasonic inspection but in my experience this could lead to more damage than it is worth.
I am aware of some techniques to monitor the effectiveness of the CP, and unintrusive surveys that can be carried out to detect flaws in the external coating. But my experience of these is limited so any help on these too would be much appreciated.
Thanks,
Irish Al
We operate and maintain a new gas fueled power station in the UK. We have a short section, approx 800 metres, of buried 450mm (18") natural gas pipeline. The gas is at 40 Bar. The line is internally and externally coated and has a sacrificial anode cathodic protectiom (CP) system.
What I want to know is what inspection techniques can be used to ensure the integrity of this pipeline? What would be the minimum accepted from the authorities?
The piping arrangement does not allow for intelligent pigging, or if necessary we would have to install temporary pigging facilities. Also the cost to carry out a pigging run would be expensive in relation to the relatvely short length of line.
Another option to pigging would be to excavate around sections of the line and carry out some ultrasonic inspection but in my experience this could lead to more damage than it is worth.
I am aware of some techniques to monitor the effectiveness of the CP, and unintrusive surveys that can be carried out to detect flaws in the external coating. But my experience of these is limited so any help on these too would be much appreciated.
Thanks,
Irish Al





RE: Inspection of on site buried natural gas pipeline
You didn't say what your flow rate is, but at that pressure you have a really good chance that any flow rate that justifies 450 mm pipe would likely be high enough to sweep any condensation (you need something like 3 m/s velocity).
David
RE: Inspection of on site buried natural gas pipeline
We have several lines that we operate, but another company owns. They don't want to operate it because of their lack of experience with pipelines.
You may not be able to do this, but it's probably worth looking into.
Pat
RE: Inspection of on site buried natural gas pipeline
Regards
Luis Marques
RE: Inspection of on site buried natural gas pipeline
RE: Inspection of on site buried natural gas pipeline
If you are connected to the UK gas network cycling stresses should not be significant - depending upon where your network connection is(assume you would have allowed for in design anyway if a possibility), internal corrosion should not be an issue either, so providing the CP is effective the pipeline should have a life at least equal to design life.
Phil...
RE: Inspection of on site buried natural gas pipeline
RE: Inspection of on site buried natural gas pipeline
The standard 'bible' in the UK is the Institute of Gas Engineers document IGE/TD1. Meet the requirements of that and you should meet the relevant regulations (Pressure Systems Regulations and Pipeline Safety Regulations, the pipeline above appears to fall under both).
Regards
Phil...