3 replies to this topic

[Manohar]

Hello dear friends,

 

We have 36" pipeline and we want to test newly installed leak detection system. Leak detection vendor is suggesting to have real leak in pipeline. So we found one 2" isolation valve on pipeline to which we are going to install a pipe with another ball valve (for quick opening) and RO. Leak will be delivered to vacuum truck during testing.

Pipeline operating pressure: 84 barg

Fluid: Stabilized crude oil

Required Leak flow rate through 2" pipe: 95 m3/h !!

 

Since we do not have any other option but to use the 2" isolation valve available on the pipeline. I tried to calculate whether it is feasible to have 95 m3/hr of liquid flow through 2" pipe.

 

I found on paper that it is feasible! Velocity is coming around 18 m/s. I am in a confusion whether based on this simple hydraulics should I tell the team to go ahead with 2" pipe or not?

 

Possible problems which I envisaged in this system is

 

1. Velocity is higher than erosion velocity: Since the piping will be used only for the period of leak testing, say 10 days, so my piping life needs to only 10 days. This ruled out the constraint of erosion velocity.

2. Vibrations due to high velocity: Piping support can take care of this during design.

3. Static electricity due to high velocity: We can install earthing connection.

 

Does anyone see any other constraint in this system?

 

Thank you for your support.

 

Kind regards,

Manohar

[Ajay S. Satpute]

Manohar,

 

95 m3/h flow with upstream pressure 84 barg and downstream pressure 0 barg would approximately require an (orifice) flow area of 300 mm2 (< 1" dia.). But as you are providing 2" opening, so it is not a concern.

 

I've not designed such system before, so I'll also wait for other forum member to provide valuable feedback on this topic.

 

 

Regards.

 

Ajay

[paulhorth]

Manohar,

Are you saying that the smallest leakage rate that your system can detect is 95 m3/hr? That is rather a lot of oil. I have worked on projects where the total production rate is less than that.

Even at today's price, it is worth about $700000 per day. Surely a leak detection system should be able to do better than that?

You will fill your vacuum truck in 10 - 15 minutes!

 

Paul

[AlertO]

Manohar,

 

based on your pressure of 84 barg, please ensure that your RO is properly sized for the flowrate of 95 m3/h. Otherwise, the flow through 2" pipe is alot higher than the required flow. Moreover, as pual mentioned, you need to ensure your oil receiver because the truck can be filled very short period of time. 

 

note to Pual, the flow 95 m3/h may be correct comparing to the large total flow through 36" pipe. This is based on the detector type which Manohar didn't mention.