Part 2 - Calculating LOF - Flow Induced Vibration

This is Part 2. If you have not read Part 1, head on here.

This is the formula to calculate the likelihood of failure (LOF) as per Energy Institute.

Determine the Kinetic Energy

We have understood that there are 5 necessary informations required before proceeding with the LOF calculation. They are;

1. Density

2. Velocity

3. Size of pipe

4. Thickness of pipe

5. Length between two supports

First, lets obtain data No 1 and 2 from Process department. Let us say that it is confirmed that the line is Multiphase, with mass flow of 300 000 kg/hr, volumetric flow of 9000 m3/hr and pipe area of 0.196 m2 (DN 500).

The density would be mass flow divide by volumetric flow = 300 000/9 000 = 33.33 kg/m3.

The velocity would be volumetric flow divide by area = 9000 / (3600 × 0.196) = 12.76 m/s

Now lets determine the kinetic energy

Kinetic energy = density x (velocity)² =  33.33 x (12.76)^{2 =} 5424.6 kg/ms2

Therefore, the likelihood classification falls under medium as per Energy Institute Guideline. See below;

Next is to determine the Flow Induced Vibration factor (Fv). But before that we will need to determine the support arrangement.

The formula to calculate Fv differs based on the support arrangement which could be;

1. Stiff

2. Medium Stiff

3. Medium

4. Flexible.

I will cover that in Part 3. Stay tuned.

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