Hi everyone,

By reasons that are far from the scope of this topic, we have to analyze level gage columns in a tower. The problem is what should be the temperature in the bridle piping. These bridles are short as couple of feet or as long as 24+ feet and are all over the length of the tower. We cannot find anyone who wants to step in from process group. The opinions are divided in how much lower would be the temperature of the bridle (if it is any lower). They are insulated as the tower is but we are expecting to have some heat loss.
The main point is that even though the temperature could be lower I have never seen a bridle with an expansion loop in the vertical run, so :or the temperature is close to the tower, or there are many “failing” bridles all over the world.
I would like to hear from you if anyone has a table, knows about any software, or has experience about this issue.
Thanks in advance for your comments.

Regards,

Hi

I can't help too much with your question directly.

However, recently on site one of our engineers noticed a vessel with a bowed level gauge bridle. The vessel was a vertical vessel made of carbon steel, the bridle was made from stainless.

Because of the different coefficients of thermal expansion between the vessel and the bridle, the bridle was being restrained by the flanges on the vessel. The solution was to add a horizontal elbow between the flange on the vessel and the bridle, hence providing some flexibility.

From this I think you have to say yes the level gauge bridle does get hot, how hot? may be the tricky question. It would be good to check the materials of the bridle and the vessel, and look at the relative thermal expansions.

I saw this thread last week but was too busy to respond at the time. I guess I forgot about it until it moved back to the top.

I would say you're probably OK on bridles up to 3 or 4 feet long. I see those installations all the time.

For 24' you definitely need to account for the differential expansion.

I had a similar situation as you and I did put in a loop for flexibility. I had a 40' tall drum with a level connection at the bottom and one at the top. We had a 4" pipe going from the bottom to the top with multiple level gauges staggered along its length. I offset the vertical pipe to the side of the level nozzles so I could get a leg at the top and the bottom for flexibility and I supported the pipe from the vessel.

Even if you are insulated, you'll have a stagnate leg with no flow in your bridles and it'll be much cooler than the tower. I recommend being conservative. Also, remember the bridles, level gauges and valves can be quite heavy when you have a long length so consider that dead weight along with any thermal loading on the supports and supporting nozzles.

Good luck,

Hi Pedro, I think you should also consider, if the bridle is too long, the case where the bridle valves are closed and the equipment is hot (maybe during some steam out), that will help you choose the right dimension for the perpendicular leg you need, as Kevin proposed.

Regards
Hector Rojas