33 replies to this topic

[Bobby Strain]

Like I commented, there should be no vapor since the fluid is pumped from the accumulator. Something else is going on.

 

Bobby

[PingPong]

@Fatema

 

If the FE is located upstream the control valve as indicated on the P&ID by UOP then the pressure there will be several bars higher than the vapor pressure of the LPG. In that case there can be no vapor as Bobby already noted.

 

However: sometimes the piping designer of the detailed engineering contractor moves the FE downstream the control valve without first checking with the process design engineer. This can be for reasons of layout, insufficient straight length available upstream and downstream the FE, or ......... whatever excuse.

 

So verify in the plant where exactly the FE is located: upstream or downstream the control valve, and at what elevation.

[Bobby Strain]

And verify the orifice ID on the tab.

 

Bobby

[Fatema1987]

I captured photos for actual arrangement. For 82FT024, we added pressure gauge from same tabbing to monitor DP.

 

82FT025 is installed at discharge of Reflux pumps but after a longer distance and around four elbows comparing with 82FT024 which is installed directly in the 2" line. 

Attached Files

•  Branches.pdf   586.64KB   5 downloads
•  transmitter tab.pdf   838.81KB   4 downloads
•  tab.pdf   754.23KB   8 downloads

Edited by Fatema1987, 03 April 2022 - 10:47 AM.

[Fatema1987]

I posted both isometric drawings for 82FT025 and 82FT024 measured in "mm" unit. Normally we dnt see any issue in measured value of 82FT025. The issue is always there at 82FT024.

Attached Files

•  82FC024.JPG   91.27KB   0 downloads
•  82FC025.JPG   129.31KB   0 downloads
•  82FE024 Orifice Plate.jpg   185.09KB   0 downloads

Edited by Fatema1987, 04 April 2022 - 02:02 AM.

[Bobby Strain]

There is something wrong with the second drawing. The left side is a repeat of the first drawing. It is confusing.

 

Bobby

[Fatema1987]

There is something wrong with the second drawing. The left side is a repeat of the first drawing. It is confusing.

 

Bobby

Yes because both FC024 & FC025 have common upstream which is discharge of reflux Pump. This is why they have same drawing at left but different drawings at right.

 

In the site photo, u can see how these lines arranged.

Attached Files

•  weld-olet.JPG   74.07KB   0 downloads

[Bobby Strain]

It's a bit confusing because the line numbers are difficult to read. But all looks OK.

 

Bobby

[PingPong]

@Fatema

I don't see anything wrong with the piping layout either.

 

FE-024 is located upstream the control valve, as intended, so pressure should be sufficient to prevent flashing.

There is sufficient straight piping length upstream and downstream FE-024.

 

The orifice diameter of 27 mm is in theory correct for a design flow of 222 t/d at a deltaP of 500 mbar.

 

From the photo of the orifice plate it can be verified that the orifice hole is indeed 27 mm, as the outer diameter of an orifice plate for a 2 inch line is 4 3/8 inch or 111 mm.

 

Forum members can't solve the mystery via the internet.

It's up to your team to think hard about what changed in the plant or the plant operation two years ago when the problem started.