Stuck Segment Orifice Dimensions Calculations

Instrumentation engineering root cause analysis of stuck segment orifice dimensions calculations.

Article Type:Root Cause Analysis (RCA)
Equipment Type:Instruments
Author:S. Raghava Chari

Note: This root cause analysis (RCA) is from real-time scenarios that happened in industries during the tenure of two or three decades ago. These articles will help you to improve your troubleshooting skills and knowledge.

Segment Orifice Dimensions Calculations

Stuck Segment Orifice dimensions calculations might need Rs 20 million pump import.

Problem: Refer to Instrument problem discussed segment orifice plate (SOP).

Segment Orifice Sizing
S.No.Col ACol B
1.    Given m =0.57 the max orifice to pipe bore area for min pressure loss0.57
2.    Pipe bore area APB =PI()*500^2785398
3.    Orifice Plate Opening area AO = 0.57*APB 447677
4.    Arc ADB subtended Angle O (see fig) – θ
5.    Interior Angle AOB(360- θ)
6.    ▲AOB area =0.5*500^2*Sin(360- θ) 
7.    Sector ADB area As = APB*θ/360 
8.    Flow opening area AFO =447677=(θAPB/360+0.5*R2Sin(360-θ)/2))  
9.    Put θ in an excel sheet cell and  =(θAPB/360+0.5*R2Sin(360-θ)/2)) in another 
10.             Key in different θ values to get closest to AFO of 447677 calculated in cell B3 
11.             Chord distance d=500*COS(RADIANS((360-B4)/2))55.1
12.             In few key ins θ = 192.651O yields AFO=447676 – a surprisingly close value. And Chord distance =55.1 as above  
13Mark the Chord 55.1 mm away from plate CL towards the tag, the arc ADB and cut Segment opening. Orifice is ready 

Calculating the chord distance from the plate CL was necessary to make the segment orifice plate.

The table shows where the engineer was stuck and how the author unstuck him.

Innovative Segment Orifice

Thanks to unsticking enabled chord distance, he calculated, the workshop cut the orifice plate opening and delivered the orifice plate for use.


The plant realized the previous problem explained the innovation of just welding a plate in the pipe cut slot with the sharp edge 55 mm away from the pipe horizontal diameter line. 

The plant realized all the Instrument Previous Problem discussed benefits

Author: S. Raghava Chari

Do you face any similar issues? Share with us through the below comments section.

If you liked this article, then please subscribe to our YouTube Channel for Instrumentation, Electrical, PLC, and SCADA video tutorials.

You can also follow us on Facebook and Twitter to receive daily updates.

Read Next:

Don't Miss Our Updates
Be the first to get exclusive content straight to your email.
We promise not to spam you. You can unsubscribe at any time.
Invalid email address

Leave a Comment