Home » Why Orifice Flow Meter Flange is not Recommended 150# Rating ?
Flow Measurement Instrumentation Design

Why Orifice Flow Meter Flange is not Recommended 150# Rating ?

This question comes to mind ? As to Restriction Orifice can have 150# but Orifice flange (Flow meter) is not recommended to have 150# rating.

Orifice Flange Rating

Orifice Flange Rating – 150#

We have the answer in one sentence.

It is due to flange integrity !

It means in simple words :- Orifice that are flange tapped have reduced strength

Due to this drilling in between them their pressure-temperature retaining capacity reduces

So to ensure flanges have Strength to withstand Design pressure and temperature a higher rating than 150# i.e 300# is used .

Now There has to be some proof supporting It !!!


The standard we use for Normal flanges below 24” is ASME B16.5

But for Orifice, the flange standard is ASME B16.36

This standard starts with 300# Flange rating.

In restriction Orifice as there are no tapping hence we go with ASME B16.5 flanges which Start with 150# Rating .

As always ! Thanks a lot for Reading !!

PS :- It is observed that for very large line sizes ( Depends few say above 10”, few say above 20”) 150# can be used as these flanges are stronger at higher line sizes but I have not found concrete proof in standards yet.

I would be very grateful if somebody knows the standard that has this documented.

Author : Asad Shaikh

Profile : Linkedin

Articles You May Like

Orifice beta ratio values

ANSI Class Relates to PSI ?

Characteristics of Flow Meter

Magnetic Meter Construction

K factor Formula of Flow Meter

Share With Your Friends

Related Articles

Is Vacuum affects Field Instruments in Industries?

S Bharadwaj Reddy

Thermowell Outer Diameter Larger than Nozzle Inside Diameter?

S Bharadwaj Reddy

Difference between Axial and Radial Diaphragm Seal Connection?

S Bharadwaj Reddy

What is Integral Flow Orifice Assembly?

S Bharadwaj Reddy

Magnetic Flow Meters Installation Guidelines

S Bharadwaj Reddy

Instrument Air Quality

S Bharadwaj Reddy

Leave a Comment

This website uses cookies to improve your experience. We'll assume you're ok with this, but you can opt-out if you wish. Accept Read More

Why Orifice Flow Meter Flange is not Recommended 150# Rating ?

WordPress Image Lightbox
Send this to a friend