B16.5 Max Flange Hydrostatic Test Pressure

[X74DJ9]

Hello everyone,

This may sound extremely silly as I’ve been banging my head against the wall and overthinking this all day…

This is a 3 part question…

1) Is A-1 table in B16.5 considered max flange hydrostatic test pressure?
And if not…
2) How does one calculate the max flange hydrostatic test pressure (per flange rating) for P1.1 materials?

3) Where do these hydrostatic test pressures originate from?
CL150=450PSI
CL300=1125PSI
CL600=2225PSI
CL1500=5575PSI
CL2500=9275PSI

This all originated from my superior telling me that max flange test pressure is 450PSI for CL150, 2225PSI for CL600 etc. yet I cannot figure out where these numbers originate from. I have also seen numerous charts where these numbers keep showing up with no explanation as to where they came from or the math to figure it out. I have even went back as far as looking into ANSI B16.5-1988 to see if the ceiling pressure matches these numbers and they do not (assuming A-1 table is max hydro test pressure)
My concern is that if A-1 is max test pressure, that the company has been over pressuring CL150 to 450PSI instead of the stated 435PSI… all other classes from question 3 are well within the A-1 table.

I should also add that piping code is B31.3.
Test pressure is always supplied by the client which is typically 428PSI CL150, 2222PSI CL600, 5558PSI CL1500, 7000PSI CL2500.
I have considered wall thickness to be a factor as well, but am more curious as to how these pressures in question 3 arise with no explanation and WT not considered.

Any help would be greatly appreciated.

 

[GD2]

Hello everyone,

This may sound extremely silly as I’ve been banging my head against the wall and overthinking this all day…

This is a 3 part question…

1) Is A-1 table in B16.5 considered max flange hydrostatic test pressure?
And if not…
2) How does one calculate the max flange hydrostatic test pressure (per flange rating) for P1.1 materials?

3) Where do these hydrostatic test pressures originate from?
CL150=450PSI
CL300=1125PSI
CL600=2225PSI
CL1500=5575PSI
CL2500=9275PSI

This all originated from my superior telling me that max flange test pressure is 450PSI for CL150, 2225PSI for CL600 etc. yet I cannot figure out where these numbers originate from. I have also seen numerous charts where these numbers keep showing up with no explanation as to where they came from or the math to figure it out. I have even went back as far as looking into ANSI B16.5-1988 to see if the ceiling pressure matches these numbers and they do not (assuming A-1 table is max hydro test pressure)
My concern is that if A-1 is max test pressure, that the company has been over pressuring CL150 to 450PSI instead of the stated 435PSI… all other classes from question 3 are well within the A-1 table.

I should also add that piping code is B31.3.
Test pressure is always supplied by the client which is typically 428PSI CL150, 2222PSI CL600, 5558PSI CL1500, 7000PSI CL2500.
I have considered wall thickness to be a factor as well, but am more curious as to how these pressures in question 3 arise with no explanation and WT not considered.

Any help would be greatly appreciated.

You don't have to break your head. Instead you need to read ASME B16.5 Para 8. Flange test pressure is 1.5x the pressure rating (MAWP) at 38C given in Tables 2-1.1 or Table II-2-1.1 rounded off to next higher 1 bar or 25 psi.

 

[X74DJ9]

Thanks GD2.

I know 2-1.1 or 2-1.1C (2020) is 1.5 x MAWP, which they follow for a minimum pressure for hydro testing, but I am more concerned about a max pressure.
For hydro testing, they always give a minimum pressure and a maximum pressure, just to ensure they don't over pressure anything. It also lets them have a wider range for temp/pressure to climb when needed.

However, it still worries me that CL150 is being over-pressured due to the max given is 450PSI (with no explanation as to where 450PSI came from).
(Side note, they do not pressure test to max flange pressure, it always starts off with the minimum, but due to the environment the temp/pressure will sometimes climb).

If I am reading/interpreting B16.5 P8.2.2 correctly, CL150 reads 20 bar (290 PSI) at 38C X1.5 =30 bar (435PSI) max flange pressure.
Or would it be 21 bar?

I hate reading code/standard, it makes me second guess myself and my head spin.

I am also still wondering where these max flange pressures 450PSI, 1125PSI (which is the only one that matches B16.5-2020), 2225PSI, 5575PSI & 9275PSI originate from?
I don't believe everything I read on the internet (especially these days), but I see these pressures pop up all over the place with no reasoning as to how they came about.
It also concerns me that this is what the company has been using but nobody knows where they came from, seems like they were just numbers pulled out of a hat at this point.

 

[GD2]

Thanks GD2.

I know 2-1.1 or 2-1.1C (2020) is 1.5 x MAWP, which they follow for a minimum pressure for hydro testing, but I am more concerned about a max pressure.
For hydro testing, they always give a minimum pressure and a maximum pressure, just to ensure they don't over pressure anything. It also lets them have a wider range for temp/pressure to climb when needed.

However, it still worries me that CL150 is being over-pressured due to the max given is 450PSI (with no explanation as to where 450PSI came from).
(Side note, they do not pressure test to max flange pressure, it always starts off with the minimum, but due to the environment the temp/pressure will sometimes climb).

If I am reading/interpreting B16.5 P8.2.2 correctly, CL150 reads 20 bar (290 PSI) at 38C X1.5 =30 bar (435PSI) max flange pressure.
Or would it be 21 bar?

I hate reading code/standard, it makes me second guess myself and my head spin.

I am also still wondering where these max flange pressures 450PSI, 1125PSI (which is the only one that matches B16.5-2020), 2225PSI, 5575PSI & 9275PSI originate from?
I don't believe everything I read on the internet (especially these days), but I see these pressures pop up all over the place with no reasoning as to how they came about.
It also concerns me that this is what the company has been using but nobody knows where they came from, seems like they were just numbers pulled out of a hat at this point.

If I am reading/interpreting B16.5 P8.2.2 correctly, CL150 reads 20 bar (290 PSI) at 38C X1.5 =30 bar (435PSI) max flange pressure.
Or would it be 21 bar?

The test pressure would be 450 psig rounding off to next higher 25 psig. It's the max test pressure.

However, note that you won't be only hydrotesting the flange. It will be connected to either a piping or vessel.
You will need to do hydrotest calculation for each part and set the pressure for the minimum.
Vessels will be hydrotested separately in the shop. When you include this in the piping system test, the hydrotest pressure will be decided on two options: 1. When piping hydrotest pressure is greater than the vessel pressure 2) when vessel hydrotest pressure is greater than the piping.

Read ASME B31.3 to learn about the above cases to qualify the hydrotest.

Don't break your head.

 

[XL83NL]

You don't have to break your head. Instead you need to read ASME B16.5 Para 8. Flange test pressure is 1.5x the pressure rating (MAWP) at 38C given in Tables 2-1.1 or Table II-2-1.1 rounded off to next higher 1 bar or 25 psi.

I think the correct paragraph that answers the OP's questions in B16.5 para 2.6:

I hate reading code/standard, it makes me second guess myself and my head spin.

Keep on doing it, at some do you'll like it and master the Code

I am also still wondering where these max flange pressures 450PSI, 1125PSI (which is the only one that matches B16.5-2020), 2225PSI, 5575PSI & 9275PSI originate from?
I don't believe everything I read on the internet (especially these days), but I see these pressures pop up all over the place with no reasoning as to how they came about.
It also concerns me that this is what the company has been using but nobody knows where they came from, seems like they were just numbers pulled out of a hat at this point.

This post may also be of interest (perhaps a little later when all the hydrotesting dust has cleared for you ;-)) - refer to BJI's attached pdf with historical B16.5 stuff;

What is basis for establishing pressure ratings of ASME B16.5 standard flanges? - Boiler and Pressure Vessel engineering

Hello Gentlemen, According to the (B16.5) 1-21 interpretation, ratings in B16.5 are a result of theoretical analysis with due consideration for experience in application. It did not mention anything about flange ratings being established by 'proof tests' or 'bursting them and adding factor of...

www.eng-tips.com

 

[X74DJ9]

If I am reading/interpreting B16.5 P8.2.2 correctly, CL150 reads 20 bar (290 PSI) at 38C X1.5 =30 bar (435PSI) max flange pressure.
Or would it be 21 bar?

The test pressure would be 450 psig rounding off to next higher 25 psig. It's the max test pressure.

However, note that you won't be only hydrotesting the flange. It will be connected to either a piping or vessel.
You will need to do hydrotest calculation for each part and set the pressure for the minimum.
Vessels will be hydrotested separately in the shop. When you include this in the piping system test, the hydrotest pressure will be decided on two options: 1. When piping hydrotest pressure is greater than the vessel pressure 2) when vessel hydrotest pressure is greater than the piping.

Read ASME B31.3 to learn about the above cases to qualify the hydrotest.

Don't break your head.

Thank you for the clarification!

I think the correct paragraph that answers the OP's questions in B16.5 para 2.6:

View attachment 5943


Keep on doing it, at some do you'll like it and master the Code



This post may also be of interest (perhaps a little later when all the hydrotesting dust has cleared for you ;-)) - refer to BJI's attached pdf with historical B16.5 stuff;

What is basis for establishing pressure ratings of ASME B16.5 standard flanges? - Boiler and Pressure Vessel engineering

Hello Gentlemen, According to the (B16.5) 1-21 interpretation, ratings in B16.5 are a result of theoretical analysis with due consideration for experience in application. It did not mention anything about flange ratings being established by 'proof tests' or 'bursting them and adding factor of...

www.eng-tips.com

Thank you! I will definitely give it a read.

 

[LittleInch]

One thing to be careful of though is that a lot of your pressures noted above are based on Maximum flange rating from ASME B 16.5 for <38C materials of group 1.1

Whilst quite a lot of people seem to like creating piping classes which then transfer that pressure as the design pressure to calculate pipe and fitting wall thickness, many piping classes have a lower design pressure than the maximum allowed for in B16.5. So the devil is in the detail of the piping spec. follow the design presusre / hydrostatic test pressure written in those documents.

Different materials also have different pressure ratings in B16.5 so this again impacts the pressure test.

As for max pressure, I'm pretty sure B31.3 doesn't actually specifiy a max hydro test pressure, only the test pressure, with the implication that you release and measure water if the pressure goes up or add water if the pressure comes down due to lower temperature.

Most people don't need to or don't look at elevation difference for piping as its usually only a few metres. but if for some reason you are testing something tall, be sure to account for the head difference between lowest point and test pressure connection / pressure guage.

 

[X74DJ9]

One thing to be careful of though is that a lot of your pressures noted above are based on Maximum flange rating from ASME B 16.5 for <38C materials of group 1.1

Whilst quite a lot of people seem to like creating piping classes which then transfer that pressure as the design pressure to calculate pipe and fitting wall thickness, many piping classes have a lower design pressure than the maximum allowed for in B16.5. So the devil is in the detail of the piping spec. follow the design presusre / hydrostatic test pressure written in those documents.

Different materials also have different pressure ratings in B16.5 so this again impacts the pressure test.

As for max pressure, I'm pretty sure B31.3 doesn't actually specifiy a max hydro test pressure, only the test pressure, with the implication that you release and measure water if the pressure goes up or add water if the pressure comes down due to lower temperature.

Most people don't need to or don't look at elevation difference for piping as its usually only a few metres. but if for some reason you are testing something tall, be sure to account for the head difference between lowest point and test pressure connection / pressure guage.

Thank you LittleInch!