Flange rating 4

[johngladstone]

Dears folks ,
Pump design pressure is 150 psi pumping 400 GPM for fluid temperature 200 F

How much flange​ rating will be suitable ?

Is iclass according ASMI / ANSI ,
150 #​ CS is​ Ohk ?

Best regards
John gladstone

 

[XL83NL]

Have you looked at the tables in ASME B16.5 for the applicable material if it can handle this pressure @ temperature?
The answer is easy but that's not what counts.

 

[MJCronin]

Examine the pump ....

What is the flange rating on the discharge nozzle of the pump ??

Check to see if the OD, ID and Bolt Circle correspond to a Class 150 flange ...

If the Pump mfr cast ASME Class 150 flanges into the casing, you must match these with your piping ...


MJCronin
Sr. Process Engineer

 

[LittleInch]

Also pump design pressure means what?

The maximum pressure the pump can see?
The differential pressure of the pump?
What is the inlet pressure / pressure it can see from inlet or discharge when installed?



Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[johngladstone]

Hi gentelem

Thank. You for your quick response

Pump design pressure equal design head which same as TDH and Dufferential pressure

Best regards
John gladstonev

 

[danschwind]

The flange's rating will be tied to the maximum pressure this flange will experience on your operation. For a centrifugal pump this will usually be considered the discharge pressure at shut-off and at maximum inlet pressure.

Daniel
Rio de Janeiro - Brazil

 

[johngladstone]

Hi folks

I appressiate You for whole input

But actually I confuse

In ASME B 31.3 para 302.2.4

parameter P :- Design pressure

Represent what :-
Is it :-
Design pressure = Design Head = TDH = Differential pressure at Inlet and outlet

This information based on Larry Buches from his book .

Or Dedign pressure represent High pressure at shutoff head

To determine minimum pipe thickness , Flange rating and leak test ??

Please clarify to me this point

Warm regards
John Gladstone

 

[mk3223]

The design pressure (DP) of the piping is set by your process requirement. this DP is used to select the proper pump for the system. And, the Vendor will provide you a suitable pump with a specific TDH.

After then, you need to verify if the pump TDH is still under the discharge piping DP, or under the pressure limit of the current piping flange rating. If not, the rating of the discharge pipe needs to be raised to accommodate the higher pressure due to the pump TDH. Of course, the wall thickness of the discharge pipe may be increased as well.

 

[johngladstone]

Hi mk 3223
Thank you
Is there practical example to enforce your idea or reference article clarify in systematic way ?

Br
John

 

[davefitz]

danschwind's reply is correct, unless there is a relief valve at the pump discharge. The code may allow a short term overpressure of 15% during such deadhead events. Please note the valve desing code allowable overpressure may be lower than the piping code's allowable overpressure.

"...when logic, and proportion, have fallen, sloppy dead..." Grace Slick

 

[johngladstone]

Hi gentlemen
Is there possible practical example to enforce the idea ?

Warm regards
John

 

[alchemon]

As everyone is mentioning... you need to design for the churn/static condition on the pump.

At pump churn, what is the differential pressure between the static inlet and the "shut off head" (i.e. what is the differential pressure that the pump will produce at a no flow condition).

AS AN EXAMPLE:

Say you have specified a pump to provide 150 psi of differential pressure at 400 GPM. Look at the pump curve and read what the shut off head (i.e. far left hand side - when flow is zero). Let's say that this is 200 psi. What also is the inlet pressure at the pump suction under no flow conditions. Let's say the pipeline has a static pressure of 100 psi, but will be 80 psi when there is load on the line.

The maximum discharge pressure, and therefore, the design condition that you should be using - will be when the pipeline is at maximum pressure (100 psi) and the pump first starts (i.e. at the shut off head).

In this case, the maximum working pressure at the pump discharge is 200 psi (shut off head of pump) + 100 psi (static inlet pressure) = 300 psi. That is the condition that you need to design the discharge flange for. That is also possibly what you need to design everything downstream for, unless there is a relief valve, etc. to prevent overpressurization. Everything between the discharge flanges and the relief valve will need to be rated for this maximum pressure scenario (300 psi in our example).

A quick search on the web will show you what the maximum working pressures for flanges (and then you pick the one you need based upon the operating conditions).

 

[davefitz]

Please note that if you are desinging the piping desing pressure based on the design pump TDH , pumps are generally permitted to be delivered with an actual tested TDH as much as 5% higher than specified. Refer to its shop tested curve to confirm the piping system will not be overpressured with the as-built pump.

"...when logic, and proportion, have fallen, sloppy dead..." Grace Slick

 

[johngladstone]

Hi gentelmen ,

Thank you very much
Thank you alchemon for your valuable example

300 psi will be result mwp will put it in 16.5 to select flange class am I right ?

Kindly is there possible now to complete last two chains

1 - Design pressure for pipe as Par 302.2 asme
How much will be base on your example

2 - Design pressure of gasket

Is there reference book can refer to it give your example I read many books but I didn't get this straight way

Thank you gentelmen again

Warm regards
John Gladstone

 

[moltenmetal]

Flange gaskets don't have design pressures. They are either suitable for the fluid service, flange class and flange facing, or they aren't.

The design pressure of a piping system depends on many things, even if it's just the discharge piping of a pump fed from a tank. It sounds like the OP is out of their depth here, and the group have tried to provide salient facts to consider- but to be honest, it's still possible for the OP to end up selecting the wrong thing in ignorance.

My suggestion: if you're even close to the maximum limit of 150# class understanding the little that you apparently do, select 300# class. If the pump has a 150# class discharge flange, you may have selected the wrong pump for the job.

 

[johngladstone]

Hi folks
Kindky help me to complete last two chain

Based on example of alchemon
Can we cimplete example base on your experience for
Pipe design pressure and flange class. ?

Thank you

Warm regards
John Gladstone

 

[LittleInch]

From the posts above, 300 psi in the example is the Maximum Operating Pressure.

As any pressure protection devices are set to this figure, your DESIGN pressure needs to accomodate (add) some margin above MOP.

How much that is is up to you, whether a fixed amount ( say 50psi) or a percent (10% is fairly common)

The design pressure is the most commonly used number for flange assessment. so inyour case with a design pressure of say 330 psi, this would be a class 300 flange.

The design pressure is the same for all components unless it changes due to a pressure regulator or similar reduction or you have a large elevation change.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[johngladstone]

Hi littlnch

Thank you , I understand
Design pressure for pipe will be 330 psi ?
Will use in asme b 31.3 par 302.2.4 ?

Regarding test pressure ?
Will be 1.5 * 330 psi for one hour ?
How much allowable pressure drop limit
within one hour ?

Regarding hight elevation is there any rule of thumb ?

Best regards
John gladstonev

 

[LittleInch]

Yes DP will be 330 psi in my example
Yes

B 31.3 allows 1.5 x Design pressure
B 31.3 does not seem to stipulate a time period, but wants all joints and welds visually examined for leaks. 1 hour is commonly applied by company specification, but it is the visual inspection which counts
The aim is to test integrity therefore there is no mention of an allowable pressure drop as visual inspection is the aim.

If your system rises up or down then the amount needs to be considered. 10m or so in this example makes no difference, but 100m would.

Not usually applicable for piping, more like a pipeline.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[johngladstone]

Thank you littlench

Is there tachnical reference putting practical examples like example mention above ?
Best regards
John Gladstone