1/2" Relief Valve Crane 2604 5

[curtis2004]

Hello Everyone,

I am writing this post to find out product data sheet for 1/2" Crane 2604 relief valve. I came across this valve installed in low pressure lube oil system and would like to know its relieving capacity. Based on drawing, it was installed in 1953. Couldn't find anything on the Internet. Please Help!

Thanks,
Kurt

 

[The Obturator]

Kurt, Installed 1953. The valve belongs in a museum! Seriously although old, the valve should have had replacement parts over its lifetime. Anyway, to answer your query.

I doubt if any catalogue exists online. This design and application is also before ASME started requiring liquid relief PRVs to be capacity certified in 1985. You therefore need to do a capacity calculation based on the 'old' API-520 liquid formula. It is still listed in current API-520 Part I (2020)- "5.9 Sizing for Liquid Relief: PRV's not requiring capacity certification".

The formula is based on 25 % overpressure (as what was required to fully open the valve on liquid), but in most cases 10% overpressure was required, resulting in a 0.6 'Kp' Overpressure correction factor to be used (this is why most PRV's then on liquid were oversized).

To calculate the capacity of this Crane 2604 you need to know;-
Orifice area (might be on the nameplate and maybe shown as 0.06 in2)
Set pressure
Overpressure
Any back pressure
SG of the lube oil (and viscosity if considered 'thick')

If you can advise the criteria above, I can do the capacity calculation for you. The result would be a 'good informed value' based on everything I mentioned.

Hope that helps you understand the situation.


*** Per ISO-4126, the generic term
'Safety Valve' is used regardless of application or design ***

*** 'Pressure-relief Valve' is the equivalent ASME/API term ***

 

[Latexman]

No PFD or P&ID, so is it acting as a PSV, a back-pressure regulator, or both? I've seen old liquid PSVs used as a back-pressure regulator before. If you are considering changing that old PSV out, it'd be a good time to look at it's function, and optimize the selection of the replacement.

Good Luck,
Latexman

 

[pierreick]

Hi,
Better to review the relevant scenario after performing a safety review and calculate a new valve . Definitely not good to keep this valve in place on a safety view point.
The document attached should help you for sizing the RV .
Good luck
Pierre

 

[curtis2004]

Hi Everyone,

Thank you for all of your inputs. I agree, it belongs to a museum! It looks so beautiful and rear and it doesn't even have a nameplate.
This valve is installed in discharge side of rotary pump with 10 usgpm capacity in lube oil system. There is an isolation valve between the pump and PRV. Set pressure for PRV is 50 psig. Based on a pressure gauge reading, the pump is also operating at 50 psig. A discharge of PRV has a short pipe connected back to an oil tank, thus I don't think there is any back pressure. I have no clue what a viscosity of lube oil. It is used to lubricate hydro turbine guide bearings.

Do you know how often recommended to test PRVs in this kind of applications? Any guidelines for maintenance and testing of PRVs?

Thanks,
Kurt

 

[Latexman]

So, it appears it's acting as a back-pressure regulator all the time. With an isolation valve between the pump and PRV, it's not acting as a PRV some of the time, unless that isolation valve is locked open. I'd re-design it with a real back-pressure regulator (it'll control pressure much smoother, unless the PRV has proportional trim) and a PRV with no intervening valve.

On lube oil, I'd start it out with a 5 year T&I frequency and use risk based maintenance to adjust as, and if, needed.

Good Luck,
Latexman

 

[LittleInch]

I'm with latexman here - looks like a Pressure REGULATING valve. Please note that PRV can mean many things including Pressure relief, pressure regulating, etc. Always best to define what you mean.

So depends how its works - if it looks like it is passing all the time then you need to remove it I would say every 6 months or 5,000 hrs and check it to see if it seals, what its pop off pressure is and then see what the disc / seal looks like if it is actually passing fluid before it hits ~50 psi. If your pressure regularly drops below 50 psi when working then strip it down. But don't operate the lube oil pump without it or a replacement in position.

In terms of capacity you could always just close off the lube oil slowly d/s the valve when its running and see if the pressure stays at 50 psi. If it does then the capacity is good enough. What else do you need to know?

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

 

[georgeverghese]

On the other hand, " if it ain't broke, dont fix it "

 

[curtis2004]

Gentlemen,

I have the following concerns. There are four units in the plant. All units have a pair of the same rotary pumps. I have checked pump motor and based on pump datasheets we should have 19 USGPM @ 50 psig flow.

One unit have 1/2" Crane RVs. Three other units have 1" Kunkle 200A-E01-M6 with set pressure @ 50 psig. Based on PRV nameplate and Kunkle datasheets 1" 200A PRV can only relief 3 USGPM @ 50 psig with 25% lift (62.5 psig at PRV inlet), 18.4 USGPM @ 50 psig with 100% lift (100 psig at PRV inlet).

Three units have 50 psig, one unit has 60 psig gauge reading at pump discharge side.

Is it OK to have set pressure of PRV so close to pump discharge pressure?
Is Kunkle PRV size and set pressure selected correctly?

Thanks,
Kurt

 

[The Obturator]

Looking at the latest Kunkle Data Sheet for a 1" 200A the capacity at 50 PSIG (25% Overpressure) is 25 USGM.

Set pressure for PRV's is typically 10% over the operating pressure (MAWP)- These (non Code) small screwed PRV's have long blowdowns (reseating pressure) which should be taken into consideration. You mentioned earlier a set pressure of 50 PSIG with an operating pressure of 50 PSIG - that doesn't make sense and the PRV would be always open.


*** Per ISO-4126, the generic term
'Safety Valve' is used regardless of application or design ***

*** 'Pressure-relief Valve' is the equivalent ASME/API term ***

 

[georgeverghese]

The PRV on each of these 4 units should be able to recycle 10usgpm at the max permissible delivery pressure for the connected downstream users. We dont know what that max permissible normal operating delivery pressure is for each of these 4 units. It may be related to the max permissible operating motor power, or it could be something to do with the operating pressure limitation at downstream consumers.

 

[LittleInch]

curtis,

I don't think you're listening to us.

These valves are NOT acting as pressure RELIEF valves, but Pressure REGULATING valves.

The 200A form emerson site

https://www.emerson.com/documents/a...-relief-valves-kunkle-valve-en-en-5197428.pdf

clearly states the 200A is for continuous flow.

Rotary pumps are PD pumps and need somewhere for any excess flow/pressure to go otherwise they explode.
So the set pressure of these valves is setting the discharge pressure of your pump. Set it at 30 psi it will be 30 psi, set it a 70 psi it will be 70 psi.

Sorry, but this makes no sense to me "18.4 USGPM @ 50 psig with 100% lift (100 psig at PRV inlet)." You can't have two pressures existing at the same point (inlet to the valve.
It is likely that 100% lift will be at some extra margin over the set point, but I can't believe it is 100%. I think you may have misread this, but please post the data sheet.

Bottom line - they look good to me, but we can't see everything you can so very difficult to judge from a distance.


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

 

[Latexman]

Is it OK to have set pressure of PRV so close to pump discharge pressure?

I'm in the LittleInch camp. The PRVs are controlling the pump discharge pressure. That's why "set pressure of PRV so close to pump discharge pressure".

Good Luck,
Latexman

 

[curtis2004]

Hi there,

I have attached Kunkle datasheet.
We have four identical systems. Why three of them have 50 psig pump pressure and only one has 60 psig? Relief valve is by-passing in that case, I guess?

Thanks,

 

[LittleInch]

No.

The 60 one has just been set a bit higher and needs adjustment I think. Read my post above....

"So the set pressure of these valves is setting the discharge pressure of your pump. Set it at 30 psi it will be 30 psi, set it at 70 psi it will be 70 psi."

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

 

[curtis2004]

LitteInch,

Thank you for your responses. When we have back-pressure regulator installed at rotary pump discharge, can there be isolation valve or check valve between pump discharge and back-pressure regulator?

Thanks,

 

[LittleInch]

There can be but it should be locked open. As we all say, there is no p&id, no photos, no schematic even so we're all making the best guess we can from the information you provide....

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