ASME SECTION I-RELIEF VALVE mounting

[mihir5577]

HI
What are the requirements for the connecting piping of the two (2) relief valves to one boiler pressure vessel opening (Cplg.) for relief valve?
Is there any calculation required to show an A.I?
Pls. advise asap.
Thanks
M.B.S

 

[metengr]

mihir5577;
Yes, a caculation should be performed to show the AI that by using a "Y" fitting with two safety relief valves installed in each leg of the "Y" fitting, the mass flow rate of steam can be handled by both SRV's simultanously thru one connection.

 

[mihir5577]

Hi
From where I'll find this?
which para of ASME SEC I?
Pls. help and advice.
Thanks
M.B.S

 

[metengr]

PG-71..71.1..71.2..

 

[MJCronin]

mihir....

For a safety valve installation on an ASME Section I boiler, why are you not using the SV mounting flanges typically provided by the boiler vendor ?

For medium pressure, industrial boilers there are typically two or three individual flanged nozzles for safety valve mounting.

Tell us more about the boiler design....are you somehow running the boiler at a higher MAWP or above and beyond the design steaming rate ???

-MJC

 

[mihir5577]

Hi MJC,
Thanks for reply.
Our boiler Design at 250 psig.
Htg. surface is 538 sq. ft and stem. cap. is 4317 lbs/hr.
We shipped this boiler with only one 2" relief valve cplg, but as per ASME sec i, pg-67.2, min. 2 valves req. for this cap. of boilers.
Now either we'll have to add one more cplg. or will have to use "Y" fittings and mount two valves on one cplg.
From where i'll find "y" fitiing or can we use any forged fittings for that?
so pls. advise me what best i can do for this case?
pls...ASAP
thanks
Mihir

 

[GenB]

The Code addresses the safety valve issue as area in sq in
(or calc in mm if you wish: sq mm)
if the smallest fitting internal (ID) area supoports the area of the 2 SV's you are okay. if not you are in trouble,
if you already shipped the boiler the trouble is bigger, you will have to convince the AI in the Jurisdiction to let you deal with new conections:
I would choose the 1/2 in drilling and tapping if the plate allows and install several SV's to Comply with the Code, if the Code allows it.
Since I am not reading you have to do the research.
genb

 

[MJCronin]

mihir...

So you shipped a boiler, possibly built to some third world boiler code, without adequate safety valve nozzles on the steam drum...

You now want to know if it is acceptable to use a "wye" type of fitting above the single safety valve nozzle you somehow did manage to install ? You also do understand that there may have been a very good reason for th ASME Code to require the use of two individual safety valves on the steam drum.....but you are not sure....

Is all of this correct ?

Where will the boiler be installed......not in the USA, I hope...???


My opinion only

-MJC

 

[GenB]

MJCronin
go ahead spank the man,
Mihir, I suspect the AI signed the Data report and now you are in trouble.
genb

 

[aclark]

The existing opening can only pass a given ammount of steam through it. You must determine if the 2" opening can pass 4317lbs/hr of steam through it. if the answer is yes then you can mount 2 valves on the single opening using a duplex valve or 2 valves on a "Y" Both vaves must be of equal capicty.
If the answer to the above question is no then you must add and additional safety valve opening. In this case in order to comply with the Code the second valve must be at least 50% of the capacity of the first valve.

As far as the AI is concerned, there is no provision for the AI to sign the P-7 data report. However I agree that the boiler should never have left the shop.