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Vani
Associate

Join Date: Aug 2011
Posts: 31

Pressure Relief Valve

01/01/2013 3:04 AM

Dear Sir,

Please give me the right orifice type as per API 526.

flow medium Water.

Specific Gravity = 1.029

Q = 717.67 L/m

Pipe Inside Dia = 49.22 mm

Set pressure = 15000 Kpag

back pressure = 0

Viscosity = 0.000894 Ns/m2

Kc= 1

Kw=1

kd=0.65

As per my calculation I got the effective discharge area = 102.5402 mm2 ~0.159 in2

In API 526 the orifice type is 1 1/2" E 2 900X300. But our client give it as 1 E 2 600X150. Please advice me regarding this descripency.

Thanks and Regards

Vani.
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lyn
Guru

Join Date: Oct 2008
Posts: 42355
Good Answers: 1693
#1

Re: Pressure Relief Valve

01/01/2013 8:23 AM

I'd ask your client for help. He seems to know what he's doing and you apparently have no one on staff who does.

I'd give the client a discount for making your job easier, too.
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terrapin
Power-User

Join Date: Oct 2008
Location: Troy, NY
Posts: 122
Good Answers: 4
#2
In reply to #1

Re: Pressure Relief Valve

01/02/2013 8:57 AM

Why do you assume he has no one on staff that knows what they are doing?
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Tornado
Guru
Technical Fields - Technical Writing - New Member Engineering Fields - Piping Design Engineering - New Member

Join Date: May 2009
Location: Richland, WA, USA
Posts: 21017
Good Answers: 795
#3
In reply to #2

Re: Pressure Relief Valve

01/03/2013 12:37 AM

Because he is asking this motley crew....

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Vani
Associate

Join Date: Aug 2011
Posts: 31
#4
In reply to #1

Re: Pressure Relief Valve

01/03/2013 4:23 AM

Dear Sir,

I wish to get the right choice of orifice, I am not familiar with the sizing of orifice . I have doubt about the set pressure. it is 2176 Psi and the flange is 600#. (The maximum allowable pressure for this rating is 1440 psi)..

I am appreciating to you if you provide the right choice from your experience and knowledge as a Guru in this section.

Thanks and Regards

Vani.
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2
Codemaster
Guru

Join Date: Jul 2005
Location: Stoke-on-Trent, UK
Posts: 4496
Good Answers: 137
#6
In reply to #4

Re: Pressure Relief Valve

01/03/2013 6:27 AM

Before you worry about the orifice size, the set pressure is much too high for MAP 1440 psi. Pipework/flanges can be tested at 1.5 x design, which is close to the 2176 psi, but that's something else. You don't give the actual operating pressure. It needs to be somewhat below PRV set pressure, to avoid frquent relieving. PRV set pressure can usually = MAP (but check with the pipe code you're using), and 10% rise over set pressure allowed at max relief flow.

If the PRV set pressure is 15000 kPa, relief orifice velocity is ~ 100 m/s and orifice area ~ 110 mm2 for 718 l/m, in theory needing about 12 mm dia seat. In practice you're likely to be offered a bigger PRV giving much less than 10% pressure rise.

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Vani
Associate

Join Date: Aug 2011
Posts: 31
#5
In reply to #1

Re: Pressure Relief Valve

01/03/2013 4:33 AM

Dear Sir,

I wish to get the right choice of orifice, I am not familiar with the sizing of orifice . I have doubt about the set pressure. it is 2176 Psi and the flange is 600#. (The maximum allowable pressure for this rating is 1440)..

I am appreciating to you if you provide the right choice from your experience and knowledge as a Guru in this section.

Thanks and Regards

Vani.
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Users who posted comments:

Codemaster (1); lyn (1); terrapin (1); Tornado (1); Vani (2)

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