Jump to content



Featured Articles

Check out the latest featured articles.

File Library

Check out the latest downloads available in the File Library.

New Article

Product Viscosity vs. Shear

Featured File

3-Stage Propane Ref Performance

New Blog Entry

Steam Tracing Design- posted in Ankur's blog

2

Line Sizing For Bursting Disc Application

bursting disc line

9 replies to this topic
Share this topic:
| More

#1 zebobo

zebobo

    Brand New Member

  • Members
  • 9 posts

Posted 06 October 2017 - 03:06 PM

Good evening,

 

I would like to know if there are line sizing requirements for bursting disc applications. 

 

We are talking about using a bursting disc only, there is no PSV upstream or downstream of the  bursting disc.

 

I know there are max pressure drop requirements for PSV lines, but do these requirements also apply for bursting discs?

 

What should one consider when checking line sizes for bursting disc applications?

 

Regards,

zebobo



#2 breizh

breizh

    Gold Member

  • ChE Plus Subscriber
  • 3,701 posts

Posted 07 October 2017 - 01:05 AM

Hi ,

Consider the document attached

Hope this helps

Breizh

 

Attached Files



#3 fallah

fallah

    Gold Member

  • ChE Plus Subscriber
  • 4,380 posts

Posted 07 October 2017 - 04:52 AM

zebobo,

 

When a bursting disk discharges directly to the atmosphere; is installed within eight pipe diameters from the vessel nozzle entry, and has a length of discharge not greater than five pipe diameters and has nominal diameters of the inlet/outlet lines equal to or greater than the nominal sizes of bursting disk's inlet/outlet nozzles; there is no requirement for inlet/outlet lines sizing for device provided that the device being sized based on section 5.11.1.1 of API 520 Part I (8th edition).

 

For the cases other than above inlet/outlet lines sizing being done through using the method of bursting disk sizing as mentioned in section 5.11.1.3 of API 520 Part I.



#4 zebobo

zebobo

    Brand New Member

  • Members
  • 9 posts

Posted 07 October 2017 - 06:55 AM

Many thanks for your replies Breizh and Fallah.

 

Regarding pipe diameter, which diameter should one consider - internal or external?



#5 fallah

fallah

    Gold Member

  • ChE Plus Subscriber
  • 4,380 posts

Posted 07 October 2017 - 07:05 AM

 

Regarding pipe diameter, which diameter should one consider - internal or external?

 

Nominal Diameter should be considered; otherwise if you have to select between internal and external, internal diameter is preferred...
 



#6 zebobo

zebobo

    Brand New Member

  • Members
  • 9 posts

Posted 19 October 2017 - 12:19 PM

I have checked the discharge piping and the 8 & 5 rule does not apply, so I have calculated the relieving capacity of the system using the resistance to flow method KR.

 

I encountered an issue when calculating the relieving flowrate. 

The sizing case is external fire heating up water. 

The relieving flowrate is given by m = heat input (kW) / latent heat of vaporisation (kJ/kg)

 

The BD will burst at 64.4barg and 281°C. 

However at these conditions all water has vaporised, hence I can't get a value for the latent heat of vaporisation? 

 

The burst pressure is +/- 5%, do I say the relieving conditions will be 67.6barg and 281°C? I can get the latent heat of vap at these conditions.



#7 fallah

fallah

    Gold Member

  • ChE Plus Subscriber
  • 4,380 posts

Posted 19 October 2017 - 02:24 PM

I have checked the discharge piping and the 8 & 5 rule does not apply, so I have calculated the relieving capacity of the system using the resistance to flow method KR.

 

I encountered an issue when calculating the relieving flowrate. 

The sizing case is external fire heating up water. 

The relieving flowrate is given by m = heat input (kW) / latent heat of vaporisation (kJ/kg)

 

The BD will burst at 64.4barg and 281°C. 

However at these conditions all water has vaporised, hence I can't get a value for the latent heat of vaporisation? 

 

The burst pressure is +/- 5%, do I say the relieving conditions will be 67.6barg and 281°C? I can get the latent heat of vap at these conditions.

 

Zebobo,

 

Please submit complete data...especially the design data of the vessel on which the BD is to be installed



#8 zebobo

zebobo

    Brand New Member

  • Members
  • 9 posts

Posted 19 October 2017 - 02:28 PM

 

I have checked the discharge piping and the 8 & 5 rule does not apply, so I have calculated the relieving capacity of the system using the resistance to flow method KR.

 

I encountered an issue when calculating the relieving flowrate. 

The sizing case is external fire heating up water. 

The relieving flowrate is given by m = heat input (kW) / latent heat of vaporisation (kJ/kg)

 

The BD will burst at 64.4barg and 281°C. 

However at these conditions all water has vaporised, hence I can't get a value for the latent heat of vaporisation? 

 

The burst pressure is +/- 5%, do I say the relieving conditions will be 67.6barg and 281°C? I can get the latent heat of vap at these conditions.

 

Zebobo,

 

Please submit complete data...especially the design data of the vessel on which the BD is to be installed

 

 

The design pressure of the vessel is 130barg.



#9 latexman

latexman

    Gold Member

  • ChE Plus Subscriber
  • 905 posts

Posted 19 October 2017 - 02:41 PM

What Code/standard is the pressure vessel?  What is vessel's MAWP?  I'm most familiar with ASME Code, which allows 21% overpressure in fire scenario.  For example, if MAWP = 64.4 barg, then maximum fire scenario sizing pressure = 77.9 barg (64.4 x 1.21) under ASME Code.

 

No, all water has not vaporized at 64.4 barg and 281oC.  Not at the instant the RD bursts.  Inside your vessel is two phases at 64.4 barg and 281oC.

 

The relief system (RD, pipe, and fittings) will restrict the water vapor to a certain flow rate given the 77.9 barg sizing pressure and the coincident temperature of the boiling water in the vessel.  Let's call this maximum flow rate = X kg/hr.  Think compressible flow.  Choked flow.

 

The heat input from fire will generate a certain flow rate of water vapor.  At 77.9 barg and 288oC, the latent heat of vaporization is about 1489 kJ/kg.  Let's call this generation rate = Y kg/hr.

 

Your job is to provide a relief system such that X > Y.



#10 latexman

latexman

    Gold Member

  • ChE Plus Subscriber
  • 905 posts

Posted 19 October 2017 - 02:50 PM

Water's critical pressure is 220 barg.  You will still have two phases at/near 130 barg.


Edited by latexman, 19 October 2017 - 02:51 PM.





Similar Topics