6 replies to this topic

[m42364236k]

Dear colleagues

As I know we consider the manual valve inadvertent close for closed out let scenario

I have to question

1-if the valve is LOCK OPEN should we consider the block out let scenario for this valve or we can give the credit and no consider for this case

2- What about the spectacle blind .can we consider the inadvertent of spectacle blind for block out let scenario

 

Thanks

[Zauberberg]

1 - this varies from company to company. If administrative procedures are strong and well established, the credit can be taken for locked open valves. This means in reality that it is highly unlikely to have the valve mis-operated.

 

2- absolutely. it is not possible to turn spectacle blind other than during shutdown conditions. There is no way one can swing the blind during operation.

[fallah]

Hi,

 

1- In general yes, provided that as Zauberberg mentioned, relevant procedure to be well established.

 

2- In general, no. Actually in process lines there would be no possibility for blocked outlet case due to putting a spectacle blind in wrong position; but in pressure relieving paths such as PSVs inlet lines (normally no flow lines) where putting a spectacle blind in wrong position can't be sensed at start up and normal operation, it's highly recommended to avoid using such facility and using a spool pipe has been approved in safety standpoint.

[Fakhri]

How is about the spectacle blind left in closed position during start-up after maintenance?

 

Best regards,

 

Fakhri

[fallah]

Fachri,

 

It would be well detectable in start-up if wrongly left in closed position in flowing lines...

[breizh]

fachri ,

The best practice  to ensure they are not forgotten is to issue a check list with the location of the blinds with 2 columns ( installed & removed) and signature of the people doing the work. Apart that nothing works , this is based on my experience.

 

hope this helps

Breizh

Edited by breizh, 23 December 2014 - 05:43 AM.

[shekhar dhuri]

Agree with Fallah,

1) Most of the times during HAZOPs, credit for the Lock Open valves is considered.
2) Spectacle blind can be turned during normal operation. Standard Operating Procedures (SOPs) shall ensure that after maintenance, spectacle blind is returned to its open position.

Regards,
Shekhar

Edited by shekhar dhuri, 23 December 2014 - 11:28 PM.