6 replies to this topic

[kasri]

Dear All,
Please clarify the following doubts
(a) Blowdown valve in system is actuated whenever the depressurising is required irrespective of the particular set pressure; then how the BDV is closed after blowdown. we had given signal for open only ;for closing the valve whether a person go to the site to close it or it has a option to reset in DCS.
(b)Similar as BDV how the SDV is closed after ESD cause problems are rectified.
Please explain.
Regards,
Kasri

Edited by kasri, 03 August 2011 - 09:27 PM.

[fallah]

kasri,

As usual,SDV/BDV are locally and manually reset.

Under specified conditions SDVs can be remotely reset.

Under specified conditions SDV/BDV can be of the auto reset type.

Fallah

Edited by fallah, 03 August 2011 - 11:22 PM.

[kasri]

dear fallah,
Thanks for your reply.
If it is autoreset ; on what basis it reset automatically.
on what basis it get signal from DCS to get closed( because there is no signal automatically from DCS to say the blowdown valve to close based on blowdown completion status)
Regards,
Kasri

[shan]

BDV/SDV's are manually activated valves. They are opened by human action and closed by human action.

[andiez]

That is the problem i am facing now.... is the following arrangement as per current practices?

SDV & BDV - reset to be local only. activation can be manual via DCS and local

but other places only local reset/open is provided but not manual activation from DCS. not sure if this is correct.

any ideas?

[fallah]

dear fallah,
Thanks for your reply.
If it is autoreset ; on what basis it reset automatically.on what basis it get signal from DCS to get closed( because there is no signal automatically from DCS to say the blowdown valve to close based on blowdown completion status)
Regards,
Kasri

Kasri,

It reset automatically when activated by SD3 (shutdown level 3), and gets signal from DCS/SD3 combination system.

Fallah

Edited by fallah, 29 August 2011 - 01:45 AM.

[fallah]

That is the problem i am facing now.... is the following arrangement as per current practices?

SDV & BDV - reset to be local only. activation can be manual via DCS and local

but other places only local reset/open is provided but not manual activation from DCS. not sure if this is correct.

any ideas?

andiez,

As per normal archtecture of the ESD system:

For SDV in SD 3 (implemented on Process Safety System or PSS) : Auto reset by giving authorization of remote opening, no local reset except for process reasons

For SDV in SD 2 (implemented on ESD PLC) : Remote reset except for process reasons

For BDV in EDP : Local reset. Auto reset if SD 3 acts on it

Fallah