3 replies to this topic

[shantanu.ghag]

Good morning all,

 

Please refer attached sketch for valving arrangement.

 

As per project scope we have new pre-filtration unit (vendor package) to be installed upstream of existing cartridge filters of RO unit.

 

New pre-filtration unit (vendor package) will serve as replacement to existing cartridge filters. Thus, existing cartridge filters will be bypassed once new pre-filtration unit comes in service.

MOV# 1, 2 & 3 will be normally closed position and MOV# 4 will be in Open position. 

 

As per normal practice I believe there should not be isolation valves requirements for the bypass valve, whether manual or motor operated valve.

 

However, client is requesting to provide isolation valves (valves with green color in sketch) for bypass MOV for the maintenance purpose. 

 

What is your thought? What is general engineering practice for isolation valves provision for MOV's in such case?

 

Thanks in advance.

Shantanu.

Attached Files

•  isolation requirement.pdf   49.39KB   16 downloads

[breizh]

Hi,

This is a requirement from client who is going to pay for it. period!

But draining valves are missing to operate safely, if you have to remove the valve for replacement.

For your last question, I would say it's case by case. You need to assess what is the weakest point, the valve or the motorization.

EDIT: additional document 

Good luck.

Breizh 

Attached Files

•  the_safe_isolation_of_plant_and_equipment.pdf   995.52KB   7 downloads

[shantanu.ghag]

Hi,

This is a requirement from client who is going to pay for it. period!

But draining valves are missing to operate safely, if you have to remove the valve for replacement.

For your last question, I would say it's case by case. You need to assess what is the weakest point, the valve or the motorization.

Good luck.

Breizh 

Hi Breizh,

 

You are spot on; it’s the client who is going to pay for it.

 

However, I would like to understand whether it is a must-have or not. Otherwise, we will end up in providing an isolation valve for each valve (which is not economical in EPC/LSTK projects).

 

In the case of control valves, bypasses (globe valves) didn’t have isolation valves unless the bypass valve is another automated control valve.

 

Regarding drain valves, yes, I have not shown them in the schematic as that is not the point of concern.

 

Thanks,

Shantanu.

[shvet1]

However, client is requesting to provide isolation valves (valves with green color in sketch) for bypass MOV for the maintenance purpose.  

 

Isolation for maintanance of pressure (wet) parts, correct? Not actuator as actuator does not need isolation for maintenance?

Block up/downstream isolation valves have the same DN and design, correct?

If so, client believes one block valve (actuated) needs maintenance, then two block valves (hand operated) also need maintenace the same type and rate, correct? They have the same wet parts as actuated valve, correct?

 

1 MOV valve needs 2 block valves for isolation

2 block valves need 2 more block valves for isolation (3 in total)

2 additional block valves need 2 more block valves for isolation (5 in total)

... and so on and on

 

The flawless logic

Edited by shvet1, 15 September 2024 - 11:51 PM.