utility connector question on P&ID

[hswang2]

Fig1 .Pump discharge fluid is acetic acid . and utility connection is nitrogen/service water.

Fig2. The process line is nonyl phenol exthoxylate and utility connection is nitrogen/service water.
(Please see attached file)



My question is why the utility connection in fig 1 have no spectacle blind like figure 2.

I know that there may be the two reasons to put spectacle blind (1). The process line is easy to leak or highly Explosive / (2) The process is batch not continuous.(3) higher design pressure

But this seems not fit the above requirement. Please help me out.

Thank you very much.

 

[Chance17]

For environental reasons, both bleeder valves should be plugged.
Check valves are not effective.
Hose connectors with plug are easily available.
I can't think of a reason to blind figure2 other than odor prevention.

 

[ash9144]

Spec blinds are normally used in those type applications to prevent back flow into the utility header. I would guess that the utility on Fig 1 gets used much more frequently than Fig 2 and so the blind has been removed for ease of operability.

 

[ChEMatt]

I have read that even block valves are not "OK" for long term process isolation. If it is perceived that one will not use a line for a long long time, a spec blind is a very secure way to isolate the process and prevent leaking. If the connection is to be used "rarely", then a spec blind may be called for depending on how hazardous the process fluid is, similar to what ash9144 said.

Hope this helps.

Onwards,

Matt