Spectacle Location
Spectacle Location
(OP)
In piping model, a spectacle which is on a removable spool, is connected to an tube&shell heat exchanger nozzle directly.
My question is: is this configuration wrong? during maintenance, the removable spool including this spectacle is removed, how to prevent fluid inside piping come out?
even there is a valve before this spool, it still can not prevent fluid leakage completely.
Should we put the spectacle before the removable spool?
thanks for your reply.
My question is: is this configuration wrong? during maintenance, the removable spool including this spectacle is removed, how to prevent fluid inside piping come out?
even there is a valve before this spool, it still can not prevent fluid leakage completely.
Should we put the spectacle before the removable spool?
thanks for your reply.





RE: Spectacle Location
thread408-94849: Double Block Bleed Valve
thread469-199677: Double block and bleed valves
If you're concerned with emptying the entire pipe on the far side of the single valve if it has a slow leak, why not just remove the spool, then blind the valve? Which also brings up the question of why you have a spec blind between the exchanger and removable spool? When you remove the spool, what's keeping the spec blind in? And why would you want to blind the exchanger when you have removed the spool?
jt
RE: Spectacle Location
thanks for your reply.
the spectacle location is exactly the same as P&ID sequence, I think it is for hydrotest to isolate heat exchanger.
If we blind the valve, that means we need put another spool between removable spool and spectacle+valve. that is: exchanger - removable spool - pup - spectacle-valve. how is it?
RE: Spectacle Location
In service:
(shell or channel) ---||-------(removable spool) -------||X||---------(pipe)
Out of service. Close valve, remove spool, put a standard blind flange on the valve. No spec blind:
(shell or channel) ---| ||X||---------(pipe)
How often is the exchanger going to be hydrotested? Shouldn't be really frequent... If a hydro is required... remove the spool and put a blind on the shell or channel flange. Or is this a high pressure exchanger and blinds are hard to come by? Class 900 or higher?
jt
RE: Spectacle Location
my visualization is like this:
In service:
exchanger-||---(removable spool---||---(pup)---|↑|X||---(pipe)
Out of Service:
exchanger-| |---(pup)---|↑|X||---(pipe)
↑=spectacle
RE: Spectacle Location
The exchanger is now positively isolated from the process related to that pipe, and a small leak of the valve will result in a few gallons (depending on pipe size)collecting between the gate of the valve and the blind. When the time comes to put the spool back, the process is reversed. Maintnance should anticipate the possibility of a bit of liquid trapped between the gate and the temporary blind and place a kiddie pool under it when the nuts are loosened.
Spec blinds serve a purpose; I just don't see it in your application.
jt
RE: Spectacle Location
your point makes sense for me if it is normal for maintenance folks have spare blind flanges on site.if so, should piping group note this material on IFC ISO? otherwise, how do they know to prepare it?
RE: Spectacle Location
Have you spoken with the plant's maintenance supervision? They don't bite. Well, not hard anyway...
jt
RE: Spectacle Location
The spectacle is shown on P&ID. As a piper, I only can decide its location to fit process requirement. That's why I asked the spectacle location.
anyway, I learned some maintenance knowledge from you. thank you again!