FBE Tail protruding from 3L-PP anticorrosion coating on pipes
FBE Tail protruding from 3L-PP anticorrosion coating on pipes
(OP)
Hi guys,
I'm working as coating engineer and I have a question regarding the FBE tail protruding from a 3L-PP or 3L-PE anticorrosion coating on pipes.
In my opinion any residual FBE at the cutback area should be avoided as it could be detrimental for field joint coating and AUT operations...
Nevertheless I hear many people asking for a minimum 10 mm tail for example.
What's your opinion on that?
Regards,
NB
I'm working as coating engineer and I have a question regarding the FBE tail protruding from a 3L-PP or 3L-PE anticorrosion coating on pipes.
In my opinion any residual FBE at the cutback area should be avoided as it could be detrimental for field joint coating and AUT operations...
Nevertheless I hear many people asking for a minimum 10 mm tail for example.
What's your opinion on that?
Regards,
NB





RE: FBE Tail protruding from 3L-PP anticorrosion coating on pipes
RE: FBE Tail protruding from 3L-PP anticorrosion coating on pipes
I agree that the main point is to ensure a proper bonding between the FBE and the PP, but I don't see how the tail could help that. when we preheat the pipe with induction coils in order to apply the HSS we pass the Tg of the FBE so we destroy the tail which in fact will be just residual FBE, not a proper protective tail. Furthermore during the blasting of the field joint area this tail can be damaged and again we will have just a damaged coating, not at all protective.
So it seems to me that this tail will not serve as a protective coating but will result just in a residual FBE wich in my opinion could cause some problems during the AUT test being seen as a defect.
thanks,
Nicolò
RE: FBE Tail protruding from 3L-PP anticorrosion coating on pipes
In any event if you are damaging FBE from the induction coil and there is no chance of saving the tail, then you would want to remove all of it during blasting (as you probably are now) so there is no residual FBE left and the shrink sleeve can adhere properly. The main thing is proper adhesion of the coating, whether it be on steel or FBE. Don't know if you will have a seam where the shrink sleeve joins the 3PLE, or the sleeve extends over top, but you don't really want to leave that seam, this is where environment can get in and start the disbondment of the shrink sleeves.
As far as AUT giving a false signal by seeing the FBE, I think that this would not be possible, as providing there is no coating under the sensors, it is shooting into the weld, the FBE should be on the backside of the machine. If you mean FBE directly under the sensors, then yes, this would actually block the signal and need to be removed.