Reasons for not using perforated impingement plate - API 660

[SJmetallurgist]

Hello

API-660, clause 7.6.4.6 states that 'perforated impingement plate baffles shall not be used'. Can anyone throw some light on the logic behind this prohibition? Any input would be appreciated. Thanks.

 

[EdStainless]

please don't double post

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P.E. Metallurgy, Plymouth Tube

 

[srfish]

The perforations slow the velocities coming off the plate. It is not desirable to slow this velocity going toward the tubesheet. Slowing this velocity can create a stagnant area where there can be corrosion and fouling.





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[SJmetallurgist]

EdStainless - i was not sure whether the pressure vessel foum would be the right one / whether i could get more expertise here. Thats the reason for duplicating. any trouble is regretted

 

[SJmetallurgist]

srFish - Thanks much for this clarification. I do find it useful and infact was also reading a paper on the same topic. Could you please clarify a bit more on the 'stagnant area'.

 

[srfish]

The stagnant area is the area from the forward front of the impingement plate and the tubesheet.
I called it an area but it is actually more of a volume.

 

[SJmetallurgist]

Thanks again. I got your point.
Unfortunately even after being prohibited by API-660, many users are still using perforated impingement plates in disguise of distributor (to achieve thermal efficiency). Any comments on this practice (of-course I am talking about those equipments where the design should comply to API 660 contractually)?