Inspection Opening

[andrewleong]

As per ASME VIII div 1, UG-46 :

"All vessels 18 in. (450 mm) to 36 in. (900 mm), inclusive,
I.D. shall have a manhole or at least two handholes or two plugged, threaded inspection openings of not less than NPS 2 (DN 50)."

"(7) Flanged and/or threaded connections from which piping, instruments, or similar attachments can be removed
may be used in place of the required inspection openings provided that:
(-a) the connections are at least equal to the size of the required openings; and
(-b) the connections are sized and located to afford at least an equal view of the interior as the required inspection
openings."

For this vessel under above requirement, only one HH is available, while other nozzles are 2", and no threaded opening.
Since min HH size is 3"x2", the 2" instrument nozzles can't be used in placed of the second HH requirement.

However can the 2" non-threaded instrument nozzles be considered as meeting the requirement of 2" threaded inspection openings and therefore meeting ASME VIII requirement ?

Appreciate very much any advise.

 

[david339933]

18" to 36" must have inspection openings of NPS 2
Flanged openings can be used if they satisfy f(7) - NPS 2

Your instrument nozzles are NPS 2, so therefore they satisfy f(7)(a). You must then check f(7)(b) and other clauses such as f(4)

 

[r6155]

If the NPS 2 non-threaded nozzle is no longer than NPS 2 threaded nozzle. it´s OK . According to ASME B16:11 NPS 2
half-coupling is 43 mm long.
Regards
r6155

 

[david339933]

r6155

Please explain where Sec VIII refers to length of inspection opening?

 

[r6155]

1)@ david339933
I consider, in this pressure vessel, that NPS 2 threaded nozzle for instrument is half-coupling. Flange opening NPS 2 is longer than half-coupling, hence not has at least an equal view of the interior.

2)@ andrewleong
Is this pressure vessel subject to internal corrosion or having parts subject to erosion or mechanical abrasion? See UG-46(a)

Regards
r6155

 

[r6155]

Interpretation: VIII-1-83-358
Subject: Section VIII, Division 1; UG-46(f), Attachments in Inspection Openings
Date Issued: May 20, 1985
File: BC85-124

Question: Would the requirements of UG-46(f)(2) be satisfied by providing two threaded
openings not less than 2 in. pipe size from which piping, instruments, or similar attachments can be removed, if the openings meet the requirements of UG-46(f)(7)(a) and (b)?

Reply: No. UG-46(f)(7) applies to flanged connections only

Regards
r6155