Threaded coupling in flat cover (manway) UG-45 6

[Mr.blu]

I have seen many posts on the forum about this topic, but I haven't found one that really answers this question.
I will try to be as clear as possible: I have a flat cover that I designed according to UG-34 for a filter, which serves as a manway to change filter elements. If I place a threaded coupling on this cover to function as the equipment vent (it will not have external loads), should it comply with the requirements in UG-45, or would it fall under the 'manway opening'? The idea is to install a 1/2" NPT Class 3000 coupling, but its thickness, while meeting the required thickness + CA and UG-16, does not reach the value in the UG-45 table + CA. It is mainly to understand if a connection placed in a manway is still exempt from what is required in UG-45 when there are no external loads.

What does the code consider within 'manway and access only nozzles' if what I'm saying is incorrect? Is there any part of the code that specifies that UG-45 is aimed at reinforcing connections due to external stresses from piping? Many people express that opinion, but I haven't found it explicitly stated.

Thank you in advance to anyone who can help me interpret this

 

[GD2]

Disregard UG-45 for ASME B16.11 fittings directly welded to a pressure vessel.

GDD
Canada

 

[Mr.blu]

GD2,
Thank you for your reply.

Based on t required, find the nearest pipe wall thickness/schedule from ASME B36.10 (if CS). Consider a typical minus 12.5% under-tolerance.
Once you have this, go to ASME b16.11 Table 8 and corelate the fitting rating. If pipe schedule was Sch 160, the required threaded coupling rating would be 3000#, if XXS 6000#.

So, If I do this, is it enough?
Sorry for doubting so much, but I want to be sure before closing the topic.

 

[DriveMeNuts]

UW-16(f)(3)(-a)(-6) says that Table UG-45 (and Table UW-16.1) is mandatory for threaded pipe fittings welded to a pressure vessel.
Is the current 2023 edition of the code correct, or an ancient 1984 enquiry?
If the interpretation is valid, then UG-45 is pointless, and would have been removed from the code decades ago. This ancient interpretation therefore needs to be re-affirmed.

Mr.blu comes across as looking for an opportunity to sneak around the code rules, and then 'claim dumb' if there is a failure.

 

[Mr.blu]

DriveMeNuts.
I think you should be more kind and not assume things about people. I never said that I manufactured that container. From the responses you give, it doesn't seem like you have a clear understanding of things to speak to me in that way (You failed to answer any of the questions I asked; you simply insisted that it was mandatory, obviously without knowing why).
I asked theoretical questions to better understand, but somehow you take it as an opportunity to feel superior. It's unfortunate that there are people like you answering queries.

 

[IdanPV]

Table UW-16.1 shall be used to determine the min. required thickness of a fitting attached to the vessel by fillet weld from outside only. The OP shows different weld detail.

UW-16(f)(3)(-a)(-6) says that in lieu of the thickness requirements of UG-45, the min. thickness of the fitting shall not be less than that shown on Table UW-16.1.

In recent years Table UW-16.1 was added to the code. There are many manufacturers making custom couplings (fittings) that the code decided to document what the minimum should be.
Table UW-16.1 is actually the dimensions for a ASME B16.11 class 3000 threaded coupling.

Example ½” 3000:
1.12” OD. The major diameter of the thread is 0.84” (pipe OD).
minimum wall is (1.12-0.84)/2 = 0.14 with matches Table UW-16.1.

Anyway,
It is my opinion that your design doesn't meet Code requirement because your fitting wall thickness is too low.
I suggest seeking clarification by submitting a request for interpretation to the ASME Section VIII Committee. This would help address any uncertainties.

https://cstools.asme.org/Interpretation/InterpretationForm.cfm

 

[DriveMeNuts]

If UW-16(f)(3)(-a)(-6) and Table UW-16.2 has been added in recent years then the 1984 interpretation is unlikely to be still valid. I deduce from "in lieu of the thickness requirements of UG-45", that if you have a fillet weld only, then Table UW-16.2 applies. Otherwise, if it is welded with a more substantial weld as per this thread, then the thinner wall thickness in UG-45 applies. Deviating from this would require clarification from the ASME committee.

As you can see from my post, I am not assuming anything. My post is a reflection of my perceptions. "For now that's not an option..." is not the sort of thing you say if this is a theoretical problem.

Occasionally on this forum you get threads where the OP says things like "So, If I do this, is it enough?", and seek consensus from a bunch of strangers on this forum. And then make firm decisions based on advice from a bunch of strangers. That is what seems to be happening in this thread. And it is my view that this is unprofessional and even dangerous conduct.

In any case, that consensus of this thread seems to be that there is not a consensus. With all the sources we have provided for you, there seems to be two of us saying it doesn't meet code, while one saying is does. And then there is you (who I presume is a professional engineer) who is .....well ..... ummmm ..... unsure.

 

[Mr.blu]

DriveMeNuts,
The only reason I said it wasn't an option at the moment is because if I switch to the S6000, there is no problem to solve. English is not my first language, and I may express myself poorly; again, that is not a reason for you to come and judge people. I understand that, besides being an engineer, you must be an excellent detective, but in a forum where people ask questions, it's normal to be... "ummm... unsure." If I knew the answer, I wouldn't ask.
I am trying to thoroughly interpret what UG-45 is asking for with an example that I was consulted on a few months ago but couldn't resolve. If I ask, "So, if I do this, is it enough?" it's because I am trying to understand the logic. I am relying on the response of the only person who actually attempted to provide a method, rather than focusing on you, who simply repeats without understanding. Please don't waste my time with your assumptions

 

[DriveMeNuts]

We have fed you with all the available resources. You also need us to teach you the reasoning and logic? And also provide you with a range of the results? Did you have any intention of putting in any thought of your own, so that we can learn from you? Or is this thread just a one way flow of free information for you.

 

[Mr.blu]

IdanPV
Apologies Idan, I accidentally skipped your response. Thank you very much for answering.

I see that Table UW16.1 is even more stringent than the UG-45 table; now the 'UW-16(f)(3)(-a)(-6)' makes more sense to me.
Logically, it seems advisable to discard the use of Class 3000 in flat covers, unless there is no corrosion allowance (thickness values comply with UG-45 and UW16.1 until corrosion allowance is added). I am referring to flat covers because, in practically all cases, the thickness "tb1" is likely to be higher than "tb3", and "tb" will eventually end up being equal to tb3.

I still don't understand how the calculation of the coupling according to B16.11 with the equivalent pipe relates to UG-45 (if it does) and what the conceptual difference is between 'inspection and access openings' in terms of the requirements for the nozzle. I will follow your advice and consult the committee; from what I've seen, there have been similar inquiries, but this specific one is not there.

Thank you.

 

[GD2]

IdanPV,
i am bit baffled when you made the following statement.
Anyway,
It is my opinion that your design doesn't meet Code requirement because your fitting wall thickness is too low.

In my opinion, the 1/2" x 3000# half coupling meets the thickness requirement of 0.14" (Table UW-16.1), which you explained through the example.

Table I-5 of ASME B16.11 also gives the "Minimum End Wall Thickness" of the 1/2" xx 3000# coupling as 0.25". This thickness is away from the threaded end (unthreaded portion).

Summary, the 1/2" xx 3000# half-coupling should be good to go.

GDD
Canada

 

[IdanPV]

Mr.blu,
1. Check out those Interpretations:
a. BPV VIII-1-18-35 - UG-45 Corrosion Allowances
b. BPV VIII-1-19-15 - UG-45 Minimum wall thickness of nozzle necks
2. I think that your assumption regarding UG-45 and tb1,tb2 and tb3 is correct. I am always assuming the worst case scenario for tb1 and tb2 and end up with tb3.
3. The National Board Bulletin, Winter 2017 Edition has very good article regarding UG-45. (pages 14-15).
4. The only relation between B16.11 and Table UG-45 is that if you are using fitting having O.D not equal to the O.D of an equivalent STANDARD NPS size, the NPS chosen from Table UG-45 shall be one having equivalent O.D LARGER than your fitting.
In your case, O.D=28mm the equivalent STANDRAD NPS is NPS 1 (O.D=33.4) and from Table UG-45 the min. thickness shall be 2.96 (+C.A).
5. I think that the reason that Table UW-16.1 is more stringent than Table UG-45 is because this table is relate to UW-16(f)(3) which allows "poor" welding method (fillet from outside only)

DriveMeNuts,
My ASME Code digital collection goes back to 2004 Edition. I can confirm that Table UW-16.1 added in the 2010 Edition.
Before that those were the requirements:
2004 Edition - no special requirements regarding those kind of fittings.
2007 Edition - clause (6) were added "The minimum wall thickness shall not be less that that of a Class 3000 fitting per ASME B16.11 for the nearest equivalent pipe size."
Note that Code Case 3035 has brought back the option of using B16.11 only.

GD2,
Based on data that provided by the OP:
O.D = 28mm (O.D of #3000 B16.11 coupling)
Thread major diameter of 1/2" NPT = 21.3mm
C.A = 1.6mm
thk.=(28-21.3)/2 = 3.35mm
Thk. per Table UG-45 (for NPS 1) = 2.96mm+1.6mm=4.56mm
He will end up with thinner wall thickness than required by Table UG-45.

 

[DriveMeNuts]

The definition of the neck thickness does baffle me. I would have thought that it would be the thickness away from the thread.

ANSI B16.11 requires 4.09mm thickness away from the thread for a half inch coupling. Subtract 1.6mm of corrosion equals 2.49mm. That scapes passed Table UG-45 minimum of 2.42mm.

Establishing the pressure rating of the corroded threaded connection will be another even more difficult mission? Going with 6000# avoids that headache. Hasn't someone else recommended this???? If the 3000# has corrosion allowance was 0.91mm, then that reduces it to the thickness and therefore pressure rating of a 2000# coupling. Pressure rating of corrosion beyond that is anyone's guess.

 

[r6155]

See UG-45

t b 1 = for vessels under internal pressure, the thickness (plus corrosion allowance) required for
pressure (assuming E = 1.0) for the shell or
head at the location where the nozzle neck or
other connection attaches to the vessel but in
no case less than the minimum thickness specified for the material in UG 16(B)

"Other connection" include the coupling, then UG-45 is required.

Regards

 

[DriveMeNuts]

Table UW-16.2 Note 1, refers to threaded coupling openings as 'nozzles'.
The part of the coupling welded to the head, isn't threaded. If this was a full length parallel thread, then the thread would need to be considered when calculating the neck thickness.
This half inch couplings is exempt from nozzle reinforcing calcs.

 

[IdanPV]

@DriveMeNuts,
Which Table are you talking about, I can't find Table UW-16.2 in VIII-1?

 

[IdanPV]

If someone could kindly point me to the section in the Code that DriveMeNuts relies on, I would greatly appreciate it. This information is of significant importance to me.

 

[david339933]

Fig. UW-16.1 Note 1.

 

[IdanPV]

Thank you david339933,
But I have a hard time understanding how he came to the conclusion he reached from Fig. UW-16.1 Note 1.
can you explain?

 

[david339933]

I can only explain the part about calling couplings "nozzles"....the rest makes no sense to me. In my experience the majority of the time the threaded part of the coupling is where the weld lies.

 

[IdanPV]

Thanks again,
I suppose I'll have to wait until he arrives to provide his explanation.

P.S.
Is there a method to directly contact members of this forum?