1. Is it permissible for manhole opening (24”) requiring reinforcement to have a reinforcement pad made from two halves, welded at “split line” at root to the shell and welded together as a V joint with full penetration. The split line is parallel to longitudinal shell axis. There are 2 telltales holes. Engineer’s calculation shows as per UG-37 round reinforcement plate. Vessel is 100% RT (Client requirement). 2. What category would be this joint if any, what NDE would be required, if any. 3. Is there any interpretation on the subject or practical approach to the problem (it is nothing new but not for me).

Thanks, Jan Chodacki

Nice question,

we will discuss it in our training session.

My first reply: - Assuming we have no special service (UW-2) and wall thickness is below the limit of UW-11 , UCS-57, etc. - ASME Code requires no RT - This is no category A, B, C, or D (read UW-3) - There is no E factor in the A5 calculation for the reinforcement. - I do not know what the customer wants, they have to ask him. If his full RT does not include fillet welds, this weld would be exempt as well.

Best regards Dirk Kölbl

I confirm answer given by Dr. Koelbl. For a nasty client who argued on 2 pieces pad whilst on approved dwg was integral I suggested, successfully,to weld two parts first (double welding and ground flush the part to be in contact with vessel shell) full XRay and then apply as an integral one. But it is not a Code issue. Regards. MG

Thanks for reply, I should put little more background info. Your assumption for this case is correct, shell and pad 13 mm thick so any RT requirement is no code issue. The manufacturer prefabricated the manhole and welded the flange to it and next started to the assembly to the vessel. At this point found that there was a difficult access weld manhole to the shell, the reinforcement pad hindered it due to its curvature (ID 2000) so they divided it. But to my mind if it is acceptable solution the joint should be treated as a category A since it is a pressure part as per UG 4a and as a compensation for taken away portion of the shell which should be of equivalent properties, UG 37 refers to Dp = outside diameter of reinforcement element … (in singular), but I may be wrong.

Sure it is a pressure part, and it needs to meet Code.

The key question is what the customer means by "full RT".

But the Code does not require RT, and does not classify it as a Category, the text is quite precise:

(1) Category A. Longitudinal welded joints within the main shell, communicating chambers,2 transitions in diameter, or nozzles; any welded joint within a sphere, within a formed or flat head, or within the side plates3 of a flat-sided vessel; circumferential welded ... etc. (4) Category D. Welded joints connecting communicating chambers2or nozzles to main shells, to spheres, to transitions in diameter, to heads, or to flat-sided vessels, and those joints connecting nozzles to communicating chambers...

This does not include the weld in the re-ring, I think.

Thank you Mr. Gonzaga for the advice it is, what I was thinking of. The trouble was that the manufacturer had taken wrong sequence of doing the job and had to split the pad to have an access for welding of the nozzle. The matter is clear no the Code worries. Best Regards.

A useful advice for welding reinforcing pads on thin wall. . Cut the hole into the shell duly chamfered . Prepare the reinforcing pad by rolling to right shape and with an internal diameter a bit larger (e.g. 4 mm.) and with much lesser chamfer angle or no angle at all. .Fit the reinforcing pad and perform a fillet weld between reinforcing pad and shell (on the crown between the two cincumferences, inner pad and nozzle opening) . Perform fillet weld on outside circumference of pad. . Fit the nozzle in place. . Complete the weld around the nozzle (the lesser angle of the reinforcing pad weld preparation will reduce amount of welding material having a U shaped groove. The advantage of this preocedure is that since pad well connected to to the shell, it makes shell double stronger to resist to set in caused by shrinkage when welding between nozzle and shell and pad. Regards. M.Gonzaga

This is a typical issue when Client has reasons to require something (it was in dwg in one piece and in addition, if there is a NC he has the right to accept or not), which is beyond Code requirements. This is also the typical situation where the AI should defend his Manufacturer by writing on headed paper a letter explaining Code requirements. The most of the times Clients is assured by an AI interpretation and accepts. You are encouraged to do so and I am sure Dr. Koelbl will have no objection. Good luck. M.Gonzaga

I feel the if the RF pad is made out of two halves then the but joint of halves should be 100% radiographed considering joint efficiency 1.0, or the pad thk. should be increased after design calculations considering E = 0.7

Regards,

anant.

Sorry, reading UG-37 I can not find an E value for the RE pad.

In my opinion it is not required to RT, except when the thickness exceeds the limits of UCS-57 or UW-2 or the material (e.g. duplex) requires it.

I would say that SecVIII-1 does not prohibit sectioning reinforcing plates. Those who need it- goto U2(g). This would be clear if the section line is parallel to shell axis. But if it's perpendicular- then it might be a nice subject to a long discussion.
UG-37:
Reinforcement shall be provided in amount and distribution such that the area requirements for reinforcement are satisfied for all planes through the center of the opening and normal to the vessel surface. For a circular opening in a cylindrical shell, the plane containing the axis of the shell is the plane of greatest loading due to pressure.

Needs a Philadelphia Lawyer to understand...

Konrad

How about in the case where the vessel is specified as a "lethal service " and UW-2(a) does not categorize the joint but only says "butt welded joints"

Unless the rules are not clearly interpreted, some manufacturers will have trouble when customer audits reveal this discrepancy and point to the fact that the split pad has a "butt weld"

Now I am not saying that I agree that it should be X-rayed per UW-2(a), just that the Code needs to clarify this requirement if they put words in the Code that say "all butt welded joints"

Here is the Code paragraph for your review: PS Lethal is defined by the User per their design specifications.

(a) When vessels are to contain lethal1 substances,
either liquid or gaseous, all butt welded joints shall be
fully radiographed, except under the provisions of
UW-2(a)(2) and UW-2(a)(3) below, and UW-11(a)(4).

_________________
A question properly stated is a question half solved.

As discussed earlier, for LETHAL SERVICE the split pad joint shall be RTed, no doubt.

My thought was to make two crescent- like pieces, so that they only touch at a point or even don't touch at all. No joint- no examination.

_________________
Konrad Anikiel

Making two cresents is not understood, Konrad. Could you explain?
I just have had the case of a reinforcing pad cut midway parallel to vessel axis and I started thinking I imagined the situation to the extreme, i.e. the long split line was not welded at all..... It would happen that the reinforcing pad is completely useless in the most unfavourable direction. That means that it shall be welded before be positioned on the shell and RTed to ensure same resistance of the integral (Table UW-12, weld Type 2) or the efficiency be taken into account in accordance with degree of RT examination (weld Type 2). In my case the most of the reinforcing pad was used to resist external loadings and even with thickness reduced to 65% was enough for the compensation due to pressure.
Mauro