PV with SW Connections Hydrotest 4

[abuanaselmasry]

Our client insists to have a socket weld coupling as a temperature gauge nozzle in NPS 1 or less Size. My question is; Does any one have a past experience with this nozzle end configuration? How was the hydrotest conducted? Is there any code reference to allow opening and welding these connections after hydrotest with some further NDT?

There is one trick which I don't like to use it. The vessel can completely fabricated according to ASME VIII Div. 1 with ignoring all SW nozzles, and then welding of all SW connection as a repair work according to NB in which the hydrotest of such small connection attachments weld. But, it is not intention of NB code to applied for new vessels, and doesn't look good to supply a new vessel with both ASME-U and NB stamps.

Could you please advise.

Regards,
M.Salaheldin
Static Equipment Mechanical Design Engineer

 

[jte]

Install a SW half coupling on the shell, weld a piece of pipe into it, then cap the pipe, then hydrotest, then ship: the client then has to either a) cut the pipe and install a SW coupling on the PIPE (1 weld) and then weld their thermowell to it (another weld), or the client needs to cut the pipe out of the socket, install the thermowell, weld it in (1 weld to the vessel's pressure boundary), and then re-hydrotest the whole vessel, plus some R-stamp paperwork and an AI visit.

Same goes for a thread that has to be seal-welded: the seal weld requires a weld to the pressure boundary requiring a re-hydrotest.

moltenmetal-

I don't understand your basis for stating that the vessel in either case above must be hydrotested. In your first example, cutting the pipe out of the socket and welding a thermowell in does not require a Section VIII hydrotest. Simply put, the weld is a piping weld, and can be dealt with using additional NDE in lieu of a hydrotest.

Seal welding a threaded connection is also not a Code weld and thus does not require a hydrotest.

Can you clarify why you feel that these are Code welds?

 

[Duwe6]

Concur, jte. Talk to the AI first, so there are no supprises. Limit the U-1 to the coupling. First joint out is always under Pipe Code. Maybe the Pipe Inspector waives another hydro, maybe he doesn't.

 

[moltenmetal]

SnTMan, I'm not trying to argue with you either- I respect your point of view. You have a very good point as to what the right solution to the problem is, depending on what stage the work has gotten to by that point.

Duwe6 and jte: your interpretation of what "first joint out" means differs from the way our vessel guys interpret ASME VIII-1. The way they interpret it, any weld to the pressure boundary requires a re-hydrotest. Doesn't matter if it's a support clip welded to the shell or head, a spot weld of an insulation support post, or a seal or socket weld to a half coupling- it's a weld to the pressure boundary.

Can you substitute special NDE for the re-hydro? I take jte's word on that, as I haven't looked into the repair section of the code too much. We try to avoid "repairs" like this by design, to the extent we can. That would include moving thermowells to a flanged nozzle or including them in the vessel scope.

The way we are currently taught to interpret the last joint out would include the weld to any socket weld coupling in the pressure boundary. Welds to the pipe itself are in pipe scope. But any weld in piping you can't hydro needs to be subjected to special NDE and a sensitive leak test, again unless I've misremembered the codes. Same problem- same solution in my opinion.

 

[Duwe6]

" your interpretation of what "first joint out" means differs from the way our vessel guys interpret ASME VIII-1"

'Therein lies the rub.'

ASME VIII is only for construction of the vessel. Thus the rehydro [in the shop] makes some sense. Installing and repairing the vessel comes under National Board - NBIC - and/or API 510. That is delineated in the front of all three Codes. And once the U-1 is signed, the first connection out is indeed a 'pipe-code' connection. That part is in NBIC [don't think it's in 510].

Don't take my word for it, just call your state Boiler & PV board [I did - Indiana]

http://www.nationalboard.org/ViewMembers2.aspx

 

[jte]

The way they interpret it, any weld to the pressure boundary requires a re-hydrotest.

I don't see a need for nor any advantage in discussing whether a ladder clip field weld to a 1" CS shell would require a rehydrotest of the vessel. This thread is about making a connection to a nozzle which by its design is meant to have a welded connection.

In this case, I'm not interpreting the code. I'm leaving that to the Code Committee, and copied their thoughts as published in Interpretation VIII-1-89-115 in my post of 17 June above.

Your folks can choose to apply requriements more stingent than the intent of the Code Committee. Certainly I require much more than simple code compliance for vessels which we purchase. But I will choose to not be more stringent when it comes to welding B31 piping to a nozzle which is meant to be welded to. For what its worth, my company vessel spec's would not allow a SW connection to a vessel; all nozzles are to be flanged. Thus, I would hope to not deal with the topic of this thread with a newly purchased vessel. But we have vessels in service which are much older than I am, and not all new vessels are purchased strictly in accordance with company spec's.

To each their own... All I ask is that we be clear about "I choose to" as opposed to "the Code requires" statements.