Weld neck flange weld to pipe dummy question

[mariolucas75]

Dear All,

I have a dummy question ....

What are the references for welding a weld neck flange to pipe - in terms to what NDT to be done and where and when?
Root pas ? subsequent passes ? What is the NDE requirements depending of fluid service ?
Code of construction is B31.3

 

[LittleInch]

B31.3 is its own code for welding and inspection, i.e. it's all in there if you look carefully.

 

[mariolucas75]

Littleinch ... please ... approaching you modestly....
To more narrow your direction ... paragraph chapter ....

 

[LittleInch]

Try chapter V or just look in the index....

 

[mariolucas75]

I ve gone through B31.3 Sections V and VI - for example

341.4.1 Examination — Normal Fluid Service:
"At least 5% of circumferential butt and miter
groove welds within each designated lot shall be subjected
to random examination by radiography in accordance
with para. 344.5 or by ultrasonic examination in accor-
dance with para. 344.6.

344.6 Ultrasonic examination - for sizes >DN 50 (>NPS 2) and ≤DN 450 (≤NPS18), once in each 1.5 m (5 ft) of welding examined

also it says at other place some particular percentage of total welds etc etc ... but in this particular case there is one 18" weld neck flange-pipe weld, also i could not find if there is anything about extent of NDE depending on number of beads .... ? P.S. No RT is available - only UT or MPI can be done...

 

[Snickster]

Would not welding of a flange to pipe be no different from welding a circumferential pipe joint? I don't recall weld of WN flanges to pipe being treated differently.

 

[LittleInch]

Not everything is in a close which generally provides the MINIMUM that you sound so. What you do is up to YOU.

A large number of weld you can take a percent approach which can vary from the minimum to 100%. A single weld is up to you. If your question is whether a flange weld is any different to a pipe butt weld the answer is no.

 

[mariolucas75]

LittleInch may I ask you what would you have specified as an NDT for 18" weld-neck flange weld to pipe (normal fluid service) ?

 

[LittleInch]

As a one off, I would X ray it probably.

 

[EdStainless]

I have a client that used 100% PT, and UT of the start/stop portion at least 1" beyond each end.
If there were tack-welds he also requires UT 1" either side of those.
That is just one person's opinion.
He is in an environment where RT isn't available (high risk of interfering with instruments that use radiation).
When he has spools fabed outside they are 100% x-ray.

 

[mariolucas75]

I have a client that used 100% PT, and UT of the start/stop portion at least 1" beyond each end.
If there were tack-welds he also requires UT 1" either side of those.
That is just one person's opinion.
He is in an environment where RT isn't available (high risk of interfering with instruments that use radiation).
When he has spools fabed outside they are 100% x-ray.

This condition is the same - no RT can be done ... can you expand in more details please ?
Why it was selected a PT ? (no carbon steel ? not practical to run MPI ?)
" the start/stop portion at least 1" beyond each end: I did not get the sentence ...

 

[EdStainless]

they were allowed to use MPI or PT.
It depended on materials, there was a lot of SS and Ni alloy in this plant.

The welders had to mark the location of start and any tacks prior to welding.
The stop was apparent after welding.
The UT had to extend at least 1" either side beyond these locations.

 

[mariolucas75]

they were allowed to use MPI or PT.
It depended on materials, there was a lot of SS and Ni alloy in this plant.

The welders had to mark the location of start and any tacks prior to welding.
The stop was apparent after welding.
The UT had to extend at least 1" either side beyond these locations.

Would a number weld beads have any impact on it ?