RT for vessel

[eegyman5000]

when a vessel is to be radiographed (full) according to design drawings and ASME VIII DIV.1,the vessel is 30 mm
wall thickness,should i include nozzle to shell in radiography,and if it is impractical should i use UT in lieu?
finally can any body tell me or give me a simplified
brief in a document form for the scope of application of radiography (shell,nozzles,...)in terms of:
wall thickness,material,service
thank you

 

[AravindSujay]

hi eegyman,

though a late answer, for the first part, answer is yes-use UT. further pls read the below,

Full radiography is mandatory of joints as per UW-11 for

1. All butt welds in shells, heads, nozzles, communicating chamber of unfired steam boilers having design pressures exceeding 50 psi and vessels containing lethal substances

2. All butt welds in vessels in which the least nominal thickness at the welded joint exceeds 1 1/4" of carbon steel and 1 1/2" of SA240 SS. exemption-cat B & C butt welds in nozzles and communicating chambers that neither exceed 10" pipe size nor 1 1/8" wall thk

3. Cat A & D butt welds in vessel sections and heads where the design of the joint or part is based on joint eff 1.0 or 0.9

4.All butt welds joined by electroslag welding and all electrogas welding with any single pass greater than 1 1/2".

Ultrasonic examination may be substituted for radiography for the final closure seam if the construction of the vessel does not permit interpretable radiograph.

Hope it is clear after reading my detailed reply. Still if you want more, refer ASME SEC VIII, DIV 1, UW-11.

Cheers,
Aravind Sujay

 

[JoeTank]

Further to AravinSujay's answer...
RT is only required for the shell-to-nozzle weld if it is truly a BUTT weld. Most of these joints are CORNER joints, not butt welds. A full penetration weld is not necessarily a butt weld.

Joe Tank

 

[decode]

That is partially true, for instance UHT requires RT for non-butt nozzle to shell/Head joints, See UHT-57 and Fig. UHT-18.2 and those are corner joints. In fact they say "...radiographable with difficulty and generally requiring special techniques..."

Decoder

 

[jehan17718]

eegyman5000 (Petroleum):

WRT to your original post, nozzle to shell welds are CAT D joints. Typically they cannot be radiographed unless they are the type shown in Fig UW-16.1 (f-1), (f-2), (f-3) or (f-4). This type is a forging (higher cost) and is agan a requirement based on the vessel service requirements and specs. For example, for certain certain service (like hydrogen), pads are not allowed and also nozzle to shell joint requires radiography. Another example is nozzle /vessels in fatigue service.

Standard nozzle [with reinf pads] to shell wellds are corner joints whose NDT cannot be done by radiographic means.

Hope this helps.

-Jehan

Hope this helps.

 

[Heehaw]

Can anyone point me toward volume and weight and surface area formulae from fisrt pricipals for 2:1 Ellipsoidal heads for r1 = 0.9 x D1 r2 = 0.17 x D1 to ASME VIII Div 1

 

[vesselfab]

heehaw
any head manufacturer can tell you this, but, it is readily available in the Pressure vessel handbook by Megyesy.

just for future reference, there are no true radii on 2:1 ellipsoidal heads. those are approximations and every head manufacturer uses a slightly different formula for attaining an ellipsoidal profiles that's depth (both sides) is one half the diameter.

And please, if you have a question....make another thread instead of tacking on another thereby hijacking it.

 

[jehan17718]

heehaw:

Offhand the volume is i.e the ID volume of a semi-ellipsoidal dishend= pi/24*D^3 where D is the inside diameter.

This volume represent the "ID volume" i.e. the volume of the fluid contained by the 2:1 SE dishend and should not be confused wit hthe metal volume.

-jehan