Is cross-wise welding strictly prohibited? 4

[etsen]

Is cross-wise welding strictly prohibited in pressure vessels? Thanks in advance.

 

[JStephen]

Cross-wise welding is not a common welding term- can you describe what you mean a little better?

 

[etsen]

---------------
| | |
| | <-- | the longitudinal weld in the top shell
|----|--------| <--the circumferential weld between them
| | <-- | the longitudinal weld in the bottom shell
| | |
|----|--------|

the two longitudinal welds are on a line and form a "cross-wise weld" with the circumferential weld.

 

[etsen]

So is this type of weld strictly prohibited in AD 2000 or PD 5500 or other standards and regulations? Thanks.

 

[unclesyd]

Are you asking if the longitudinal seams can be in line and form a cross with horizontal weld?

 

[SJones]

PD5500 is not definitive: "where practicable, longitudinal seams of adjacent courses shall be staggered by 4 x wall thickness or 100 mm whichever is greater"

Steve Jones
Materials & Corrosion Engineer

http://www.pdo.co.om/pdo/

 

[JoeTank]

It is permitted in ASME VIII, Div 1, but radiography is required at the joint. RT is not required if the long seams are offset by at least 5t (t = plate thickness).

Joe Tank

 

[decode]

UW-9(d) is what you need, this is specifically accepted under the listed conditions

 

[etsen]

Thank everyone very much for replying to me. The longitudinal seams are in line and form a cross with the horizontal weld beween shells in a pressure vessel. Is it permitted in AD 2000 code - technical rules for pressure vessels. Thanks.

 

[MJCronin]

etsen,

Here is my "two cents worth".....

As stated above, these joints are permitted by ASME VIII (with additional radiography)......but many clients sure as hell do not like them. Old timers are suspicious of them and have seen leaks start at these locations.

They also know that they can be prevented with proper shell segment planning.

Clients seem to feel that they are symbolic of a poorly fabricated vessel and poor design work.

Many API-653 tank inspectors are instructed to look very carefully at these joints on flat-bottomed tanks.

-MJC