UNI EN 12952-3

[mrgg]

Hi everyone,
i have an issue with the European Standard in subject.
In particular, ther para 6.3.6 says:

"When the creep properties of the welded connection are not known, but those of the filler material are known,
the design strength for this loading shall be reduced by 20% from the smaller of the design strengths of the
joined materials. When the creep strength of the filler metal is not known, the joint strength shall be reduced
by a further 20%"

In the second case, when the creep strength of the filler metal is not known, the joint strength shall be reduced by a further 20% means that the strenght shall be reduced of:
-20%+20% of initial strenght ( so 40%) or
-20% of 20% Initial strenght (so 36%) ?

Thanks

 

[hardbutmild]

It's not my area of expertise, but as I see that no one has given any advice I'll try to give you my point of view. I know a bit about the way standards are written (although not much, and only for structures, but I guess the same principles apply).

"Further 20%" seems like a first option to me the way it's written. In addition, it seems to me that a welded connection is a critical part of a system and I'd rather overdesign it by a few percent, than underdesign it since its failure may lead to problems. Then again, I know nothing about the design of these elements so maybe I'm wrong, maybe it's not a problem if it fails or a few percent of difference is a lot to you. The difference between 36 and 40% seems extremely small to me.

 

[XL83NL]

Sounds like 40% to me.
Regardless I’d go with 40%. It’s hard to imagine that extra 4% would make a big difference.
The other way around is more difficult. You don’t want to end up in a situation where you have to convince someone that 36% is acceptable when that person thinks it should be 40%: it ain’t worth trying to take credit for 4%.

 

[mrgg]

Thanks for your help.
Understood the point, and it seems legit.

Thanks again