Welding joint as per ASME SEC VIII Div1, figure UW-16.1 (a) for lethal service

[ChiangJaron]

Dear All,

I have a urgency question as subject mentions about welding joint.
Refer attached figure.

The design base code is ASME SEC VIII Div.1
It's a lethal service of internal liquid.

As per UW-2 request that all category D joint shall be full penetration welded.
In order to reduce welding thermal effective such as deformation of flange during welding.
I would like to change welding method from insert type to abutt type as attached figure.

A corrosion resistance alloy sleeve to partial welding, and long welding neck flange abutt welding on blind flange.
The LWN flange beveling and full penetration welded as it.

My question, the welding whether satisfy the code requirement or not ?

Thanks

 

[stan000]

My understanding
for optimum strength all butt weld should be full penetration welds . in corrosion services , any cervice resulting from lack of penetration is also a potential site for crevice corrosion.

stanly

 

[SnTMan]

ChiangJaron, it appears to me that your detail - LWN to blind - does meet the Part UW rules for lethal service, it is a full penetration detail.

I am less happy with your lining detail, but I don't think it is within the scope of the lethal service requirements. I'd prefer weld overlay of the opening in the blind.

Refer to Part UCL, especially as regards fabrication and inspection.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[ChiangJaron]

Dear all,

Thanks for your suggestions and discussion in this matters.

As you say, the best method one is application full inset nozzle and penetration welding,
and the other is deposited welding instead of sleeve into opening.
But, there are further question as above method in actually activity.

What do you think about that the blind flange thickness over 100 mm and more? full penetration welding is not easy proceeding.
What do you think about that the opening hole size too small such as 20 mm and less? deposited welding is not feasible.

I think above situations may occur in actually.

Are there any better ideas to do that.

 

[SnTMan]

ChiangJaron, for a situation such as yours, I think a set-on, full penetration detail such as Fig UW-16.1 (a) is acceptable.

I know some weld overlay equipment is available that will overlay into about a 2" opening, such as a 2" LWN. For smaller openings, or in the absence of the proper equipment, a loose type liner would have to do.

Again, I don't think Code rules for lethal service apply to cladding / overlay / liners, so that your proposed detail is acceptable from that standpoint. Just wouldn't be my first choice

On Edit: I am concerned about your detail where the sleeve joins the liner at the blind inside surface. Better to eliminate the apparent crevice by welding the two together.

Regards,

Mike


The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[r6155]

Lethal service require special details. Costs are in second plane.
My suggestions are:

1)Change location of this nozzle, not on blind flange.
or
2)Blind flange of alloy steel same as nozzle. Nozzle weld details as per fig UW-16.1(a) and 100% UT.

Regards
r6155

 

[GenB]

Why not using a std weldneck and but weld it per Code. Insert the alloy tube and do the same overlay. Consider inserting the machined L.W.neck buttweld it and weld the end at the bottom. Instead of the flat blind cover. Just a suggestion worth studying.

General Blr. CA,USA