Grade P11 Weld failure between ellipsoidal head and tubesheet 2

[qualitypro]

We encountered a weld failure between an ellipsoidal head and the tubesheet material in the field even before the equipment had been started up. The head in the new HX equipment was over 3 inch thick and had gone through all necessary preheat, NDE, PWHT, hydros etc in an overseas shop with no anomalies. What could be the potential causes for this failure? Appreciate if anybody can share any past experiences with HX weld failures.

 

[EdStainless]

So you witnessed all of the welding, NDT, PWHT and such?
My hunch is that somewhere in that list something wasn't done correctly.
Exactly what is the nature of the failure?
Centerline or fusion line? How long is it? What location?

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[0707]

your question is too vague...

 

[dik]

I suspect as Ed notes... something may not have been done correctly.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[qualitypro]

@EdStainless..the crack starts in the weld centerline from its initiation point and went circumferentially for abt 5 feet along the weld before it propagated diagonally into the dish head for about 3 feet.

 

[r6155]

More info: CODE, picture, sketch with complete dimensions, material, WPS, .........????

Regards

 

[qualitypro]

@r6155...ASME VIII Div.2, Grade P11 material, 60 feet tall x 6 feet ID x 3" thick bottom dished thick end

 

[r6155]

More info: sketch?, any photo?
What does the manufacturer say?

Regards

 

[r6155]

Was RT taken before or after PWHT?

 

[DriveMeNuts]

What code sketch is it?
If the head is welded to the tubesheet, some sketch geometries require that the straight flange be less than 2 inch and greater than 7 inch, and ban in between.

 

[0707]

Whom witnessed the "so called no anomalities" in overseas shop?

 

[weldstan]

What was the time between weld completion and final PWHT?

 

[david339933]

What is Grade P11 material?

 

[GD2]

Where in overseas the HX was manufactured?
What is the shell thickness?
Did you do a local hydrotest at your facility? If so, what was the ambient and test temperature?

GDD
Canada

 

[weldstan]

david339933, This is a low alloy steel containing approximately 1.25% to 1.5% Cr and 0.5% Mo and </= 0.15% C depending on grade.

 

[david339933]

Thanks, weldstan...it was kind of tongue in cheek, as there is no specification listed. Is it SA-387? There is no P-11 only grade 11, Is it SA-335 P11? Not for a tube sheet or head...

 

[qualitypro]

The weld was RT before and after PWHT with no relevant indication and hence accepted. The ellipsoidal head material is ASTM A387 Gr.11 and 3 " thick while the tubesheet is ASTM A336 Gr.F11 and 9" thick. Joint design is attached herewith.

 

[r6155]

Incorrect design. Internal fillet weld is required according to table 4.2.6 detail 2
This weld is not readily radiographable.

Regards

 

[weldstan]

If this weld was RT'd, any information obtained is highly doubious.

 

[r6155]

@ qualitypro
Now you have SCRAP, not a pressure vessel.
You should contact a pressure vessel engineer with extensive experience in design, manufacturing and inspection. This person acts as an inspector during manufacturing.

Also contact a lawyer

Regards