Need help from experts to solve this problem 2

[Ramezadel]

good morning
i am facing a critical problem with one of my company pressure vessels used in transporting (propane and butane ) according to ASME 8
Here is the case :

while trying to weld a crack appears at front head at the semi trailers made of (ASTM A 517 grade B )
The crack was about L1 = 14 CM (crack no.1) as shown in fig and it passes through weld line between head and shell (12 mm ) we stop the crack and weld it using filler metal 11018 M notice that the thickness at front head range from (5.6 mm to 7.5mm ) .
The day after while we inspecting crack and ready to perform post weld heat treatment another crack appears of length L2 = 7cm (crack no.2) at distance around D1= 9 cm from first crack almost parallel to first crack .
While trying to preform same operation another crack appear (crack No.3) with length of L3=7 cm at distance around D2=10cm from crack no.2

 

[r6155]

It is seen that the welding repair is not of good quality.
I understand that it was welded in overhead position, and welding procedure was not applied.
Consult a welding engineering.

Regards

 

[Dhurjati Sen]

Dear Ramezadel,

From the figure, it seems that you need to partially replace the plate (weld to weld) NOW.

Regards.

DHURJATI SEN
Kolkata, India

 

[Don56]

When you PWHT'd the first repair was the area of repair 2 and/or 3 heated?
What was your PWHT procedure? Ramp up,soak temp, time, ramp down?

 

[david339933]

Shouldn't you be using Sec XII?

 

This is ugly.
Call in a welding engineer who has actual experience with this alloy, which if I am not mistaken is preferred for transport tank construction due to its favourable strength/weight ratio. Repairing with E11018M may be jumping from the frying pan into the fire (that expression is more apropos than I would wish).
Prepare yourself and your boss for the possibility of completely scrapping this tank. Because LPG.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[chicopee]

Being an LPG tank used in the transportation industry, isn't the tank bearing an affixed ASME/NB plate with all required information about the tank? if so then the repaired tank will required a R stamp that can only be provided by a welding firm having all the necessary paper work and stamps as well as qualified welders performing the repair.

 

[Sharik]

I would recommend getting a 'boat' sample of the base metal and HAZ and sending to a qualified lab. If there is HIC or SOHIC present, then the welding required for the repair gets much more complicated, preheat temperatures, PWHT, etc.

 

Red herrings Sharik. This problem is happening on the vessel exterior.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[Ramezadel]

ironic metallurgist
can you explain more ?

@DON 56 this happened before performing PWHt

 

[DekDee]

Is this what you really meant in your posting ?

Need help from experts (who will work for free) to solve this problem (because I have no money to pay for the appropriate person to resolve this - a Welding Engineer)

 

[Ramezadel]

@ DEkDee
Easy man
we share experience and some post are very helpful

 

[DekDee]

Ramezadel,
In your first post you stated you had a " critical" problem.
Instead of hiring an expert you have decided to try and resolve it for free via an internet forum.

 

Two comments on these types of enquires in general:

1) It would be more helpful to the OP if non-experts refrained from posting their uninformed speculations about mechanisms and causes. If I have nothing to say I don't say it.
2) Failure analysis is NOT done by crowd-sourcing on internet forums, it is done by experts. That will cost money.


"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[CuMo]

All I can think off without being an expert - if you weld one crack - there would be a certain amount of shrinkage in material
which will cause the appearance of another crack and so on.
I would suggest replacing a whole section of the vessel as it doesn't look safe at all.

 

[weldstan]

I would think that this is a material related problem possibly created during head manufacture in addition to the potential restraint of the nearby welded attachment plate. Only a metallurgical analysis will provide appropriate cause of cracking and repair remediation.

 

[r6155]

I remember my work 50 years ago in an international company during the construction of cargo tank with SA-517 Gr E
Quality control was performed minute by minute. Nothing was left uninspected
Very different from what I see in this case.

Regards