Non-pressure Welds to Section VIII Div I Vessel

[mechhou]

Hello:

Eventhough I have benefitted a lot from reading the various posts, this is my first one. Hopefully not a repeat post.

We have a water seal drum which is designed to ASME Section VIII Div I but not code stamped. Is it possible to weld non-pressure attachments to it without having to hydrotest it again.

Also, what determines when a vessel has to be stress relieved.

 

[metengr]

We have a water seal drum which is designed to ASME Section VIII Div I but not code stamped. Is it possible to weld non-pressure attachments to it without having to hydrotest it again.

Yes. This would be an in-service weld repair.

Also, what determines when a vessel has to be stress relieved.

Base material thickness and chemical composition.

 

[DVWE]

Read the first part of UG-99.

For your stress relief question, do you mean Post Weld Heat Treatment? The two are often mis-used. PWHT requirements will be spelled out in the sub-section for which the material of construction is found (i.e. Carbon steel vessels fall under part UCS. UCS-56 dictates PWHT requirements).

My thoughts are this: If the vessel is not code stamped, it should be agreed upon by the end user and the manufacturer if the vessel should be re-hydroed.

 

[bam8888]

To answer the first question, if the vessel is not stamped then it technically does not have to follow the requirements of Sec. VII, Div. 1, thus you should be able to weld non-load bearing attachments w/o hydrotest per ASME code.
That being said, you need to be sure and comply with local jurisdictions and contact your local AI to see if they require any specific testing. Also make sure that the attachment is truly non load bearing.

The National Board Inspection Code-Part 3-S4.18.2.6 - Type 5 - Miscellaneous General External Repairs or Alterations, states that external repairs or alterations on non-pressure parts shall be "calculated" to the original code of construction, and reviewed by the AI and a P.E., but it does not require a pressure test.

 

[bam8888]

Sorry, when I say "load bearing", I also mean non-pressure retaining parts as well.

 

[curtis2004]

Correct me if I'm wrong. I guess if it's not U stamped, you can do whatever you want. Because it won't change it into "U" stamped unit anyway. This is from ASME BPVC Section VIII, Div.2. prospective.
However, if you ask what can be done in order safely and properly to weld - that's another question.

 

[bam8888]

I agree with curtis2004, if it is not code stamped, you wont need a repair or alteration stamp. I am concerned however, that you asked about stress relief in the same query. Is the original vessel PWHT?. If so, you cannot make any further weld attachments to the vessel w/o subsequent heat treatment, at least around the area of the weld.
On a side note, please disregard my previous reference to particular NB spec, that was an incorrect paragraph reference.

 

[metengr]

If so, you cannot make any further weld attachments to the vessel w/o subsequent heat treatment, at least around the area of the weld.

Incorrect. The NBIC, Part 3 Repairs and Alterations allows alternative weld repair methods in lieu of PWHT.

 

[jte]

metengr-

If the shell was 2" thick SA516-70 and PWHT for code reasons only, would adding a 3/8" ladder clip with a double 3/8" fillet require PWHT? Unless I'm mistaken, that particular weld would not require PWHT per Div. 1.

jt

 

[metengr]

jt;
You are correct, no PWHT would be required for the attachment welds.

 

[starrproe]

metengr,
Can you please direct me to relevant section of Code (ASME-VIII-1) which says that PWHT will not be required for the attachment welds?

Regards,
Starrproe

 

[metengr]

starrproe;
In Section VIII, Div 1 look at Part UCS, UCS-56 for P-No 1 material. Review the definition of nominal thickness.

 

[DVWE]

Also in addition to metengr's comments above, UCS-56 (f) will permit welding for P-No. 1 materials without PWHT. But, as per the OP, this should be done prior to final hydro.

 

[jte]

...unless the welding is being performed in the field post-construction under the auspices of a repair code such as NBIC (NB-23) or API 510.

In addition to reviewing the definition of nominal thickness as it pertains to weldments, review Table UCS-56 Note (2)(c)(3). In my example above, provided a preheat is provided on the shell the fillet welds could have been 5/8" and still had a throat thickness less than 0.50" so no PWHT would be required for that weld.

It's sometimes useful to remember that we PWHT individual welds, not vessels. For convenience we sometimes place the entire vessel in the oven, but that is not a requirement.

jt

 

[DVWE]

4 Feb 10 13:29
...unless the welding is being performed in the field post-construction under the auspices of a repair code such as NBIC (NB-23) or API 510.

Agreed. But since the vessel is not code stamped, the end user should be at least made aware that his vessel is going to have parts welded on to it after final hydrotest.