Certification of Tack Welds ASME-BPE, B31.3 2

[Spike2000]

Folks
for ASME-BPE Certification it is required for tack welds to be certified, similar to full GTAW welds.
the welders are to be certified Section IX as full welds are.
not an issue, however does any one know how to qualify the welds? you obviously cannot bend test
thank you

 

[XL83NL]

Never thought of it but it isn’t mentioned. What I’d assume is that whoever welds the tack welds, root, fill layers and final cap, needs to be ASME IX certified, using a certified PQR/WPS. I.e., the tacks fall under a previously qualified method. Whether or not that method was qualified initially with tack welds in place, doesn’t seem to be mentioned.
Section IX does mention however tacks (QW-303.1):

QW-303.1 Groove Welds — General. Welders and welding operators who pass the required tests for groove welds in the test positions of Table QW-461.9 shall be qualified for the positions of groove welds, tack welds in joints to be groove or fillet welded, and fillet welds shown in Table QW-461.9. In addition, welders and welding operators who pass the required tests for groove welds shall also be qualified to make fillet welds in all thicknesses and pipe diameters of any size within the limits of the welding variables of QW-350 or QW-360 and tack welds in joints to be groove or fillet welded as limited in Table QW-461.9, as applicable.

Huub

 

[EdStainless]

We always took it to mean using certified welders and procedures for the tacks, just like for the full welds.

There are some BPE jobs that either prohibit tack welding or have their own special requirements.

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P.E. Metallurgy, consulting work welcomed

 

[gtaw]

AWS structural welding codes have provisions that permits the qualification of tack welders. ASME Section IX has no such provisions.

Best regards - Al

 

[DekDee]

Interpretation: 22-35
Subject: ASME 831.3-2008, Para. 328.5.1(c), Tack Welding Welder Performance Qualifications
Date Issued: October 5, 2009
File: 09-1003
Question (1): Does ASME B31.3, para. 328.5.1(c) require that tack welds, whether they are to
be incorporated into the final weld or be removed, be made by a qualified welder?
Reply (1): Yes.
Question (2): Does ASME B31.3, para. 328.5.1(c) require that tack welds be made to a qualified
WPS for that joint?
Reply (2): Yes; see para. 328.5.1(a).
Question (3): Does ASME 831.3, para. 328.5.1(c) allow tack welds on a groove weld joint to be
made by a welder qualified on a fillet weld test?
Reply (3): No. See ASME BPV Code Section IX, para. 303.2.

 

[EdStainless]

Thanks

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P.E. Metallurgy, consulting work welcomed

 

[DekDee]

A proposed B31.3 Code Case was discussed a while ago to require qualification of tack welders (both permanent and temporary) but this was not proceeded with as the changes to ASME IX (as noted in post by XL83NL) and QW 303.2 were deemed to be adequate.

QW-303.2 Fillet Welds — General. Welders and
welding operators who pass the required tests for fillet
welds in the test positions of Table QW-461.9 shall be
qualified for the positions of fillet welds, and tack welds
in joints to be fillet welded, shown in Table QW-461.9.
Welders and welding operators who pass the tests for fillet
welds shall be qualified to make tack welds in joints to
be fillet welded as limited in Table QW-461.9 and fillet
welds only in the thicknesses of material, sizes of fillet
welds, and diameters of pipe and tube 27/8 in. (73 mm)
O.D. and over, as shown in Table QW-452.5, within the applicable
essential variables. Welders and welding operators
who make fillet welds on pipe or tube less than
27/8 in. (73 mm) O.D. must pass the pipe fillet weld test
per Table QW-452.4 or the required mechanical tests in
QW-304 and QW-305 as applicable.

I have always wondered about " bullet" or " bridge" tacks in a butt joint - would they require the full groove weld qualification ?
IMHO " bullet" would fall under fillet but " bridge" I am unsure - you are intentionally not penetrating the root of the joint ?
Any thoughts ?

 

[gtaw]

My understanding has been that a tack weld made by an unqualified welder could not be incorporated into the final production weld, i.e., they had to be removed before the production weld was deposited.

A bridging weld is not intended to be incorporated into the production weld, i.e., it is the intent that the bridging weld be removed before depositing the production weld. That being the case, the welder making the bridging weld need not be qualified.

Best regards - Al

 

[r6155]

A serious company uses only qualified welders for butt welds in pressure vessels. I worked with several of them (including nuclear)
Skilled fillet welders are outside that work area.

I can't imagine a lifting lug welded with a welder qualified for fillet.

Welder identification symbol implies responsibility for that weld and this welder cannot be held responsible for any other non- qualified welder.

Welders qualified for fillets are used in welding of parts which have essentially no load -carrying function such as extended heat transfer surfaces,, etc. -

UW-31 CUTTING, FITTING, AND ALIGNMENT
Tack welds, whether removed or left in place, shall be
made using a fillet weld or butt weld procedure qualified
in accordance with Section IX. Tack welds to be left in
place shall be made by welders qualified in accordance
with Section IX, and shall be examined visually for defects,
and if found to be defective shall be removed.

Regards

 

[DekDee]

After a bit of research I have found.
B31.1 and ASME VIII appear to allow unqualified personnel to tack weld on open root butt joints but they must be removed before completion of the weld by a qualified welder.
B31.3 does not address the issue and I am currently trying to get some feed back on this issue.

 

[XL83NL]

B31.3:2018 addresses this in 328.5.1(c):

(c) Tack welds at the root of the joint shall be made with
filler metal equivalent to that used in the root pass. Tack
welds shall be made by a qualified welder or welding
operator. Tack welds shall be fused with the root pass
weld, except that those that have cracked shall be
removed. Bridge tacks (above the weld) shall be removed.

Huub

 

[DekDee]

XL83NL,
I am trying to understand the differences between the three main ASME fabrication codes.
B31.1 and ASME VIII seem to state anyone can tack weld an open root joint but if they are not qualified then the tack must be removed before completion by a qualified welder.
B31.3 seems to state all tack welds must be made by a qualified welder (including temporary bridge tacks) which is contrary to the other two codes.
Cheers,
Shane

 

[gtaw]

I don't sit on any of the ASME committees, so what I have to say is pure conjecture. Here's my take on the subject, the materials used for piping in the case of B31.1 Power Piping are primarily steels; carbon steel, carbon manganese steel, high strength low alloy steel, etc. Most steels are relatively easy to weld. A tack weld can be removed and the joint welded with little probability of permanent damage or degradation of the mechanical properties once the offending tack weld is removed. That isn't the case for some of the base metals permitted by B31.3 for use in chemical plants, refineries, etc. Reactive base metals like titanium or zirconium see increasing use. Reactive base metals can be permanently damages if a qualified WPS isn't followed when the tack welds are made. Once the material is "damaged", simply removing the tack weld doesn't make the problem disappear. Once damaged, the nature of the damage may not be apparent.

Best regards - Al

 

[XL83NL]

Although I concur with gtaw, this can easily be a small item/subject overlooked by the B31 committees to be consistent in all main codes.

Huub

 

[weldstan]

Owners have much more influence in determining the requirements of B31.3 and rightly so because of the myriad of service conditions in petrochemical and chemical plants. Root flaws generated from the removal of tacks could be detrimental to corrosion resistance of the weld or life of the weld in cyclic service. I have also seen similar contract requirements for pressure vessels by Owners of petrochemical and chemical plants.

 

[DekDee]

XL83NL,
If you get a chance have a look at TN 13-766.
It seems there was a proposed Code Change that would have bought B31.3 in line with the other two codes but it was never actioned.
Cheers,
Shane

 

[XL83NL]

Indeed. Reasoning for closure of action item were changes made to sec IX (by that time)

Huub

 

[DekDee]

That is where I am confused.
What in ASME IX is relevant to the proposal ?
ASME IX clarifies the qualification of tack welders but it has nothing to do with whether tack welders must be qualified or not.
That is mandated in the respective fabrication / construction code.

 

[r6155]

I can't believe anyone thinks that an unskilled welder can make pressure component welds.
An unskilled welder is not a welder.

Regards