SMAW Vertical up techniques

[chenjing]

I'm a CWI on a code job and today inspected some 1/2" vertical fillet welds.(SMAW, 1/8" lo-hy) The welders had oversized the welds to approx. 5/8", some a little larger. That isn't an issue on this joint however their side to side weave oscillations as they progressed up the joint were getting to be 1 to 1+ inches side to side. This seems excessive to me as they were in effect just creating horizontal stringer beads. My question is whether or not there's a standard or limit to weave oscillations.

 

[DVWE]

Usually where heat input is an issue, such as impact tested welds, the weave is limited to 3X the diameter. The only limiting document would be the WPS.

 

[DVWE]

3X the diameter of the electrode that is...

Have you checked the WPS?

 

[Ron]

Agree with DVWE ; however, assuming this is under AWS D1.1, you are likely using a pre-qualified joint welding procedure and no WPS exists. In that case, they are probably outside the range of the pre-qualified joint and would need to qualify the procedure or get back in line with the pre-qualified procedure.

 

[gtaw]

As a CWI you should know to refer to the WPS and the applicable welding standards to answer your own question.

It is very disappointing to have a CWI ask such a basic question. Regardless of which open code book examination you took, you should have learned that it is your responsibility as a CWI to refer to the applicable documents to determine if there are limitations on such things as the width of individual weld beads or layers, heat input, interpass temperature, etc.

As a third party CWI, your job is to verify the welders are working within the parameters of the approved WPSs. In other words, you need a copy of the applicable WPSs, codes, and contract documents to see what is required and what is approved. You don't make the rules, you only verify they are followed.

If you are working as QC for your employer; a manufacturer or contractor, you may have the responsibility of verifying the welders are adhering to the parameters of the WPS, however, in accordance with AWS B5.1 Table 1, it is not within the scope of a CWI's responsibility to develop WPSs. Still, you need to refer to the applicable contract documents to determine if there are limitations that need to be addressed.

If, after researching the applicable documents, you still have concerns, you should be directing them to the appropriate individuals in your organization or the EOR.

You didn't mention what code or welding standard is being invoked by the contract. That is the first question that must be answered. Next, what base metals (material specifications) are being welded? After that, what is the application or service environment? Only after those questions are answered can a meaningful response be provided. Answers to those questions should also be answered by a close review of the contract documents.




Best regards - Al

 

[gtaw]

OK, tonight is another evening and I'm a little more mellow.

If you are working to AWS D1.1, there are no limitations imposed on the width of a weld bead deposited with SMAW, low hydrogen type or otherwise. Take a look at Table 3.7 of D1.1-2008. A single pass vertical fillet is limited to 1/2 inch, however, there is no restrictions when multiple layers are used (next item down in the list).

Best regards - Al

 

[HgTX]

What about the effect of the weave on travel speed?

Hg

Eng-Tips policies: faq731-376

 

[gtaw]

The weave technique will increase heat input. That isn't necessarily a bad thing.

A single pass 1/2 inch vertical fillet weld, permitted by AWS D1.1, would have a face dimension, i.e., toe to toe, of just less than 3/4 inch. That would be six times the diameter of an 1/8 inch diameter electrode. I've made many of these welds over the years with no difficulty.

The structural welding code places no restrictions on the width of individual layers in the case of multiple pass welds. Again, I've made plenty of wide weave groove welds over the years with no problems passing radiographic or UT requirements.

The real issue is one that no one has broached. What is the anticipated service requirements?

If toughness at low temperature is a concern, the Engineer must make those concerns known and specify notch toughness testing if the anticipated service conditions make it necessary. The Engineer then has to specify the test temperature and the minimum requirement for the absorbed energy. That opens up a whole different regime of concerns and different testing requirements.

At issue is the grain size of the weld and HAZ. High heat input, high preheat, and high interpass temperatures promote coarse grains which perform adequately where low temperatures and impact loading are not anticipated. They perform better than fine grain structures when high temperature creep is a design factor.

Service conditions that require superior notch toughness at low temperatures would benefit from lower heat inputs, lower interpass temperatures, faster cooing rates, and finer grain structures in the HAZ and weld.

Back to my original, somewhat terse response, it isn't the CWI's purvey to impose restrictions or limitations that are not imposed by the applicable welding standard or project specification. There is nothing wrong in asking the question, but the questions should be directed to the appropriate individuals responsible for those types of decisions, e.g., the Engineer.





Best regards - Al