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Frequently Asked Questions


Is a NR-311 Ni Electrode E70 Equal to a E80?

 

I have a project where we are welding ASTM A913-Grade 65 I-sections to each other. Our specification calls for E80 electrodes for these welds, in conformance with AWS D1.1. The steel erector submitted a WPS for these welds using NR-311 Ni electrodes. The WPS listed these electrodes as E80, thus we approved the WPS. However, the label on the weld wire box out in the field lists this electrode as E70, as does Lincoln Electric's literature on the electrode. When asked by the special inspector, the steel erector claimed that NR-311 Ni electrode is equal to an E80 even though it is technically listed as E70. They have submitted documentation, with Lincoln Electric letterhead, stating that the electrode is E70 but meets the requirements of E80.

We are trying to determine if the electrode they are using meets the specifications, which specifically call for E80 electrodes. We're attempting to contact Lincoln Electric directly to get their opinion but we could use some outside advice, especially since the testing agency for the project seems reluctant to suggest anything and is looking to us for direction. Have you ever encountered a similar situation and if so how was it resolved? Please let me know what you would suggest.

Strictly speaking, "E80" is not explicitly defined in any  AWS document that I am aware of, although it clearly  suggests an 80ksi minimum UTS electrode.  If the specification did not specify a consumable classification, then "matching" requirements for an ASTM A913, Grade 60 or 65 would be the classifications listed in AWS D1.1, Table 3.1, Group III.  These do not all start with "E80", although they are nominally 80ksi minimum UTS. If the consumable manufacturer states in writing that the particular electrode meets the properties of an E8XTX-X classification, then the Engineer could accept it.  I would not expect any inspector or test lab to accept a classification unless it is shown as such on the consumable manufacturer's literature or it was approved by the Engineer.

AWS A5.29-98 classifies the Lincoln NR-311 Ni electrode as E70T7-K2 indicating that it is has a minimum tensile strength of 70,000 psi.  To add value to his or her service, the special inspector should have researched the contractors claim that this electrode met the requirements of the specifications.  The special inspector, or his or her support personnel at the inspection agency’s laboratory, should have gone to The Lincoln Electric Company’s web site (www.lincolnelectric.com) and downloaded information for this electrode from the manufacturer’s catalog as well as the electrode Certificate of Conformance.  Both of these documents indicate that the electrode meets the requirements of the specifications, 80,000 psi minimum tensile strength, as well as FEMA 353 requirements.  These documents then should have been forwarded to the EOR for review, and either approval or rejection. 

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NDT of Fillet Welds?

 


 What NDT inspection criteria is required by code for fillet welds?

  

There are no general requirements for NDT of fillet welds in the 2001 CBC, AWS D1.1, AWS D1.8, or the AISC Specifications. The requirements in CBC Section 1703 apply only to the welds noted, and are the minimum NDT requirements. The Engineer has the option of requiring testing beyond the minimum requirements, including NDT of fillet welds, as part of the Statement of Special Inspections prepared by the responsible design professional. However, such testing is not specifically required by code.

Appendix Q of the 2005 AISC Seismic Provisions for Structural Steel Buildings (AISC 341) now lists specific locations where NDT is required for connections resisting seismic forces. The only connections that could potentially involve fillet welds are welds within the "k-area" of the section and repairs within the plastic hinge region of reduced beam section (RBS) moment frame connections. These provisions have not yet been adopted into the California Building Code.

FEMA-353 recommends the Engineer to develop a Quality Assurance Plan and indicate the appropriate Seismic Weld Demand Category and Seismic Weld Consequence Category for each welded joint on the design drawings.  Magnetic particle testing is specified for fillet and PJP welds in all but two categories. 

If desired, Magnetic Particle Testing (MT) should be used to test fillet welds. Ultrasonic Testing (UT) should not be specified for fillet welds.

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Is an Overhead Puddle Weld Possible?

 

I have specified a overhead puddle weld on a project and the contractor is claiming that they cannot perform this weld. I’m attempting to determine if the contractor is correct. Do you have any thoughts on this?

Puddle welds are typically used to join sheet metal to underlying structural steel elements.  These welds are generally completed by using high heat settings to allow for burning through of the sheet metal.  With the higher heat required for this welding technique a larger weld puddle is formed than would typically be created with the use of a lower heat (amperage) setting.  The connection strength of the puddle metal is a function of the perimeter area of the weld.  With the larger puddle area of a puddle weld versus that of a linear weld or plug weld, and the higher heat of the molten metal, the application of a puddle weld is governed by gravity.  The forces of gravity do not allow for the creation of a larger weld puddle as is common for a puddle weld in any position other than the flat position. 

The completion of welds on a vertical surface and in the overhead position requires a much greater degree of control on the heat settings so that sufficient heat is applied to obtain proper penetration while excessive heat is avoided.  This does not allow for burning through of the sheet metal to create the weld.  By avoiding the “overheating” of the metals the molten metals will freeze much quicker and the effects of gravity are overcome.  By designating a plug weld as opposed to a puddle weld a hole of the required size (perimeter) is provided in the sheet metal prior to the start of welding.  The weld is then made along the perimeter of the hole using a lower heat setting that provides for proper penetration while controlling the size of the weld puddle to avoid loss of metal due to drop out associated with gravity. Where the interior of the hole is to be completely filled with weld metal a plug is created that can be ground and dressed to create a uniform surface with that of the surrounding metal.

Arc spot (puddle) welds and arc seam welds are only done in the flat position. See AWS D1.3-98, Table 1.2 It is almost impossible to do them in any other position.

The simple answer is that if the contractor won’t do it, it’s not going to get done - regardless of theory.

See D1.3-98 Table 4.1 for standard joints. #4.4, Arc spot weld-sheet to supporting structural member is only shown for F, i.e., flat weld only. #4.5B is only shown for the Horizontal position.

The relevant all-position weld might be #4.5, the arc plug weld.

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UT Acceptance Criteria, FEME-353 VS AWS D1.1


I need some advice on the UT acceptance criteria for CJP welds. The welding inspector for the project that I’m working on claims that the acceptance criteria specified in AWS D1.1 differs from that specified in FEMA–353, and he is asking us to specify which criteria they should use. Our project uses special moment resisting frames, so the welds at the connections and the column splices are critical elements. The project specifications state the following: “Ultrasonic testing (UT) shall be conducted by the Owner’s Testing Agency for the percentage of joints designated in Table 2-1. UT shall be performed in accordance with AWS D1.1.” FEMA-353 is cited elsewhere in the specifications but not in regards to UT. I looked at AWS D1.1 and cannot determine if or how it differs from FEMA–353. I also reviewed AWS D1.8 and it appears to match FEMA-353 and thus adds to my confusion.

What concerns me about the specification is that I’m sure that the differences between AWS D1.1 and FEMA-353/D1.8 were not taken into account when the provision was written. That’s why I need the clarification. Should we be using D1.8 or D1.1 or both?

  

  

 AWS D1.1 has two ultrasonic testing procedures and acceptance criteria.

The primary one, used for decades and most commonly accepted, is contained in Section 6, Part F.

Annex K, referenced in FEMA 353, UT Examination of Welds by Alternate Techniques, is relatively new.

Since FEMA-353 was not specified for ultrasonic testing in the project documents, AWS D1.1, Section 6, Part F would be the procedure to be used.  Some reasons for this are as follows:

FEMA-353, Section 5.8.3 allows the engineer the option of either AWS D1.1 Annex K or Table 6.2 (Section 6, Part F).

Annex K (moved to Annex S in 2006), states, “This annex is non-mandatory unless specified in the contract documents.”

AISC 341s1-05 and AWS D1.8-06 specify AWS D1.1, Section 6, Part F unless alternative procedures are approved by the engineer.

If given the choice, I prefer the D1.1 criteria, primarily because there are precious few UT technicians that can accurately and reliably size flaws in 3 dimensions. As the welding inspector suggests, in his original request, the FEMA-353 criteria may not be as conservative as D1.1, particularly considering the lower probability of detection and accuracy of sizing for technicians whose experience is predominantly with the D1.1, Sec. 6, Parts C & F criteria and methods.

 

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What Variations can be Developed from a WPS?

 

 

 Does a PQR for a butt joint qualify a WPS for a T or corner joint with the same weld size?

 Also, does a PQR for a groove weld qualify a WPS for a fillet weld of the same size?

 

Yes, WPS qualification of a complete joint penetration (CJP) groove weld (butt joint) qualifies tee and corner (CJP & PJP) joints within the limits of the qualified WPS, it also qualifies fillet welds within the limits of AWS D1.1 Table 4.1 & 4.2 Note 4. Most fillet welds are afforded pre-qualified status per AWS D1.1 Section 3.9.

When responding to frequently asked questions, the apparent code answer is not always what the inquirer may be seeking.  When reviewing and approving welding procedure specifications, the Engineer has the authority to “relax” code requirements or enforce more stringent requirements.  In this case, it is possible that the project team was looking for a more comprehensive analysis due to a critical connection required by their design. Following is an interpretation of the code with that thought in mind.

1.       For a complete joint penetration (CJP) groove weld, at first glance, yes.  AWS D1.1-06, Section 4.9.1.1 Corner or T-Joints states “Test specimens for groove welds in corner or T-joints shall be butt joints having the same groove configuration as the corner or T-joint to be used on construction….”


However,  AWS D1.1-06, Table 4.3, Note 2. states “If a PJP bevel- or J-groove weld is to be used       for T-joints or double-bevel- or double-J-groove weld is to be used for corner joints, the butt joint shall have a temporary restrictive plate in the plane of the square face to simulate a T-joint configuration.”
 
Welding Procedure Specifications (WPSs) requiring qualification by test, resulting in Performance Qualification Test Records (PQRs), are typically done to qualify an unproven joint configuration, base metal, weld metal combination.  The ability of a/any welder to accomplish a sound weld during construction using this type of WPS is very important.
 
 It is recommended that WPSs that are not pre-qualified for T-joints and/or corner joints with J-grooves or double-bevel groove or double-J-groove, whether CJP or PJP, be qualified using a temporary restrictive plate, prior to approval by the Engineer.
 
2.   Yes.  AWS D1.1-06, Table 4.2, Note 4. states “CJP groove weld qualification on any thickness or diameter shall qualify any size fillet or PJP groove weld for any thickness.”

 

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 Are Ceramic Back-ups Prequalified?

    

Upon partial completion of a project the project manager rejected one of the WPS’s used.  The contractor had used an AWS prequalified TC-U4a-GF joint configuration that by code requires metal backing. But, the contractor used ceramic backing.  He removed the ceramic backing, back-gouged and welded the root. Is there any way that this might be considered acceptable?

Answer: Possibly.

 

AWS D1.1 - 2.17 Prohibited Joints and Welds

2.17.1 One-Sided Groove Welds. Groove welds, made from one side only without backing or made with backing, other than steel, that has not been qualified in conformance with Section 4 shall be prohibited…

We aren’t taking about “One-Sided Groove Welds”, so this restriction does not apply.

 In an attempt to mitigate this situation, from an administrative point of view, we designate the prequalified joint configuration to be TCU4b-GF, similar to the TC-U4a-GF joint configuration.

Next, we look at “D1.1 - Fabrication”. We cannot prohibit the contractor from using his own “methods and means” to produce welds, as long as they are within the limitations of the code.

 The contractor uses the TC-U4b-GF joint configuration, elects to use the widest “As Fit-Up” root opening allowed, uses ceramic backing, and cites the following:

AWS D1.1 - 5.10 Backing

Roots of groove or fillet welds may be backed by copper, flux, glass tape, ceramic, iron powder, or similar materials to prevent melting through.

Since the weld is to be back-gouged and welded, as an inspector, I would have to allow this, verifying that the groove angle was within the tolerances of the 45º bevel preparation and not the 30º that may be used in the case of the TC-U4a-GF joint configuration.

(After back-gouging, the other side of partially welded joints should resemble a prequalified U- or J-joint configuration at the joint root, and, for administrative purposes, would require an additional WPS.)

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