The Facts about Weld Porosity   As printed in The Welder Magazine

Do you give the Welder "test taking tips"? -or- Do you shut up and let the Welder pass or fail on their own?

So, a company is paying you to help them comply with AWS/D1.1 You've written the WPS's and now it's time to qualify the Welders. Do you give the Welder "test taking tips"? -or- Do you shut up and let the Welder pass or fail on their own? -and- Once they fail, do you give the Welder test taking tips before the re-test?

Keep in mind the premise... a 3rd party inspector helping a company that requested it, comply with AWS-D1.1

Often, in fact usually, when I'm in this situation, it's a small company looking to bid on a job that is requiring them to do something they've never had to do before; show proof of compliance to the structural welding code. These companies are too small to have a Welding Engineer on staff and wouldn't have a Certified Inspector. Generally, what I find, they have a Welder they've hired, or has been working for them for some time. His/Her qualification documents (if any) are from a previous employer. The company is counting on their Welder to know all that is needed to know about welding the product.

I'll also find that the company needing to comply with AWS-D1.1 doesn't own a copy of the code (or the copy they have is 2-3 revisions old).  So now they've called me to see if I can help them out. I'll typically tour the shop, view the product, watch how the sausage is made... then I'll come up with a list of recommendations;

• These are the codes you need to comply with (typically D1.1 and D1.3, but often others as well).
• These are the Pre-Qualified WPS's needed.
• These are the Qualified WPS's needed.
• These are the Welder Qualifications required.

Total cost can easily fall around $3k-$10k, so we break it into small chunks. 1st the Pre-Qualified WPS's, then some Welder Quals... and that brings us back to my original question, "Do you give the Welder test taking tips?"

I'm going to provide the Welders a detailed WPS. I'll provide detailed test instructions. I'll let them know the acceptance criteria (visually acceptable root pass, cover reinforcement/crown not greater than 1/8"...). I'll answer every question they'll ask. Beyond that, I have to leave them on their own. Under this scenario I have to know / they have to know, "Do the skills and techniques that they have/use today get them the required result?" Most of the time, they do not. Failing the Welder Qualification test shows the Welder and the company that the process they currently have in place doesn't work. Something needs to change.

Had I offered helpful tips on the initial Welder Qualification, and the test fail, the only response would be, "The Inspector told me to ____ and that's why I failed." On the retest I will always ask, "Can I give you some tips?", but never on their initial test.

In a School or Training situation, that is a different scenario, but this isn't training. This is determining if the process you currently have in place yields the result you need and if not, what needs to change.

Thanks for reading and following.
PWC

The Same Welder Quals Over and over and...

Paul,
Why do companies require so many different test from one place to the next if your always doing the same kind of work?
Jacob M.

Jacob,
Certain tests are required to qualify you for the correct material, process, thickness and position.  The code you're welding to will specify the test requirements.  Often, these tests can look far different than the actual welding you'll do in production or on the job site.
Each employer is responsible for their Welders qualifications, so if you hop from employer to employer each of those employers are required to give you the required tests.  The employer is held liable for your qualifications, so they would not typically accept a qualification from another employer.

PWC

Check That Liner First

Jason G - Is it acceptable to use .045 wire with a 1/16th contact tip?

Jason,
That's not a "code" question, that's a "weld process" question.
My answer:  You should not have to and there is good reason not to.
The contact tip is the location where current from the electrode lead is going to transfer to the actual electrode (wire).  The larger diameter the hole the wire is passing through, the poorer the transfer.
Of course, a contact tip that is too small a diameter will lead to feed problems, but it would not be common for a contact tip manufacturer to manufacture 0.045 inch diameter contact tips with too small of hole.
You may find yourself experiencing feed or burn-back issues and thinking that increasing tip diameter should solve your problems.  Doing so may help minimize a symptom, but you have not corrected your core problem.
The first place I'd look for solving THIS problem is the gun liner installation.  Gun liners, when installed, need to rest tight against the defuser (part holding the contact tip).  Many mistakes can be made when installing a liner.  One of the biggies I see, is cutting it too short.  A short liner leaves a space between the end of the liner and the back of the defuser.  This space will allow the wire to wobble before entering the contact tip, leading to burn back.  It will also leave space for the buildup of metal shavings which can eventually become the "point of transfer" and lead to burn back.
Someone who does not understand the proper technique for installing a liner will change the liner once problems develop and then not realize they have just set themselves up for failure and frustration.
Always follow the gun manufacturer’s instructions and before cutting it to its final length keep these tips in mind:
1 - Keep the gun as straight as possible.
2 - Mount the gun securely onto the feeder.
3 - Calculate the length the liner needs to extend past the end of the gun (often the gun manufacturer will list this dimension).
4 - **MOST IMPORTANT** Before cutting the liner at that dimension, apply pressure pushing the liner into the gun (you'll find the liner will easily move 1/8" - 3/16"), hold that pressure, measure and cut.
5 - **EQUALLY IMPORTANT** File down the bur formed by cutting.
Give that a try.
PWC

Don't forget to Ping that Weld

Paul, Got a question for you. I work in the mines, when we are welding something thick our boss tells us to "ping" our welds (excessive chipping /with air-chipper). I've never heard of that before. What’s your input?
Matt

Matt, Your Boss is offering some good advice.  He's actually asking you to peen your weld (I'm sure he says "ping" but this is what he means).
Peening a weld helps reduce what's called "residual stress". When you heat and cool metal it wants to move, but typically the weldment doesn't allow it to move. This builds residual stress in the part.  When residual stress exceeds "Yield Strength" you'll get distortion.  When residual stress exceeds "Tensile Strength" you'll get weldment failure.
Also, welding screws with the materials grain structure (at an atomic level). There are several ways to deal with this. You can Post Weld Heat Treat the weldment: raising it to what's called the transition temperature (Around 1600f), holding it there for some predetermined time and then allowing it to cool in some controlled manner. Or you could apply vibration (vibratory stress relief), vibrating the weldment during welding and shortly thereafter. Or you can peen, hitting the weldment with a peening hammer (or a scaler) to help reduce this stress.
So, what your Boss has you doing is stress relieving each pass to reduce distortion and /or the risk of cracking.  Listen to him.

Good question.
PWC

Become the "Qualification Guru of Choice"

Hello Paul,

Much like yourself, I am a CWI, CWE, teaching welding classes and following the guidelines of AWS D1.1, Structural Welding Code Steel.

I have purchased a number of the pre-qualified weld procedures from the AWS bookstore that fit the specific circumstances of the most common welding practices used in our area (6010 open root, 7018 fill/cover passes).  These weld procedures are referenced in the area on the WPS for welding procedure.

Students are given a written, step by step procedure with illustrations, dimensions and weld parameters for the fit-up and welding of their test plates. Each section must be followed by the students, and signed by the Instructors. The guided bend test is performed by a qualified AWS CWI, and the test results are documented by the same Welding Inspector.

My question is: does this weld test constitute a Welding Certification?

W.P.

 My answer is: It does, but will the contractors, manufacturers or company the Welder works for accept it?

AWS D1.1 tells us that Qualification (not “Certification”) is the responsibility of the “Contractor”.  They can “farm” the work of qualifying a welder out to an educational facility, but the responsibility for that Welder Qualification still falls on the contractor.  That’s the reason contractors give their own welding test regardless of any past qualifications the welding candidate may have.

Setting up a “Certification” program (meaning; backing up a Welders qualification with documentation) in a vocational school isn’t uncommon, but if that program is sold to Welders as a means of becoming “Certified”, you’ve done those Welders a disservice. They could go through your certification process not understanding that their new “Certification” is not valid anywhere.

Setting up that same “Certification” program and making your ”pitch” to area employers as the 3rd party qualification guru of choice would be far more honest and code user friendly.

I spent many years in the welding industry filling the role of Welding Engineer (The person responsible for the qualification of persons and processes), Welder qualification was a messy and time consuming part of my job.  When testing Welders “off the street” I would have a 10/1 pass rate (and then my 1 would fail the piss test).  I would always look to my area technical schools to help me with that, but I found either a welding program that didn’t give me confidence that ALL the requirements of qualification would be adhered to, or the program was nonexistent.

What do I mean by adhered to?:

•  Test plate fit-up met the WPS requirements

•  Test plate position was maintained from start to finish

•  The root pass was visually inspected (by someone who knows the acceptance criteria) and found acceptable

•  Fill passes were randomly monitored

•  The cover pass met the acceptance criteria without requiring repair to do so

•  The bend coupons were from the correct location and same test plate (I use steel stamps)

•  Removal of the backing and weld reinforcement did not fall below the plane of the base material

•  The samples were bent in the correct fixture

•  The person evaluating the bend samples understood the acceptance criteria

Seems simple enough, but at all of the locations I evaluated over my career, one or more (usually many more) of the requirements listed above were not met.

There’s a great need for the service you’re suggesting, just insure you are selling it to the right people.

Good Luck,

PWC

How Many Weld Passes?

What determines how many passes you need to make? My understanding is the weld needs to be the same profile as base metal.
Tim K.

Tim
There is a lot that goes into determining the number of passes.  First and foremost, you have to review your WPS to see what the minimum or maximum pass number requirements might be.  When the WPS does not specify then you're free to use as many or as few as your skills allow.
Here are some things that will determine number of passes:
*Travel Speed - The higher the travel speed, the lower volume of weld, the more individual passes needed.
*Weave Width or Oscillation - As with Travel, the smaller the weave the lower the volume and the higher the required number of individual beads.
*Joint Configuration - All other parameters the same, a bevel groove will need more passes then a V- groove.
*Electrode Diameter and Wire Feed Speed (WFS) - Again, all other parameters the same, larger diameter electrodes or higher WFS will increase volume per pass and decrease the overall number of passes.

Example:
A 3/8" Welder Qualification plate test completed in the 1G (flat) position might be done in as few as 2 passes, or, in as many as 7 or more.  Either can be perfectly acceptable welds made by a skilled Welder.
That same joint in the 2G (horizontal) position would probably require a minimum of 4 passes and may take as many as 9-10.  Same weld quality, just different Welder technique and comfort level.
Same joint in the 3G (vertical) would typically take a minimum of 3 passes but would be of equal quality if it took 5-6 passes.

Code books typically limit minimum and maximum pass size.  That is dependent on process, heat input requirements, material thickness and position of welding.

I've given 1000's of Welder Qualification tests and I'm almost always asked, "How many passes do I use?"  My response is always, no less then 3, and as many as it takes to insure the Groove is full, and has no more then 1/8" of Weld Reinforcement (Crown).  Other then that, you're on your own.

PWC

Essential and non-Essential Variables... they can make ya nuts

Dear sirs, I have a doubt about WPS (Weld Procedure Specification) by API 1104 - 2013. For me is not clear if “is outside diameter an essential variable in wps api 1104”, because of in 5.3.2.4 say “The ranges of specified outside diameters (ODs) and specified wall thicknesses over which the procedure is applicable shall be identified. Groupings are shown in 6.2.2 d) and 6.2.2 e).”, and in 5.4 is not included as an Essential Variables.
Thanks regards
Rafael

Rafael,
Essential and non-Essential Variables... they can make ya nuts.
We're often familiar with Essential Variable (those variables that, once changed beyond specific limits, require re-qualification of a WPS.), but what is a non-Essential Variable?
These variables may not show up in a table or list telling us what are allowable variations but they are equally important when writing your WPS.  I often find them left off of WPS's and that only leads to confusion when customers, inspectors or Welders try and interpret or apply your WPS.

When a non-Essential Variable is changed no additional testing is required, but the WPS needs to be changed to reflect the new variable.
Some examples would be:
     *Base materials - Although base material Groups can be Essential, the individual material types are considered non-Essential.  You completed a WPS of a specific material and it qualified you to within a Group.  If you want to change (or develop new) your WPS to reflect a different material within the Group
it is simply a matter of paperwork.
     *Joint Type - Once I qualify a specific joint type that test qualifies a large number of joint types.  I only need to change my paperwork to reflect a different joint design.  (You can now see where a single PQR can qualify a large number of WPS's.)
     *Electrode extension - As a Welder I can vary current by as much as 50 amps by simply changing my stick-out.
     *Electrode type - (GTAW)
     *Technique - Can I weave? Can I whip? Am I allowed to oscillate?  All should be addressed.
It surprised me, that Diameter is not be an Essential Variable per Section 5.4 of API-1104.  But listing it on the WPS is required.
“5.3 Welding Procedure Specification
5.3.1 General
The welding procedure specification shall include the information specified in 5.3.2 where applicable.”
So thickness IS an Essential Variable but Diameter is considered a non-Essential Variable.  Both must be listed on the WPS.
Good Question, Good Luck,
PWC

Combination GMAW & FCAW

I was wondering if you could shed some light on this subject. We have two different processes being used, GMAW and FCAW. The GMAW is used for tacking stiffeners to panels up to 60 feet long the joint configuration is a T joint. The tacks are between 1/8" and 3/16" weld sizes and they vary from 3" to 4" in length about every 18" in between tacks.  The FCAW is then used from a welding gantry, welding over the previous tack welds from the GMAW with the FCAW process with a continuous weld.

D1.1 2010 in table 4.5 PQR Essential Variables. Comparing the processes there are substantial variables. Our thought is to run a PQR using the two processes together on a V groove weld to qualify both processes. GMAW and FCAW using 100% CO2 welding the root pass with GMAW and then the second pass with FCAW mixing the two processes until the groove joint is completed. Clause 4 in table 4.4 groove test figure 4.23 1 G test.

Will this suffice what we're trying to achieve? I appreciate your input on the matter.

Best Regards.
Gabriel M.

Gabriel,
There are a couple ways you could approach this.  First, are PQR's needed?  This should fall under prequalified unless I'm missing something.  If it is, all you'd need to do is write the prequalified WPS using both processes.

If it is not able to be considered prequalified you could do the required PQRs for each process (GMAW & FCAW).  Or, you could combine processes in your PQR's.  A GMAW root would be sufficient, then a FCAW fill and cover.  Don't switch back and forth between processes for the fill and cover, you are qualifying each to a depth (GMAW to about 3/16 and FCAW to the remainder).

Another option might be to qualify these fillet welds using a fillet welded T-Joint just like you do in production.

Keep in mind, all Welders shall be qualified.  If you are using both processes they will require qualification to both processes.

PWC

You’re getting your “qualified” and “certified” all cobbled together…

Hi Paul,

As I was looking through the AWS website I found accredited test facilities listings. Then digging a little deeper I found AWS QC4-89 (standards for accreditation of test facilities). I was of the understanding that given the CWI endorsement, I could certify welders to the standards laid out in D1.1.

Am I to understand that as a school, accreditation is where we need to get to in order to send welders out the door with a certification? If not, what is the accreditation good for, besides marketing?
I thought that I had a pretty good handle on where I was going with this, but now I am second guessing myself.
Once again, thanks for any clarification and/or advice you can give.

Richard F.


Hey Rich,
You’re getting your “qualified” and “certified” all cobbled together…
You may have been a qualified Welding Inspector (meaning you have the skills needed) and once a 3rd party evaluated those skills you became a Certified Welding Inspector (to QC-1).
I may be a qualified Welder (meaning I have the skills needed) and once someone evaluated my skills against a standard and found that I met that standard I became a Certified Welder (to my employer or my trade union…)
The AWS runs a Certified Welder Program (Much like a Certified Inspector, Certified Educator or Certified Supervisor).  To run a program like that the AWS would need testing facilities around the country to do the testing.  The AWS wants to keep “tight wraps” on the program to maintain the programs integrity so they developed a program to certify a facility.  So there are guidelines your facility would need to meet to become an AWS Certified Test Facility.
You can still administer welder qualification tests without being an AWS Certified Test Facility, but those welders would be certified per AWS-D1.1, not AWS Certified Welders.  There is a difference.
A Welder takes a test at your facility or at his/her employer and those test results are not transferable employer to employer.  That Welders qualifications/certifications are the property/responsibility of the company.  A Welder who goes through the steps of becoming an AWS Certified Welder keeps that certification and that certification is portable.

There ya have it.
PWC

GMAW Globular Transfer

Paul,
I work at a machine shop where I am employed as a qualified welder to AWS-D.1.1. I was wondering why it is that you can certify 75% argon and 25% CO2 when you are not allowed to use a short circuit transfer on materials over 3/16". I read your article every month and in order to obtain a spray transfer you need at least 83% Argon but yet I passed on a 1 inch test piece.

Thanks K. B.

Your question insinuates that if your shielding gas mixture is not Argon rich enough to obtain a Spray Transfer mode the only alternative is Short Circuit Transfer, that's just not the case.
When using a 75% Argon and 25% Co2 mix you would not be able to achieve a Spray Transfer, but achieving a Globular Transfer would be no problem. It is quite common to complete the test you discribed (Unlimited Thickness to D1.1) in the GMAW Globular Transfer mode for all positions (3G/4G) successfully.  This is a fairly typical test commonly given in todays construction industry.  I think you will find Globular Transfer a prefered transfer mode in industries that utilize a 75/25 mix.
As for Short Circuit, when I mentioned in an earlier article, the possibility of incomplete fusion being a concern on materials greater than 3/16th inch, I prefaced that by including, "... in certain positions and progressions...".  Completing an open root limited thickness Welder Qualification in the Vertical progression (Root Down/Fill & Cover Up) is a very common transfer mode used during testing.  In fact, a test of that nature, Root Pass with Short Circuit, Fill and Cover Pass in Globular, would successfully qualify a Welder in 2 processes (GMAW-S & GMAW) in a single test.
That would be a good Welder Qualification to have in your wallet.
PWC

GMAW-S & Pre-Qualified Weld Procedures

The company I work for welds with GMAW-S and all of the Weld Procedure Specifications (WPS) that we have are from pre-qualified AWS-D1.1 welds. When I look in D1.1 I find that GMAW-S is not a pre-qualified transfer mode. Are all of our WPS's therefore null? If I understand D1.1 correctly we would need to have a PQR for all of our WPS's because they are GMAW-S, is this correct?

 It seems like GMAW-S is the most common, or at least a very

common, GMAW transfer mode why in the world is it not pre-qualified?

Thank you for your insight, Martin

Martin, Love the question(s). The short answer is... Yes, but just to clarify…

When you mention GMAW-S the transfer mode referred to is Short Circuit Transfer (See AWS-D1.1 Annex K, “GMAW-S”). You are right to note that GMAW-S’s use is wide spread. You are also correct that GMAW-S is not a pre-qualified process, per AWS-D1.1.

So what’s up with that?

AWS-D1.1 is the Structural Welding Code for Steel. Its intent is to be used with materials 1/8 inch thick and greater. The concern by those who determine the requirements for pre-qualified procedures is, welding using the Short Circuit Transfer mode has the potential to generate a lack of fusion. It has been my experience, after running hundreds of PQR’s, that this lack of fusion becomes consistent on material thicknesses over 3/16 of an inch in certain positions and progressions.

That’s not to say GMAW-S can not be used with a pre-qualified procedure. AWS-D1.3 is the Structural Welding Code for Sheet Steel. Its intent is to be used with material 3/16 inch thick and less. Clause 3 of AWS-D1.3 lays out the requirements for developing pre-qualified weld procedures using Short Circuit Transfer.

AWS D1.1 in Clause 1.2, “Limitations”, encourages the use of D1.3 on materials 3/16 inch thick and less. So using pre-qualified procedures for Short Circuit Transfer is do-able, it simply has to be done to a different Structural Welding Code.

PWC

Weld Penetration Problems

Ken P...

Our problem, we get linear porosity at the furthest point of penetration (heavy plate). The size of porosity is 0.3mm dia. but occurs regularly in every weld sectioned so far. Please suggest any steps, which should be checked.
Weld Info: Semi-Automatic process, Spray Transfer, Blasted Material, Electrode: 0.045" ER70S-6, Gas: 91Ar / 5Co2 / 4O2 @ 35cfh, WFS: 485ipm, Travel Speed: 13ipm, Amps: 335A, Voltage: 29.3, Finished weld size is 12mm

Ken,
I would suspect that your weld penetration profile is showing “finger penetration” (Not sure if that is a real term but), a real deep area of penetration at the weld root. The profile is much deeper (at this location) than it is wide. This will cause this area to open up during solidification.
Grab your copy of AWS D1.1 and check out the Commentary section at C3.7.2 “Width/Depth Pass Limitations” also, Figure C-3.2 “Examples of Centerline Cracking”.
I was asked to troubleshoot a similar condition during a job interview for a former employer. To save money, they had changed a process from an 0.045 dia. electrode to an 0.052 dia. When they made the change they did not change any other parameters. The high wire feed with the larger diameter electrode created a considerable increase in current which equates to a considerable increase in root penetration. Like you, everywhere they sectioned, they had this pore, which I believe was more of a linear void. A reduction in WFS, although not popular, eliminated the problem. P.S. I got the job!
Typically, a reduction in current (WFS) will reduce this finger penetration and this should remedy your issue. One other thing; yours is a weird shielding gas mixture. Not sure why you would go with so much Oxygen but I don’t know your whole story. If you can, replace the Oxygen with more Co2. Perhaps that will change your weld profile as well.

Good Luck! PWC

"It's Good to be Me!"

Which welds are required to be visually inspected and by who?

Ed called: “We work on Off-Road and Lifting Equipment and our welders are qualified per AWS D1.1. Which welds are required to be visually inspected and by who?”

Ed, A few documents you should consider adding to your welding library are:
• AWS D14.1- Specification for Welding Industrial & Mill Cranes & Other Material Handling Equipment,
• AWS D14.3- Specification for Welding Earthmoving, Construction & Agricultural Equipment -and-
• AWS D14.4- Specification for Welded Joints in Machinery & Equipment
These welding specifications are a little more applicable to the industry <> services.

You asked which welds are required to be visually inspected and I had to snicker… There was a time in my life when on one side of my Hard Hat was printed “AWS D1.1 Sec 6.9” I would get this question, smile, point to my Hard Hat and say, “Look it up!”

AWS D1.1 keeps it simple, Clause 6.9 – Visual Inspection, “All welds shall be visually inspected…” Section 10.6 of D14.1 is similar, “All welds shall be visually examined.” That doesn’t leave a lot of “wiggle room”. A qualified inspector needs to visually inspect all welds.

As to who the qualified inspector is, I told you over the phone that a Certified Welding Inspector (CWI) isn’t required. Welding codes and standards typically accept the qualifications of a CWI but they don’t require certification. AWS D1.1 and D14.1 require inspectors to be qualified and that the bases for qualification are documented. In addition, D1.1 requires a regular eye exam.

As long as <> writes a qualification procedure for your inspectors, the inspectors conform to Para: (1), (2) or (3) [see D1.1 Para: 6.1.4.1 or D14.1 Para: 10.1.3] and <> maintains documentation that those inspectors meet the qualification requirements, visual weld inspection can be handled internally.

A great document to use as a guide for developing your Weld Inspector Qualification Procedure is AWS B5.1 – Specification for the Qualification of Welding Inspectors (http://files.aws.org/certification/docs/b5.1-2003-errata.pdf). This is a free download made available by the American Welding Society at www.aws.org

As for what I had printed on the other side of my Hard Hat… “AWS D1.1 Sec 3.1, 2nd Sentence”. Look it up! But that’s a whole other column.

"It's Good to be Me."

PWC

Pulsed Welding Equipment

Cory G. from Norther Iowa asks:

"We use the Pulsed GMAW process with Lincoln equipment. When setting weld voltage the Trim can be adjusted between 0.5 and 1.5
What do those numbers mean and how to they relate to weld voltage?"

Pulsed welding equipment can challenge the conventional wisdom we’ve picked up over the years using a good ol’ constant voltage (CV) GMAW (Mig) welder. With typical CV equipment, the Welder will select a voltage and wire feed speed (WFS) combination, possibly a percentage of slope and/or inductance and then be ready to weld. Today’s pulsed Mig equipment changes most of that.

Most pulsed Mig welders run on pre-set programs. The Welder will select the type of wire, the wires diameter, possibly a base material and the shielding gas used. From this information the equipment will look at the WFS selected and do a calculation as to what the optimum weld voltage should be.

Of course, this optimum voltage may need some type of adjustment depending on the needs of the Welder. Example: The optimum weld voltage to weld a flat position, 3/8 inch fillet (1F) at 475 ipm may not be optimum to weld a root pass in a horizontal groove (2G) at the same WFS. Understanding that, each manufacturer of this equipment has built-in, an adjustment for voltage. Think of it as a percentage of optimum voltage.

Manufacturers may give you a 0.50 to 1.50 range, or a 0 to 50 range, or something similar. All will call this “Trim”. Using the 0.50 to 1.50 range as an example, 1.00 would be considered the optimum setting. When you reduce your Trim from 1.00 to 0.85, you have reduced arc length and, in doing so, reduced weld voltage. Similarly, when you increased Trim to, say 1.15, you’ve increased arc length and, in doing so, increased weld voltage.

This is very similar to what you were doing all along on that old CV Mig equipment. When you reduced voltage, you were reducing arc length. Even with this new fancy equipment the age-old understanding that “Weld voltage has a direct relationship to arc length” doesn’t change.
What’s different is that a Trim of 1.00 for a given electrode (type/dia.) will give you a completely different weld voltage when you change electrode, shielding gas or WFS.

Most of today’s pulsed equipment will display average weld voltage as the equipment is welding, and some will continue to display it for a short period (seconds) after welding has stopped. This feature helps the welder monitor compliance to the weld procedure (WPS).

PWC

"It's Good to be Me."

B31.3 Processes

Question: Paul, I enjoyed reading your article printed in Practical Welding this
month, thank you!
I have a question relative to ASME B31.3 the code for chemical plant piping.
The area of this code referring to the type of welding process that is
acceptable is un-clear to me. I am referring to section 328.2.2,
..."welding procedures qualified by others may be used, provided that the
following conditions are met:( f ) The welding process is SMAW or GTAW or a
combination thereof"

Does this mean that the only acceptable process for welding has to be either
SMAW or GTAW, or is GMAW acceptable as long as it follows a written and
acceptable WPS?
And if GMAW is acceptable, must it be performed by a certified welder who
has been qualified in that WPS?

With your article being written about WPS's and referencing the same code I
have questions about, I thought it wise to seek your council.

I truly appreciate any enlightenment you can provide.
Thank you and regards,
Randi Kremer
Engineer

Answer: The section you are referring to (328.2.2) is specific to the use of weld procedures qualified by others (not qualified by you). When a fabricator wishes to utilize these procedures, they face many limitations. One of those, as you’ve discovered, is the process used.
There are many other allowable processes available but all would require you to produce a qualified Weld Procedure Specification (WPS).
ASME B31.3 section 328.2.1 mentions, “Qualification of the welding procedures to be used… shall conform to the requirements of… Section IX…” So ASME Section IX will layout your requirements for qualification.
The process that you are wishing to use, Gas Metal Arc Welding (GMAW), is included in Section IX as an allowable process. So, yes, you can use the GMAW process but you will need to qualify a WPS to do so.
As for your Welder being qualified to the new WPS, that is a bit of a “Chicken or the Egg” scenario.
A Welder typically wouldn’t be qualifie

d to a WPS before the WPS has been tested and developed and a WPS won’t be qualified until a competent welder completes it.
Code writers recognize this. ASME notes that a procedure qualification has a distinctly different purpose than a welder qualification.
ASME Section IX QW-100.1 makes the statement, “…the welding procedure qualification test establishes the properties of the weldment, not the skill of the welder…” Prior to that statement you’ll read, “It is presupposed that the welder… performing the welding procedure qualification test is a skilled workman.”
As for Welder Qualification, QW-100.2 notes that, “the basic criterion established for welder qualification is to determine the welder’s ability to deposit sound weld metal”.

So how does this apply to Campbell Fittings and their desire to utilize the GMAW process?
It sounds like you need to qualify the GMAW process. This can be done by any of your competent Welders. Once your Welder has successfully completed the Process Qualification testing he/she will be considered qualified. The limiting factor will be that the process will be qualified within a given range of essential variables and the performance (welder qualification) will be qualified within a different given range of essential variables.
Once the WPS is completed the welder who qualified it may need additional testing to utilize it in your specific application.

Example: Your Welder completed the Procedure Qualification test (PQR) in the Vertical (3G) position, on a Single V-Groove, with a backing strip and the progression was up. You would like to apply this same Procedure Qualification Report (PQR) to a similar joint but you intend to change the groove by eliminating the backing and weld vertical down. A new WPS could be written to reflect these changes and would not require testing, but your Welder would not be qualified to this new WPS.

Confusing? I know. When talking “Code Talk” always make sure you separate Procedure Qualification from Performance Qualification. I often see where these two consistently trip people up when talking weld qualifications. Consider contacting a competent Certified Welding Inspector who understands the ASME Codes to review your specific needs and advise you on additional testing requirements.

PWC

It's Good to be Me!

Vertical-up or -down in robotic welding?

Vertical-up or -down in robotic welding?

We have a weldment that incorporates 0.375-in.-diameter steel rods and a 0.060-in.-thick sheet metal stamping of 1018 CR material. Each weld is the same, 0.75 in. long with a 0.25- in. fillet, perhaps including weaving. The assembly is fixtured and welded robotically using GMAW with CO2 gas and repeated 100 to 300 times.

We utilize vertical welding, but which is a better progression, down or up?

Richard P.

Vertical-up and vertical-down welding are significantly different from one another in the technique used and the resulting finish weld. This is the reason welding codes consider this change in progression an essential variable and require additional testing when changing from one to the other.

From your description, I would have to conclude that of all the possible positions (flat, horizontal, vertical, and overhead), this is an ideal candidate for welding vertical-down. Your greatest concern in this application is going to be burn-through on the 0.060-in. sheet metal. Welding vertical-up will be difficult, if not impossible, in this configuration because of the low travel speed and high heat input. Welding vertical-up with GMAW typically requires a weave technique to carry the puddle and give you the proper bead profile. GMAW vertical-up is a deep-penetrating technique, and this characteristic is going to lead to consistent burn-through.

GMAW vertical-down, on the other hand, tends to lack penetration and side-wall fusion. These characteristics are undesirable in most applications, but given that you are using a fully automated system, tight control of wire feed speed (WFS), voltage, travel speed, and bead placement should allow you to counteract these characteristics and control your finish weld quality.

I’ve had a lot of success setting up similar applications in what I call the 45-degree vertical-down position. The key is using a slight drag angle (10-15 degrees) and keeping the arc on the leading edge of the puddle at all times. This is a little easier to do at a 45-degree incline than at straight 90 degrees.

If possible, consider a mix shielding gas (minimum 85 percent argon/maximum15 percent CO2) as opposed to the straight CO2 you are using today. This should reduce chances of burn-through and reduce weld spatter considerably. A 0.035-diameter solid electrode should work well in this application.
You stated the weld size was 0.25 in. Talk to the engineering team and your customer about reducing the weld size to 0.19 or even 0.125, which will help increase travel speed, ensure penetration into the root, and reduce cost. Large welds with no root penetration or side-wall fusion are of little benefit to your customers.

Do I need a welding procedure specification?

Question
Do I need a welding procedure specification (WPS) for my company when it is just me and all I do is on-site portable welding of a wide range of items?

Steven B-

Answer

Whether your company requires a WPS depends on the customers you serve. For example, if your company is hired to fabricate your neighborhood association’s new flagpole, using your skills and best judgment would most likely be acceptable. On the other hand, if you are contracted to fabricate steel supports for a new government facility in your hometown, a little more paperwork probably is involved.

Review all the documentation from your clients in detail. Ask questions if you are unsure. A common statement found in contract documents is "All welding shall meet the requirements of the latest revision of AWS D1.1, D1.2, D1.5, ASME B31.1, B31.3, API 1104 ..." This statement indicates written weld procedures and documentation are required that show your welders and welding process meet the code requirements. You need to know, before you strike an arc ... before you bid the job, if there are specific code requirements.

Does your company need (as opposed to require) written WPSs? Yes!
Without a clearly documented and followed process, it is difficult to communicate details of your welding to your customers. With a clearly defined WPS, everyone involved knows what is to take place. Should something go wrong, say that new flagpole drops on top of the neighborhood association president’s new MINI Cooper, you'll be able to show the insurance investigators that you are a professional and the failure was clearly not caused by an uncontrolled weld process.

In your company name you use the term Certified. To be a certified welder requires testing, typically to a nationally recognized standard. This is monitored by a third party, often a professional organization such as the American Welding Society (AWS) or a governing agency like the state department of transportation, and administered at an accredited test facility. These organizations would most likely require your work be completed per a qualified WPS to maintain your welder qualifications.

PWC
It's Good to be Me!

Look Inside >>  May/June 2009

Good Call!

We have is a stiffener bar (continuity connection) in a column that calls for (AWS D1.1) BTC-P4 for the flanges and fillet welds both sides in the web. The stiffeners were field welded. After assembling 35 connections we discovered no fillet weld on the bottom side in the web. Problem is we can't weld the bottom side of the stiffener now because of clearance. What are our options? Could we add more than the required 1/4” fillet on top of stiffener to satisfy the inspector? He is not offering any solutions. He just wants the requirements to be met, fillet weld both sides. If you can help, it will be greatly appreciated.
Thank you,
Brian N.

Brian,
Thank goodness for “on-the-ball” inspectors. The inspectors’ part in this construction project is to monitor the fabrication and erection. Should issues arise, he is to bring them to the attention of those who need to know. Speaking from past experience that can be a thankless job.
The inspector on your site is insisting the welding completed meets the requirements of the jobs documentation. When things go wrong and an inspector raises the “red flag”, it is often the case that those on the ground will look to him and ask, “What should we do?”
The inspectors’ first response should be “Contact the Engineer and come up with a documented solution”.
Often, when we start to brain-storm solutions on the job site, we don’t have all the facts or we may not understand all the requirements, to make the call. Example: Your suggestion for missing weld on one side of the joint was to increase weld size on the opposite side. There may be times when this is an acceptable solution, but if the engineers concern is the stress riser created from the missing fillet (which is often the case in today’s building construction) that oversized fillet would be of little benefit. And better to bring the issue into the light for engineering analysis now, than to find out after the concrete has set, that the fix was unacceptable.
Inspectors may or may not have the engineering back ground to make this call, but it is the engineer responsible for the project that should come up with an acceptable solution.
Brian contacted me by email to let me know that the solution to his welding issue was to backup, disassemble each connection, and add the original required ¼” fillet weld. Good call!