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Welding Frequent Questions and Answers


Weld-FAQ-C.
Welding Frequently Asked Questions, fourth page.

This is the fourth page of Practical Answers to frequent Questions concerning Welding.

Your question may have been already answered.

The list of Titles of Frequently Asked Questions, is in the first page.

Please note that the answers are spread on four pages:

Page one:
FAQ.
Page two: FAQ-A.
Page three: FAQ-B.
Page four (this page): FAQ-C.

Browsing through the list of question titles in the FAQ first page, look for the question you seek.
Clicking on the Weld-FAQ specific question title brings the answer into view.

Or, if you prefer, simply go to any one of the four pages and scroll down to see the answers.

Weld-FAQs

Aligning a Long Shaft.
[From PWL#112 - Section 3]

It happened while working on a consultancy for an application involving a long shaft. Upon pondering on fatigue failures that had plagued its history, it dawned on me that something seemed missing from the design.

The shaft was intended to transmit sufficient torque to perform a processing operation while rotating at low turning speed. It had been made by bar and tube sections of various length, with sturdy flanges welded to each end by double fillets. It was supported by two bronze bearings at its ends and by four more between its sections.

The design did not include any element capable of mitigating the loads due to possible misalignment at assembly. Even by assuming that on assembling any pair of flanges the run out had been measured and minimized with a dial indicator, it is fair to assume that aligning had not been an issue.

To assemble the long shaft, the flanges were bolted together in pairs, with opposite spring washers in between.
In operation the shaft became heated to temperatures that were not measured systematically, worsening the alignment even more.

No detailed metallurgical investigation could be performed on the failed elements: nevertheless the lack of alignment stood out as a major culprit to be addressed in any future design revision.

Anyhow, given the mysterious origins that often fatigue failures seem to present, it could possibly help to consider, in any specific case investigated by our readers, if misalignment could be one of the causes.

While researching the issue I stumbled upon two online references that could possibly help readers confronting similar problems:

Update your shaft-alignment knowledge (13 pages)
Peerless.
and
An Engineer Guide (192 pages)
Pruftechnik.

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Manual Torch Brazing
[From PWL#113 - Section 3]

Readers fighting against the variability of results and quality of routine manual torch brazing, especially if from a large group of brazers, are addressed to an article written by Tim P. Hirhte in the Brazing Q&A section of the December 2012 issue of the Welding Journal at page 16.

Answering to an inquirer who asked how to take the manual aspects out of the operation in order to achieve more consistency, the Author recognizes the difficulties. Training is important but there is a limit to the willingness of operators to follow instructions.

The basics of the process should be understood and practiced. Proper cleanliness and correct clearance must be assured.

The somewhat reducing flame should heat the base metal parts, not the filler. This is probably the most important message that brazers should absorb.

Standardizing equipment and procedures throughout the company may make it easier to control the process.
Infrared temperature sensors may help, as other sophisticated feeders. Gas flow rates can be held consistently under control.

Alternate heating methods like hand held inductors may be suitable in certain cases. Concluding the article, the Author recognizes that there are no simple answers to the concerns of the inquirer.

Interested readers are urged to seek the original article to glean useful information.

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Friction Stud Welding of Dissimilar Metals
[From PWL#114 - Section 3]

A study was performed to explore the suitability of friction welding a steel stud to an aluminum plate. This research is reported at page 54 in the January 2013 issue of the Welding Journal.

A regular milling machine was used for the program. It was used without a brake to stop the stud rotation.
A 10 mm diameter medium carbon steel bar was used as stud. The 1060 Aluminum plate was 2.8 mm thick.
Upsetting was done by manually raising the table with the machine crank.

Notwithstanding the simple welding set up, the analysis of results was performed with proper testing instrumentation to measure upsetting load and joint separating force.

Fracture and microstructure were studied by Scanning Electron Microscope with Backscattered electron image analysis system, and the interdiffusion behavior at the interface was examined by energy-dispersive X-ray spectroscopy (EDS).

The force needed to pull out the welded stud was determined. Friction welded studs with upsetting, where mixed materials were extruded out of the joint, showed that the force needed at fracture was three times that without upsetting.

The research examined and explained the appearance of a crack in the aluminum welded without upsetting. Such a crack was absent when upsetting was applied.

Voids were absent and intermetallic compounds were minimal in the upset samples. This research, remarkably performed with a standard machine tool, demonstrated that stud friction welding of dissimilar materials can be a viable solution when required.

Readers are urged to seek the original article referred to above.

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Braze Welding Galvanized Steel
[From PWL#115 - Section 3]

Normally it is not recommended to resort to unique commercial materials for solving production problems. This is because a robust solution should permit the use of standard materials, well proven and used successfully, without the premium usually requested for trade marks.

Occasionally however, a practical solution may be worth abandoning general principles, if the results are positive, reliable and economic.

For this reason it is possibly useful to explore special filler metals, if the actual situation is disappointing.

A published note was found at page 20 of the October 2009 issue of the Welding Journal, while researching suitable solutions for joining galvanized steels.

Modern high strength galvanized steels for manufacturing crash proof cars, need reliable but quick joining processes, even when wide gaps are unavoidable in production.

The commercial company, sensitive to market requests, researched the issue and developed copper base materials of two similar compositions.

Applications were demonstrated by using gas metal arc weld-brazing and also by plasma and laser brazing.
The experience gained by two manufacturers, at the time of publishing, justified the expectations and satisfied the engineering and manufacturing requirements.

Readers facing similar challenges may wish to check the article referred to above, to determine if practical tests should be undertaken.

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Underwater Inspection and Welding
[From PWL#116 - Section 3]

For young people considering a welding career, it may be important to get updated evaluations on what their profession will look like, in the long term. One such introduction to underwater welding trade was recently published in the March 2013 issue of the Welding Journal at page 76.

Written by a person familiar with the training of scores of candidates, the article may offer new perspectives to be taken into account before coming to such a fateful decision.

As the contact address of the author is given there, the opportunity to inquire on other aspects not fully clear to the reader, may be a much needed incentive to dig deeper in this fascinating subject.

The article describes a number of scenarios where a welder diver may find him/her/self while working on assignments in the water. These look somewhat scaring to the unprepared, but quite routine for experienced workers.

Inspecting possible damages on structures subjected to storms or hurricanes may be part of the work. Oil rigs, pipelines and partly submerged bridges are among constructions in need of inspection and possible repair.

Proper education and certification are part of the necessary preparation that lasts between five and nine months. Special techniques must be acquired by welders working underwater, to cope with the unusual conditions.

Readers looking for an informed introduction to this kind of work are urged to look for the original article whose details are shown above.

Quite by chance, in the same Journal issue, at page 20, a welder recounts his own experience. At age 54, after a successful dry welding career that lasted more than 30 years, he took the plunge. He became first a commercial diver, and then learned underwater welding.

He describes his development one of his most challenging and rewarding career moves. He describes his expanded career as exciting and rewarding.

Here are his closing remarks: "You accomplish something unique in the welding world; most people can only imagine what it’s like working or welding underwater. I know I did until five years ago."

Prospective students are urged to seek this welder-diver note as indicated above.

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Selecting and Maintaining GMAW Torches
[From PWL#117 - Section 3]

Two articles on GMAW Torches, both in the April 2013 issue of the Welding Journal, may have important information for welders using them in their daily work.

The first, at page 34, explains basic points to consider before selection. The right selection for the job may have considerable influence on suitability for the job, on personal satisfaction and on overall cost of ownership in the long run.

The gun should be rated at maximum amperage for the job and compatible with the power source. No advantage is to be expected by selecting higher then needed rating.

Duty cycle has to be determined according to job requirements: in semiautomatic flux cored welding applications, a 60% duty cycle is most commonly used and should be sufficient when used with CO2 shielding gas, except that for robotic work 100% duty cycle is preferred.

The shielding gas used when assessing duty cycle reported by the manufacturer should be ascertained. This is because when using argon or mixtures, the gun runs hotter.

Therefore in that case the amperage rating should be reduced at a given duty cycle or the duty cycle should be reduced at the given amperage.

Air or water cooled? The second type runs cooler and is lighter but costs twice as much for the same rating and duty cycle.

Other recommendations suggest to select tips with flattened threads that assure extended service life, massive contact tips and harder materials, besides longer and tapered nozzles that permit easier access to tight areas, if required.

The second article, at page 44, stresses the importance of routine maintenance. Attention should be paid to clogging of liners, either by overtensioning of flux cored electrodes or by dirt. Blowing out with compressed air the liner whenever changing filler metal spool is recommended.

Cleaning pads as offered by manufacturers can be used but should be firmly secured. Worn liners must be replaced as soon as possible. Liner length is critical to correct operation. No void space should remain between liner and diffuser.

Trimming the liner to exact length should not leave any burrs on the inside, likely to scratch the wire. Spatter should not accumulate inside the nozzle, possibly by dipping in anti-spatter compound. Discard the tip rather than damaging the orifice by trying to remove spatter.

Contact tips, preferably of high quality, should be kept in plastic containers and changed frequently. Using the gun as a chipping hammer to remove spatter(!?) seems preposterous: welders should be warned not to do so.

All O-rings must be inspected and replaced regularly. Worn insulators must be replaced. Cables must be kept straight as much as possible, and hanged free of knots at the end of the day. Feeder connection is to be checked regularly.

Suitable and timely maintenance goes a long way in keeping costs low and weld quality high. Interested readers are urged to look for the quoted articles referred to above.

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Welding Apps for Mobile Devices
[From PWL#118 - Section 3]

Looking for practical data used to be a laborious search of many Handbooks, Tables and Manuals. It was best done in the office, by consulting a rich set of publications tuned to actual job requirements. That is now becoming time consuming, less practical and almost obsolete.

With the explosion of smartphone diffusion, huge amounts of information can now be stored in a limited volume and reached instantly, by young and knowledgeable people, whenever they need it.

This is done by using a number of Applications, apps for short, realized for solving all sort of problems.
A team of editors of the Welding Journal set out to explore which help is available for welders.

The results can be found in an Article on Welding Resources was published at page 36 in the May 2013 issue of the Welding Journal.

It reviews no less than 17 recent Apps available to busy welding professionals who my profit from the convenience of having usable help at their fingertips.

A Power Generator Selector may help to find out the size needed. A Calculator from Miller Electric Fine Tunes the Welding Machine parameters according to the job involved.

A 3M respirator guide provides information on cartridges and filters for industrial environments.

A Pipefitter's Reference on a smart phone may be easier to use than searching through a book of tables.

Help is available as a reminder of basic ultrasonic techniques and another one deals with phase arrays.

A Lincoln’s app enables exploration of a robot’s in limit, out of limit, and total welds to Check Live Welding Machine Status Reports.

A basic app is an easy-to-use Tube/Bar Weight Calculator. Other apps help to find correct parameters for grinding, a ShopFloorTalk (SFT) app by End of Time Studios, LLC, provides discussion forums for users interested in welding and metalworking.

A Tool Steel Selection Guide may help in finding the right material for the tool to be made.
The ESAB Welding Parameter Setup Guide app offers the lists of recommended settings for GMAW and FCAW.

Help with Interpreting Industrial Radiographs in accordance with ASME B31.3 - Process Piping is available to verify one's own interpretation.

A further app helps to quickly compare labor, gas, and filler metal costs.

Then one can find a Troubleshooter for resistance welding, a series of app calculators for welding, mechanical, and materials engineering, and a Thermal Dynamics Cut Chart designed for the company’s Ultra-Cut series of high-precision automated plasma systems.

All in all, it seems quite a complete list of welding help apps that interested readers might check for picking up what is applicable to their own requirements. The article can be found as indicated above.

No efforts were done until now to render the pages of this website, www.welding-advisers.com more friendly when viewed by smartphone, as opposed to desktop computer. Maybe this position should be reconsidered, should readers request it.

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Reporting Ferrite Number
[From PWA#119 - Section 3]

On Ferrite Number we published a short note (7) in PWL#053B and on Constitution Diagrams an article (11) in PWL#108.

See also our page on Stainless Steel Welding.

An article titled Sources of Variation in Ferrite Number Predictions vs. Measurements, published at page 175-s in the Welding Research Supplement of the Welding Journal for June 2013 advises on how to perform and report such values. The importance of correct measuring such values stems from the following facts.

The minimum amount of ferrite content in austenitic stainless steel plays an important part in determining if the subject material is prone to solidification cracking upon welding.
The maximum allowed assures against formation of brittle constituents upon long time exposure to elevated temperatures.

In duplex structure ferrite-austenite stainless steels the minimum ferrite number assures suitable resistance against chloride stress corrosion attack while the maximum guarantees acceptable toughness and ductility.

Also prediction of possible outcome of ferrite content may be useful for selecting suitable filler metal for welding dissimilar material or for cladding applications. That is done by using constitution diagrams that relate ferrite content to chemical composition.

The article reports that about ten years ago a large interlaboratory research was initiated by the International Institute of Welding (Commission II) to find the reproducibility of results between different sources.

The methods available include metallographic quantitative examination, magnetically based Ferrite Number (FN) system, chemical analysis (usually by optical emission spectrophotometry (OES) methods).

The article analyzes and discusses the results reported by various laboratories and points out that chemical analysis methods and also metallographic examinations produced too variable results.

The article concludes that "Ferrite requirements for weld metals should be based as much as possible upon measurement of FN by instruments calibrated according to the ISO 8249 or AWS A4.2 standards".

It also points out that it is unrealistic to require that a measurement and a prediction agree.

Interested readers should check the original article indicated above, that is available at:
http://www.aws.org/wj/supplement/WJ_2013_06_s175.pdf

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Storing Thorium Containing Materials
[From PWL#121 - Section 3]

The rules are changing, taking effect on August 27, 2013. Tungsten electrodes for GTAW containing Thorium are now falling under new rules emitted by the US Nuclear Regulatory Commission.

Check the following NRC NEWS page:

NRC Finalizes Rules on Using and Distributing Uranium and Thorium.
http://pbadupws.nrc.gov/docs/ML1314/ML13149A381.pdf

Download the final document (35 pages) from the Federal Register, using the link given there.

It should be noted that using inverter technology permits the use of rare earth elements like lanthanum and cerium alloyed with tungsten, possibly reducing or eliminating the need of storing thoriated electrodes. See 7,
PWL#120.

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Aluminum Welding Safety Tips
[From PWL#122 - Section 3]

While safety practices risk to be dismissed and neglected by busy welders, it is essential that they be studied and rehearsed at regular intervals by all involved, and be enforced by management.

This is important both at the single individual level, for the responsibility one has for proper self well being (including one's family) and at the working place, where accidents should not be tolerated.

An Article titled as this note was published at page 34 of the September 2013 issue of the Welding Journal. It should be studied thoroughly by all involved, by dedicating sufficient attention to each precaution and by translating each recommendation in action items to be implemented as required.

The article singles out specific considerations affecting aluminum welding. In particular the following areas are dealt with in detail: Hot Metal Burns, Electrical Shock and Radiated Light.

To avoid the described painful consequences of these hazards, one should be aware of the dangers of careless behavior, and one should make a habit of using the prescribed personal protective equipment.

Additional factors to keep in mind are excessive Noise, Fume Emissions, Cleaning Fluids and Explosions, to be taken care of with suitable attention.

Serious reading of the original article in the magazine quoted above is recommended to all involved with aluminum welding. Safety in the workplace is imperative.

Precautions are never excessive. Avoidable accidents should never occur.


NOTE - Additional answers appear in the other pages of Weld-FAQ, but are reachable by clicking on the titles of the list at the top of the first page:

Weld-FAQ

Any questions or comments or feedback? Write them down and send them to us by e-mail. Click on the Contact Us button in the NavBar at top left of every page.

PAST ISSUES of Practical Welding Letter can be found at the:

Index of Past Issues of PWL.

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