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Vertical-welding-tips:the Theory behind the Practice.SOLUTIONS with Effective, Powerful Advice
Vertical-welding-tips are offered to the apprentice welder that has already mastered the basic welding skills. In this presentation most of the tips refer to welding in the upward direction. A welder using covered electrodes for Shielded Metal Arc Welding (SMAW), should have acquired sufficient skill before training for welding in vertical position. Mastering the arc, manipulating the electrode and managing the weld pool to produce acceptable welds in easier placing, should have been acquired during previous training period. The easiest position for welding is without doubt the flat one, used to weld from the upper side of the joint. The face of the weld is approximately horizontal. It permits to achieve the highest deposition rate with adequate penetration. When making out of position welds some knowledge and experience with a few tricks of the trade should be applied for successful performance.
In this page on Vertical-welding-tips we remind that, in order to weld in vertical position, the necessary skills should be mastered.
The manual technique of manipulating the electrode is explained in the information from knowledgeable sources provided hereafter. Furthermore the shielded electrodes to be used for vertical welding should be selected with optimized composition of the coverage to produce the best results. The right combination of technique selection and of suitable electrodes is needed for successful application of Vertical-welding-tips. The conscious welder should strive to test personally different types of shielded electrodes, from those recommended for vertical welding, to develop his/her personal preference. Personal application and training will develop confidence in selection and use of suitable electrodes for applying successfully Vertical-welding-tips. A short explanation on the functions and types of flux covering of shielded electrodes for Vertical-welding-tips used to be found in a page on Welding consumables provided by the Welding Institute (TWI) as Job knowledge No.82. TWI has later restricted the accessibility of all Best Practice pages to Members only. Readers able to register at TWI may find there useful information. Some essential characteristics of the covering are obtained by fine tuning its composition especially for vertical welding. Much depends on the ingredients, out of a list of about a dozen of them, which make up the slag produced by the electrode. The main task of the covering or core flux is to produce a shielding gas around the arc, normally carbon dioxide, to protect the arc and the weld zone from contamination from the air. It also provides deoxidizers for purifying the weld metal. It develops a suitable slag that insulates the weld bead to avoid oxidation at high temperature and helps to shape it. It includes ionizing elements to stabilize the arc and to allow operation with alternating current. And finally it may include alloying elements or additional iron powder for meeting special requirements. Some of the characteristics essential for making possible out-of-position welding are explained hereafter in Vertical-welding-tips. The slag must be more fluid to flow readily out to the weld pool surface. But to provide support to the weld pool it should have a higher surface tension and be fast freezing.
See the article "Filler Metal for Welding - Part two at Most common weld metal grades have been designed with various types of shielding. They offer a suitable variety of welding characteristics, with specific advantages in different welding positions. Some of these ingredients influence also the properties of the molten slag, like viscosity, surface tension and melting range. Therefore one should always select the electrode that is most suitable to perform the work at hand. "All positions electrodes", as sometimes advertised, is a misleading indication because one cannot optimize all the characteristic of the molten slag for whatever position including Vertical welding. In particular, for vertical welding one prefers to enhance certain properties of electrode covering, like fast freezing and a certain viscosity (to avoid too rapid dripping away) even at the cost of lower deposition rate than that attainable in flat position. Vertical down is done with electrodes having a cellulosic cover, which permits the use of high currents for welding at high travel speed. In general vertical down is used on thinner sheets, because it is considered less prone to burn through, as it provides for reduced penetration, and it is faster than vertical up. Skilled welders familiar with Vertical-welding-tips are said to prefer positioning thin sheets for vertical down welding even if the flat position is available, to increase welding speed and avoid burn through. An Article on Welding Pipe Downhill was published (2) in Issue 166 of Practical Welding for June 2017. Vertical up is used for thicker plates, the border being somewhere between 3 and 6 mm (1/8 to 1/4"). Using reverse polarity (direct current electrode positive) concentrates the heat on the tip of the electrode, leaving the work cooler. This is what one would want for out-of-position welding, because cooler work permits faster weld cooling, with less risk of drip off. A number of practical hints likely to be of substantial help to welders engaged in vertical welding, can be found in the following Vertical-welding-tips resources, available online. "Stick Electrode Welding Guide" - Lincoln (44 pages) available at that includes detailed explanations of manual out-of-position welding. A thorough treatise discussing the fine points of vertical welding and the differences to be taken into account when the progression is in the down direction as opposed to the up direction is presented with special emphasis to applications in pipeline constructions in a useful booklet by Lincoln Electric, called In the page on Fundamentals of Professional Welding, at Navy Manual. The page is reproduced from a Navy Manual.
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