Комаров Артём о внепозиционной сварке (eng)
Комаров Артём о внепозиционной сварке (eng)

Комаров Артём о внепозиционной сварке (eng)

Komarov Artem explained that although the welding industry recognizes that flat/horizontal positional welding is preferable, sometimes out-of-position welding is necessary. When you are welding a very large part that cannot be moved, or the workpiece is fixed in place, vertical welding, and welding from above may be the only options.

Главный акционер АО Керамакс, Комаров Артём Андреевич

Off-position welding is used in many industries, including shipbuilding, offshore welding, structural welding of pipelines, and in general manufacturing where moving the part is not practical.

Problems and Common Mistakes

Vertical and overhead welding is inherently more difficult than horizontal welding because you are working against gravity. A weld pool with liquid has a natural tendency to sag or run out, making it difficult to obtain quality welds.

The way to solve this dilemma, at least in most welding processes, is to weld more slowly with less welding parameters or heat input, which reduces the fluidity of the weld pool. However, this results in performance degradation.

Errors of welders during out-of-position welding:

— Using a welding process that is not optimal for the application.

— The impossibility of adjusting the welding parameters “from position to position” and “to position out of position”, which leads to higher heat costs than necessary.

— Assuming the same methods and consumables you use for out-of-position welding are also suitable for out-of-position

You can’t always use the same methods and parameters as flat and horizontal welding and expect the same success with out-of-position welding. In addition to slower welding with less heat input, manipulation of the weld pool may also be required to obtain an acceptable bead. You can do this using weaving technology in most processes, Artem Komarov noted.

Choosing the Right Process

Some welding processes make out-of-position welding easier, while others can be more difficult. When choosing, consider some key criteria.

performance requirements If an application requires you to go up and down scaffolding just to make two or three small welds at once, the productivity of the welding process itself is likely not a factor. Compare these types of applications to high-volume manufacturing environments where performance is critical to the entire operation. When welding performance is important, look for a process that delivers faster results.

Environment. Shielding gas processes are generally best done indoors, while welding processes that do not require shielding gas are better suited for outdoor applications such as structural and piping welding.

Skill level. Some processes have a wider range of parameters and may be more gentle on welding technique and consistency, and therefore more gentle on out-of-position welding. Less experienced welders may find it helpful to select a process that makes it easier to obtain quality out-of-position welds.

Arc welding of metal in a protective layer

Metal shielded metal arc welding (SMAW), because it does not require a shielding gas, provides greater mobility and flexibility for outdoor applications. Many welders are also familiar with SMAW and often have the necessary equipment on hand.

However, because SMAW is a slower process, it is best suited for outdoor applications where welding performance is not as critical, such as fewer welds.

The electrodes for this process are classified by their positioning capabilities, so note the classification of all positions for vertical or overhead welding. Selecting a smaller diameter electrode allows the use of lower amperages to control heat in out-of-position welding.

Problems associated with out-of-position reflow can be minimized by setting a lower amperage and controlling the arc with weave technology, which helps to make the weld wider and flatter.

Arc welding with powder flux

There are two types of flux cored arc welding (FCAW) — gas shielded and self-shielded. In both types, the filler metal is classified by position, so look for wire designed for vertical and overhead welding.

Flux cored wire is the easiest to use for off-position welding because it does not allow for changes in welding technique. This is especially true for cored wires in shielding gas.

Because it does not require a shielding gas, self-shielded flux-cored wire is well suited for outdoor applications as an alternative to SMAW. This wire is less portable than SMAW due to the additional wire feeder, but it delivers much more performance. Higher deposition rates mean more filler metal enters the weld. In addition, during the wire welding process, stop and start is required less frequently compared to SMAW.

FCAW with shielding gas is often the preferred option for off-site indoor work. This produces very little spatter, provides a high deposition rate, and requires less pre-cleaning of the material compared to gas metal arc welding (GMAW).

The slag systems in FCAW all-position filler metals provide much higher heat inputs and deposition rates than other processes. In out-of-position welding, FCAW can more than double the deposition rate compared to GMAW. In addition, FCAW achieves excellent bead quality without any manipulation.

For these reasons, FCAW wire is considered more forgiving and easier to use for vertical and overhead welding — even for less experienced welders.

FCAW processes are well suited for applications that require high volume welding, especially off-position. In many applications, positional welding can use the same welding parameters as non-positional welding because FCAW provides a wide range of parameters. This saves time and helps improve productivity.

Arc welding of metal with gas

There are two types of metal filler in the GMAW process: solid wire and metal core wire. These filler metals are not classified according to their positioning capabilities.

When out-of-position welding, the process must use short circuit transfer or pulsed GMAW to achieve less heat generation and produce acceptable welds. Keep in mind that less heat input will result in reduced productivity and deposition rate in the process. Vertical down welding is often used to avoid the productivity loss of vertical up welding, but vertical down welding is very prone to lack of fusion and is unacceptable for many applications.

Off-position GMAW welding often requires you to spend more time connecting to the machine, and weaving technology is usually required to get a good weld appearance. The lower heat input required for off-site GMAW can also result in no melting in the weld.

When comparing GMAW with FCAW in shielding gas, the powder welding process is more productive and tolerant of parameter changes. GMAW can be used — and is often used — to make acceptable out-of-position welds. However, if a lot of welding is required, this may not be the best option.

Gas tungsten arc welding

Like GMAW, gas tungsten arc welding (GTAW) is also an all-position welding process; filler metals are not classified according to positioning possibilities. Successful out-of-position GTAW welding requires attention to technique and heat input.

During out-of-position welding, it is again important to reduce heat. Weaving technology can be used, but this is not as important as with GMAW or SMAW welding.

Manufacturers would not change the welding process to GTAW to improve out-of-position welding, but those who already use GTAW can successfully use the process for these welds.

The right choice of process and filler metals

In out-of-position welding, factors ranging from heat input and travel speed to weld pool manipulation are more difficult to control. Achieving success in out-of-position welding depends on choosing the right process for the job and knowing the proper parameters and techniques. And, as with any application of welding, constant practice always helps to achieve the best results, Komarov Artem concluded.