Pickling devices

When the right choice makes the difference (part 2)

Pickling TIG welding with patented torch – Nitty Gritty

Electrochemical pickling – Nitty Gritty

In the first part, two fundamental aspects were discussed in order to have a judgment measure in the choice of an electrochemical device:

With these parameters you can have a general view of the situation. To go into more detail we can consider two other parameters which are also fundamental:

  • Safety devices and technologies for the optimization of the pickling process;
  • Type of weld, length of weld.

These parameters focus on company productivity and the operator’s way of working.

Safety devices and technologies for the optimization of the pickling process

Pickling machines are devices that convey electricity and an electrolytic solution to clean welds. These two factors, if handled incorrectly, can damage the operator and slow down the production process.
On the market, some pickling machines are equipped with a “dip & work” system. This system provides a small tray filled with corrosive acid in which the insert gets wet and then proceeds with the cleaning of the weld. This method, in its simplicity, leads to numerous defects:

  • Continuous interruptions;
  • Drops of electrolytic liquid in unwanted areas;
  • Contamination of welding residues inside the electrolytic solution.

The electrochemical reaction is fast and immediate. Locally, between welding and the final part of the insert (which is generally a carbon fiber brush), high temperatures and chemical reactions are generated which quickly deplete the electrolyte. The operator is unable to determine the exact time to wet the insert again, causing unwanted fumes generation and consumption of the insert.
It may happen that the acid, by impregnating the insert, escapes from the insert before cleaning, inexorably dirtying parts that are not involved in the pickling process. This leads to damage when the operator, during the process, does not neutralize and acid from the surface. During pickling, the insert becomes impregnated not only with acid but also with welding residues removed over time. With this method, these residues are dispersed inside the jar when the operator returns to wet the insert.
These residues, contaminating the electrolyte, lower the efficiency of the welding cleaning and can create corrosion points because they introduce unwanted elements back onto the bead.
All these disadvantages affect production, causing slowdowns for:

  • Small interruptions;
  • Neutralizations or damages on surfaces not involved in the process;
  • Increased pickling time due to contamination of residues in the electrochemical solution.

Automatic suction\blowing patented torch- Nitty Gritty

Manual patented torch- Nitty Gritty

Nitty-Gritty has developed two patented torches characterized by the possibility of drawing the liquid from a tank (100 ml or 2 liters depending on the model) through an automatic or manual pumping system. With this technological leap:

  • The liquid wets the pad / brush directly and intervenes directly on the weld;
  • It leaves no residue on other surfaces;
  • No liquid comes into contact with the operator;
  • There are no interruptions;
  • The electrochemical liquid inside the tank is not contaminated;
  • Interventions even in areas difficult to clean.

Sometimes operator safety is a marginal aspect of a company. In this process it must be a priority as the risk of injury is always around the corner. Much discussed is the issue of the development of vapors / gases during the pickling process. The most dangerous electrolytic solutions are corrosive and high in phosphoric acid. In this case. the exposure limit is 1 mg / m3 (TWA, 8h). The manufacturers that make use of the “dip & work” system are almost at the limit (about 0.8 mg / m3). This involves the potential use of protective masks and antacid gloves.From this point of view, Nitty Gritty has studied two systems that can radically reduce the development of corrosive gases:

In this way, hot and corrosive vapors are instantly or conveyed inside the machine by means of a suction motor expertly designed for acid vapors or condensed with a jet of cold air with the right pressure coming from a compressor connected to the machine. With these technological devices, the exposure limit is lowered to a value of about 0.04 mg / m3.

Type of welding and its dimensions

Welding ART –  TIG welding

A fundamental and essential point of electrochemical pickling is the quality of the welded joint, which has been mentioned several times in several articles of this blog. In addition to this very important parameter, there are two other factors that can change the prospects for a good purchase of a pickling machine. One of these is the type of welding: producing an article with MIG rather than TIG welding has a different impact on the electrochemical pickling time. MIG welding produces more slag than TIG. For these reasons, for the same time, you could choose a machine with a power equal to or greater than 900W using an acid with a very high acid concentration (around 75%). With this solution, many of our customers are satisfied with the quality / price ratio. Likewise, a TIG welding will require less pickling power and solutions with a very low acid concentration (about 20 – 25%) up to 0% acid concentration (neutral pH) could be adopted. On TIG welds, with the same power and quality of the weld, the electrochemical cleaning takes place in the same timing if we had to choose between a mildly acidic solution and one with a neutral pH. Another important parameter is the length of the weld hinges. Put simply, how many meters of welding need to be cleaned in one production cycle? If the welding meters are around 200-300 meters, it is advisable to adopt systems such as Clinox Pro, Clinox PowerClinox Surface which allow a continuous and automatic process of electrochemical cleaning, exploiting a very high pickling power. In this way, the dead times and the continuous interruptions of a simple “dip & work” system are eliminated with all the problems connected to the system and its technology, which we talked about previously. If the welds are less than 200 meters and are TIG welds, the dedicated machine is the Clinox Eco. With its power (450 W) and its patented torch, it is possible to clean impeccably all the welds that make up the small product. Unlike welding, the thickness of steel is not a fundamental parameter because electrochemical cleaning involves only the surface and does not need high powers to act in depth.

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