When to use low hydrogen electrodes
The steady development of new alloys over the years has shaped the design and specification of arc welding stick electrodes.
As increasingly demanding welding applications became standard in fab shops and in the field, the need for durable, low hydrogen stick electrodes became more prevalent across a variety of industries involved in welding. As a result, low hydrogen stick electrodes emerged.
These versatile consumables have become a primary electrode for a variety of welding applications and have gained wide acceptance in the industry. They are ideal for use in other applications where base metals have a tendency to crack, where thick sections are to be welded or where the base metal has an alloy content higher than that of mild steel, such as high carbon and low alloy steels.
Today, there are many types of low hydrogen electrodes available for use in shielded metal arc welding (SMAW) applications. These electrodes, which include EXX15, EXX16, EXX18, EXX18-X, EXX28 and EXX48, are often specified to reduce the likelihood of hydrogenrelated cracking during the stick welding process. Low hydrogen electrodes are recommended for three broad areas of application: On steels with poor weldability: low alloy, high carbon, high sulphur, or other steels where cracking can be a problem. When specified by governing codes. For high-deposition, outof-position welds on heavy plate. Low hydrogen electrodes offer fast-fill (high-deposition) or fill-freeze (out-of-position) characteristics and are designed to produce sound welds of X-ray quality with excellent notch/impact properties and high ductility.
Some low hydrogen stick electrodes have a -1 suffix in the AWS classification. This indicates the stick electrode meets the requirements for improved toughness.
Welding consumables can be classified with an optional diffusible hydrogen designator.
These designators include an H4, H8 and H16 designation. The “H” and corresponding number indicates millilitres of diffusible hydrogen per 100 grams of weld metal.
The “R” designation for an electrode indicates that it has a moisture-resistant coating. While low hydrogen electrodes ideally should run on DCEP polarity (especially if the size is 5/32-inch or less), they also can be used on AC polarity.
Low hydrogen electrodes, incidentally, are the most widely used class of welding consumables for such applications as power generation, general