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What Do American Welding Society Wire Filler Metal Designations Mean?

07 September, 18 2:58 pm · Leave a comment · reddarc
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Selecting Welding Wire

coil of welding wire
When selecting a wire electrode for welding, one will most likely run into an American Welding Society (AWS) filler metal classification. A purchaser who isn’t familiar with the AWS classification system might select the wrong type of wire. If the purchaser is only familiar with gas metal arc welding (GMAW) wire and is attempting to purchase self-shielded flux-cored wire (FCAW-S), confusion may arise about the differences between the two classifications. This too could result in selecting the wrong wire electrode. To help prevent this from happening, we’ve created this welding wire reference guide to remind welders exactly what the different AWS classifications designations mean. We’ve included references for solid wire electrodes, metal-cored wire electrodes, gas-shielded flux-cored electrodes, and self-shielded flux-cored electrodes.

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Pipe Welding Methods and Equipment

27 June, 18 3:49 pm · Leave a comment · reddarc
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Pipe welders at work
The method you select for welding pipe will depend on the location where the welding is taking place, materials and pipe size.
For welding steel pipes in the open (e.g. pipe installation in trenches), manual arc welding (SMAW) is most common. This technique used is downhill using cellulosic electrodes (also basic electrodes are used for higher strength steel applications). A root pass and a hot pass are followed by the fill passes. The weld is finalized by the top pass. Welding units optimised for downhill welding are utilised.

Welding Smaller Pipes

For small diameter and short length pipes which are free to rotate, the pipe is rotated while the welding torch is held stationary. The processes used are MIG (GMAW) and TIG (GTAW). In the case of TIG welding a wire feeder is necessary. A process cell is best for this type of welding.

Welding Large Pipes

In applications involving larger pipe sizes, welding is generally carried out using the orbital process. MIG is usually employed, but TIG with automatic feed of the filler wire can also be used. Orbital process using closed head welding units is also utilized for applications where smaller pipes cannot be rotated.

There are a number of advanced methods of depositing pipe welds currently in use. These include precisely controlled short circuit transfer for root pass (Miller – Regulated Metal Deposition), optimized pulsed welding (Miller – Pro-Pulse) and high frequency waveform control (Lincoln – Surface Tension Transfer) in order to speed up and improve the quality of the pipe welds.

Red-D-Arc has a wide range of pipe welding equipment for rent including the following:

Have a look at our entire selection of pipe welding equipment which includes pipe cutters and bevelers.

Read more on orbital welding

Strengthening Metal Parts with Hardfacing

27 April, 18 2:42 pm · Leave a comment · reddarc
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Metallic parts sometimes fail their intended use at a lower stress than they are designated for.
Various forms of wear such as abrasion, impact, metal to metal contact, heat, and corrosion can compromise the strength of metal pieces. This is where hardfacing comes in. Hardfacing is a technique which can be applied to minimize the damage from these types of wear, helping to prolong the life of metal pieces.

What is hardfacing?

Hardfacing —often called hardsurfacing— is the covering of the metallic part with a wear resistant metal by welding. Alloys which commonly need to be hardfaced include carbon alloy and low alloy steels whose carbon content is lower than 1 %. These include stainless steels, manganese steels, cast iron as well as nickel and copper-based alloys.

Metallic parts sometimes fail their intended use at a lower stress than they are designated for.

Techniques, Materials and Costs

The particular hardfacing technique for a job depends on the geometry of the part and relative cost of the hardfacing method. Costs can vary with the deposition rate of the material.

These cost variations can be summarized as follows:

  • Flux cored arc welding (FCAW) 8 to 25 lb/hr
  • Shielded Metal Arc Welding (SMAW) 3 to 5 lb/hr
  • Gas Metal Arc Welding (GMAW), including both gas-shielded and open arc welding 5 to 12 lb/hr
  • Oxyfuel Welding (OFW) 5 to 10 lb/hr

 

Applied materials commonly include cobalt based alloys such as STELITE, and nickel based materials like chromium carbide alloys. More advanced materials such as complex carbides containing columbium, molybdenum, tungsten, or vanadium can also be used and provide more overall abrasion resistance. They also have a very low friction factor, which can be used in situations involving severe abrasion.

Hardfacing can be applied to both newly manufactured pieces, in order to prevent deterioration, or to strengthen and extend the life of worn pieces currently in use.

Red-D-Arc provides welding machines suitable for hardfacing using techniques including SMAW, FCAW and GMAW.

Preheating Applications in Welding

16 March, 18 2:47 pm · Leave a comment · reddarc
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Importance of Preheating in Welding – Equipment Options

Preheating pipe for welding

Why preheat?

Preheating reduces the risk of cracking in weld metal and heat-affected zone (HAZ) by:

  • Lowering the cooling rate of the weld – prevents formation of brittle weld metal/HAZ, allows more time for hydrogen to escape the molten weld.
  • Removing moisture (hydrogen source) from the part.
  • Reducing shrinkage by lowering the temperature differential.

Preheat or not?

The requirement and level of preheating for steel is determined by the relevant welding code and is dependent on the weld heat input, chemical composition of steel (carbon equivalent), thicknesses, diffusible hydrogen etc. Non-ferrous materials generally require preheat because of their high thermal conductivity.

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Producing High Quality Welds in Stainless Steel Welding

14 November, 17 2:46 pm · Leave a comment · reddarc
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drilling platformBy guest Blogger Katarzyna K.

Katarzyna has an Msc in Materials Science and has worked in the oil and gas industry in jobs related to hydraulics, welding and the retrofitting of oil rigs.

Stainless steel is used extensively in the petrochemical industry due to its high resistance to severe conditions. When welding inox steels, the smallest details matter and have an impact on weld quality. The following are some tips for stainless steel pipe welding based on my oil rig repair experience:

During an oil rig repair project that involved 2205 duplex stainless steel pipe TIG welding, we could not achieve the required weld properties. Despite using the recommended filler metal with higher nickel content, compared to the base metal, and controlling the interpass temperature, the weld tensile strength was still too low. In order to reach the required weld quality we dug deeper and found a solution – (more…)

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