Most people who have been in a technical profession know the constant need for a variety of tools. One minute you may need a pliers, then a knife, then a file, then a screwdriver, and once the day is all done, a bottle opener. This is the reason why multi-tools have become so popular; they combine all of these tools into one. In the world of welding, there is something similar to a multi-tool. It is known as a multi-process welder. Red-D-Arc carries multi-process welders because we know that one minute you might be self-shielded flux core welding some dirty, ½” thick steel and then the next minute be fitting up 18 gauge aluminum that you need to gas tungsten arc weld.
Red-D-Arc provides a wide variety of multi-process power sources to suit many customer needs. The Miller XMT is a type of multi-process welder that Red-D-Arc carries. All XMT variations provide the capability to MIG, TIG, flux core, and stick weld. The Field Pro series also possesses Miller’s proprietary pulse waveform known as Regulated Metal Deposition (RMD).
This is a pulsed short arc MIG welding process that is excellent at bridging wide gaps that can result from poor fit-up.
Red-D-Arc is aware that multi-process welders aren’t always operated in ideal conditions. Extreme heat and environments with high amounts of dust can destroy welding power sources. That is why Red-D-Arc provides the EX360. The “EX” is for extreme, because this power source can handle extreme conditions. If protection from dust and heat are a concern while using multiple welding processes, the EX360 may be your solution. The EX360, as well as several other multi-process welders offered by Red-D-Arc, are available in four-pack and six-pack configurations to enable increased productivity.
Submerged arc welding is an excellent process to achieve high deposition rates, and Red-D-Arc has them. However, some applications require additional welding processes besides just submerged arc welding. When this is the case, Red-D-Arc also has multi-process submerged arc welding machines. The DC1000, for instance, provides end users with the ability to not only submerged arc weld, but also provides stick, MIG, and flux cored arc welding capabilities.
For additional information on Red-D-Arc’s multi-process welding product offerings, visit our multi-process welder page.
Stainless steel contains a minimum of 10.5% chromium which imparts it corrosion resistance by forming an oxide layer on the surface. The most common stainless steel is the austenitic type (300 series) which contains chromium and nickel as alloying elements. Other types include ferritic, martensitic and duplex stainless steels. Most stainless steels are considered to have good weldability characteristics. Most common processes used for welding stainless steel are TIG (GTAW) and MIG (GMAW). But, stick welding (SMAW) is also utilized.
Differences in Properties:
The properties of stainless steel differ from mild steel, and these differences need consideration when welding as below:
- Higher coefficient of expansion, 50% more for austenitic – this results in more distortion
- Lower coefficient of heat transfer – welding requires lower heat input as it is conducted away slowly
- Lower electrical conductivity – using the correct and consistent stick-out distance is more critical when using MIG/TIG, higher wire speed for the same current is required when MIG welding
Why segregated work area?
Welding of stainless steel is carried out in a work area segregated from carbon steels. Moreover, tools dedicated for use with stainless steel must not be used to work on carbon steels. These tools include brushes, hammers, clamps, grinders etc. The segregation of work area and tools safeguard the contamination from carbon steels, which may cause welding defects and corrosion (rust) on stainless steel. You must also wear gloves when working with stainless steel as this will prevent oil from the hands passed onto the stainless steel.
Preparation is key!
With stainless steel, it is important that the joint surfaces are thoroughly cleaned before welding to remove any dirt, grease, oil etc. The filler wire also needs to be completely clean.
Additionally, the joint design including the joint gap must cater to the higher expansion rate of stainless steels.
Filler Material Selection:
Filler materials used generally are the same as the base metal. Special considerations are required to select a filler material if welding dissimilar stainless steels or stainless steels where no identical filler material exists. Furthermore, filler materials are selected to reduce the risk of intergranular corrosion and hot cracking.
It is essential to protect the weld during welding using a mainly inert gas. Additionally, the weld root needs to be purged using a pure inert gas.
When welding austenitic stainless steels, it is important to restrict the heat input to a level which is just sufficient to ensure a good weld. The interpass temperature is limited to 350 F. Preheating is not carried out on austenitic stainless steels. Very low carbon grades (suffixed with L e.g. 304L, 316L) are used to prevent the formation of chromium carbides in the heat affected zones which causes intergranular corrosion.
Martensitic stainless steels are generally used as wear resistant materials in overlaying applications. To avoid cracking, accurate preheat needs to be applied and a minimum interpass temperature maintained.
Ferritic stainless steels are used mostly in automotive applications. The heat input in these steels during welding needs to be limited, and a maximum interpass temperature of 300 F is recommended. This will ensure that the grain growth in the material is controlled and the strength is maintained.
With duplex stainless steels, the heat input also needs to be restricted.
Cleaning and Passivation:
Stainless steel welds must be cleaned and passivated after completion to ensure corrosion resistance and good appearance. This is performed manually by mechanical (brushing, grinding, blasting), chemical (applying pickling agents and other chemicals) or electrochemical means.
Red-D-Arc has a wide range of equipment suitable for stainless steel welding for rent including the following:
Multi process welders capable of stick, TIG, MIG, submerged arc, air carbon arc cutting, flux core, up to 1500 A
MIG welding units up to 750 A
TIG welding units up to 750 A
Stick welding units – up to 625A
Also 4 and 6 Paks of welders available
Orbital welders – suitable for stainless steel pipe/tube welding
Various brands including Miller, Lincoln, Red-D-Arc
Have a look at our complete range of welding products.
Importance of Preheating in Welding – Equipment Options
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.
By guest blogger David H.
Some years back I was working in a shipyard in San Francisco. The yard had several small repair jobs going, plus a fairly large project building six ocean-going barges. The supervisor who was in charge of the barge-building project was looking for volunteers to operate semi-automatic wire feeders, using flux-cored wire, to weld stiffeners to the skin of the barges. I had never used a wire feeder before, so I volunteered out of curiosity.
After a very short training period, possibly all of 30 minutes but I think a bit less, I was off and running. I was impressed by the <strong>quality of the welds</strong> and the speed at which they were deposited. Without question I was <em>outpacing anything</em> that could be done by stick welding, and I felt it was easier to maintain a <strong>uniform weld size</strong> too. The machine itself was light enough and small enough to move without difficulty, and the spools of wire lasted long and were <em>quick and easy </em>to replace when the spool of welding wire was finished.
Red-D-Arc has nearly a dozen <a href=”https://www.red-d-arc.com/rental-equipment-subcategories.aspx?sub_cat=175″ target=”_blank”>semi-automatic wire feeders available</a> for almost any application. We also carry <a href=”https://www.red-d-arc.com/rental-equipment-subcategories.aspx?sub_cat=178″ target=”_blank”>fully automatic wire feeders</a>, which are faster still and appropriate in certain circumstances – like <a href=”https://www.red-d-arc.com/rental-equipment-subcategories.aspx?sub_cat=289″ target=”_blank”>building storage tanks</a> – especially for large-deposition welds.
A Red-D-Arc customer based out of the UK was awarded three large offshore wind farm projects …all commencing simultaneously. This manufacturer was comfortable taking on so many large scale, specialized projects because they have a reliable, knowledgeable, tier 1 supplier capable of meeting all of their welding and weld automation equipment needs! Red-D-Arc was able to quickly accommodate all of the welding equipment requirements for the project, providing more than 150 welders and a variety of weld automation equipment. The equipment consisted of multi-operator welding paks, diesel welders, advanced power sources, wire feeders, submerged arc welding packages, and rotators.
Two Red-D-Arc technicians were assigned to the facility to install, service and maintain the equipment to minimize downtime. The facility allocated a permanent workshop and storage container for back-up equipment which could be used to quickly replace any equipment as necessary. With Red-D-Arc’s support, the customer was able to work on all three projects simultaneously and avoid lost time due to equipment breakdowns.
By 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…)
“You should give as much consideration to the preparation as you do to the actual welding”
Pipe welding is utilized all around the world in diverse industries. A variety of pipe sizes and material grades are joined to manufacture components of various shapes and lengths – from a few feet to many miles. Even though most pipe welding jobs have custom specifications – there are some fundamental aspects of pipe welding that form a common thread for welders and welding engineers alike in order to achieve high quality welds in pipes.
Selecting The Right Pipe Welding Equipment
Equipment selection is the top requirement for producing good quality pipe welds. The highest priorities when selecting welding equipment for pipeline welding are reliability, consistency, accuracy and process control. It is also critical that the equipment is easy to use and the controls are intuitive. In addition to equipment performance, the work environment also needs to be a key factor for equipment selection. There are pipe welding configurations designed for offshore welding, remote land based pipeline welding, general fabrication shop use and custom configured automated pipe welding systems. Selecting the right one can be a daunting task – it is always good practice to seek expert advice. Be sure to ask about the various options, capabilities and limitations of each system. When welding CRA (Corrosion Resistant Alloy) grades, it is necessary to use weld purging in order to guarantee the corrosion performance of the root run. The importance of this should not be underestimated.