SPA Purge Systems
The upside is protected through shielding gas
Welding a tube on the upside by using shielding gas the welding seam is sufficiently protected through the outpouring shielding gas. Oxidation of the material on the upside is thereby prevented. But what happens inside the tube?
The problem: No shielding gas at the root weld inside the tube
Here the “air-atmosphere” has an unhampered access to the root weld and the result is tinder, temper stains and scale. Oxidized surfaces are no longer corrosion-resistant as they have to be!!
Welding corrosion resistant steels like austenitic CrNi or CrNiMo steels, unhampered access of air leads beside the higher corrosive effect to a cracked and porously root weld. Welding titanium or tantal one has to work more cautious. These so called gas-sensitive materials absorb for as little as 300°C (850 °F) perceptible more oxygen and nitrogen. Here you have to gas backing both the root weld and the upper weld for cooling down to 200 °C (500°F).
CAUTION !
Mechanical remove of the oxide skin by i.e. grinding destruct also the passive skin. Thus results in a less corrosion-resistance surface. The solution: The SPA Purge System SPA Purge Systems consist of different components. These components can be customized in the twinkling of an eye to any tube diameter or application. This is called a forming gas chamber. SPA Purge Systems are made out of high quality materials and resist temperatures up to 300 °C (700°F).
Which Forming Gases do I need for which material?
In the first place this depends on the material which has to be welded and the structural elements of the construction. Generally we use:
- Argon as an inert, non reacting shielding gas
- Nitrogen as a quasi-inert, indolent-reacting shielding gas
- Argon or Nitrogen mixed with Hydrogen as reduce shielding gas mixes
| Kinds of Shielding gases |
Material |
|
Argon
|
all kinds of steel, also gas-sensible, austenitic CrNi and CrNiMo steel. austenitic-ferritic steel (Duplex), gas-sensible materials like titanium, zirconium, molybdenumhydrogen-sensible materiales like copper, copper alloys, aluminum and aluminum alloys, fine-grain steel and non ferrous and ferritic.
|
| Nitrogen |
austenitic CrNi-steels |
| Argon-Nitrogen-Mixes* |
Duplex- and Superduplex-steel |
| Nitrogen-Hydrogen-Mixes* |
Structural steel with the exeption of high strength fine grain steel austenitic CrNi- and CrNiMo-steel. |
| Argon-Hydrogen-Mixes* |
austenitic CrNi- and CrNiMo-steel nickel und nickel-based materials |
The solution: SPA Master Purge Systems
The SPA Master Purge Systems consist of individual elements, from which with few handles mitrogen-hydrogen mixture chambers can be built for the most diverse applications and pipe diameters. The components are manufactured from materials of highest quality; the seals resist temperatures up to 350 °C/662 °F.
Contact us - gladly we inform you in detail about the advantages of the SPA Purge Systems.
Supporting- and sealing discs
The supporting- and sealing discs are to be put on the Root Protection Elements and are fixed through the knurled Set Nut. There are at least 1 sealing disc and 2 supporting discs required. SPA Master Purge Systems are designed also to affix more supporting- and sealing discs which increases the stableness and denseness inside the tube. We recommend this as a precaution when welding pipe diameters 10” and over.
Advice:
The diameter of the sealing disc should be 10 mm larger than the inner diameter of the pipe. The supporting disc should be 20 mm smaller than the inner diameter of the pipe. Sealing discs are heat resistant up to 250°C. Other dimensions are deliverable on request.
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