Presentation on Porosity.pptx

Different causes of Porosity

1. Porosity in Welds

2. Porosity in Welds Porosity simply put, signifies gas pocket(s) that form into the welded metal. Normally porosity can be easily detected with the naked eye in the form of small holes. However, testing devices like X-Rays are used in the case of critical welds.

3. Porosity in Welds Porosity simply put, signifies gas pocket(s) that form into the welded metal. Normally porosity can be easily detected with the naked eye in the form of small holes. However, testing devices like X-Rays are used in the case of critical welds.

4. Porosity in Welds Distributed: Pores that are distributed throughout the weld.

5. Porosity in Welds surface breaking pores: Pores that break the surface.

6. Porosity in Welds Crater pipe: A shrinkage cavity at the end of the Weld Run caused by shrinkage during solidification .

7. Porosity in Welds Wormholes: Elongated pores that show up resembling a herringbone pattern on the radiograph 1 2

8. Porosity in Welds How to solve Porosity Problems Remove any surface contamination, in particular, oil, grease, rust, and residue from NDT operations Remove any surface coatings from the joint area to expose bright material Check the primer thickness is below the manufacturer’s maximum Avoid a joint geometry that creates a cavity Use run-off tag to enable the welding arc to be extinguished outside the welded joint Grind out the weld run stop crater before continuing with the next electrode or depositing the subsequent weld run Welder technique Progressively reduce the welding current to reduce the weld pool size (use slope-down or crater fill functions) Add filler (tig) to compensate for the weld pool shrinkage

9. Porosity in Welds Air entrainment Seal any air leak Avoid weld pool turbulence Use filler with an adequate level of deoxidants Reduce the excessively high gas flow Hydrogen Dry the electrode and flux Clean and degrease the workpiece surface Surface coatings Clean the joint edges immediately before welding Check that the weldable primer is below the recommended maximum thickness .