This place I'm at is using a sandblaster to prep fittings. That's all they do, no grinding the land down to sharp edge or cleaning of any kind. It makes it really tough to get a nice TIG root in, that sand residue does not want to wet out and flow at all. And the land, just turn the heat up, that's all you have to do, so they say. They claim all the sand floats to the top, therefore not a problem. They must not go around looking at roots, because most of the ones I see look like crap.
The welding procedure says: "Pipe to be prepared by grinding, sanding or polishing." No mention of blasting anywhere.
What do you guys think about it?
Sand blasting is generic and does not tell us the entire story. The blast media can vary from crushed slag (iron making by product), silica, glass beads, steel or stainless shot, etc. The bottom line is that you have to be more specific.
If glass bead, crushed slag, or silica is used, a residue can be left on the base metal surface. As an oxide, the residue can lead to porosity problems if the filler metal used does not contain sufficient levels of deoxidation.
As for the grit getting into the pores of the base metal; there ain't no pores in the base metal and the water that collects on the surface of the base metal when applying the preheat flame ain't coming for the base metal. Good Lord, I'm never going to be able to retire!
As for the root face, it is a nonessential variable per ASME Section IX, so buck up little fella; it is a welder skill issue. I am being sarcastic with my last comment. The dimension of the groove angle, root face, and root opening have a direct influence on the welder's ability to achieve consistent joint penetration and fusion. Unfortunately, because too many people at the management level have no clue about welding, they depend on the code to provide some direction on welding issues such as fit-up, electrode selection, etc. As such, they assume any nonessential variable is an insignificant factor in obtaining a sound weld. In this case, if ASME is their guide, they are driving at night without their headlights on and it is a moonless night. Thank God for these poor folks, without them I would actually have to work for a living. As it is, solving their welding problems provides a good cash flow for my practice.
Best regards - Al
We can cure ignorance, but there ain't no cure for stupid.
We all do our part to educate each other. Fortunately, the fact that individuals gravitate to the Forum is a strong indication stupidity isn't a problem with our community of members.
A keen sense of humor and a thick skin are essential characteristics for anyone that visits this community more than once. Those people that lack humor or have thin skins rarely return to share information or to become the subject of a quick jab of humor when it is at their expense. Those quick jabs may sting, but they are a reminder we don't know every thing. There is always more to learn when it comes to the subjects of welding and inspection.
I have to run, there are a few wounds on my back side that need some attention and a couple of bandages.
Best regards - Al