The preheat would only be for the welding, and the penetrant test (PT) would be done after waiting 48 hours after welding was complete to check for delayed hydrogen cracking. We would also check to make sure Brinnell hardness readings were <200.
I guess I should expand the question to include...
My refinery has always done this in the past but I'm not sure it is necessary (small bore piping <2" and service with H2S >50 ppm in water phase). Would it be sufficient to maintain a preheat of ~200 degF, use E7018 low hydrogen electrodes, and follow up with a PT 48 hours after welding...
I don't know off the top of my head, but typically the liners aren't installed for pressure bearing capability and the plates are attached by fillet welds. If overlay was used you could take credit since the corrosion resistant material would then be integral with the tank wall.
Good luck...
Xeros,
Is your company currently using inspection software like PCMS? Switching to RBI is a major undertaking, and whoever does your RBI study will also be trying to sell you their software. We use one of the companies mentioned above, and let me tell you it wasn't cheap, but we needed to...
Is H2S the product or a by-product? In a refinery if there is a sulfur recovery unit there can be large amounts of H2S generated, which can be used in other areas of the refinery for different processes or the elemental hydrogen and sulfur can be separated for other uses. It's also a nasty...
For corrosion to occur you need an anode, a cathode, and an electrolytic solution; remove any one of these from the equation and you will eliminate the corrosion mechanism. The anode will experience an oxidation reaction and the cathode will experience a reduction reaction, or more simply the...
Witchdoc,
Does the tank have a U-1, and if so was it built to ASME code? You'll need the joint efficiency value E from the U-1 (0.7 if unknown), and the maximum allowable hydrostatic test stress in lbf/in^2; use the smaller of 0.88Y or 0.472T for bottom and second courses, use the smaller of...
