According to Nb / T 47014-2011, the category number of TA3 base metal is TI-2.Nb / T 47014-2011 standard stipulates that the butt weld test piece welded with 6 mm thick base metal can cover the butt weld weldment with unequal thickness with base metal thickness ≥ 1.5 mm, At the same time, the material standard has no impact test requirements, so the welding evaluation of 6mm butt weld can cover the butt weld weldment with the thickness of the base metal of 1.5 ~ 12mm. The maximum cylinder thickness of the titanium pressure vessel is 10 mm and the thinnest nozzle thickness is 3.5 mm, all welded joints are required to use tungsten argon arc welding. Therefore, based on the principle of covering the largest number of welded products with the minimum number of welding procedure qualifications, all welding production of the equipment can be met as long as one butt welding seam welding procedure qualification with a base metal thickness of 6 mm is carried out.
The welded joints of the main body of the equipment are in the form of conventional butt welds. During welding, the welding procedure specification shall be prepared according to the qualified welding procedure qualification report. The manhole cover and nozzle flange cover are manufactured with 16Mn Ⅱ forging and TA3 lining plate. Generally, they are fixed with screws, and then the titanium layer and deposited metal are overlaid on the screw surface. Because titanium and steel cannot be fusion welded and there is no transition layer, the screw is also made of TA3 material, which does not need the support of corrosion-resistant surfacing process qualification. As long as the butt weld welding process qualification with a base metal thickness of 6 mm can meet the process requirements of the surfacing joint. The sealing surface must be processed after the lining plate and flange cover are welded. See Fig. 1 for the welded joint.
|
|
The manhole and connecting pipe shall adopt looper flange, and the stop shall be added on the connecting pipe, with the specification of 20mm × 20 mm × 6 mm, TA3 material, 2 stops for connecting pipes with DN ≤ 80 mm, and 4 stops for connecting pipes with DN > 100 mm. The welded joint is shown in Figure 2. Finish machining of the sealing surface shall be carried out after the welding of the welding ring with the same material as TA3.
JB / T 4745-2002 standard requires that vessels with extreme or high toxicity, or medium and high-pressure vessels with design pressure ≥ 1.6 MPa, need to prepare product welding test plates according to sets, so the equipment can be exempted from product test plates.
