1. What is the welding seam quality requirement for Q195 welded pipes?
The welding seam of Q195 welded pipes should be free of defects such as cracks, pores, slag inclusions, and incomplete penetration. The weld width and height should meet the design requirements, and the tensile strength of the weld should not be lower than 90% of the base metal (Q195 steel).
2. How to detect the welding seam quality of Q215 welded pipes?
Common detection methods for Q215 welded pipe seams include visual inspection (VT), ultrasonic testing (UT), radiographic testing (RT), and liquid penetrant testing (PT). Visual inspection is used for surface defects, while UT and RT are used to detect internal defects such as cracks and incomplete fusion.
3. What is the standard for Q235 welded pipes?
Q235 welded pipes are mainly produced in accordance with Chinese national standards, such as GB/T 3091-2015 (Welded steel pipes for low pressure fluid transport) and GB/T 9711-2011 (Steel pipes for petroleum and natural gas industry). The specific standard is selected according to the application scenario.
4. What is the difference in ductility between Q195, Q215, and Q235 welded pipes?
Q195 welded pipes have the best ductility (elongation >=33%), followed by Q215 (elongation >=31%), and Q235 (elongation >=26%). With the increase of the grade number, the strength increases, but the ductility decreases slightly.
5. Can Q195 welded pipes be used in outdoor environments?
Yes, but they must undergo anti-corrosion treatment (such as hot-dip galvanizing). Without anti-corrosion treatment, Q195 steel is prone to rust in outdoor humid or rainy environments, which will reduce the service life of the pipes.
