What do stainless steel 347 pipe fittings mean?
These fittings are specifically designed for applications that need to undergo welding. The chemical makeup of the Stainless Steel 347 Pipe Fittings is very similar to grade 304, differing by the inclusion of columbium and tantalum.
How to test ASTM A403 WP347 buttweld elbow corrosion resistance?
Fittings including elbows produced under specification ASTM A403 are tested with the ISO 3651 standard. Here, a Buttweld Elbow will be soaked in an acidic solution for 20 hours following which they are bent to check the resistance of the alloy to intergranular attack.
Standard welding processes for SS 347 fittings
While welding grade 347, the corrosion resistance of the filler metal needs to be taken into account. It is preferable to use a highly alloyed metal due to the structure of the weld cast. Both pre and post-heating treatments are not usual to weld this grade. Since the fittings have an austenitic microstructure, they have to be welded at a lower temperature (as they have a lower fusion point). Using a higher welding speed reduces the risk of overheating or burning through. For fittings whose thickness is over 12mm, ideally, a double-V butt weld is the conventional practice. The welding angle is to be 60° – 70°. But with a MIG-welding process, using a 50° angle is perfectly acceptable. Tack welds need to be shorter compared to non-alloyed steel. They need to be cleaned, ground and free from crater cracks. Accumulation of weld seams is to be avoided. The rate of cooling needs to be rapid. This reduces the alloy’s vulnerability to intergranular corrosion and embrittlement. To prevent oxidation, while the surface is being welded by a laser beam, helium is used as an inert gas. Laser fusion welding can also be carried out with nitrogen or flame cutting with oxygen. The cut edges generally have very small HAZ or heat-affected zones. This means that the fittings tend to be free from microcracks. Passivation is encouraged by using stainless steel tools such as steel brushes and pneumatic picks. The layer of passivation is preserved by removing slag, tramp iron, spatters, scales and annealing colours. To clean the surface of the fitting, processes such as pickling, brushing (with stainless steel), blasting or pickling are very common. Usually, pickling is carried out with either a paste or solutions or by dipping and spraying. After this process, the fittings need to be carefully flushed with water.
347 stainless steel reducer applications
Reducers are used to reduce the flow of media in piping systems across different sectors such as waste management, chemical processing, food processing, petroleum refineries, and in the production of pharmaceutical products.
What are the advantages of 347 stainless steel seamless fittings?
Good resistance to general corrosion, aside, grade 347 Stainless Steel Seamless Fittings perform well in strongly oxidizing environments up to a temperature of up to 1500°F. In hydrocarbon applications, the fittings are resilient to polythionic acid stress corrosion cracking. They have good resistance to many diluted organic acids and to nitric solutions in moderate temperatures.
What makes AISI 347 equal tee rust-resistant?
Many steel alloys get corroded and rust easily because the iron content from the alloy reacts with oxygen in the air. However, AISI 347 Equal Tee has good resistance to oxidation at elevated temperatures. Thus, making it a rust-resistant alloy.
