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Specifications required for stainless steel architectural products
• Material composition (304 vs. 316)
• Material finishing (turning vs. turning & polishing)
• Material treatment (pickling and/or passivating)
Please quote to research, develop and present a material and process standard for the finishing of all of our architectural stainless steel products, one that will provide us with the ultimate oxidation resistant stainless steel surfaces.
We sell several (architectural) stainless steel products (http://www.bollards.ca/All-Stainless-Steel, for example), produced by a variety of suppliers who employ their own processes and standards. We want to develop the ultimate specification for the sourcing and processing of these materials, which will be used to standardize this production across all product lines & vendors.
Some of our stainless products have displayed oxidation in the field. We want to prevent such occurrences by determining the ultimate material selection (304 SS vs. 316 SS), the ultimate process standard (knowing that the majority of our products do require welding and machine turning), the ultimate surface finish (i.e. mirror finish *, directional, non-directional, #4 satin brush finish, etc.), and if required, the ultimate post production treatment (sand blasting, pickling, and/or passivating).
* a mirror finish, if determined to be a wise oxidation resistant surface finish, has already proven somewhat undesirable as it poses a dangerous traffic distraction.
We have experienced similar problems with oxidation on some of our high grade stainless steel castings in the past, which we rectified by employing a rather complicated process (below) that we have used for the past several years with grand success. Employing such a process on fabrications such as bollards, bollard covers and bike racks may be needlessly complicated, however, and may be cost prohibitive.
Process used to prevent oxidation of CF8 and CF8M Stainless Steel castings
• CF8 is the equivalent of wrought 304 stainless steel
• CF8M is the equivalent of wrought 316 stainless steel
• Castings are to be produced under ASTM A743
o All castings shall be solution annealed per table 1 in ASTM A743
o All castings shall be subject to post production pickling, and/or passivating
o Final shot cleaning shall use either stainless steel or glass beads - no steel shot shall be employed
o Weld repairs are allowed if performed prior to solution annealing, pickling and passivating
o All castings must have no visible rust after a 24-hour salt fog test. The salt fog test shall be conducted per ASTM B117
o All parts need to be INDIVIDUALLY wrapped and securely packaged for long distance freight in boxes or crates (heavy weight cardboard, wood or plastic), c/w cardboard sheets between layers of parts.
o Packaging: Protective Film + 3-5 layers foam tape (15-20mm thick) + plywood crates
o No ferrous packaging of any kind can be used.
o Parts cannot come in contact with any ferrous hand tools, storage vessels, carts, bench tops, etc.
References (some details found during our initial research on this subject);