Most engineers and professional in the business of stainless steel understand how to assess stainless steel tubes, but what about a regular housewife or a fixer-upper who is going into a new DIY project with no idea whatsoever how to recognize and pick quality? Here are some quick guidelines to help you:
Know The Purpose
Stainless steel is made up of 5 main types but there are different manufacturing processes that use a variety of formulas, combination of elements, and sizing. Before you even go out and start buying your materials, know what the application will be. If you are planning on something aesthetic and decorative, the stainless steel tube should be the welded type. If you need it for plumbing, you should get the seamless tubes. For the kitchen, restaurants or hospitals, you will need sanitary tubes.
As for the sizing, you will need a tube with thick walls for anything that handles pressure. The location of the tube is also significant. For indoor use, you can buy the 200 series while for outdoor use, you will need to buy the 304 series with the exception of areas that are close to sea air like coastal areas which would need 316 or higher material.
Choosing the Tube
Do not be misled by pricing. There are some 304 tubes that are priced cheaper than the 301 grade. If you happen to be in this situation, delve further into the chemistry of the 304 tube. Look at the name of the supplier of the cheaper tube and find out if they have a good reputation in quality products. You could also research on the composition of the tube and find out what elements were used to produce it. You could also ask the seller for a certificate to authentic its quality and manufacturer.
There is a test you can do to determine if a stainless steel tube is 304 grade or not. Use an acid reagent, manganese or sulphur spot tests but you must know that there are limitations to these tests such not being able to sort out the heat levels. Spot tests also need to be done under 30 seconds for the 201 or risk discoloration.
If you plan to buy in bulk, do get from a reliable supplier. This way you only need to test one sample and be confident that the tubes given to you will be the right grade. Other tests you can try which work quite well is by looking at the surface, inner and outer. Check for roughness, shine, uniformity, and thickness. This is a good test for all stainless steel tubes except the welded ones. You will also find some seamless tubes with a few flaws depending on the manufacturing process.