What is SS, DSS and SDSS

As a professional supplier of stainless steel pipes and fittings, we often see SS, DSS or SDSS in our enquiries and we are always asked by our customers what is SS, DSS or SDSS. So we will briefly explain what these abbreviations stand for today.

SS – Stainless Steel

It is easy to understand that SS is the abbreviation for stainless steel. Stainless steel in this context usually refers to austenitic stainless steel, which is what we most commonly refer to as 304, 316L. We not only supply 304, 316L SS pipe and fittings, but also 321, 316Ti, 317L, 347H and other materials. Perhaps we could also introduce SSS – super stainless steel, which refers to the special, high performance and expensive stainless steels 904L and 254 SMO. You are also welcome to contact us if you want to know more.

DSS – Duplex Stainless Steel

Perhaps DSS was not common until 2005 – at least in China. As I remember in 2006, when I met a customer who needed duplex steel tubes, and as we were only producing normal 304, 304L and 316, 316L stainless steel tubes at that time, we needed to get a factory that could supply 2205 duplex tubes for the customer. But finally it was failed. It is not because there were no manufacturers in China. As an innovated material, the prices in China were very high at that time.

Nowadays, as the material has matured and become more widely used, DSS 2205 has become as common as 304 and 316L. In the case of seamless tubes, the price is now similar to 316L seamless tubes. However, for the buttweld pipe fittings, duplex 2205 fittings is still more expensive than 316L due to the difficulty of processing. If you need DSS material, please feel free to contact us.

Types of DSS

Duplex 2205 is the common type, the equivalent grade of ASTM is S32205, S31803. They are difference is mainly the element of Mo: S32205 is 3.0 ~3.5%, and S31803 is 2.5~3.5%. Usually, S32205 can replace S31803 in most of projects. S32205 is also the common grade of our stock, we are ability to supply it from stock in a short time without min. quantity limited.

SDSS – Super Duplex Stainless Steel

SDSS means Super Duplex stainless steel 2507, i.e. S32750, S32760. We currently supply SDSS S32750 pipe and fittings, while S32760 is harder to obtain and is currently mainly available in ASTM A182 F55 flanges and forged fittings. SDSS is more difficult to machine and more expensive. Compared to duplex 2205, SDSS 2507 is much more expensive, it is about twice as much as 2205. I have also been in contact with SDSS 2507 in Europe and their prices is very closed to China’s suppliers, especially for super duplex tubes and plates. Therefore, we can say super duplex 2507 from China is not enough competitive in the international market in terms of price. But usually Chinese manufacturers can offer faster delivery times, which is probably an advantage for us.

SDSS has a better corrosion resistance than DSS and is therefore widely used in desalination, offshore oil and marine heavy industry. We offer super duplex pipes, super duplex fittings, A182 F55, A182 F53 flanges and more.