Details about the 904L pipeline that you don't know.

904L pipe is corrosion resistant

Although originally developed for sulfuric acid resistance, it also has a very high tolerance to a variety of environments. A PRE of 35 indicates that the material has a good tolerance to warm seawater and other perchloride environments. The high nickel content results in better resistance to stress corrosion cracking than standard austenite grades. Copper increases resistance to sulfuric acid and other reducing acids, especially in the very aggressive "medium concentration" range.

In most environments, the corrosion resistance of 904L falls between the standard austenite grade 316L and the extremely alloyed 6% molybdenum and similar "super austenite" grades.

In corrosive nitric acid, 904L stainless steel tubes have lower resistance than molybdenum-free grades such as 304L and 310L.

In order to obtain maximum resistance to stress corrosion cracking in critical environments, steel should be treated with solid solution after cold working.

904L stainless steel tube heat-resistant

Good oxidation resistance, but like other high alloy grades, it suffers from structural instability at high temperatures (precipitation of brittle phases, e.g. sigma). The 904L should not be used above about 400°C.

904L stainless steel tube heat treatment

Solution treatment (annealing) - heating to 1090-1175°C and rapid cooling. This grade cannot be hardened by heat treatment.

904L stainless steel pipe welding

The 904L can be successfully welded by all standard methods. Care is needed because this grade completely solidifies austenite and is therefore prone to thermal cracking, especially in restrained weldments. Preheating should not be used, and post-weld heat treatment is not required in most cases. AS 1554.6 prequalifies 904L grade and electrodes for 904L welding.

904L stainless steel pipe manufacturing

904L is a high purity, low sulfur grade and therefore does not process well. Nevertheless, the material can still be processed using standard techniques.

It bends easily to a small radius. In most cases, this is cold executed. Subsequent annealing is usually not required, but should be considered if manufacturing is to be used in an environment where severe stress corrosion cracking conditions are expected.