Welded
steel pipes and tubing are used in a number of applications where high
demands are set on reliability, strength and corrosion resistance. These
high performance pipes and tubes are alloyed with higher contents of
molybdenum and nitrogen in order to improve the corrosion resistance and
the strength, and are welded with over alloyed filler metals and/or with
nitrogen added to the shielding gas, in order to become as high pitting
corrosion resistance as possible in the weld.
Pipes made of nitrogen alloyed chloride resistant grades in the
presented applications are welded with the addition of nitrogen in the
shielding gas. Most of the pipes are also welded with filler metal and
heat treated when specified. Welded steel pipes and tubing come in
improved design properties and are much higher corrosion resistance than
other conventional steel pipes.
Depending on how and where the pipes will be used it is up to the end
user to decide which type of heat treatment is necessary. Chloride
environments give however a risk for pitting, crevice and stress
corrosion for standard steels. The pipes are used in all types of
corrosive environments in industries such as, chemical, metallurgical,
energy, oil & gas, pulp & paper, ships, desalination, and food.
