1.4404 seamless stainless pipe is the European (EN/DIN) designation for low carbon, molybdenum-bearing austenitic stainless steel, equivalent to UNS S31603 and ASTM A312 TP316L. This grade is specifically designed for applications requiring superior corrosion resistance combined with excellent weldability, particularly where post-weld heat treatment is not practical or desired.

The "1.4404" designation follows the EN 10088 and EN 10216-5 standards, which govern seamless stainless steel pipes for pressure and general purposes. The corresponding material number 1.4404 identifies a composition of 16.5-18.5% chromium, 11-14% nickel, and 2-2.5% molybdenum, with a maximum carbon content of 0.030%. This low carbon content prevents sensitization – the precipitation of chromium carbides at grain boundaries during welding – eliminating the risk of intergranular corrosion in the heat-affected zone.

The addition of 2-2.5% molybdenum provides significantly enhanced resistance to pitting, crevice corrosion, and stress corrosion cracking in chloride-containing environments, as well as improved resistance to reducing acids such as sulfuric, phosphoric, and organic acids. This combination makes 1.4404 one of the most versatile stainless steel grades for chemical processing, pharmaceutical, food and beverage, marine, and power generation applications throughout Europe and globally.

The seamless manufacturing process ensures uniform wall thickness, consistent mechanical properties, and complete absence of a longitudinal weld seam. This seamless construction provides superior pressure-holding capability and reliability, essential for high-pressure

Product Parameters

Chemical Composition (EN 10088-1 / EN 10216-5)

The chemical composition of 1.4404 is strictly controlled to ensure corrosion resistance and weldability.

Mechanical Properties (EN 10216-5)

1.4404 seamless stainless pipe delivers the following mechanical properties in the solution annealed condition:

High-Temperature Mechanical Properties (Typical):

Maximum allowable service temperatures (EN 10216-5):

Manufacturing Process (EN 10216-5)

The seamless manufacturing process for 1.4404 pipe follows EN 10216-5 requirements.

Step 1 – Billet Preparation
Solid round billets of 1.4404 composition are inspected, cut to length, and heated to approximately 1200°C.

Step 2 – Piercing (Hot forming)
The heated billet is pierced to form a hollow shell using a rotary piercing mill.

Step 3 – Elongation
The hollow shell is elongated and rolled to achieve target dimensions.

Step 4 – Cold Drawing (optional)
For tighter tolerances and better surface finish, the pipe is cold drawn through a die and over a mandrel. Multiple passes with intermediate annealing are used.

Step 5 – Solution Annealing
The pipe is heated to 1020-1120°C (1870-2050°F) and then water quenched to achieve the required microstructure and corrosion resistance.

Step 6 – Descaling (Pickling)
Scale and oxide layers are removed using a nitric-hydrofluoric acid pickling bath.

Step 7 – Bright Annealing (optional)
Final annealing in a controlled hydrogen or nitrogen atmosphere produces an oxide-free, bright surface.

Step 8 – Straightening, Cutting, and Finishing
The pipe is straightened, cut to length, and ends are prepared (plain, beveled, or threaded).

Step 9 – Testing and Inspection
Hydrostatic testing, non-destructive examination (NDE), dimensional checks, and surface inspection.

Surface Finishes

Why Choose 1.4404 Seamless Stainless Pipe?

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