- Austenitic SS 304 Pipes and Tubes
Austenitic SS 304 Pipes and Tubes
SS 304 Tube and SS 304 Pipe is made from austenitic stainless steel also known as 18/8 stainless steel because of its chemical composition. SS 304 pipes and tubes due to its austenitic structure are ductile in nature. It also has excellent low temperature properties and responds well to hardening by cold working. If intergranular corrosion in the heat affected zone may occur, it is suggested that SS 304L be used.
Chemical Composition
GRADE | NI | CR | Si | C | MN | P | S | N | Fe | |
|---|---|---|---|---|---|---|---|---|---|---|
SS 304 | MIN % | 8 | 18 | – | – | – | – | |||
MAX % | 13 | 20 | 0.75 | 0.08 | 2 | 0.045 | 0.03 | 0.1 | BALANCE | |
SS 304H | MIN % | 8 | 18 | – | – | – | – | |||
MAX % | 12 | 20 | 0.75 | 0.03 | 2 | 0.045 | 0.03 | 0.1 | BALANCE | |
SS 304L | MIN % | 8 | 18 | – | 0.04 | – | ||||
MAX % | 10.5 | 20 | 0.75 | 0.1 | 2 | 0.045 | 0.03 | BALANCE |
Specification
Stainless steel 304/H/L Seamless Pipe : ASTM/ASME SA 312/ A 312
Stainless steel 304/H/L Seamless tube : ASTM/ASME SA 213/A 213
Stainless steel 304/H/L ERW Pipe : ASTM/ASME SA 312/ A 312
Stainless steel 304/H/L ERW Tube :ASTM/ASME SA 249/ A 249
General Specifications
GRADE | UNS | OLD BRITISH | EURONORM | SWEDISH SS | JAPANESE JJ | ||
|---|---|---|---|---|---|---|---|
BS | EN | NO | NAME | ||||
SS 304 | S30400 | 304S31 | 58E | 1.4301 | X5CrNi 18-10 | 2332 | SUS 304 |
SS 304L | S30403 | 304S11 | – | 1.4306 | X2CrNi 19-10 | 2352 | SUS 304L |
SS 304H | S30409 | 304S51 | – | 1.4948 | X6CrNi 18-10 | – | – |
Production Process
Stainless steel 304 Tube and Stainless steel 304 Pipe or UNS 304000 are manufactured by 304 stainless steel pipe supplier such as ERW ( Electric Resistance Welded), Seamless and EFW ( Electric Fusion Welding) Pipes and Tubes having different form such as round, square, rectangle, etc. having specific end as Plain End, Bevel End and Threaded End with nominal thickness of different schedule ranging from SCH 5 to SCH XXS.
The process through which stainless steel pipe SS 304 and tubes can be manufactured include cold pilgering process, Extrusion process, tube mill Process also Piercing process followed by heat treatment and mechanical testing.
Fabrication and Heat treatment
According to the 304 stainless steel pipe specifications, this grade readily hardens. In SS 304 pipes and tubes fabrication methods involving cold working may require an intermediate annealing stage to alleviate work hardening and avoid tearing or cracking.
Fabrication methods, like forging, that involve hot working should occur after uniform heating to 1149-1260°C. The fabricated components should then be rapidly cooled to ensure maximum corrosion resistance.
Stainless steel 304 cannot be hardened by heat treatment. At the completion of fabrication a full annealing operation should be employed to reduce internal stresses and optimise corrosion resistance. Solution treatment or annealing is done by rapid cooling after heating to 1010-1120°C.
Properties
Stainless steel 304 has good resistance to oxidation in intermittent service up to 870°C and in continuous service to 925°C. However, continuous use at 425-860°C is not recommended if corrosion resistance in water is required. In this instance 304L is recommended due to its resistance to carbide precipitation.
Mechanical Properties
Grade | Tensile Strength | Yield Strength | Elongation | Hardness, MAX | |
|---|---|---|---|---|---|
[MPA] | [MPA] | (% in 50mm) min | HBW | HRB | |
SS 304 | 515 | 205 | 40 | 95 | 217 |
SS 304H | 260 | 90 | 40 | 95 | 217 |
SS 304L | 485 | 170 | 35 | 95 | – |
Where high strength is required at temperatures above 500°C and up to 800°C, grade 304H is recommended. This material will retain aqueous corrosion resistance.
SS 304 Tube and SS 304 Pipe has a higher corrosion resistance than regular steel and is widely used because of the ease in which it is formed into various shapes.
Physical Properties
Grade | Density (g/cm3) | Elastic Modulus (GPa) | Mean Co-eff of Thermal Expansion (μm/m/°C) | Thermal Conductivity (W/m.K) | Specific Heat 0-100°C (J/Kg.K) | Electrical Resistivity (nΩ.m) | |||
|---|---|---|---|---|---|---|---|---|---|
0-100°C | 0-315°C | 0-538°C | at 100°C | at 500°C | |||||
SS 304/H/L | 8 | 193 | 17.2 | 17.8 | 18.4 | 16.2 | 21.5 | 500 | 720 |
Application
- Food processing equipment, particularly in beer brewing, milk processing & winemaking
- Kitchen benches, sinks, troughs, equipment and appliances
- Architectural paneling, railings & trim
- Chemical containers, including for transport
- Heat Exchangers
- Woven or welded screens for mining, quarrying & water filtration
- Threaded fasteners
- Springs