Pipes and Tubes

Pipes and Tubes

Inconel 601 pipe fittings are crafted with a nickel-chromium alloy named Inconel 601 which is highly resistant to oxidation as it is a nickel based alloy with a chromium content of approx 25wt% along with aluminum. Alloy 601 pipes are resistant to high temperature oxidizing environments in the heat treatment of metals and materials. Due to its contents of aluminum and chromium, Inconel 601 pipe fittings readily form a refractory surface oxide during heating.

Chemical composition

GRADE   Ni Cr Si C Cu Al S Fe
Inconel 601 MIN 58 21 1   BALANCE
MAX 63 25 0.5 0.1 1 1.7 0.015

Production Process

Inconel 601 pipe fittings and tubes are manufactured with ERW (Electric Resistance Welded),
Seamless, and EFW (Electric Fusion Welding) methods. These pipes and tubes are made with
alloy 601 or UNSN0601. These pipes and tubes are formed in different shapes such as round,
square, rectangle, etc. with specific ends like a plain end, bevel end, and threaded end with a
thickness of different schedules ranging from SCH 5 to SCH XXS.

Some of the processes through which pipes and tubes are produced are the cold pilgering
process, extrusion process, tube mill process, and piercing process where heat treatment and
mechanical testing are needed afterward.

Specifications

GRADE UNS DIN AFNOR ASTM
INCONEL 601 NO6601 2.4851 NC 23 FeA B 167, B 166, B 564, B 366, B168

Inconel 601 Seamless Pipe & Tube: ASTM/ASME B 167/ SB 167
Inconel 601 ERW Pipe & Tube: ASTM/ASME B 167/ SB 167

Fabrication and Heat Treatment

Inconel 601 tube suppliers say that it cannot be bright-annealed in the nominal industrial
furnace. Pickling is usually needed to produce bright surfaces on parts that have been heated.
Specialized pickling techniques are needed to give alloy 601 pipe fittings resistance to chemical
attack.

The hot forming temperature range of Inconel alloy 601 is around 1600°F – 2250°F (870°C –
1230°C). Hot-working operations with large deformations need be performed at 1900°F –
2250°F (1040°C – 1230°C). The annealing temperature of Inconel 601 is 1149°C (2100°F). It then
needs to be cooled at temperatures in the range of 538°C to 760°C (1000°F to 1400°F) in order
to prevent thermal cracking.

Properties

The Inconel 601 seamless pipe fittings have low ductility temperatures are from 1200°F to
1600°F (650°C – 870°C) and not recommended to be worked in that range. Light working at
temperatures below 1200°F (650°C) can be used to develop the popular high tensile properties.
Inconel 601 pipe fittings and tubes are used in oxidizing atmospheres at high temperature
ranges.

Physical properties

Grade Density (g/cm3) Melting Range °C Thermal Expansion (μm/m/°C) Specific Heat (J/Kg.K) Electrical Resistivity (μΩ.m)
INCONEL 601     20-300°C 0-100°C  
8.11 1360-1411 14.9 448 119

To attain the maximum oxidation resistance, Inconel 601 seamless alloy pipes & tubes should
be welded with similar composition 601 alloy GTAW wire. The weld fillers developed for RA 602
CA can also be used for a weld that is stronger and more resistant to oxidation than the 601
alloy base metal.

Mechanical properties

Grade Tensile Strength Yield Strength Elongation
[MPA] [MPA] (% in 50mm) min
Inconel 601 552 207 30

Alloy 601 seamless pipes can be welded by the regular resistance and fusion welding processes
commonly used for stainless steel. Various welding rods and wires are commercially available
for combining Alloy 601 to itself and other materials. Since the aluminum content in the alloy
forms a tightly adhering oxide, which can be removed with processes such as grinding, inert gas
shielding is desirable.

Applications

  • Chemical Processing.
  • Aerospace.
  • Heat treating industry.
  • Power generation.
  • Heat treating muffles and retorts.
  • Radiant tubes.
  • Catalysts support grids in nitric acid production.
  • Steam super heater tube supports.

NOTE: Inconel 601 Pipes and Tubes is a registered trademark of  Special Metals Corporation.