A Subsidiary of Mitsubishi Materials Corporation

Thermal Processing Product

Thermal Processing Products


PT. MMC METAL FABRICATION is an innovative leader in the development and manufacture of fabricated products for high-temperature and corrosive industrial applications in installations around the world. Our thermal processing products such as

  • Radiant-tubes
  • Muffles
  • Retorts

for several type of heat treat furnaces.Radiant tube using equivalent UNS No. N06230 is a flagship product due to its good strength, its resistance to carburization, and its resistance to thermal fatigue after repeated temperature cycling.


Fabricated Radiant Tubes

Radiant Tubes for Heat Treating Furnaces

The  System

Controlled atmosphere heat treating furnaces use in-direct radiant tube heating system to heat work-pieces, in carburization furnaces and in bright annealing furnaces, heating through the use of radiant tubes is used commonly in many industries.

The Benefit

Radiant tube furnaces have specific characteristics, which make them the preferred choice for fast and effective heating, lower fuel consumption and less down time for maintenance. The radiant tube system is used in figure #1.



Work-pieces in the furnace are heated by radiation generated from fuel combustion, and then channeled through heat resistant metal tubes. Fuel sources may include city natural gas, LPG, butane, kerosene and others.
An alternate fuel source is electricity. The electric tube heating system eliminate the need for a fuel burner.


Tube Configuration

Radiant tubes are offered in different configurations as shown in Fig #2.
Each tube shape has specific characteristic, however radiant tubes of popular configurations include types “I”, “U” and “W”. Heat resistant radiant tubes are processed either as centrifugal cast or fabricated.

Tube Materials

Table #1 shows a typical heat resistant alloy of both cast and fabricated.
Centrifugal cast tubes are produced from “HK” and “HP” materials, Alloy 600, Type 330 stainless steel, type 310S stainless steel and equivalent “UNS N06230” alloy are generally used in the production of fabricated radiant tubes.

Alloy C Cr Ni W Fe Others
Casting Alloy HH 035 28 16 Bal
HK 0.40 25 20 Bal
HP 0.55 26 35 Bal
SS310S 0.05 25 20 Bal
RA330 0.05 19 35 43 Mn:1.5, Si:1.25
Fabricated Alloy Alloy 600 0.03 16 bal 7
Alloy 601 0.04 13 Bal 14 Aℓ:1.4
UNS N06230 0.10 22 Bal 14 Mo:2, La:0.03

Properties of Tube Materials

Heat resistant alloys have properties, which make them advantageous for use in cast and fabricated radiant tubes.

These properties includes:

  1. High strength at high temperature
  2. High resistance to corrosion
  3. High resistance to oxidation
  4. Good creep properties at high temperature
  5. Good resistance to specific atmosphere
  6. Good nitriting resistance
  7. Good carburizing resistance
  8. Good metallurgical stability for long life
  9. Ease of fabrication
  10. Low thermal coefficient of expansion


Tube Type Comparison (Centrifugal Cast vs Fabricated)
  1. For ease of handling and installation, the fabricated tube is first choice. With a 3mm wall thickness, the fabricated tube is much lighter than the cast tube. A cast tube has a wall thickness of 8 -10mm. The cast tube is almost 3 times heaver than the fabricated tube.
  2. For reliable quality, the fabricated tube is first choice. The centrifugal cast radiant tube may be subject to defects due to the existence of wall cavities or shrinkage. Fabricated tubes are not subject to these flaws and offer better quality and reliability.
  3. For high temperature resistance to metal fatigue, the fabricated tube is first choice. Fine grain alloy materials are used in the manufacture of fabricated radiant tubes. This gives the fabricated tube better high temperature resistance to metal fatigue than the cast tube.

Several Types of Radiant Tube and Features of equivalent N06230 alloy

【I Type Radiant Tube】                  【U Type Radiant Tube】                    【W Type Radiant Tube】

Features of equivalent N06230 Radiant Tube

Longer operating life

Equivalent UNS No. N06230 R/T can be expected to have a longer life relative to casting type of R/T

Weight saving

Because of using thin metal sheet  (most of thickness is 3mm)  for Equivalent UNS No. N06230 R/T,  the weight is lighter than casting R/T using  8~10mm

Energy-saving effect

Equivalent UNS No. N06230 R/T can be expected to conserve energy cost compared to casting R/T, because  the temperature rising & falling respond well due to thinner of R/T

Fabricated Muffles