Applications:
Kanthal APM® alloy protective radiant tubes are designed to provide significantly longer service life in hostile and high temperature industrial heating environments. They are used worldwide in a broad range of applications, and are ISO 9001 certified.

User Benefits:
APM alloy radiant tubes have a number of unique performance characteristics that lower furnace operating costs.

• Mechanically stronger than graphite and ceramic tubes.
• Three to five times longer service life than nickel/chrome radiant tubes.
• Resist carburization, sulfurous atmospheres, flaking, and spalling.
• Minimize failure due to thermal shock.
• Reduce furnace downtime for tube replacement and repair.
• Contribute to longer heating element life.
• Higher power output.
• Increased furnace loading.

Furnace Type:
Widely used in all styles of electric and gas furnaces and ovens, including hardening, carburizing aluminum melting, and aluminum holding furnaces. Also ideal for high temperature waste incineration applications.

Material:
APM is an iron/chrome/aluminum powder metal alloy. When heated, an aluminum oxide layer is formed on the inside and outside surfaces of the tube. This protective layer provides up to four times the carburization resistance of nickel/chrome, and is equally resistant to sulfurous atmospheres. The aluminum oxide layer does not spall during prolonged use or severe thermal cycling. This eliminates the problem of loose oxides contaminating the tube interior and reducing heat transfer efficiency.

Temperature Range:
Up to 2280° F (1250° C).

Sizes:
See chart below.

Custom Electric offers APM and AF alloy tubes specifically designed to accommodate gas-fired furnaces and ovens. APM tubes can be manufactured in a broad range of standard and special lengths to support most styles of gas-fired furnaces.

Standard Sizes and Weights		Carburization Rate Vs Temperature for Various Alloys
OD/ID (in) Weight (lb/ft) OD/ID (mm) Weight (kg/m) 8.7/8.0* 7.8/7.1* 7.0/6.4* 6.5/6.0* 6.1/5.6* 5.8/5.3* 5.0/4.6*** 4.5/4.1*** 4.3/3.9*** 4.0/3.5*** 3.6/3.1*** 3.4/3.0*** 3.3/2.9*** 3.0/2.6** 2.9/2.5** 2.5/2.2** 2.4/2.1** 2.0/1.5** 1.6/1.3** 1.3/1.1 1.3/0.9 1.0/0.8 0.9/0.7 0.9/0.8 0.8/0.65 0.6/0.5 0.23/0.2 26.90 25.50 20.40 14.20 13.30 12.60 10.10 9.00 7.80 7.10 8.20 6.10 5.80 4.60 4.40 3.60 3.50 4.30 1.70 1.40 2.30 1.10 0.64 0.40 0.35 0.28 0.04 220/203* 198/182* 178/162* 164/152* 154/142* 146/134* 128/117*** 115/104*** 109/99*** 100/90*** 91/78*** 87/77*** 83/73*** 75/66** 73/64** 64/56** 60.5/52.7** 50.8/38.1** 40.0/34** 33.7/27.7 33.7/21.7 26/20.2 22/18 22/19.4 19.1/16.5 15/12.4 6.0/5.2 40.10 38.00 30.30 21.20 19.80 18.70 15.00 13.40 11.60 10.60 12.20 9.10 8.70 7.10 6.90 5.40 5.10 6.40 2.50 2.10 3.80 1.70 0.95 0.60 0.52 0.41 0.06 *Outer Tube, Single-Ended Radiant Tube (SER) **Inner Tube, SER ***Inner or Outer Tube, SER. Special sizes available on request.		Maximum Surface Loading for Various Types of Radiant Tubes   Tf = Furnace temperature To = Temperature of outer tube of single-ended radiant tube     Note: Kanthal, APM, APMT, and Nikrothal are registered trademarks of Kanthal, a Sandvik Co.

After initial sagging, the iron/nickel/chrome material follows a fairly linear behavior with time. In the case of Kanthal APM and APMT alloys, the deformation rate continues to decrease with time.

Application:
Kanthal® APMT alloy radiant tubes are extruded from a modified version of Kanthal’s APM iron/chrome/aluminum alloy. Improved form stability minimizes sagging when longer tubes are horizontally mounted. APMT alloy tubes can be used as burner tubes, protective tubes for bayonet elements, and other high temperature operations.

User Benefits:

• Resist sagging deformation.
• Up to four times longer life.
• Superior form stability.
• Improved hot strength.
• Ideal for horizontal mounting.
• Operate at higher temperatures.
• Higher furnace loading.
• Excellent corrosion resistance.
• Tubes need not be rotated.
• Resist sulphurous atmospheres.

Furnace Type:
Electric and gas furnaces where tubes are horizontally mounted, higher temperatures and power ratings are required, and high carbon potential atmospheres are present.

Material:
Modified chemistry of the iron/chrome/aluminum APM alloy with a slightly lower aluminum content and 3% molybdenum for improved hot strength and form stability.

Temperature Range:
2280° F (1250° C).

Standard Sizes:
1.05 in. to 7.8 in. (26.67 mm to 198 mm) O.D.

As North America’s first and largest distributor of Kanthal APM alloy radiant tubes, Custom Electric has many customers with more than a decade of experience using this high temperature, long life products. Their production experience is the best testimonial for this technology.