Induction Heat Treating Complexities for the Tube and Pipe Industry. After working with multiple end users who have had issues with off brand heat treating systems we presented this outline to help customers to understand that Heat Treating is very complex and requires expertise beyond just the ability to heat pipe with induction.

2. • Ajax Electrothermic Corp., 1916
• TOCCO Inc., 1935
• Ajax Engineering Corp., 1941
• Magnethermic Corp., 1948
• Ajax Magnethermic Corp., 1959
• Japan Ajax Magnethermic Corp., 1965
• Pillar Induction, 1966
• American Induction Heating in 1968
• Industrial Electric Heating in 1973
• Lectrotherm Inc., 1989
• Foundry Services, Gmbh 2000
• INTECH, Gmbh 2000
Over 1,500 employees in
20 + worldwide facilities
Staffed with Over 140
Mechanical, Electrical,
Metallurgical and
Process Engineers

5. • Sales approximately $1.2 Billion (2013)
• Employees approximately 5,000
• NASDAQ as PKOH
• Headquarters in Cleveland, Ohio USA
• www.parkohio.com

6. EMMEDI MosWeld

8. Topic #2
• Should you install in-house heat treat capability?
• Understanding the primary manufacturing
complexities of tube and pipe heat treat, quench
and tempering.

9. Complete Solutions for Heat Treat,
Quench and Temper Lines
From
2 – 42 t/hr.
induction
systems for
ERW and
Seamless

10. • Should a distributor produce in-house heat
treat finishing capability?
• Answer/Question = Why Not? In the past 3 years we know of several distributors
have purchased and/or are installing new heat treating lines.
• An Investment estimate for induction heat treating capability is:
6 - 8 ton/hr.
$4 - 6 million
Equipment
$1.5 – 2 million
Installation
$5.5- 8 million total
Investment
12 – 20 tons/hr.
$5 – 7 million
Equipment
$2 – 2.5 million
Installation
$7 – 9.5 million total
Investment
30 – 42 tons/hr.
$6 – 8 million
Equipment
$2.5 – 3 million
Installation
$8.5 – 11 million total
Investment

11. • Understanding the primary manufacturing
complexities of tube and pipe heat treating
Loading
System
Austenitize Quench
Drain/
Transfer
Temper
Cooling
Table
Primary Progressive System Components
1 2 3 4 5 6

12. • Understanding the primary manufacturing
complexities of tube and pipe heat treating
Input
Harmonics
(IEEE519)
MCC Controls
Quench
Sys.
Water
Sys.
7 8 9 10 11 12
Ancillary System Components

13. Complexity:
• Casing and tubing
length variation
identification.
• End Justification
• Adjusting makeup
drive rollers to
achieve pipe butting
before heating.

14. Austenitizing
Austenitizing is to heat iron-based
metal or steel to a critical (Ac3)
temperature to achieve changes in
the crystal structure from ferrite to
austenite.
Quench Hardening of pipe increases its
tensile strength and abrasion resistance. The
as-quenched metallurgical grain structure is
martensite as shown in
figure (a)
14
Austenitize
2
(a) 1045 microstructure of
as-quenched martensite
(b) 1045 microstructure
of tempered martensite

15. Progressive Heat
Austenitize
2
Typical Austenitize
Line Configuration

16. In-line Upset Tube and Pipe Uniform
Heating Versus Upset Preheating.
• Modeled two upset
pipes butted
2
Complexity Considerations:
• Upset Pipe must be processed utilizing
sophisticated frequency scheming to heat
the body and the Upset uniformly.
• Drive rollers and pinch roll drives must be
designed to handle upsets.
Austenitize
2

17. Austenitize
2

18. Flux intensity distribution showing end
effect with gaps between pipes while
heating.
Austenitize
2
Additional lines of
Flux Induced,
“Current Crowding”
causes an increase
in power density/
temperature in the
pipe ends.
“End Effect”
Pipe Wall
Gap between Pipes
At 3 kHz Frequency
Induction Coil

19. Flux intensity distribution showing end
effect at lower frequencies.
Austenitize
2
“Current Crowding”
Thus “End Effect”
Changes significantly
with frequency
changes
Pipe Wall
Gap between Pipes
At 350 Hz Frequency
Induction Coil

20. Thermal “End Effect” modelling of
gaps between pipes.
Austenitize
2
Complexity
Considerations:
• A thermal peak is
produced upon
introduction of
gaps between
pipes.
• Over heating
produces high
metallurgical grain
growth making
the metal brittle.
At 350 Hz
Frequency
At 3 kHz
Frequency
Over
heated
Ends
“End Effect”
Same pipe size
frequency
influence
modelling

21. Effects of Seamless pipe +/-
6% wall thickness variations
Complexity
Considerations:
• -6% wall variations can
overheat the pipe.
• +6% wall requires
additional line length
to allow temperature
to conduct through
thicker mass.
• Sporadic over/under
heating of the pipe
wall produces crooked
pipe. Complex
frequency and power
density scheming is
required as a means of
control.
Austenitize
2

22. Austenitizing Pinch Roll Drives
Complexity
Considerations:
Pinch wheel drives are used
to assure positive feed of
pipe due to:
• Distortion in green pipes
• Rust or other coatings on
the surface of the pipe.
• Stresses relieved during
heating.
Austenitize
2

23. Quench hardening is a metallurgical
process in which steel and iron alloys are
strengthened and hardened.
Uniform and rapid quenching is critical
to the metallurgy quality and distortion
of the pipe.
23
Quench
3

24. ATM Barrel Quench
Cooling Rate
TTT Curve
(Time-Temperature-Transformation Curves)
Quench
3
Complexity
Considerations:
The temperature
must rapidly and
uniformly be
reduced below the
Martensite phase
(Ms).
MS
MR
Martensitic Reaction
Start (Ms)

25. Quench Vapor Phases
Quench
3
Complexity Considerations:
• With high Austenitize temperatures in body of the pipe, a Vapor Phase (Steam
Barrier) is formed around the metal upon initial contact with quenchant.
• A quench system must be designed to muscle through the (Vapor Phase) to produce
rapid dissipation (Boiling Phase) to achieve efficient heat removal through
conduction (Convection Phase).
Vapor Phase Nucleate
Boiling Phase
Convection
Phase
Martensitic Reaction Start (Ms)
(Ms)

26. Cooling Curves by Depth of Quench
Penetration
Quench
3
Complexity
Considerations:
Rapid equal quenching
must be achieved or
distortion and/or
spotty hardness may
result.

27. The red curves represent
different cooling rates (velocity)
when cooled from the upper
critical (A3) temperature.
V1 produces martensite.
V2 has pearlite mixed with
martensite,
V3 produces bainite, along with
pearlite and martensite.
TTT Curve with Varying Quench
Designs
Quench
3

28. Quench System Components
Complexity Considerations:
• Quenchant temperature must be
consistent during production.
• 5-8 °F temperature rise is typical

29. Quench Pit
Scale
COLD Out to Line HOT Out to Tower
Cold
Return
from
Tower
Hot
return
from
Line
Weir Walls
Quench
3
Complexity
Considerations:
Scale dropout must
be removed on a
regular maintenance
schedule.

30. Quench Scale Filtration
Quench
3
Complexity
Considerations:
Particulate mater
(scale) in the system
must be removed.

31. Post Quench Pinch Roll Drives
Complexity
Considerations:
Pinch wheel drives are used to
assure positive feed of pipe due
to:
• Quenchant on the OD of the
pipe causes slippage.
• Distortion from stresses
relieved through quenching.
• Pipe distortion due to
unequal quenching.
Quench
3

32. Drain/
Transfer
4
Complexity
Considerations:
• Quench must be purged
from the pipe ID or it will
cause unequal tempering.
• Quenchant in the temper
coils will cause damage from
thermal shocking.
• Makeup drives keep pipe
butted through temper
heating.

33. Tempering
Tempering is accomplished
by reheating the hardened
pipe below the (Ac1) phase
to reduce brittleness
and/or increase ductility.
Stresses are also relieved
from the Quench
Hardening process.
The metallurgical goal is to
achieve a tempered martensitic
grain structure as shown in
figure (b)
33
Temper
5
(b) 1045 microstructure
of tempered martensite

34. Progressive Heat
Temper
5
Typical Temper
Line Configuration
Pacer II
1500
KW
500 HZ
Pacer II
1500
KW
300 HZ

35. Relational Quench and Tempering
TTT Curve
Temper
5
Complexity
Considerations:
(Relational Time-Temperature-Transformation Curve)
A = Arrest (Critical Transformation Temperatures)
c = chauffage (Heating)
Typically OCTG tube and
pipe tempering requires
more toughness than
hardness. Accordingly,
there must be
controlled heating to
remain below the Ac1
transformation
temperature.

36. Magnetic Curie Point Influence
In addition to the primary I2R
heating of Induction there is
also an additional heating
component of hysteresis losses
below the Curie point. The Curie
point is where magnetic
material become non-magnetic.
Magnetic “Curie”
36
Complexity Considerations:
Temper
5

37. Magnetic Curie Effects on
Induction depth of Penetration
The reference depth of
current penetration is 4.5
times deeper above Curie
than below Curie.
37
Complexity Considerations:
Temper
5
Pacer II Induction Power Supply

38. Temper
5

39. Effects of Seamless Pipe +/- 6%
wall thickness variations
Temper
5
Tempering
Temperature
Complexity
Considerations:
• -6% wall variations can
overheat the pipe.
• +6% wall requires
additional line length
to allow temperature
to conduct through
thicker mass.
• Sporadic over/under
heating of the pipe
wall produces crooked
pipe. Complex
frequency and power
density scheming is
required as a means of
control.

40. Tempering Pinch Rolls
Complexity
Considerations:
Pinch wheel drives are used to
assure positive feed of pipe due
to:
• Austenitizing and Quenching
introduces stresses in the
pipe. Stress in the pipe
renders distortion.
• Quenchant on the OD of the
pipe can cause slippage
Temper
5

41. 1250 F
To 700 F
Natural Convection
To 50 F Above
Ambient
Forced Convection
Cooling
Table
6

42. Cooling
Table
6
Natural/
Forced Air
convection
hybrid cooling
systems are
use to reduce
space and
cost.

43. Natural
Convection
Forced
Convection
Cooling
Table
6

44. Cooling
Table
6
Complexity Considerations:
• Slow even cooling through rotation, equal support and feed is critical to reduce stresses
relieved within the Temper heating.
• Pipe distortion is more prone from the output Temper temperature down to around 600 F.
From 600 F to ambient the pipe can be more rapidly cooled.

45. By: Donald A. Gibeaut
41 Tanglewood Dr.
Huntsville, TX 77320
713-589-5722 phone
713-589-5357 fax
936-391-9442 cell
dgibeaut@ajaxtocco.com
End of Presentation
AjaxTocco Magnethermic
1745 Overland Ave. N.E.
Warren, OH 44483
330-372-8511 phone
330-372-8608 fax
800-547-1527 24 hr. Parts/Service
www.ajaxtocco.com