Material Boiler
Material Boiler
Material Boiler
CARBON STEEL
SA178
Carbon steels show mild corrosion resistance and fair strength up to 1000F. However, their usage above 800F
must take into account the susceptibility to graphitization. Graphitization has not been a significant problem in
thicknesses encountered in boiler tubing. Use of heavy section pipe above 800F, however, is not recommended.
The application of seamless and welded carbon steel tubing in boilers is restricted to a maximum temperature of
800F for rimmed and 1000F for killed steel by the ASME Boiler and Pressure Vessel Code, Section I, Power
Boilers. The Code does not list maximum allowable stresses beyond 1000F for carbon steels.Carbon-molybdenum
steels
CARBON-MOLYBDENUM STEELS
SA209
Carbon-moly steels exhibit higher creep strengths than plain carbon steels, and are widely used in hightemperature boiler service. These steels nominally contain 0.5% molybdenum. When exposed to temperatures
TUBEsteels
GRADES
above 850-900F for long periods of time, theBOILER
carbon-moly
are also prone to graphitization. Again, the
phenomenon
is section-size
dependent,stainless
and usingsteels
pipe of this grade above 850F is not recommended. The carbide
STAINLESS
STEELS - Austenitic
phase is not stable, and will revert to graphite. The ASME Boiler and Pressure Vessel Code, Section I, lists
Austenitic
stainless
steels
presented in the ASME Boiler and Pressure Vessel Code
allowable stresses for
carbon-moly
steels
up toare
1000F.
with two sets of allowable stresses. The reason for this is their relatively low yield
INTERMEDIATE CHROME ALLOYS
strength. The higher allowable stress values were determined at temperatures where the
usage would be restricted by the short-time tensile properties.
SA213-T2
The higher stresses exceed 62-1/2%, but do not exceed 90% of the yield strength. At
This low alloy steel these
exhibits
graphitization
resistance
greater
creep strength
than the carbon-moly
steels.
stresses,
small amounts
of and
plastic
deformation
can be expected.
These higher
Corrosion resistance
is comparable
carbon-moly.
has allowable
stresses
listed
up to 1000F in the ASME
stress
values aretousually
used forT2super-heater
and
reheater
tubing.
Boiler Code.
The Boiler Code lists maximum allowable stresses for varying temperatures depending
on the individual austenitic stainless grade.
SA213-T12
The SA213-T304
chromium in allVariations
of the Croloys
stabilizes
the carbon
as chromium
carbides,
making
of this
18 chromium,
8 nickel
grade include
304L, thus
304LN,
304Hthem
and immune
304N. to
graphitization.
Each of these offers excellent corrosion and oxidation resistance along with high
strength.
This is a 1-chromium, 1/2-molybdenum alloy which is limited to a maximum temperature of 1200F by the ASME
Boiler and PressureHigh
Vessel
Code, Section
I, Allowable
T12
is sometimes
used the
in place
of T2 tubing
strengths
are maintained
in theStresses.
low carbon
grades
by controlling
nitrogen
because of its greater
strength.
content.
SA213-T11
SA213-T22
ThisSA213-T321
2-1/4 chromium,
1 molybdenum
has exceptionally
properties,
but is tensile
limited properties.
for applications to
T321
and 347 arealloy
variations
of T304 and high
havecreep
comparable
minimum
1125F
because
higher
temperature
scalewith
exfoliation.
It is
in the
Boilerrespectively,
Code for
and
T347 of possible
These two
grades
are stabilized
additions
of listed
titanium
andASME
columbian
temperatures to 1200F.
along with proper heat treatment.
To insure good long-time strength at elevated temperatures, T321H and 347H-like 304HA 9-chromium-1 molybdenum alloy, T9 offers very good corrosion resistance with good high-temperature strength.
were developed with higher carbon contents and specified minimum solution annealing
It also has good oxidation resistance and can be used to 1200F maximum. Some times T9 is an adequate
temperatures.
substitute for the more expensive stainless grades. The Boiler Code limits T9 to 1200F.
Of all the stainless steels, T309 (25 chromium, 13 nickel) and T310 (25 chromium, 20
nickel) offer the maximum resistance to oxidation and corrosion. They also offer good
high-temperature properties. Since these steels contain ferrite, however, they are more
susceptible to sigma phase.
SA213-T9
Material Boiler
ASME Grade
A
ERW or Smls.
ERW
ERW
ERW
Description
Low carbon steel - C=0.18
max.
Medium carbon steel C=0.35 max.
Carbon-manganese steel -
Typical uses
Boiler tubes, economizers,
low temp. superheaters
Boiler tubes, economizers,
low temp. superheaters
Not in common use
Smls.
SA-192
SA-210
SA-210
A1
Smls.
Smls.
C=0.27 max
Low carbon steel - C=0.18
max
Medium carbon steel C=0.27 max.
Medium carbon steel C=0.35 max.
Waterwalls, economizers,
low temp. superheaters
Waterwalls, economizers,
superheaters
Waterwalls, economizers,
superheaters
SA-209
T1
Smls.
Superheaters
SA-209
T1a
Smls.
Superheaters
SA-209
T1b
Smls.
Superheaters
SA-213
T2
Smls.
SA-213
T11
Smls.
Waterwalls, superheaters
SA-213
T22
Smls.
Waterwalls, superheaters
SA-213
T5
Smls.
SA-213
T9
Smls.
SA-213
T91
Smls.
SA-213
Tp-304
Smls.
Superheaters
SA-213
Tp-304H
Smls.
SA-213
Tp-316
Smls.
Superheaters
SA-213
Tp-316H
Smls.
SA-213
Tp-321
Smls.
Superheaters
SA-213
Tp-321H
Smls.
SA-213
Tp-347
Smls.
SA-213
Tp-347H
Smls.
Untuk tabung boiler, SA-178A adalah pilihan yang paling umum, dan paling ekonomis.
Economizers biasanya terbuat dari SA-178A atau SA-210-A1.
Bahan superheater bervariasi, dengan SA-178A dan SA-192 digunakan paling umum dalam
rentang suhu yang lebih rendah. SA-210-A1, SA-213-T11, dan SA-213-T22 yang biasa terlihat
dalam rentang suhu menengah, dengan nilai stainless, yang paling sering Tp-304H dan Tp-347H,
disediakan untuk superheaters suhu yang lebih tinggi, meskipun SA-213-T91 semakin ditentukan
untuk suhu tertinggi
rt Boil