ASTM A335 P11 seamless alloy-steel pipe is a 1.25Cr-0.5Mo ferritic
alloy pipe designed for high-temperature and pressure-bearing
service in boilers, superheaters, reheaters, and process piping. It
is supplied as seamless pipe under ASTM A335 / ASME SA335 and is
suitable for bending, flanging, forming, and fusion welding when
proper welding procedures and heat treatment controls are applied.
Specifications
Item
Description
Material
Seamless ferritic alloy steel pipe
Standard
ASTM A335 / ASME SA335
Grade
P11 / UNS K11597
Outside Diameter
6-420 mm, custom sizes available
Wall Thickness
1-50 mm, schedule or custom wall available
Length
1-12 m, random length or fixed length available
Tolerance Range
According to ASTM A335 / ASTM A999 requirements or purchase
specification
Straightness
Controlled for boiler and pressure piping installation requirements
Surface Condition
Black, bare, pickled, oiled, varnished, or anti-rust coated
Heat Treatment
Normalized and tempered, annealed, or full annealed according to
grade and order condition
Pipe Ends
Plain end, beveled end, or threaded end upon request
Testing
Chemical analysis, tensile test, hardness test, hydrostatic test or
NDE, visual and dimensional inspection
Main Characteristics
Characteristic
Technical Value
Nominal Alloy System
1.25Cr-0.5Mo chrome-moly alloy steel
Chromium Content of P11
1.00-1.50%
Molybdenum Content of P11
0.44-0.65%
Minimum Tensile Strength
415 MPa / 60 ksi
Minimum Yield Strength
205 MPa / 30 ksi
Typical Maximum Hardness Control
Commonly controlled not above 250 HBW / 25 HRC where applicable
Service Orientation
High-temperature pressure service, boiler piping, refinery piping,
and power plant piping
Weldability
Suitable for fusion welding with qualified WPS, controlled preheat,
interpass temperature, and PWHT where required
Positive Material Identification can be arranged for Cr-Mo
verification, with heat number traceability from raw material to
finished pipe.
Hardness and heat-treatment consistency
Heat treatment records, hardness inspection, and mechanical test
reports are provided to confirm that pipe properties match the
ordered ASTM A335 grade.
Boiler welding and site installation reliability
Pipes can be supplied with beveled ends, dimensional inspection,
hydrostatic test or NDE records, MTC 3.1, and packing suitable for
long-distance export handling.
Executive Standards
Standard System
Applicable Standard
ASTM / ASME
ASTM A335 / ASME SA335 seamless ferritic alloy-steel pipe for
high-temperature service
EN 10216-2 seamless steel tubes for pressure purposes, alloy
high-temperature grades
JIS Reference
JIS G3458 alloy steel pipes
GB Reference
GB/T 5310 seamless steel tubes and pipes for high-pressure boilers
GOST Reference
GOST pressure and boiler pipe grades selected by project
equivalence
Application Field
Superheater tube outlet header connection pipe for high-pressure
boiler systems. ASTM A335 P11 is commonly selected where the pipe must retain
strength at elevated temperature while maintaining compatibility
with Cr-Mo boiler fittings and forged flanges.
Chemical Composition
Grade
C %
Mn %
P Max %
S Max %
Si %
Cr %
Mo %
Other Key Elements
P5
0.15 max
0.30-0.60
0.025
0.025
0.50 max
4.00-6.00
0.45-0.65
--
P9
0.15 max
0.30-0.60
0.025
0.025
0.25-1.00
8.00-10.00
0.90-1.10
--
P11
0.05-0.15
0.30-0.60
0.025
0.025
0.50-1.00
1.00-1.50
0.44-0.65
--
P22
0.05-0.15
0.30-0.60
0.025
0.025
0.50 max
1.90-2.60
0.87-1.13
--
P91
0.08-0.12
0.30-0.60
0.020
0.010
0.20-0.50
8.00-9.50
0.85-1.05
V, Nb, N controlled
Mechanical Properties
Grade
Tensile Strength Min
Yield Strength Min
Elongation Min
Hardness Requirement
P5
415 MPa / 60 ksi
205 MPa / 30 ksi
According to ASTM A335 test specimen requirements
Controlled by grade/order requirement
P9
415 MPa / 60 ksi
205 MPa / 30 ksi
According to ASTM A335 test specimen requirements
Controlled by grade/order requirement
P11
415 MPa / 60 ksi
205 MPa / 30 ksi
According to ASTM A335 test specimen requirements
Commonly controlled up to 250 HBW / 25 HRC where specified
P22
415 MPa / 60 ksi
205 MPa / 30 ksi
According to ASTM A335 test specimen requirements
Controlled by grade/order requirement
P91
585 MPa / 85 ksi
415 MPa / 60 ksi
According to ASTM A335 test specimen requirements
250 HBW / 265 HV / 25 HRC max commonly specified
Product Images
Frequently Asked Questions
Q: Are you trading company or manufacturer?
A: Manufacturer, also can do trading.
Q: How long is your delivery time?
A: Generally speaking, it is 10-15 days if the goods are in stock,
or it is 30-40 days if the goods are not in stock, according to
quantity.
Q: Do you provide samples? Is it free or extra?
A: Yes, we could offer the sample for free charge but need pay the
cost of freight.
Q: What is your terms of payment?
A: Payment ≤ 2000 USD, 100% in advance. Payment ≥ 2000 USD, 30% T/T
in advance, balance before shipment. If you have another question,
please feel free to contact with me.
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