ASTM A213 T91 Alloy Seamless Steel Pipe
A-213 t91 is ASTM A-213 / A-213m standard steel grade: in 1970s, based on 9Cr-1Mo steel, a new type of ferritic shape steel was formed by adding a small amount of Nb and V microalloying elements and controlling the content of n elements in 9

Description

ASTM A213 T91 Seamless Ferritic Alloy-Steel Boiler Tubes
Standard:ASTM A213/ASME SA213
Standard Specification for Seamless Ferritic and Austenitic Alloy-Steel Boiler, Superheater, and Heat-Exchanger Tubes

ASTM A213 T91 Seamless Ferritic Alloy-Steel Boiler Tubes sizes and thicknesses usually furnished to this specification are 1 ⁄ 8 in. [3.2 mm] in inside diameter to 5 in [127 mm] in outside diameter and 0.015 to 0.500 in. [0.4 to 12.7 mm], inclusive, in minimum wall thickness.

A-213 T91: “A” is the mark of ASTM steel material. “213” refers to the specification reference number, “T91” refers to the steel grade classification, “T” refers to small diameter pipe, equivalent to China’s 10Cr9Mo1VNbN small diameter pipe.)

A-213 t91 is ASTM A-213 / A-213m standard steel grade: in 1970s, based on 9Cr-1Mo steel, a new type of ferritic shape steel was formed by adding a small amount of Nb and V microalloying elements and controlling the content of n elements in 9Cr-1Mo steel by several laboratories and burnxiao engineering company in the United States. The steel has good comprehensive mechanical properties, stable structure and properties before and after aging, good welding and technological properties, high endurance strength and oxidation resistance. In 1995, the steel was transplanted into GB5310 standard in China, and the grade was 10Cr9Mo1VNb.

ASTM A213 T91 Seamless Ferritic Alloy-Steel Boiler Tubes Quick Details
Manufacture:Seamless process ,Hot-finished or Cold-finished
Wall thickness(WT): 0.9 mm——12.7 mm.
Outer diameter (OD): 12.7 mm——127 mm
Length: 6M or specified length as required.
Ends: Plain End, Beveled End, Treaded

Specification of ASTM A213 T91 Boiler Tubes

OD (mm) Wall Thickness(mm)
2 2.5 3 3.5 4 4.5 5 6 6.5-7 7.5-8 8.5-9 9.5-10 11 12
Φ25-Φ28 ● ● ● ● ● ●
Φ32 ● ● ● ● ● ●
Φ34-Φ36 ● ● ● ● ● ●
Φ38 ● ● ● ● ● ●
Φ40 ● ● ● ● ●
Φ42 ● ● ● ● ●
Φ45 ● ● ● ● ● ●
Φ48-Φ60 ● ● ● ● ● ● ●
Φ63.5 ● ● ● ● ● ● ●
Φ68-Φ73 ● ● ● ● ● ●
Φ76 ● ● ● ● ● ● ● ● ● ●
Φ80 ● ● ● ● ● ● ● ● ● ●
Φ83 ● ● ● ● ● ● ● ● ● ●
Φ89 ● ● ● ● ● ● ● ● ● ●
Φ95 ● ● ● ● ● ● ● ● ● ●
Φ102 ● ● ● ● ● ● ● ● ● ●
Φ108 ● ● ● ● ● ● ● ● ● ●
Φ114 ● ● ● ● ● ● ● ● ●
Φ121 ● ● ● ● ● ● ● ● ●
Φ127 ● ● ● ● ● ● ● ● ●

Materials and Manufacture
ASTM A213 T91 Seamless Ferritic Alloy-Steel Boiler Tubes are made by the seamless process and shall be either hot finished or cold finished, as specified.

Grain Size
Grain size shall be as given in Table 1,
Grain size determinations, shall be made on one end of one finished tube from each lot.

Heat Treatment of ASTM A213 T91

TABLE 1 Heat Treatment and Grain Size Requirements
Grade UNS
Number		 Heat Treat Type Austenitizing/ Solutioning Temperature,
min or range ºF [ºC]		 Cooling Media Subcritical Annealing or Tempering Temperature,
min or range ºF [ºC]		  ASTM
Grain S
Ferritic Alloy Steels
T91 K90901 normalize and temper 1900–1975[1040–1080] … 1350–1470 [730–800] …

Note:1.Heat treatment shall be carried out separately and in addition to heating for hot forming.
2.ASTM Grain Size No. listed, or coarser, unless otherwise indicated.

Chemical Composition of ASTM A213 T91 Seamless Boiler Tubes

Chemical Composition(%)
C Mn P S Si Cr Mo V N Ni Al Nb
0.07-0.14 0.3-0.6 ≤0.02 ≤0.01 0.2-0.5 8.0-9.5 0.85-1.05 0.18-0.25 0.03-0.07 ≤0.4 ≤0.04 0.06-0.10

Mechanical Properties of ASTM A213 T91 Seamless Boiler Tubes

Low Alloy Steels
Grade UNS
Designation		 Tensile
Strength,
min, ksi[MPa]		 Yield
Strength,
min, ksi[MPa]		 Elongation
in 2 in. or
50 mm,
min, %		 Hardness
Brinell/Vickers Rockwell
T91 K90901 85 [585] 60 [415] 20 190 to 250 HBW/
196 to 265 HV		 90 HRB to 25

Mechanical property requirements do not apply to tubing smaller than 1 ⁄ 8in. [3.2 mm] in inside diameter or thinner than 0.015 in. [0.4 mm] in thickness.

The dimensional tolerances of ASTM A213 Seamless Boiler Tubes
Tolerances of  Wall Thickness

Wall Thickness, %
Outside
Diameter
in. [mm]		 0.095 [2.4] and Under Over 0.095 to 0.150[2.4 to 3.8], incl Over 0.150 to 0.0180[3.8 to 4.6], incl Over 0.180 [4.6]
Over Under Over Under Over Under Over Under
Seamless, Hot-Finished Tubes
4 [100] and under 40 0 35 0 33 0 28 0
Over 4 [100] …. …. 35 0 33 0 28 0
Seamless, Cold-Finished Tubes
Over Under
1 1 ⁄ 2 [38.1] and under 20 0
Over 1 1 ⁄ 2 [38.1] 22 0

Tolerances of  Outside Diameter

Pecified Outside Diameter,in. [mm] Permitted Variations, in. [mm]
Over Under
Hot-Finished Seamless Tubes
4 [100] or under 1 ⁄ 64 [0.4] 1 ⁄ 32 [0.8]
Over 4 to 7 1 ⁄ 2 [100 to 200], incl 1 ⁄ 64 [0.4] 3 ⁄ 64 [1.2]
Over 7 1 ⁄ 2 to 9 [200 to 225], incl 1 ⁄ 64 [0.4] 1 ⁄ 16 [1.6]
Cold-Finished Seamless Tubes
Under 1 [25] 0.004 [0.1] 0.004 [0.11]
1 to 1 1 ⁄ 2 [25 to 40], incl 0.006 [0.15] 0.006 [0.15]
Over 1 1 ⁄ 2 to 2 [40 to 50], excl 0.008 [0.2] 0.008 [0.2]
2 to 2 1 ⁄ 2 [50 to 65], excl 0.010 [0.25] 0.010 [0.25]
2 1 ⁄ 2 to 3 [65 to 75], excl 0.012 [0.3] 0.012 [0.3]
3 to 4 [75 to 100], incl 0.015 [0.38] 0.015 [0.38]
Over 4 to 7 1 ⁄ 2 [100 to 200], incl 0.015 [0.38] 0.025 [0.64]
Over 7 1 ⁄ 2 to 9 [200 to 225], incl 0.015 [0.38] 0.045 [1.14]

Tolerances of Length

Method of
Manufacture		 Specified Outside
Diameter, in.[mm]		 Cut Length, in. [mm]
Over Under
Seamless, hot-finished All sizes 3 ⁄ 16 [5] 0 [0]
Seamless, cold-finished Under 2 [50.8] 1 ⁄ 8 [3] 0 [0]
2 [50.8] or over 3 ⁄ 16 [5] 0 [0]
2 [50.8] or over 3 ⁄ 16 [5] 0 [0]

Hydrostatic or Nondestructive Electric Test
Each tube will be subjected to the nondestructive electric test or the hydrostatic test.

Tests
(1)Tension test——One tension test shall be made on a specimen from one tube for lots of not more than 50 tubes. Tension tests shall be made on specimens from two tubes for lots of more than 50 tubes.
(2)Hardness Requirements—— Brinell, Vickers, or Rockwell hardness tests shall be made on specimens from two tubes from each lot.
(3)Flattening Test——One flattening test shall be made on specimens from each end of one finished tube.
(4)Flaring Test——One flaring test shall be made on specimens from each end of one finished tube.

Surface Condition
Ferritic alloy cold-finished steel tubes are free of scale and suitable for inspection.
Ferritic alloy hot-finished steel tubes are free of loose scale and suitable for inspection.

Note: Material furnished under ASTM A213 conform to the applicable requirements of the current edition of Specification A1016/A1016M

Application of ASTM a-213 T91 alloy steel pipe:
Allowable service temperature: ASTM A213 T91 alloy steel pipe is mainly used for manufacturing high temperature superheater, reheater and other pressure parts of subcritical and supercritical power plant boilers with metal wall temperature not exceeding 625 ° C, and also for pressure vessels and nuclear power high temperature pressure parts.
Application of T / P91 boiler pipe in petrochemical industry:
T / P91 can be used to replace T / P22 and T / P5 tubes in distillation, cracking units and refineries because of its good high temperature mechanical properties and high temperature hydrogen resistance. Moreover, t / P91 is more suitable for boilers in sulfur rich environment than t / P22 and T / P5. Generally speaking, P91 pipe with pipe diameter greater than 168mm and T91 pipe with pipe diameter less than or equal to 168mm belong to the same steel type, and the requirements for chemical composition and mechanical properties are the same.