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API 5L Specification | API 5L Pipes X42, X46, X52, X56, X60, X65 etc. in Seamless and Welded Form.

API 5L X42 Pipe | API 5L X46 Pipe | API 5L X52 Pipe | API 5L X56 Pipe | API 5L X60 Pipe | API 5L X65 Pipe in PSL-1 and PSL-2.

Material Data Sheet

Alloy Steel tubes for high-temperature service

Steel designation: Name Material No.
P91 UNS Designation: K91560
T91 K90901
X10CrMoVNb9-1 1.4903

Scope
This data sheet applies for Seamless Tubes.

Application
The material P91/T91 is especially suited for steam boiler, boiler parts, boiler drum, and pressure vessel for the apparatus engineering and similar purposes. It can be used in permanent operation with wall temperatures up to about 650°C (1202°F).

Chemical composition (Heat analysis in %)

Chemical Requirements

  Grade P-5 P-9 P-11 P-22 P-91 P-91 shall also include the following:
Element UNS Designation K41545 S50400 K11597 K21590 K91560
Carbon 0.15 max 0.15 max 0.05 – 0.15 0.05 – 0.15 0.08 – 0.12 V at 0.18 – 0.25
Manganese 0.30 – 0.60 0.30 – 0.60 0.30 – 0.60 0.30 – 0.60 0.30 – 0.60 N at 0.030 – 0.070
Phosphorous, max 0.025 0.025 0.025 0.025 0.020 Ni at 0.40 max
Sulfur, max 0.025 0.025 0.025 0.025 0.010 Al at 0.02 max
Silicon 0.50 max 0.25 – 1.00 0.50 – 1.00 0.50 max 0.20 -0.50 Cb at 0.06 – 0.10
Chromium 4.00 – 6.00 8.00 – 10.00 1.00 – 1.50 1.90 – 2.60 8.00 – 9.50 Ti at 0.01 max
Molybdenum 0.45 -0.65 0.90 – 1.10 0.44 – 0.65 0.87 – 1.13 0.85 – 1.05 Zr at 0.01 max

Tensile Requirements

  Seamless    
  P-5 P-9 > P-11 P-22 P-91 P91 shall not have a hardness not exceeding 250 HB/265 HV [25HRC].
Tensile Strength, min., psi          
ksi 60 60 60 60 85
MPa 415 415 415 415 585    
Yield Strength, min., psi              
ksi 30 30 30 30 60    
MPa 205 205 205 205 415    

Permissible Variation in Wall Thickness

NPS [DN] Designator Tolerance, % from Specified
    Over   Under
1/8 to 2 1/2 [6 to 65] incl., all t/D ratios   20.0%   12.5%
Above 2 1/2 [65], t/D < or = 5%   22.5%   12.5%
Above 2 1/2 [65], t/D > 5%   15.0%   12.5%
(t = Specified Wall Thickness; D = Specified Outside Diameter)

Elongation Requirements

Calculated Minimum Elongation Values
Elongation in 2 in. or 50 mm, min %
Wall Thickness P5, P9, P11, P22 P91
in. mm Longitudinal Transverse Longitudinal
5/16 (0.312) 8 30 20 20
9/32 (0.281) 7.2 28 19 19
1/4 (0.250) 6.4 27 18 18
7/32 (0.219) 5.6 26   17
3/16 (0.188) 4.8 24   16
5/32 (0.156) 4 22   15
7/8 (0.125) 3.2 21   14
3/32 (0.094) 2.4 20   13
1/18 (0.062) 1.6 18   12

Permissible Variations in Outside Diameter

Outside Diameter at any point shall not vary from standard specified more than:

NPS [DN] Designator Over Under
  in. mm in. mm
1/8 to 1 1/2 [6 to 40], incl. 1/64 (0.015) 0.40 1/64 (0.015) 0.40
Over 1 1/2 to 4 [40 to 100], incl. 1/32 (0.031) 0.79 1/32 (0.031) 0.79
Over 4 to 8 [100 to 200], incl. 1/16 (0.062) 1.59 1/32 (0.031) 0.79
Over 8 to 12 [200 to 300], incl. 3/32 (0.093) 2.38 1/32 (0.031) 0.79
Over 12 [300] +/- 1% of the specified outside diameter

Processing / Welding

Standard welding processes for these steel grades are:
TIG-welding
Arc welding (E)
MAG-welding massive wire
Submerged arc welding (SAW)

MAG-welding cored wire Depending on the welding position and the plate thickness, may be other filler metals have to be applied,which can be inquired at the manufacturer in case of need.

These steels can be welded within all thickness ranges according to the afore mentioned welding processes. Preheating upto 200°C is permitted for workpieces with thicknesses >10mm.

After welding for workpieces, which are subject to the technical regulations for steam boiler plants, a heat treatment has to be defined in particular. In all cases stress relieving anneal has to be performed.

When flame cutting of larger wall thicknesses is performed the cutting area has to be preheated upto 200°C.