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Alloy Steel tubes for high-temperature service
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.