Esshete 1250 Tube and pipe, seamless

Datasheet updated

2022-05-10 07:44
(supersedes all previous editions)

Esshete 1250 is a fully austenitic chromium-nickel steel with excellent high- temperature strength and good resistance to corrosion in boiler applications. The grade can be used at temperatures up to about 650°C (1200°F), it is easily fabricated and also characterized by:

  • High strength in relation to other typical candidate austenitic alloys
  • Very good resistance to steam and flue gas atmospheres
  • Good structural stability at high temperatures
  • Good weldability

Standards

  • UNS: S21500
  • EN Number: 1.4982
  • EN Name: X10CrNiMoMnNbVB15-10-1

Product standards

  • ASTM A213
  • EN 10216-5

Approvals

  • VdTÜV-Werkstoffblatt 520
  • PED (Pressure Equipment Directive) 2014/68/EU

Chemical composition (nominal)

Chemical composition (nominal) %
C Si Mn P S Cr Ni Mo V Nb B
0.1 0.5 6.3 ≤0.035 ≤0.015 15 9.5 1.0 0.3 1.0 0.005

Chemical composition (nominal), %

C Si Mn P S Cr Ni Mo V Nb B
0.1 0.5 6.3 ≤0.035 ≤0.015 15 9.5 1.0 0.3 1.0 0.005

Applications

The high creep strength of Esshete 1250, combined with its good resistance to steam and flue gas atmospheres, makes it a very suitable material for use in coal-fired boilers. The grade was developed in the United Kingdom in the 1960's, and the bulk of the material has been used in the UK power industry in 500 and 660 MW boilers.

The main application has been superheaters and reheaters operating at 570oC (1058oF), steam pressure 170 bar (superheaters) and 40 bar (reheaters). Typical metal temperature 600–700oC (1112–1292oF), in flue gas temperature 900–1200oC (1652–2192oF). The corrosion environment on the fireside in the UK boilers was historically very aggressive as the British coal has, typically a high chlorine content of up to 0.6%, sulphur at 1–2% and a high ash content of 20%.

Esshete 1250 has also been used successfully in superheaters in biomass boilers, burning various biofuels and producing steam at 580–540oC (1076–1004oF) at 60–200 bars pressure.

Trademark information: Esshete 1250 is a trademark owned by Corus

Corrosion resistance

Air

Good resistance to scaling up to 800°C (1472oF).

Gaseous corrosion

Good resistance to steam and flue gas atmospheres. In service conditions typical of coal-fired boilers, the alloy has a very similar fireside corrosion to alloys of the ASTM 316H type. However, the much increased high-temperature strength gives significantly improved service performance. Fireside corrosion resistance in coal-fired, biomass-fired or coal/biomass co-fired boilers is similar to that of type ASTM 347H. Steam-side corrosion is similar to that of type ASTM 347H.

Bending

Esshete 1250 can be cold bent to narrow bending radii. Heat treatment after cold bending is not normally necessary, but this must be decided after considering the degree of bending and the operating conditions.

If post bending heat treatment is carried out, it should be in the form of solution annealing.

Hot bending is carried out at 1100–850°C (1832–1652°F) and should be followed by solution annealing.

Forms of supply

Seamless tube and pipe in Esshete 1250 is supplied in dimensions up to 260 mm (10.24 in.) outside diameter, in the solution annealed and white-pickled condition or in the bright annealed condition.

Heat treatment

Tubes are delivered in the heat treated condition. If another heat treatment is needed after further processing the following is recommended:

Stress relieving

850–950°C (1560–1740°F), 10–15 minutes, cooling in air.

Solution annealing

1050–1150°C (1920–2100°F), 5–20 minutes, rapid cooling in air, gas or water.

Mechanical properties

Metric units, at 20°C
Proof strength Tensile strength Elongation Hardness
Rp0.2a) Rp1.0a) Rm Ab) A2" HRB
MPa MPa MPa % %
≥230 ≥270 540–740 ≥35 ≥35 ≤90

1 MPa = 1 N/mm2

Imperial units, at 68°F
Proof strength Tensile strength Elongation Hardness
Rp0.2a) Rp1.0a) Rm Ab) A2" HRB
ksi ksi ksi % %
min. min. min. min. max.
33 39 78–107 35 35 90

a) Rp0.2 and Rp1.0 correspond to 0.2% offset and 1.0% offset yield strengths, respectively.
b) Based on L0 = 5.65 √S0 where L0 is the original gauge length and S0 the original cross-sectional area.

At high temperatures

Metric units
Temperature Proof strength
Rp.02 Rp1.0
°C MPa MPa
min. min.
50 213 254
100 188 232
150 171 210
200 161 195
250 153 190
300 148 187
350 145 184
400 144 182
450 141 179
500 139 178
550 136 175
600 133 170
650 130 165
700 125 159
Imperial units
Temperature Proof strength
Rp.02 Rp1.0
°F ksi ksi
min. min.
100 31.2 37.4
200 27.9 33.7
300 25.1 30.8
400 23.1 28.6
500 21.7 27.1
600 21.0 26.4
700 20.8 26.2
800 20.6 26.1
900 20.3 25.8
1000 19.8 25.4
1100 19.3 24.7
1200 18.7 23.9
1300 18.1 22.9

Creep strength

The creep rupture strength values correspond to values evaluated by Sterling tubes Ltd. The data from creep tests made by Alleima correspond well to the given data.

Metric units
Temperature Creep rupture strength, MPa
°C 10 000 h 100 000 h 250 000h
600 241 199 177
610 231 185 158
620 221 167 134
630 210 147 109*
640 198 122 90*
650 184 100 78*
660 167 84 69*
670 147 74 52*
680 124 66 56*
690 102 59 51*
700 86 54 46*
710 75 49 42*
720 67 45 37*
730 61 40* 32*
740 55 36* -
750 51 30* -
760 46 - -
770 42 - -
780 38 - -
790 34 - -

* Values, which have involved extended stress/time extrapolation

Imperial units
Temperature Creep rupture strength, ksi
°F 10 000 h 100 000 h 250 000 h
1100 35.2 30.7 28.8
1125 33.9 27.2 23.3
1150 32.0 23.5 18.5
1175 29.6 19.5 14.6*
1200 26.7 15.3 11.5*
1225 23.2 10.7 9.2*
1250 19.1 9.8 8.3*
1275 14.5 8.6 7.3*
1300 11.6 7.5 6.3*
1325 10.0 6.4 5.3*
1350 8.6 5.5 4.4*
1375 7.4 4.6 -
1400 6.5 3.9 -
1425 5.7 - -
1450 5.1 - -

* Values, which have involved extended stress/time extrapolation

Physical properties

Density: 7.9 g/cm3, 0.29 lb/in3

Thermal conductivity
Temperature, °C W/m °C Temperature, °F Btu/ft h°F
20 13 68 7
100 14 200 8
200 15 400 9
300 17 600 10
400 19 800 11
500 20 1000 12
600 22 1200 13
700 23 1400 13.5
800 24 1500 14
Specific heat capacity1)
Temperature, °C J/kg °C Temperature, °F Btu/lb °F
20-100 505 68-200 0.12
20-200 530 68-400 0.13
20-300 540 68-600 0.13
20-400 545 68-800 0.13
20-500 555 68-1000 0.13
20-600 560 68-1200 0.13
20-700 565 68-1400 0.14
20-800 575 68-1600 0.14
20-900 580 68-1800 0.14
20-1000 585 - -

1) Mean values in temperature ranges

Thermal expansion1)
Temperature, °C Per °C Temperature, °F Per °F
20-100 15 68-200 8.5
20-200 16 68-400 9
20-300 17 68-600 9.5
20-400 18 68-800 10
20-500 18.5 68-1000 10.5
20-600 19 68-1200 10.5
20-700 19 68-1400 11
20-800 19.5 68-1600 11
20-900 20 68-1800 11
20-1000 20 - -

1) Mean values in temperature ranges (x10-6)

Resistivity
Temperature, °C μΩm Temperature, °F μΩin.
20 0.74 68 29.1
100 0.80 200 31.3
200 0.88 400 34.6
300 0.94 600 37.5
400 1.00 800 39.9
500 1.05 1000 41.8
600 1.09 1200 43.6
700 1.13 1400 45.1
800 1.16 1600 46.3
900 1.18 1800 47.2
1000 1.20 - -
Modulus of elasticity1)
Temperature, °C MPa Temperature, °F ksi
20 192 68 27.8
100 184 200 26.6
200 176 400 25.5
300 168 600 24.2
400 160 800 22.9
500 151 1000 21.5
600 143 1200 20.2
700 135 1400 18.9
800 127 1600 17.7
900 120 - -

1) (x103)

Structural stability

As in other austenitic stainless steels, sigma phase can be formed after long heat treatment in the range 550–950°C (1022–1742oF). Due to the low chromium content, Esshete 1250 is significantly less sensitive to sigma phase formation than steels of e.g. the ASTM 316 type, according to tests involving ageing for 100000 h.

Welding

The weldability of Esshete 1250 is good. Welding must be carried out without preheating and subsequent heat treatment is normally not required. Suitable methods of fusion welding are manual metal-arc welding (MMA/SMAW) and gas-shielded arc welding, with the TIG/GTAW method as first choice.

For Esshete 1250, heat input of <1.5 kJ/mm and interpass temperature of <150°C (300°F) are recommended.

Recommended filler metals

TIG/GTAW or MIG/GMAW welding

ISO 18274 S Ni 6082 / AWS A5.14 ERNiCr-3 (e.g. Exaton Ni72HP)

MMA/SMAW welding

ISO 14172 E Ni 6182/ AWS A5.11 ENiCrFe-3 (e.g. Exaton Ni71)

Disclaimer: Recommendations are for guidance only, and the suitability of a material for a specific application can be confirmed only when we know the actual service conditions. Continuous development may necessitate changes in technical data without notice. This datasheet is only valid for Alleima materials.