FASTENING MEANS FOR A TURBINE- OR VALVE HOUSING

Abstract

A fastener for connecting a first housing part of a steam or gas turbine to a second housing part of the turbine which is made of a parent metal with a high degree of stress relaxation.

Claims

1. A fastening means for connecting a first housing part of a steam or gas turbine to a second housing part of the steam or gas turbine, wherein the fastening means is formed from a base material, wherein the base material comprises the following composition: C: 0.10 to 0.17% by weight, Mn: 0.20 to 0.60% by weight, Cr: 8.0 to 11.0% by weight, Mo: 1.0 to 2.0% by weight, Co: 0.50 to 2.00% by weight, N: 0.010 to 0.050% by weight, B: 0.005 to 0.015% by weight, V: 0.10 to 0.30% by weight, Al: at most 0.010% by weight, Nb: 0.02 to 0.08% by weight, Ni: 0.10 to 0.50% by weight, Si: at most 0.10% by weight, P: at most 0.010% by weight, S: at most 0.005% by weight, Fe: remainder, wherein the base material is formed such that a ratio of N/B (in % by weight) is between 1.0 and 5.0.

2. The fastening means as claimed in claim 1, wherein the base material comprises 0.5 to 1.5% by weight of Co and at most 5% by weight of W.

3. The fastening means as claimed in claim 1, wherein the fastening means comprises a bolt.

4. The fastening means as claimed in claim 1, wherein the fastening means comprises a union nut for connecting two components.

5. The fastening means as claimed in claim 1, wherein the fastening means comprises a housing-joint bolt which connects the first housing part to the second housing part in a flange-like housing-joint region.

6. The fastening means as claimed in claim 1, wherein the base material is optimized in terms of strength in a temperature range of from 400° C. to 650° C.

7. The fastening means as claimed in claim 1, wherein production of the fastening means comprises: melting material constituents, subjecting the melt to a preliminary heat treatment and further processing to form a round profile, and quenching and tempering the round profile at tempering parameters of T<720° C.

8. The fastening means as claimed in claim 1, wherein the fastening means consists of the material X13CrMoCoVNbNB9-2-1.

9. A turbine housing for a steam or gas turbine, comprising: a first housing part, a second housing part, a fastening means as claimed in claim 1 for connecting the first and second housing parts in a flange-like housing-joint region of the housing parts.

10. A valve housing for a steam or gas turbine, comprising: a valve housing top part, a valve housing bottom part, and a fastening means as claimed in claim 1 for connecting the valve housing top part to the valve housing bottom part.

11. A turbine for a thermal power plant, comprising: a turbine housing as claimed in claim 9.

12. A turbine for a thermal power plant, comprising: a valve housing as claimed in claim 10.

13. A turbine for a thermal power plant, comprising: a turbine housing, a valve housing, and a fastening means as claimed in claim 1; wherein the turbine housing comprises a first housing part, a second housing part, and the fastening means for connecting the first and second housing parts in a flange-like housing-joint region of the housing parts; and wherein the valve housing comprises a valve housing top part, a valve housing bottom part, and the fastening means for connecting the valve housing top part to the valve housing bottom part.

14. The fastening means as claimed in claim 6, wherein the base material is qualified with a strength Rp 0.2 of at least 700 MPa at room temperature.

15. The fastening means as claimed in claim 8, wherein the fastening means consists of the material X13CrMoCoVNbNB9-2-1 up to 100% thereof.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] One exemplary embodiment of the invention will be described below with reference to the drawing.

DETAILED DESCRIPTION OF INVENTION

[0026] This is intended not to illustrate the exemplary embodiment to scale, but rather the drawing, where it is conducive to clarification, is set out in a schematized and/or slightly distorted form. With regard to additions to the teaching which is directly apparent in the drawing, reference is made to the relevant prior art.

[0027] This drawing shows a sectional view of a flange-like housing-joint region of a turbine housing, having a housing-joint bolt.

[0028] The figure shows a detail of a turbine housing 12 of a steam turbine 10 in the region of a housing joint 18. Here, turbine housing 12 denotes the inner housing, which is surrounded by an outer housing, of the steam turbine 10.

[0029] The invention may also be used for a valve housing.

[0030] The turbine housing 12 has an upper, or first, housing part 14 and a lower, or second, housing part 16. The housing joint 18 is located between the first housing part 14 and the second housing part 16. The first housing part 14 and the second housing part 16 have a flange-like form in the region of the housing joint 18. A housing flange 15 of the first housing part 14 and a housing flange 17 of the second housing part 16 are provided with a bolt bore 20 having an internal thread.

[0031] The bolt bore 20 is designed to receive a housing-joint bolt 22. The housing-joint bolt 22 is an embodiment of a fastening means 22. Further embodiments of the fastening means 22 would be stud bolts or nuts, in particular union nuts. In this case, the bolt bore 20 extends completely through the housing flange 15 of the first housing part 14 and partially in the housing flange 17 of the second housing part 16. The housing-joint bolt 22 can be screwed into the bolt bore 20 from the top, i.e. from the top side of the housing flange 15 of the first housing part 14. The housing-joint bolt 22 is configured as a hexagonal bolt in the present example and has a bolt head 24 and a bolt shank 26 with an external thread which is adapted to the internal thread of the bolt bore 20. In the position, shown in the figure, of the housing-joint bolt 22 in which it has been completely screwed into the bolt bore 20, said housing-joint bolt constitutes a fixed connection between the first housing part 14 and the second housing part 16 via the respective housing flanges 15 and 17. The housing-joint bolt 22 may also be designed in various other forms of configuration in addition to the form of configuration shown in the figure. For example, the housing-joint bolt 22 may also be in the form of a threaded bolt with corresponding bolt nuts on its respective end faces.

[0032] The housing-joint bolt 22 is formed from a base material.

[0033] The chemical composition of the base material of the housing-joint bolt 22 is composed of the following chemical elements:

[0034] C: 0.10 to 0.17% by weight,

[0035] Mn: 0.20 to 0.60% by weight,

[0036] Cr: 8.0 to 11.0% by weight,

[0037] Mo: 1.0 to 2.0% by weight,

[0038] Co: 0.50 to 2.00% by weight,

[0039] N: 0.010 to 0.050% by weight,

[0040] B: 0.005 to 0.015% by weight,

[0041] V: 0.10 to 0.30% by weight,

[0042] Al: at most 0.010% by weight,

[0043] Nb: 0.02 to 0.08% by weight,

[0044] Ni: 0.10 to 0.50% by weight,

[0045] Si: at most 0.10% by weight,

[0046] P: at most 0.010% by weight,

[0047] S: at most 0.005% by weight,

[0048] Fe: remainder.

[0049] The base material is formed in such a way that the ratio of N/B (in % by weight) is between 1.0 and 5.0.

[0050] The bolt (22) consists of the material X13CrMoCoVNbNB9-2-1, in particular the bolt consists up to 100% of this material.

[0051] The base material of the bolt (22) is optimized in terms of strength in the temperature range of from 400° C. to 650° C., in particular is qualified with a strength Rp 0.2 of at least 700 MPa at room temperature.

[0052] The production of the bolt (22) comprises the following steps: melting the material constituents, subjecting the melt to a preliminary heat treatment and further processing to form a round profile, and quenching and tempering the round profile at tempering parameters of T<720° C.

[0053] C=carbon, Mn=manganese, Cr=chromium, Mo=molybdenum, Co=cobalt, N=nitrogen, B=boron, V=vanadium, Al=aluminum, Nb=niobium, Ni=nickel, Si=silicon, P=phosphorus, S=sulfur, Fe=iron, W=tungsten.