JPH04252926A - How to install a metal thermometer - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for attaching a metal thermometer to a steel pipe for steam generation such as a header, boiler tube, or heat exchanger tube.

0002

[Prior Art] Generally, a steam generator, such as a boiler, which recovers heat such as combustion heat as steam through a steam-generating steel pipe, uses pipes to control the temperature of the fluid in the boiler and the superheated steam generated. A large number of metal thermometers are attached to steam generation steel pipes such as pipes, boiler tubes, and heat transfer tubes.

[0003] The pad type (
(with sheathed wire) are often used, and the pad is welded directly to the steam generating steel pipe.

0004

[Problems to be Solved by the Invention] When using 9Cr-1Mo steel for steam generation steel pipes, if metal parts are directly welded to this material, it becomes brittle and requires annealing (approximately 740±
15℃) is required. For this reason, it is necessary to perform annealing after directly welding the pad to the steel pipe for steam generation.However, since a thermometer is attached to the pad, if annealing is performed due to the structure, parts are damaged.

[0005] Therefore, the present invention was made in consideration of these circumstances, and its object is to provide a method for attaching a metal thermometer that makes it possible to attach a pad without damaging the temperature measuring part. It is about providing.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a method for installing a metal thermometer in which a pad is attached to a steam generating steel pipe formed of 9Cr-1Mo steel. A thin plate-like receiving plate made of 2.25 (2 1/4) Cr-1Mo steel with relatively good bondability is welded to the steel pipe for use, and after annealing, the above-mentioned pad is welded onto this receiving plate. This is what I did.

[0007]

[Action] Relatively good bondability for steam generation steel pipes 2.25
A thin plate-like receiving plate made of Cr-1Mo steel is welded and annealed. Since the receiving plate is a thin plate, there is almost no problem in measuring the temperature inside the steam generating steel pipe. A pad is welded onto the receiving plate. This welded part does not require annealing, so there is no damage to the metal temperature part.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

In FIGS. 1 to 3, reference numeral 1 indicates a steam generating steel pipe such as a header, boiler tube, heat exchanger tube, etc., and this steam generating steel pipe 1 is made of 9Cr-1Mo steel.

[0010] On the steam generating steel pipe 1, a thermocouple 2 as a pad-type (with sheath wire) metal thermometer similar to the conventional one is attached by a pad 4 via a first receiving plate 3a. A strap 5 for protecting the sheath wire is attached via the second receiving plate 3b.

[0011] The receiving plate 3 consisting of the first and second receiving plates 3a, 3b, etc. is formed into an arcuate shape with a thickness of about 2 mm so as to be in close contact with the outer periphery of the steel pipe 1, and is made of a 2.25 mm (2.2 mm) thick plate having relatively good bonding properties. 2
1/4) It is made of Cr-1Mo steel (STBA24) and is formed into a larger shape than the pad 4 and strap 5.

Now, in order to attach the pad-type thermocouple 2 as a metal thermometer to the steam generating steel pipe 1, first, a receiving plate 3 (first receiving plate) is attached to the pad mounting position of the steam generating steel pipe 1 in a factory or the like. 3a and the second receiving plate 3b) are welded, and after welding, they are annealed (about 740±15°C). As a result, even if the steam generation steel pipe 1 is made of 9Cr-1Mo steel,
The receiving plate 3 is attached to the steam generating steel pipe 1 with good adhesion.

Next, the pad 4 is welded onto the first receiving plate 3a, and the strap 5 is welded onto the second receiving plate 3b at the site. Thereby, the thermocouple 2 will be attached to the steam generation steel pipe 1.

[0014] Therefore, the receiving plate 3 is attached to the steam generating steel pipe 1, and the pad 4 is welded onto the receiving plate 3, which has relatively good bonding properties, so that annealing of the pad 4 is not necessary, so that thermoelectric 9Cr without damaging the temperature measuring part of pair 2.
The pad 4 can be attached to the steam generation steel pipe 1 made of -1Mo steel.

[0015] It has been confirmed that by forming the receiving plate 3 with a thickness of about 2 mm or less, it does not pose a practical problem when measuring, for example, the steam temperature within the steam generating steel pipe 1.

That is, thicknesses of 2 mm, 3 mm and 4
It was found from an experiment using a receiving plate 3 of mm.

(Experimental example) The main tube has a diameter (φ) of 38
．． 1mm, thickness 8.0mm, length 500mm, using 9Cr-1Mo steel as the material, this main pipe has a thickness of 2m.
A pad 4 (SUS304) is welded through a receiving plate 3 (STBA24) with a diameter of 3 mm, 3 mm, and 4 mm.
A 2 mm sheathed thermocouple was attached.

[0018] Sheathed heaters each having a temperature control thermocouple attached to the surface thereof were inserted into each of these main tubes to heat the main tubes from inside. Attach a K-sheath thermocouple with a diameter of 0.5 mm to the surface of each main pipe, and use this indication as the reference surface temperature.
It was heated until its reference surface temperature stabilized at about 600°C. Each main pipe was insulated with 175 mm of Kao wool.

Then, the reference surface temperature at the time when the temperature became stable and the temperature of the thermocouple at each thickness were measured.

As a result, the temperature difference from the reference temperature was 2 mm.
-0.6℃ for the receiving plate, -2.6℃ for the 3mm receiving plate,
The temperature was -3.3°C with a 4mm receiving plate. In addition, the pad without a receiving plate is different from the standard thermocouple (φ 0.5K thermocouple).
All were within the tolerance of K thermocouples of class 0.4 (±2.4°C at 600°C).

[0021] As a result, in the case of a 2 mm receiving plate, the difference in temperature indication is small and there is almost no problem in measuring the temperature inside the steam generating steel pipe.

[0022] Therefore, the steam generation steel pipe 1 has a thickness of approx.
By attaching the receiving plate 3 of 2 mm or less, the pad 4 can be attached to the steam generation steel pipe 1 made of 9Cr-1Mo steel with good adhesion without causing any practical problems in temperature measurement and without damaging the temperature measuring part of the thermocouple 2. be able to.

[0023]

Effects of the Invention In summary, according to the present invention, 9Cr-
We welded a thin receiving plate with relatively good bonding properties to a steam generating steel pipe made of 1Mo steel, annealed it, and then welded a pad (with sheath wire) onto this receiving plate.
It has the excellent effect of allowing a metal thermometer to be attached without damaging the temperature measuring part of the pad.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a state in which a metal thermometer is attached by the method according to the present invention.

FIG. 2 is a sectional view taken along line A-A in FIG. 1;

FIG. 3 is a sectional view taken along line BB in FIG. 1;

[Explanation of symbols]

1 Steel pipe for steam generation 3 Receiver plate 4 Pad

Claims (1)

[Claims] Claim 1. A metal thermometer mounting method in which a pad is attached to a steam generation steel pipe formed of 9Cr-1Mo steel, wherein the steam generation steel pipe is made of 2.25Cr-1Mo steel with relatively good bondability. A method for attaching a metal thermometer, characterized in that a thin plate-shaped receiving plate is welded, the plate is annealed, and then the pad is welded onto the receiving plate.