JPH0619924Y2 - Boiler tube construction or repair studs - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a stud for constructing or repairing a boiler tube.

[Prior Art] For example, in a boiler tube of a paper mill or the like, in general, a large number of studs are welded along at least a part of the outer periphery in order to enhance protection against corrosion and a heat insulating effect, and these studs form a refractory material layer. I support you. The refractory material layer is usually formed by spraying or applying a mixture of a refractory material and a binder onto a boiler tube having a large number of studs.

By the way, the refractory layer and the many studs supporting the refractory layer differ depending on the usage conditions of the boiler tube, but normally the stud head burns off as the refractory layer wears out after about 3 to 5 years. Wear out. Therefore, it is necessary to regularly inspect and make necessary repairs. The conventional repair method is to remove the refractory layer and surface deposits, and then cut the studs that need to be repaired out of the studs implanted around the boiler tube to a flat surface from the base or at a predetermined height. Then, a method is known in which a repairing stud is welded to the cut surface by a stud welding method or manual welding, and a refractory layer is applied to the portion by the above method. In such a repair method, it is necessary to cut the burned studs one by one, which requires a lot of labor and time for repair and is not efficient.
In order to save labor and time in such repair, there is a method of repairing by directly welding repair studs onto a tapered head without cutting the worn studs.
No. 8 and JP-A-59-195002.

The studs used to construct or repair such a boiler tube are generally substantially cylindrical, as shown in Figure 2, and have a flat head end surface. In addition, JP-A-60-14880
Japanese Patent Publication No. 5 discloses heat resistance and corrosion resistance consisting of a root member having a hollow portion at the head and an end member made of a ceramic material having a constricted portion inserted and sandwiched in the hollow portion at the head of the root member. A superior stud is disclosed.

[Problems to be solved by the invention] By the way, when constructing or repairing a boiler tube used in a paper mill or the like, the work is substantially closed and the work in a relatively narrow space is forced. Therefore, even if the conventional method as disclosed in the above-mentioned publication is used, the number of studs to be implanted is very large, which is a very painful work for the operator. When welding a repair stud directly onto a tapered stud head that has been abraded by the above method, even if the method disclosed in the above publication is used, the welding is done firmly on the same axis as the abraded stud. It is very difficult, if not impossible, to often bend and weld or create poorly welded studs.

In addition, since the head of the conventionally used stud is flat as described above, it is avoided that the stud gradually wears away from the peripheral edge of the stud head as the boiler is used after construction and repair, and it does not become tapered. I can't. Furthermore, the above-mentioned JP-A-60-1
In the stud as disclosed in Japanese Patent No. 48805, since the end member made of a ceramic material is inserted and sandwiched in the hollow portion of the head of the root member, the heat resistance and the corrosion resistance are excellent, but the fireproof layer When the end member is worn out due to the wear of, the constricted part of the end member remaining in the hollow part of the head of the root member is removed, the hollow part is expanded to the original state, and the end member for repair is opened. Although it is necessary to newly insert and clamp it, repairing such end members with a boiler tube is practically difficult from the working environment and structure where many studs are closely fixed to the boiler tube. However, it is necessary to replant the stud itself, which requires a considerable amount of work for repair work, which is not practical.

Therefore, an object of the present invention is to improve a stud that has been conventionally used for constructing or repairing a boiler tube so that the boiler tube can be constructed or repaired easily without the above-mentioned drawbacks. To provide studs for construction or repair.

[Means for Solving the Problems] In order to achieve the above-mentioned object, according to the present invention, which is adapted to be welded and fixed to a boiler tube directly or on the tip of a worn stud on the boiler tube by a stud welding method. Boiler tube construction or repair studs have a central recess that extends axially inward from the head end to increase the contact area with the fill coating refractory material and to be planar as it wears. It is characterized by being configured in.

[Operation] In the stud for constructing or repairing the boiler tube according to the present invention, since the central recess is provided in the head, it is of course possible to firmly support the refractory material for filling and covering, and of the boiler after construction or repair. Even if the stud gradually wears from the periphery of its head as it is used, it does not substantially taper until it wears to the level of the bottom of the central recess, thus reducing the depth of the central recess. The studs can be welded to the head if they are substantially flat, if properly repaired so that they are repaired when they have worn down to the level of the bottom of the central recess.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of a stud for constructing or repairing a boiler tube according to the present invention, in which 1 is a stud main body, and a central recess 2 having an appropriate depth is provided in the head thereof. The central recess 2 acts to tightly support the refractory material for filling coating. Further, the depth of the central recess 2 can preferably be designed appropriately to suit the repair time. In the illustrated embodiment, the peripheral portion that defines the central recess 2 is continuous, but in some cases it may be formed into a split groove type, and therefore the term "central recess" is used in this specification. It also includes a structure in which at least a part of the peripheral edge of the stud head remains.

[Effect of the Invention] As described above, the stud for constructing or repairing the boiler tube according to the present invention has the central recess extending axially inward from the head end and supporting the refractory material for filling coating. Therefore, it is of course possible to firmly support the refractory material for filling coating, and even if the stud gradually wears from the peripheral portion of its head after construction and use of the boiler after construction and repair, There is no substantial taper until it is worn down to a level, so if repairs are performed at the depth level of the central recess, the stud will be welded to the head if it is substantially flat. Not only is it easier to weld, but it can also be welded firmly in the correct orientation.

[Brief description of drawings]

FIG. 1 is a view schematically showing an embodiment of a stud for constructing or repairing a boiler tube according to the present invention, and FIG. 2 is a view schematically showing a conventional stud. In the figure, 1: stud body, 2: central recess.

Claims (1)

[Scope of utility model registration request] 1. A stud for constructing or repairing a boiler tube, which is adapted to be welded and fixed to a boiler tube directly or on the tip of a burned stud on the boiler tube by a stud welding method, in an axial direction from a head end. A boiler tube characterized by comprising a central recess extending toward one side, the central recess being configured to increase the contact area with the refractory material for filling coating and to make the head end planar as it wears or Repair stud.