JPH04133065U - Low alloy steel pressure vessel - Google Patents

Abstract

(57) [Summary] [Purpose] To prevent creep embrittlement cracking in the weld heat-affected zone of the shell plate and skirt band of a low-alloy steel pressure vessel. [Structure] A skirt band 4 made of a low-alloy steel material is welded by fillet welding, and a container body made of a low-alloy steel material with a heat-affected zone removed at the toe of the fillet weld, and a skirt band 4 made of a low-alloy steel material. It consists of a butt-welded skirt 5.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

This invention relates to low-alloy steel pressure vessels used under high temperatures and high pressures such as oil refining. Ru.

0002

[Conventional technology]

Figure 3 shows a conventional low-alloy steel pressure vessel used at high temperatures and high pressures such as in oil refining. show. In Fig. 3, 101 is a low alloy steel body plate, and 102 and 103 are low alloy steel bodies. The mirror plate, 104 is a low alloy steel skirt band, and 105 is a low alloy steel skirt. .

0003 The low alloy steel body plate 101, the low alloy steel skirt band 104 and the skirt band The welding of the lead 104 and the low alloy steel skirt 105 is shown in FIG. In Figure 4, low The alloy steel body plate 101 and the low alloy steel skirt band 104 are welded by fillet welding 106. The skirt band 104 and the low alloy steel skirt 105 are welded together 107. be welded.

0004

[Problem that the idea aims to solve]

As in the conventional pressure vessel described above, the low-alloy steel shell 101 and the low-alloy steel steel When the cart band 104 is welded by fillet welding 106, the fillet welding of the low alloy steel body plate A weld heat affected zone occurs at the weld end. On the other hand, the shape of the fillet weld toe is Because it is a discontinuous part, stress concentration occurs at the fillet weld toe during pressure vessel operation. arise. For low-alloy steel pressure vessels, especially those operated in the creep region, Among the welding heat shadow zones, the coarse-grained heat affected zone is said to have a particularly low creep rupture elongation. If the force concentration areas coincide in location, cracks often occur in the coarse heat affected zone, causing damage to the shell plate wall. It often spreads internally.

[0005] On the other hand, the attachment part of the low alloy steel skirt band 104 and the low alloy steel skirt 105 In addition to being a geometric discontinuity, the skirt band and skirt are Therefore, inspection during manufacturing is only performed for magnetic particle inspection, which is for the purpose of detecting surface defects. However, radiological inspections for the purpose of detecting internal defects could not be carried out, and internal This may leave defects.

[0006] For the above reasons, conventional low-alloy steel pressure vessels are free from internal defects during operation. The crack may propagate and open on the weld surface.

[0007] The present invention proposes a low-alloy steel pressure vessel that can eliminate the above-mentioned drawbacks. This is what we are trying to provide.

[0008]

[Means to solve the problem]

The low-alloy steel pressure vessel of the present invention has a skirt band made of low-alloy steel material at the fillet. Welded by welding and with the heat affected zone removed at the fillet weld toe. A container body made of alloy steel material and a skirt butt welded to the skirt band. It is characterized by consisting of two parts.

[0009]

[Effect]

In this invention, creep occurs from the stress concentration point of the fillet weld toe on the low-alloy steel body plate. Creep embrittlement cracking during operation is prevented by removing the heat-affected zone where the elongation at break decreases.

0010 In addition, by butt welding the skirt band and skirt, stress concentration is reduced. Weld internal defects can be detected and removed by radiological inspection. This prevents internal manufacturing defects from developing during operation.

[0011]

【Example】

An embodiment of the low alloy steel pressure vessel of the present invention will be explained with reference to FIGS. 1 and 2. do. In Figure 1, 1 is a low-alloy steel body plate, 2 and 3 are low-alloy steel head plates, and 4 is a low-alloy steel body plate. The gold steel skirt band 5 is a low alloy steel skirt.

0012 FIG. 2 shows an enlarged sectional view of the welded parts of the body plate 1, skirt band 4, and skirt 5. Shown below. In FIG. 2, the low-alloy steel body plate 1 and the low-alloy steel skirt band 4 are Fillet welding is performed at fillet weld portion 6.

[0013] This fillet weld 6 is usually formed by welding several times. By welding, mother The low-alloy steel of the shell plate 1 becomes coarse-grained, but the subsequent welding increases the coarse-grained steel. The granulated particles regrain and are no longer affected by welding. Therefore, the body plate 1 by fillet welding The heat affected zone is the fillet weld toe, that is, the upper part in contact with the fillet weld 6 in FIG. Occurs on the upper and lower parts.

[0014] In this embodiment, the heat affected zone 1a of the shell plate 1 has a depth of approximately 3 mm, as shown in FIG. , removed by machining and grinding over a height of 30 mm.

[0015] On top of that, the low alloy steel skirt band 4 and the low alloy skirt 5 are butt welded. Butt welding is performed at section 7.

[0016] In this way, in this example, the heat affected zone of the fillet weld of the low alloy steel shell plate 1 is removed. By doing so, it is possible to prevent creep embrittlement cracking that occurs in the heat affected zone. Ru. In addition, internal defects in the butt weld between the skirt band and skirt can be detected by radiographic inspection. can be easily detected and removed, and can be easily detected and removed from internal manufacturing defects during operation. In addition to preventing friction, the skirt band and skirt can be butt welded. By this, stress continuity can be maintained.

[0017]

[Effect of the idea]

As explained above, according to the present invention, the heat-affected zone at the fillet toe of the low-alloy steel shell plate It can prevent creep embrittlement cracking that occurs in the skirt band and Internal defects during the fabrication of the butt weld with the skirt can be easily removed and the operation It is possible to prevent the development of cracks due to internal defects during manufacturing of the same part during rolling. .

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a low-alloy steel pressure vessel according to an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of a welded portion between a low-alloy steel body plate and a low-alloy steel skirt band, and between the same skirt band and a low-alloy steel skirt in the same embodiment.

FIG. 3 is a cross-sectional view of a conventional low-alloy steel pressure vessel.

FIG. 4 is an enlarged sectional view of the low-alloy steel body plate and the low-alloy steel skirt band of the conventional low-alloy steel pressure vessel, and the welded portion of the skirt band and the low-alloy steel skirt.

[Explanation of symbols]

1 Body plate 1a Removed part of body plate 2,3 End plate 4 Skirt band 5 Skirt 6 Fillet welds 7 Butt welds

Claims (1)

[Scope of utility model registration request] 1. A container body made of a low-alloy steel material, to which a skirt band made of a low-alloy steel material is welded by fillet welding, and a heat-affected zone is removed at the toe of the fillet weld, and the skirt band A low-alloy steel pressure vessel characterized by a skirt butt-welded to the bottom.