JPH0253658B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Field of Application) The present invention relates to a gland packing used in a shaft seal of a fluid machine, and more particularly to an asbestos-free gland packing for use at high temperatures and high pressures. (Conventional technology) Conventionally, as a gland packing for high temperature and high pressure,
Some were made of asbestos fibers.
This type of gland packing is suitable for use under high temperature and high pressure because asbestos material has excellent heat resistance and has a low weight loss rate under high temperature. However, due to its nature, asbestos tends to generate dust when handled, so it is not sanitary for those involved in packing materials and packing manufacturing. That is, if asbestos dust is inhaled for a particularly long period of time, the respiratory system may be affected, and if it is deposited on the skin, it may induce occupational diseases such as mesothelioma. Therefore, in recent years, packing companies have developed so-called asbestos-free packings that do not use asbestos. An example of this is a packing made of expanded graphite as a core material, surrounded by bag-knitted metal fibers with excellent heat resistance, and the surface of which is treated with graphite. (Problems to be Solved by the Invention) Although the packaging of this prior art can avoid the adverse effects that would occur when asbestos fibers are used, the expanded graphite used as the core material cannot be heated to 500°C in an oxidizing atmosphere. Because it will burn out nearby,
The problem is that the rate of weight loss of the packing in the high temperature range is extremely large, and the properties under high temperature and high pressure are unstable. The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a gland packing that has stable high-temperature and high-pressure characteristics in an oxidizing atmosphere and is suitable for high-temperature and high-pressure applications. (Means for Solving the Problems) The gland packing according to the present invention includes a core material of ceramic fiber and a surface braided material of metal fibers with excellent heat resistance surrounding the core material. It is. (Function) In the present invention, since the core material is formed of a ceramic fiber whose properties are stable at high temperatures, it will not burn out even in an oxidizing atmosphere exceeding 500°C. Therefore, the weight loss property is low and the original shape at room temperature can be maintained in the high temperature region, so good sealing performance is ensured and leakage of high pressure fluid can be prevented. (Embodiment) FIG. 1 is a perspective view showing an embodiment of the present invention, in which a ceramic fiber core material 1 and a surface braided material 2 of metal fibers with excellent heat resistance surrounding the core material 1 are shown. and a surface lubricant impregnated into the surface braided material 2, that is, a plugging material 3. The core material 1 is made of ceramic fibers having the characteristics shown in Tables 1 and 2 below. In particular, in this embodiment, a large number of ceramic fibers are concentrated and made of stainless steel wire 1a with a diameter of 0.15 mm (for example, SUS
310S) is knitted into 8 square stitches using 2 to 3 reinforcement yarns.

【table】

[Table] The surface braided material 2 is a metal fiber with excellent heat resistance, that is, in this example, stainless steel with a diameter of 13μ (for example,
The knitting yarn is made up of a large number of SUS 316L (SUS 316L), and the yarn is braided into 16 bag stitches. And as surface lubricants, NBR, phenolic resin,
Clogging material 3 having a composition of graphite powder, silicone oil, etc.
The proportions of core material 1, surface braided material 2, and filling material 3 are set as shown in Table 3 below.

[Table] As is clear from Tables 1 and 2 above, the ground packing is formed using ceramic fiber as the core material 1, which has high high temperature strength and excellent heat resistance. But damage does not reduce weight. FIG. 2 shows the experimental results of the relationship between heating temperature and weight loss rate. In FIG. 2, the solid line shows the characteristics of the gland packing of the present invention based on the above Table 3, and the broken line shows the characteristics of the gland packing having the structure described in the section of the prior art, that is, the gland packing using expanded graphite as the core material. In this figure, it can be seen that the weight loss rate of the product of the present invention at high temperatures is extremely low, and it has the property of being able to maintain its original shape, that is, it has excellent shape retention. Therefore, good sealing performance is ensured even at high temperatures, and it has excellent properties as a gland packing for high temperatures and high pressures. FIG. 3 shows an example of the use of the gland packing of the present invention, in which a valve stem 5 and a stuff-in box 6 are used.
The space between the back of the box 6 and the packing presser 7
A pair of front and rear gland packings of the present invention located on the sides
A shaft seal is provided between the GP1 and these gland packings GP1 by a plurality of (four) gland packings GP2 whose core material is expanded graphite as described in the prior art example. With this configuration, not only can sufficient sealing performance be ensured under high temperature and high pressure, but also the inner surface of the stuff-in box 6 and the valve stem 5 can be easily removed, for example, when replacing or inspecting the gaskets GP1 and GP2. The eluted substance (expanded graphite) from GP2 adhering to the outer surface is wiped off by the gland packing GP1 at the inner part, which is extracted last. In other words, with the wiper function of Grand Packkin GP1,
Since the inner surface of the stuff-in box 6 and the outer surface of the valve stem 5 can be cleaned, the gland packing GP1,
The troublesome work of removing the eluted substances after removing GP2 can be omitted, and the workability for replacing or inspecting the gland packings GP1 and GP2 is improved. In addition, since the eluted substance from the gland packing GP2 is sealed by the gland packing GP1, it does not leak along the inner surface of the stuff-in box 6 and the inner surface of the valve stem 5. That is, Grand Packkin
GP1 has a flow function to prevent leakage of eluted substances from gland packing GP2. (Effects of the Invention) As explained above, according to the ground packing of the present invention, the core material of the ceramic fiber,
Since the core material is surrounded by a surface braided material of metal fibers having excellent heat resistance, the high temperature and high pressure characteristics are stable. Moreover, because it conforms well to the inner surface of the stuff-in-box and the outer surface of the shaft member, it can ensure excellent sealing performance under high temperature and high pressure, and ceramic fiber is cheaper than expanded graphite, making it economical. It has a practically useful effect.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing one embodiment of the present invention;
The figure is a graph showing the relationship between heating temperature and weight loss rate of the gland packing according to the present invention and the conventional gland packing, and FIG. 3 is a longitudinal sectional view showing an example of use of the gland packing according to the present invention. 1... Core material, 2... Surface braided material.

Claims (1)

[Claims] 1. A ground packing characterized by comprising a core material of ceramic fiber and a surface braided material of metal fibers with excellent heat resistance surrounding the core material.