GB2060801A - A nipple for a valve, faucet, coupling element, union or the like - Google Patents

Abstract

A nipple 1 for a valve, faucet, coupling element, or union, in particular for heating, or sanitary systems, has a threaded portion provided with a sealing coating (13) firmly anchored thereon. As the sealing material, synthetic materials, plastics materials and varnishes, e.g. epoxy varnishes, polyamides or plastically deformable materials can be used. The sealing material can be applied by known methods, such as fluid bed dipping, brushing, or spraying. The sealing coating can also be provided on the sealing surface of the nipple. <IMAGE>

Description

SPECIFICATION A nipple for a valve, faucet, coupling element, union or the like DESCRIPTION The present invention relates to a nipple for a valve, facuet, coupling element, union or the like, particularly for heating, sanitary systems, or the like.

As it is known, such nipples are generally sealed by interposing movable sealing means, such as hemp, Teflon tapes or shaped gaskets (see for example Italian Patent Application No.

27,920 A/77 filed on September 26, 1977 by Alberto Giacomini and Mario Giacomini).

Couplings sealed by using hemp, jointly with a softening paste, have the following well known disadvantages: a) a great deal of time is needed for applying the rquired amunt of hemp on the threaded portion of the nipple or union, as well as for screwing together the portions to be coupled; b) the necessity of applying on the rolled hemp a film of a paste effective to soften and precisely locate the individual hemp yarns; c) a shifting to the outside of the hemp during the screwing on operation, with a consequent visible build up of hemp on the outside of the coupling.

An advantage attributed to the use of hemp consists in a satisfactory adhesion of the hemp onto the male thread.

On the other hand, the drawbacks associated with the use of a Teflon tape as a sealing means are: a) a great loss of time in applying three or four tape turns on the male thread; b) poor adhesion between the Teflon tape and the thread grooves, whereby, during the screwing on operation, it frequently happens that the Teflon tape is outwardly displaced and has to be applied again; c) possible easy breakage of the Teflon tape under tension.

The advantage of the Teflon tape consists of its resistance against high temperatures and corrosive chemical agents.

While the sealing means disclosed in the Italian Patent Application mentioned above, which consists in a tubular resilient sleeve provided with a side nut, was effective to provide satisfactory quick couplings, it has the practical disadvantage of requiring the provision of a range of different diameter sleeves, and a preliminary assembly together of the sleeve and nipple or union.

Accordingly, the present invention provides a nipple for a valve, faucet, coupling element, union or the like, the nipple having a threaded portion with a coating of sealing material firmly anchored thereon.

According to the present invention, there is thus used as a sealing means, instead of hemp, Teflon tape or intermediate sleeves, a sealing material firmly anchored on the nipple or the like body. Advantageously, a synthetic material, e.g. rislan, is used.

In practising the invention, expoxy varnishes or any other suitable plastics materials can be used, provided that the materials are plastically deformable and capable of being firmly anchored on the nipple.

The sealing material can be applied by any suitable method, such as dipping, fluid bed dipping, or brushing, spraying and so on, the nipple being susceptible to be heated before the application of the sealing material.

Thus, on the threaded portion of a nipple or coupling element, which may be a male threaded portion, and optionally at least on a sealing front surface thereof, there is formed a continuous sealing material film. This film on the thread, may have a varying thickness, that is, it will be thinner at the thread ridges and thicker in the thread grooves. This advantageously affects the sealing properties.

This is a further advantage of the invention since the sealing material is able to compensate for practically the overall clearance range originating in the different threads, the diameter being the same.

In fact it is known that in these nipples the threads are made with rather coarse tolerances and accordingly the tolerances are quite different from nipple to nipple. This was in fact a problem that required the use of hemp as a solution.

While the sealing materials as well as the methods for applying the sealing materials, and elements treated thereby, such as gate wheels, valve handles and the like are known, in these the plastics materials were applied only as a protective or surface finishing material. According to the invention, on the contrary, the synthetic material, or plastics material, or varnish, is used as a sealing material proper. By means of the invention, the advantage is achieved that the assembly time can be drastically reduced, that perfect sealings can be obtained under all conditions, regardless of the individual thread tolerances, and that it is possible to prevent the sealing material from building up on the outside of the coupling element, as occurs in the use of hemp and Teflon tape.

The invention, furthermore, completely eliminates the assembling step between a resilient sleeve and coupling element.

In order to permit perfect couplings to be obtained the invention provides for the use of a slightly tapering thread. Preferably, the starting portion of said thread has a taper slightly greater than that of the remaining thread, in order to facilitate the initial thread engagement.

The invention is further described below, by way of example, with reference to the accompanying drawing, in which: Figure 1 is a side view, partly in longitudinal section, illustrating the coupling of a nipple to a duct on one side, and to a valve on the other side, in accordance with the prior art; Figure 2 is a partial sectional side view of a nipple or union embodying the present invention; Figure 3 is a view on a larger scale of the detail A of Fig. 2; and Figure 4 is a sectional side view showing a sealing front portion, at the end opposite to the threaded end, of a nipple of the type illustrated in Fig. 2.

Although the invention relates to nipples in general, or in unions and single threaded coupling elements, and to nipples for valves, faucets and the like, these latter being used in particular in heating, sanitary water, industrial and the like systems, the following illustrative description is confined for simplicity to a union to be coupled to a valve by a cup member.

As shown in Fig. 1, a nipple or union 1 is provided with an external screw thread 2 and a front sealing portion 3 having an annular recess or slot 4 housing a ring gasket 5. The union 1 is furthermore provided with a slot 6 housing a cup member 7 for connection to a nipple 8, forming part for example of a valve 9. A tubular duct 10 is provided at the end shown with an internal screw thread 11. As a sealing means, there is employed in known way, hemp 12, which during assembly, accumulates to form a visible projecting portion 1 2a. This known arrangement presents the disadvantages mentioned above.

According to the invention, there is provided on the nipple or union 1 a continuous film 13 of a suitable sealing material, such as a synthetic sealing material, a plastics material, or a varnish.

As shown in the illustrated nipple, in Fig-. 3, the thickness of the continuous film 13 is not even, but is of minimum value at the thread ridges and of maximum value at the thread grooves. This permits the nipple to be perfectly fitted to the female thread on the mating portion or nipple, independently of the tolerances involved.

The front portion of the nipple union 1 of Fig. 2, at the end opposite to the threaded end, provides, in known way, for the housing of a gasket 5a, which is in this case of rectangular cross-section. It is advantageous to provide an outwardly upturned edge 1 a, effective to locate the gasket 5a precisely and firmly. The nipple or union 1 instead may be provided with a sealing end, on the end opposite to the threaded end, having a continuous sealing coating consisting of a plastics material or varnish film firmly anchored on the union body. In this way, in particular by providing for a flat sealing end surface, it is possible to form a perfect seal without using the known ring gaskets.

The effectiveness of the seal made by the union according to the invention is assured by the plastic deformability of the sealing material. Satisfactory results have been obtained by using as the sealing material rilsan, which has been anchored on the union body by using a known type of rilsanization method.

The plastic deformability of the sealing material, as well as the nearly complete filling up of the grooves of the thread by this material, ensure a perfect seal, in spite of the conventionally coarse tolerances provided for these nipples or unions.

In order to faciltate the engagement of the screw threads, the nipple of the invention advantageously provides a slightly tapering thread, the starting portion of which preferably presents the greater taper, in order to facilitate the initial screwed connection between the parts to be coupled.

From the above description, it will be apparent that the invention makes it possible to achieve considerable advantages over the prior art.

Specifically, the time for effecting the coupling of the threaded parts is drastically reduced, all gaskets are eliminated, visible accumulations of the sealing material externally of the threads (as in the case of hemp and Teflon tapes) are prevented from occurring, the necessity of holding sealing materials, or gaskets in stock, and furthermore the couplings can be effected even by unskilled operators.

In the case of nipples, unions or coupling elements made of a relatively soft material, such as brass, more stringent tolerances are provided and a sealing material film of less thickness than for nipples of harder material can be used, This can be achieved, for example, by exploiting centrifugal forces, or causing the nipple to rotate during the application of the sealing material.

Known methods for applying sealing material, such as rilsanization, spraying, dipping and so on advantageously lend themselves to mass production and quick processing so that these methods, like the materials employed, do not adversely affect manufacturing costs.

A further important advantage enjoyed by nipples or unions embodying the invention is that the sealing material film, being firmly anchored on the nipples, is also effective to provide, in known way a surface protection action.

It is possible in practice to provide for the application of the sealing material also to the female or internally threaded portion as well as to provide for coatings of different colours, depending on diameters or other parameters of the nipples, thereby additionally reducing the coupling assembly time in systems requiring a large number of threaded couplings, and also reducing inventory requirements.

In practising the invention, plastics materials or varnishes, as well as application methods the#refor effective to provide a firm anchoring of the resultant film or coating, can be employed.

Claims (13)

1. A nipple for a valve, faucet, coupling element, union or the like, the nipple having a threaded portion with a coating of sealing material firmly anchored thereon.

2. A nipple as claimed in claim 1 wherein the coating comprises a continuous film.

3. A nipple as claimed in claim 1 or 2 wherein the sealing material consists of a plastics material or paint capable of being plastically deformed.

4. A nipple as claimed in claim 3 wherein the sealing material comprises a polyamide, an epoxy paint or vanish.

5. A nipple as claimed in claim 1, 2, 3 or 4 wherein the sealing material is applied by fluid bed dipping or spraying.

6. A nipple as claimed in any preceding claim wherein the threaded portion having the coating of sealing material thereon is tapered to facilitate engagement with a mating threaded portion.

7. A nipple as claimed in claim 6 wherein the leading end of the threaded portion has a greater taper than the remainder of the threaded portion.

8. A nipple as claimed in any preceding claim having a relatively small manufacturing tolerance, the thickness of the coating being substantially uniform.

9. A nipple as claimed in any one of claims 1 to 7 having a relatively large manufacturing tolerance, the thickness of the coating being greater in the thread grooves than on the ridges of the threaded portion.

10. A nipple as claimed in any preceding claim having a front sealing head arranged to house a gasket ring, wherein the front portion of the inside edge of the sealing head is slightly outwardly upturned in such a way as to firmly lock to the gasket ring.

11. A nipple as claimed in any one of claims 1 to 9 having a sealing portion, at least the sealing portion having a coating of sealing material firmly anchored thereon.

12. A nipple as claimed in claim 11 wherein the two coatings are of the same sealing material.

13. A nipple substantially as herein described with reference to Figs. 2, 3 and 4 of the accompanying drawing.