DE1023942B - Intermediate pieces with neck for fittings without a stuffing box - Google Patents

Description

GERMAN

In. the chemical. There is a great need for industry For fittings without a stuffing box, especially for aggressive media such as acids and alkalis, in a wide variety Concentrations and Mixtures. Leaky stuffing boxes in acid fittings not only bring unpleasant and costly breakdowns, but also mean a great danger for the company working people, These fittings are also required in chemical plants, their processes must run under vacuum, with leaky stuffing boxes causing a failure of the chemical. reaction occur, or the yield is too poor. A special need for fittings without a stuffing box also exists in potentially explosive chemical plants for flammable and explosive gases.

The use of metal bellows in fittings without a stuffing box is known. The metal bellows are today manufactured as multi-layer bellows also for higher pressures. The length of the metal bellows depends on the required lifting height of the closure member for the opening and closing process of the respective valve type. With regard to the clear diameter of the flow cross-section, the length of the bellows is smaller in the case of cone shut-off valves, it is greater in the case of piston valves, and in the case of gate valves, the stroke of the closing element requires a length of the metal bellows which constructively no longer appears economical.

The individual wave of a metal bellows allows only a relatively small deformation for reasons of skill, on the negative and on the positive side. A large number of shafts is necessary for a small lifting height. The permissible expansion of a metal bellows (bellows stroke) is on average around 25% of the corrugated length L (maximum 40 ¹ Vo). In view of the long service life, based on the experience available, a quarter of the permissible elongation should be in the tension area and three quarters in the compression area. For economic reasons, the allowable expansion of a metal bellows should therefore be used in the construction, so that the number of waves is a minimum for a given stroke of the closing element.

So that the permissible expansion of a metal bellows cannot be exceeded, which would result in the early destruction of the bellows, is for everyone. Bellows a stroke limitation on both sides is essential. According to the tests and experience of the metal bellows manufacturers, the permissible internal pressures generally apply to bellows whose corrugated length is not greater than their external diameter (L = D). For longer bellows, an external support must be provided for internal pressure to prevent buckling. This is unnecessary with bellows under external pressure, which is 30% intermediate pieces with a neck
for fittings without stuffing box

Applicant:

Theo Schulte,

Dortmund, Thomas-Mann-Str. 11

Theo Schulte, Dortmund,
has been named as the inventor

may be higher than the permissible internal pressure. The bellows should therefore be subjected to external pressure will.

There is already a valve according to German patent specification 703 985, in which the Spindle by three coaxially arranged, one behind the other Bellows diaphragms is sealed to the outside. Still, here is for the stem seal a stuffing box is also provided. When this valve is closed, the inner membrane only becomes pulled and is under external pressure, the intermediate membrane is only pressed and is under internal pressure, the outer membrane is only pulled again and is under external pressure.

There are also known stuffing box-less slide in which the metal bellows have the same diameter are connected in series, resulting in a very long spindle and a high structure, which makes the operations is not wanted.

It has now been found that the disadvantages of the known constructions can be avoided, when the bellows are used with spacers in the manner described below which are the elongation and compression of each Limit bellows and with which the bellows are connected so that they are actuated the spindle is all stressed in the same direction, i.e. - either for compression or all for extension will.

In the drawing there is a solution for those without a stuffing box Valves shown with large lifting height, as they are, for. B. have gate valves, with a relative low overall height is achieved.

The outer intermediate piece d has a collar through which it is fixed between the normal Armaturengehiäusea and the hood b, which is not under operating pressure, by means of the screws c

709 878/156

is tightly clamped in a central position. The fixed intermediate piece d further has a neck, the length of which is the respective. Bellows length can be adjusted. The outer bellows f is tightly connected to the upper end of the neck. Any number of intermediate pieces with neck attachment e can be arranged concentrically within one another but freely movable in the fixed intermediate piece d. The number depends on the respective lifting height of the closing organ. With the movable intermediate pieces e two bellows are f, at top and one below, in, any distance close verbunden.i The inner bellows g at its lower end with the closure member also sealed, thereby known to be achieved that the spindle h and the inner surface of the hood b does not come into contact with the flow medium. In the case of acid fittings made of austenitic, stainless steel, the hood b can therefore be made of cast iron and the spindle h of ordinary steel.

The collar i and a second, downwardly positioned neck k, create the stroke limitation necessary for bellows on both sides, which can be adapted to the permissible bellows stroke in each case. The movable intermediate pieces e can be pushed into one another through corresponding recesses in the collars ι bayonet-like or through other structural solutions.

The valve design without a stuffing box described above differs from the valve known from German patent specification 703 985 not only in that the compression and expansion of the bellows when the spindle is operated is limited by stops, but also in that the bellows are each stressed in the same direction and the stops are arranged so that the length of the bellows changes only by the allowable amount. This has the advantage that the bellows do not compress and stretch with the same force as in the case of the valve according to German patent specification 703 985, but that the forces during compression and extension can be kept different. Furthermore, all bellows are acted upon by external pressure. No special model has to be made for the fitting housing α , but a normal cast can be used.

Claims (2)

Patent claims: 1. Spindle seal for valves with several concentrically arranged bellows, characterized in that rigid intermediate pieces are provided between the bellows are, with each of which two bellows are tightly connected and carry the stops that the Limit stretching and compression of the bellows, all in the same when the spindle is operated Direction, i.e. either all of them are subjected to compression or all to extension. 2. Spindle seal according to claim 1, characterized in that it is used to seal the spindle a slide is used. Considered publications:
German patent specifications No. 693 630, 703 985. 1 sheet of drawings © 709 878/156 1.