US 3182855 A
Description (OCR text may contain errors)
Filed Oct. 18, 1962 May 11, 1965 A. L. STOCK 3,182,855
BLOW-OUT DOOR FOR OVERPRESSURE PROTECTION 2 Sheets-Sheet l INVENTOR Alvin L. Stock May 11, 1965 A. STOCK 3,132,355
BLOW-OUT DOOR FOR QVERPRESSURE PROTECTION Filed Oct. 18, 1962 2 Sheets-Sheet 2 United States Patent 3,182,855 BLOW-OUT DOOR FOR OVERPRESSURE PROTECTION Alvin L. Stock, Drexel Hill, Pa., assignorto Westinghouse Electric Corporation, Pittsburgh, Pa, a corporation of Pennsylvania Filed Oct. 18, 1962, Ser. No. 231,474 6 Claims. (Cl. 220-89) This invention rel-ates to apparatus for providing protection against overpressure in fluid containing shell structure, and, more particularly, to an explosive or blow-out door structure for quickly relieving a fluid overpressure condition in such shell structure.
Heretofore, blow-out door structures have employed discs of either a frangible or shearable nature arranged to provide a fluid-tight seal but adapted to rupture at a predetermined pressure. Although blow-out door structures of this type have proven to be highly satisfactory and dependable, they are costly to manufacture, relatively heavy in weight due to the number and arrangement of the components, and expensive to reseal in the field after rupture of the disc since the ruptured disc is not reusable.
In view of the above, it is a primary object of the invention to provide a blow-out door structure that obviates the rupturable disc.
It is a further object to provide a blow-out door structure that is less expensive to manufacture, lighter in weight and in which all of the manufactured components may be reused as often as desired.
Briefly, in accordance with the invention, there is provided a blow-out door structure including a body structure having an enlarged opening and a door member overlying and blocking the opening. The body structure and the door member have mating surface portions encompassing the opening gnd bonded to each other by a layer of adhesive material, thereby fastening the door member to the body structure and providing a pressure-tight seal preventing leakage of fluid therethrough in normal operation. By properly proportioning the door, the mating surfaces and the area of the adhesive material layer, the adhesive material layer is effective to yield at a substantially predetermined overpressure value, thereby explosively releasing the door and permitting fluid to quickly escape through the opening to the atmosphere before a dangerous overpressure condition is attained.
. Although not limited thereto, the above blow-out door structure 'may be advantageously employed to provide overpressureprotection on low pressure steam turbines by mounting on the shell structure in registry with a suitable opening. In such an environment, the temperatures encountered may attain values of about 500 F. and the overpressure values are on the order of about to p.s.i.g. Adhesive materials found to be suitable for such application are epoxy resins and silicone cements.
The foregoing and other objects are effected by the invention as will be apparent from the following description and claims taken in conjunction with the accompanying drawings, forming a part of this application, in which:
FIGURE 1 is an axial sectional view of a blow-out door structure formed in accordance with the invention;
FIG. 2 is a plan of the blow-out door structure shown in FIG. 1 with a portion cut away;
FIG. 3 is an axial sectional view showing a second embodiment of the invention; and
FIG. 4 is a side elevational view of the structure shown in FIG. 3 with a portion cut away.
Referring to the drawings in detail, in FIGS. 1 and 2 there is shown an explosion or blow-out door structure 5, formed in accordance with the invention, including a body structure 10 of generally tubular configuration and having a generally cylindrical side wall 11 and a circumferential end portion 12. The end portion 12 is provided with a radially inwardly extending flange portion 13 forming an annular recessed surface portion 14 and defining an enlarged central opening 15. There is further provided an imperforate door-member 16 of circular or disc-like configuration having a circumferential flange portion 17 providing an annular surface portion 18.
The door member 16 is of slightly smaller radial dimensionthan the flange 13 and is freely received therein with the surface portions 18 and 14 disposed in mating face-to-face relation with each other, thereby positioning the door in the flange 13 for support thereby and preventing movement of the door member 16 downwardly when viewed as shown in FIG. 1. Accordingly, when the door member 16 is positioned on the flange 13, as shown, the opening 15 is blocked thereby.
The door member 16 is bonded to the flange 13 by a continuous layer of adhesive material 20 interposed between the mating surfaces 14 and 18 and substantially coextensive therewith, thereby forming a pressure-tight seal to prevent leakage of fluid therepast.
The body structure is formed with its cylindrical wall portion 11 of substantial axial extent to form a chamber 21. The chamber 21 is covered at the upper end of the cylindrical wall 11 by an open framework guard or grid member 22 of any suitable type having a plurality of apertures 23 formed therein to permit fluid to escape freely past the grid member 22. The grid member 22 is attached to the wall portion 11 by any suitable fastening means, for example, an annular array of screws 24.
The blow-out door structure 5 may be welded or otherwise attached to a shell structure 25 (shown in fragmentary form) of a fluid containing device to be protected against overpressure, for example, a low pressure steam turbine unit, and is disposed in registry with a suitable aperture 26. As well known, low pressure steam turbines are operable at relatively low or even subatmospheric steam pressure values which may, from time-totime and for various reasons, exceed their maximum fluid pressure rating. Accordingly, for economic reasons such shells may be made to withstand relatively low pressures on the order of from 5 to 10 p.s.i.g., and protected against overpressure by the blow-out door structure.
Such shell structures further may contain steam at temperatures up to about 500 F. When the blow-out door structure is employed for overpressure protection in such an environment, the selection of the adhesive material must take into account the deteriorating effect of long exposure to such temperature on the adhesive material. Epoxy resins and silicone cements have been found highly suitable for such applications, since both of these adhesives are readily available, have the special characteristic of being readily bondable to metals and do not appreciably age, maintaining their optimum properties at temperatures of up to at least 500 F. in a steam atmosphere. These adhesives, further maintain a high quality vacuum seal, While their shear and tensile stress values are adequate and may be easily and concisely determined in designing the blow-out door structure to yield at a predetermined overpressure value.
In operation, the blow-out door structure prevents leakage of steam from the shell 25 during normal operation. However, should the internal pressure within the shell member exceed a predetermined safe value, the layer of adhesive material 20 will commence to yield, thereby permitting the door member 16 to move outwardly and relieve the internal pressure. As the door member 16 moves outwardly, under the influence of the steam, it has imparted thereto a relatively high degree of kinetic energy. However, this kinetic energy is absorbed by the guard member 22 which also serves to hold the door member 16 captive within the chamber 21, while permitting the excessive steam to flow freely through the central opening 15 and the chamber 21 to the atmosphere.
The cylindrical wall portion 11 serves to direct the flow of escaping steam in any desired direction, for example, ,in a direction away from operating personnel or apparatus that may otherwise be harmed by the steam. Accordingly, the blow-out door structure may be connected to the shell structure 25 in any suitable position or attitude, as desired.
To restore the blow-out door structure to its original operative and sealing status after a blow-out has been incurred, the guard member 22 is first removed by removing the screws 24, thereby rendering the door member 16 readily accessible. The door member 16 is then removed and the annular surface 18 thereon, as well as the flange surface 14, is prepared for a new layer of adhesive material by removing therefrom the old adhesive material. This may be accomplished by a knife or other suitable scraping device. After a new layer of adhesive material is applied to the mating surfaces 14 and 18 and the door member 16 is replaced, the guard member 22 is repositioned and attached by the screws 24. After a suitable length of time to permit the epoxy resin or the silicone cement to become fixed or cured, the blow-out door structure is ready to be put into service again.
By suitably proportioning the door member 16, the
opening and the mating surfaces 14 and 18, the blowout door structure may be made effective to safely vent fluid from the shell 23 at any predetermined over-pressure value. This may be more readily understood by considering that the layer of adhesive material has a substantially uniform tensile strength per unit of surface area. Hence, by increasing the surface area of the adhesive layer, the force that the layer will withstand is proportionately higher. Conversely, by reducing the area of the adhesive layer, the force that it will withstand is proportionately reduced. The invention is susceptible of many embodiments, and modifications, and, as illustrated in FIGS. 3 and 4, there is shown a second embodiment of a blow-out door structure 35, similar to the blow-out door structure shown in FIGS. 1 and 2. This embodiment may be employed with a vertically extending shell portion 36 of a steam turbine or the like and includes an annular mounting member 37 defining an enlarged opening 38. The mounting member 37 may be connected to the shell portion 36 in any suitable manner, such as by welding, as indicated at 39. A body structure 40 is clamped on the mounting member by an annual array of suitable bolts 41 received in suitable apertures provided in a radially outwardly extending flange portion 42. The flange portion 42 is of circular configuration and encompasses an enlarged central opening 43'disposed in registry with the opening 38. The body structure 40 further includes an upstanding wall portion 44 of arcuate cross-section (FIG. 4) to which is attached a generally circular deflector plate 45. The deflector plate 45 is attached to the wall portion 44 by an annular array of screws 46.
The wall portion 44, the flange portion 42 and the deflector plate 45 define an outlet opening 49 providing a fluid communication between the atmosphere and the opening 43. A plurality of spaced rods 50 extend across the opening 49 and are connected at opposite ends to the flange 42 and to the deflector plate 45, thereby forming an open framework dividing the outlet 49 into a plurality of openings of smaller extent in substantially the same manner as the grid member 22 described in conjunction with the first embodiment. The body 40 is, in the same manner as described in conjunction with the first embodiment, provided with a radially inwardly extending circumferential flange portion 52 having an annular surface portion 53 encompassing the opening 43 and disposed in face-to-face relation with a mating annular surface portion 54 provided on a circular door member 55. Between the mating surfaces 53 and 54 there is provided a layer of suitable adhesive material 56 bonding the door member to the flange portion 51. This material may be selected as desired to suit its particular environment, as mentioned previously.
Since the body portion 48 is detachably connected to the mounting member 37 by the screws 41, a suitable sealing gasket 57 may be employed to provide a leakproof seal therebetween. This gasket 57 may be formed of any suitable material, for example, silicone sponge rubber. v
The blow-out door structure 35 operates in substantially the same manner as the blow-out door structure 5 described in connection with the first embodiment. That is, when the internal steam pressure within the shell 36 exceeds a predetermined safe value, the layer of adhesive material yields and permits the door member 55 to move outwardly, thereby venting the interior of the shell 36 to the atmosphere through the opening 43.
As the door member 55 moves explosively outwardly by the steam flowing therepast, its motion is arrested by the deflector member 45 and its kinetic energy safely dissipated. The escaping steam is directed outwardly through the opening 49 in a direction generally transverse to the axis of the opening 43 so that the flow path of the steam after it is ejected to the atmosphere is generally parallel to the surface of the shell 36 and directed upwardly as viewed in FIG. 3.
After an explosion, the blow-out door structure may be serviced in substantially the same manner as described in connection with the first embodiment and restored to service in the field.
With this arrangement, the blow-out door structure 35 may also be employed as an access door, permitting access to the interior of the shell 36 for inspection or servicing purposes, since to remove the door structure 35, it is only necessary to remove the mounting bolts 41. Hence, a separate access door (usually provided in apparatus of this type) is not required.
It will now be seen that with both of the embodiments described in connection with the invention, the door members 16 (FIGS. 1 and 2) and 55 (FIGS 3 and 4) are not impaired or damaged in any way and may be used repeatedly. Hence, the only material required to restore the blow-out door structure to the original factory obtained sealing condition is a supply of the sealing material desired.
It will now be further seen that the invention provides a readily serviceable blow-out door structure that includes a minimum of essential components and that these components may be made of relatively light material, no heavier than required to withstand the pressures required in service.
While the invention has been shown in several forms, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various changes and modifications without departing from the spirit thereof.
I claim as my invention:
1. A blow-out door structure for protecting a shell structure against damage due to internal overpressure, comprising a body structure having an enlarged opening defined by a flange portion,
said flange portion having a substantially continuous first peripheral face portion,
a door member having a second peripheral face portion disposed in face-to-face relation with said first face portion,
a layer of adhesive material disposed between said first and second face portions and coextensive peripherally therewith,
said layer of material bonding said door member to said body structure and providing a fluid-tight seal therebetween at total internal pressures below a predetermined value, but being yieldable at substantially said predetermined value to break said seal and re lease said door, and
means for holding said door captive in said body structure.
2. The structure recited in claim 1 in which said door holding means includes an open framework structure,
said framework structure being connected to said body structure and permitting the door to move freely within the body structure.
3. A blow-out door structure for protecting a shell structure against damage due to internal overpressure, comprising a body structure having a first planar surface portion,
said body portion having an enlarged opening encompassed by said surface portion,
a door member blocking said opening and having a second planar surface portion disposed in face-to-face relation with said first surface portion,
a layer of adhesive material disposed between said first and second surface portions and bonding said door member to said body structure,
said layer of material providing a fluid-tight seal between said door member and said body at total internal pressures below a predetermined value, but being yieldable at substantially said predetermined value to break said seal and permit said door to unblock said opening, and
means for holding said door captive in said body structure after said opening is unblocked.
4. A blow-out door structure for explosively releasing internal fluid overpressure in a shell structure, comprismg an annular mounting structure defining an enlarged first central opening,
a body structure connected to said mounting structure,
said body structure having a second central opening disposed in registry with said first opening,
said body structure having a first annular surface portion encompassing said second opening,
an imperforate door member blocking said second opening and having a second surface portion disposed in face-to-face relation with said first surface portion,
an annular layer of adhesive material disposed between said first and second surface portions and bonding said door member to said body structure,
said layer of material providing a fluid-tight seal between said surface portions at total internal fluid pressures below a predetermined value, but being yieldable at total internal fluid pressures above said 5 predetermined value to rupture said seal and permit said door to explosively unblock said second open- 111g,
said body structure further including an open framework,
a wall portion disposed in spaced relation with said door and at least partly defining a third opening for directing the fluid to the atmosphere, and
an open framework extending across said third opensaid wall portion being further effective to arrest the movement and dissipate the kinetic energy of said door during an explosion.
5. The structure recited in claim 4 in which said body structure is detachably connected to said mounting structure by an annular array of bolts, whereby said body structure and said door member may be removed as a unit from said mounting structure to provide access to the interior of the shell structure.
6. The structure recited in claim 4 in which said mounting structure is attached to an upwardly extending portion of the shell structure,
said wall portion has an upwardly extending deflector plate attached thereto and partly defining said third opening,
said third opening facing upwardly whereby upon rupture of the seal to relieve the internal fluid pressure, the escaping fluid is deflected by said deflector plate and vented through said third opening in an upward direction.
References Cited by the Examiner UNITED STATES PATENTS 833,694 10/06 Parker.
2,17%:686 11/39 Georgiev et al. 220--89 THERON E. CONDON, Primary Examiner.
FRANKLIN T. GARRETT, Examiner.