GB2394752A - A modular mechanical seal - Google Patents

Abstract

A modular mechanical seal includes a gland member 11 which is common to more than one generic seal configuration, e.g. single and/or double seal, as shown in Figs 5 to 11, which reduces the number of parts from which a variety of modular mechanical seal formats can be assembled.

Description

A MODULAR MECHANICAL SEAL

This invention relates to mechanical seals which are fitted to rotating equipment in virtually all types of 5 industries.

A Mechanical seal comprises a "floating" component which is mounted axially movably around the rotary shaft of, for example, a pump and a "static" component which is 10 axially fixed, typically being secured to a housing. The floating component has a flat annular end face, i.e. its seal face, directed towards a complementary seal face of the static component. The floating component is urged towards the static component to close the seal faces 15 together to form a sliding face seal, usually by means of one or more spring members. In use, one of the floating and static components rotates; this component is therefore referred to as the rotary component. The other of the floating and static components does not rotate and 20 is referred to as the stationary component.

Those seals whose floating component is rotary are described as rotary seals. If the floating component is stationary, the seal is referred to as a stationary seal...

25. À. If the sliding seal between the Rotary and Stationary components are assembled and pre-set prior to despatch from the Mechanical seal manufacturing premises, the.

industry terminology for this is "cartridge seal". If 30 the Rotary and Stationary components are despatched....DTD: individually (unassembled) from the Mechanical seal...

manufacturing premises, the industry terminology for this is "component seal".

Mechanical seals are used in all types of industries to seal a variety of different process media and operating conditions. The general industry term which defines the area adjacent to the process media is "inboard". The 5 industry term which defines the area adjacent to the atmospheric side is "outboard".

Like most industries, the mechanical seal industry is highly competitive.

As a result, mechanical seal manufacturers constantly seek methods of improving competitive advantage.

One such method is through component modularity. This can 15 help a company to reduce inventory levels and gain component economies of scale through its production processes. For most types mechanical seals, one of the most costly components in any given product assembly, is the seal 20 gland. Typically, in some high technology applications one seal gland is employed for each size of single seal and two glands are employed for each size of double (dual) seal formats. With over 30 standard seal sizes, in any given product range and at three two gland formats, 25 the companies gland inventory costs can be considerable.

A design which offers a modular seal gland for both a single seal gland and one of the glands used in the dual seals, is deemed to be advantageous.

It is deemed to be further advantageous if a maximum number of component configurations can be used for a minimum number of components.

This reduces the cost to supply a number of seal configurations. Figure 1, shows a cross sectional view of a conventional 5 prior art single cartridge mechanical seal.

Figure 2, shows a cross sectional view of a conventional prior art double cartridge mechanical seal.

10 Figure 3, shows a cross sectional view of a single cartridge mechanical seal of the invention.

Figure 4, shows a cross sectional view of a double cartridge mechanical seal of the invention.

Figure 5, shows an alternate single seal configuration showing by way of example only, a rotating pusher design.

Figure 6, shows an alternate single seal configuration 20 showing by way of example only, a rotating bellows design. Figure 7, shows an alternate single seal configuration showing by way of example only, a stationary bellows I.

25 design. À '.

Figure 8, shows an alternate dual seal configuration À.

showing by way of example only, a stationary pusher.

inboard and a stationary pusher outboard design.

30.,. À Figure 9, shows an alternate dual seal configuration À. À showing by way of example only, a stationary pusher inboard and a rotary bellows outboard design.

Figure 10, shows an alternate dual seal configuration showing by way of example only, a rotary pusher inboard and a rotary bellows outboard design.

5 Figure 11, shows an alternate dual seal configuration showing by way of example only, a rotary pusher inboard and a stationary pusher outboard design.

Figure 12, shows an alternate dual seal configuration 10 showing by way of example only, a rotary bellows inboard and a stationary pusher outboard design.

Figure 13, shows an alternate dual seal configuration showing by way of example only, a rotary bellows inboard 15 and a rotary bellows outboard design.

Figure 14, shows an alternate dual seal configuration showing by way of example only, a stationary bellows inboard and a stationary pusher outboard design.

Figure 15a shows an alternate dual seal configuration showing by way of example only, a modular outboard non-

contacting seal face design.

:'. a.

25 Figure 15b shows an axial end view on one of the non-..

contacting seal face design, which employs a hydrodynamic principle. À. À: Figure 15c shows an axial end view on an alternate non À.. 30 contacting seal face design, which employs a hydrostatic..

principle. À. À Figure 16 shows an alternate dual seal configuration showing by way of example only, a tandem design with a

modular set of inboard and outboard non-contacting seal faces. Figure 17 shows an alternate dual seal configuration 5 showing by way of example only, showing a back to back design with a modular set of inboard and outboard non-

contacting seal faces.

An experienced person in the art of engineering 10 production would recognise that the individual prior-art designs, shown in Figures 1 and 2 require at least three gland members, one for the single seal and two for the dual seal.

15 From Figure-3, of the invention, the stationary and axially floating seal face (1) is spring biased towards an axially static rotary seal face (2). The rotary seal face (2) is allowed to slide on the stationary seal face (1). The interface between the rotary seal face (2) and 20 stationary seal face (1) forms sealing area (3). This sealing area (3) is the primary seal that prevents the process media (4) from escaping from the process chamber (5). :e 25 In addition to the sliding seal face (3), the process media (4) is sealed by a sleeve elastomer (6) in contact with the shaft (7) and sleeve (3). This has been termed À..

the first secondary sealing area (9).: I. À.. 30 The second secondary sealing area (10) is formed between À stationary seal face (2) and stationary gland (11) using I. elastomer (12).

The third secondary sealing area ( 13) is formed between the rotary seal face (1) and the sleeve (8) using elastomer (14).

5 The fourth secondary sealing area ( 15) is formed between the gland (11) and the process chamber (5) using elastomer (16).

The four secondary sealing devices and the primary 10 sliding sealing interface prevent the process media (4) from escaping.

A clamp ring (17) contains screws (18) which secure to the shaft (7) and transmit rotational drive from the 15 shaft (7) into the clamp ring (17) and sleeve (8). Said rotational drive is transmitted to the rotary seal face by at least one drive mechanism (19).

Bush (20), Bush retaining plate (21), gland insert (22) 20 and spring plate (23) are further components of the assembly. Figure 5 corresponds to Figure 3, but shows a rotating pusher (30) assembly. Rotating pusher holder (31) is 25 spring energises the seal face (2) to axially contact the stationary seal face (32). The experienced reader will note that stationary seal face (32) fits into the same cavity in gland (11) as did gland insert (22) from Figure 3. This design feature of the invention is of Àe 30 considerable benefit since one common gland can À..

accommodate more that one stationary member design. From À..

Figure 5, Stationary seal face (32) is mechanically held in place by flow ring (34) and circlip (35).

Again, from Figure 5, the interface between rotating seal face (2) and stationary seal face (32) forms sealing surface (33) which prevents the process media (4) from escaping. s It will be noted that Figure 5 contains many modular components to that of Figure 3, yet two very different single seal configurations have resulted. Said modular components include the rotary seal face (1), gland (11), 10 clamp ring (17), Bush (20), and Bush retaining plate (21). Deflector (24) is an optional component and may or may not be included in the seal assembly as the application dictates.

15 Figure 6 also corresponds to Figure 3, but shows a rotating metal bellows (40) assembly. The rotating metal bellows (40) is spring energises the seal face (41) to axially contact the stationary seal face (1). This forms sealing surface (43) which prevents the process media (4) 20 from escaping. It will be noted that Figure 6 contains many modular components to that of Figure 3, yet two very different single seal configurations have resulted. Said modular components include the stationary seal face (1), gland (11), clamp ring (17) Bush (20), and Bush retaining.,..

25 plate (21)..

À À. Figure 7 also corresponds to Figure 3, but shows aA.

stationary metal bellows (40) assembly. The stationaryA.

À. metal bellows assembly (40) is the same metal bellows 30 assembly used in Figure 6, however, in the case of FigureÀ 7, it is stationary mounted. À A This stationary metal bellows assembly (40) spring energises the seal face (41) to axially contact the 35 rotary seal face (50). This forms sealing surface (51)

which prevents the process media (4) from escaping. It will be noted that Figure 7 contains many modular components to that of Figure 6, yet two very different single seal configurations have resulted. Said modular 5 components include the metal bellows assembly (40), gland (11), Bush (20), and Bush retaining plate (21).

Figures 3, 5, 6 and 7 show four very different seal designs all utilising modular components. Each design, 10 Stationary Pusher (Figure 3), rotary pusher (Figure 4), Rotating bellows (Figure 6) and Stationary bellows (Figure 7) essentially all use the same modular gland (11). The seal designs shown are typically used in high duty 15 applications where gland castings are not permissible.

As such each and every gland (11) must be made from solid material. This means that it is very expensive to supply many different seal configurations, as detailed by 20 exacting internationally recognized specifications such

as API682 version 2 (Rotating equipment).

One modular gland is therefore of considerable benefit to any supply and customer company... À.

25 À. Figure-4 shows the dual seal version of the invention.

Once again, like Figure 3, the stationary and axially...

floating seal face (1) is spring biased towards an I.

À. - axially static rotary seal face (2). The rotary seal face 30 (2) is allowed to slide on the stationary seal face (1). À The interface between the rotary seal face (2) and À I stationary seal face (1) forms sealing area (3). This sealing area (3) is the primary seal that prevents the process media (4) from escaping from the process chamber

(5). The other secondary sealing points remain identical in concept to Figure-3.

It will be noted that many modular components, from 5 Figure 3 single seal, have been utilised in Figure 4 dual seal. These include the seal gland (ll), rotary (2) and stationary (l) seal faces, gland insert (22), drive mechanism (l9), spring plate (23), deflector (24), clamp ring (17) and elastomers (12), (14), (16) and (25).

10 Towards the outboard side of the seal, the outboard rotary and axially static seal face (26) is the same seal face as the inboard rotary seal face (2).

The axially floating stationary seal face (27) is spring 15 (28) biased towards the axially static rotary seal face (26). The rotary seal face (26) is allowed to slide on the static seal face (27). The interface between the rotary seal face (26) and stationary seal face (27) forms sealing area (29). This sealing area (29) is the primary 20 seal that prevents the barrier media (100) from escaping from the barrier chamber (lOl). The barrier media (100) is sealed at the inboard side of the assembly, by sealing area ( 3).

25 Dual seal gland (103) is attached to gland (ll) and sealed using static oring (104). Angled defector (106) is used with pumping scroll (105) to create fluid flow inA.

the barrier chamber (lOl). Sleeve (107) transmitsA.

rotational drive to both sets of rotary seal faces (2) 30 and (26) using drive mechanism (l9) which is also modularÀ for the inboard and outboard seal faces.À A. It will become apparent from Figure-3 and Figure-4, that a common, modular gland (ll) is employed for both 35 assemblies. This is of considerable benefit.

The experienced reader will note that due to the considerable modularity, Figure 8 is a combination of Figure 5 (inboard) with a rotating bellows assembly (60) 5 spring energised onto a modular stationary (27) used from Figure 4.

Again many other components are modular to Figure 4 also.

These especially include the dual seal gland (103).

Again the experienced reader will note that due to the considerable modularity, Figure 9 is a combination of Figure 4 (inboard) and Figure 8 outboard.

15 This seal assembly is created by using no additional components to what haven't already been described / shown previously. Figure 10 corresponds to Figure 8 and shows an alternate 20 inboard stationary seal face (70) employed in a dual seal operation yet entirely modular to Figure 6. Again resulting in an alternative dual seal arrangement created by using no additional components to what haven't already been described / shown previously...

À À 25À. Figure 11 corresponds to Figure 10 inboard and Figure 4 outboard. Again resulting in an alternative dual seal...

arrangement created by using no additional components to,..

À. - what haven't already been described / shown previously.

À.. Figure 12 illustrates yet another seal configuration and À I. is a combination of outboard Figure 4 and inboard Figure 6.

Figure 13 illustrates yet another seal configuration and is a combination of outboard Figure 9 and inboard Figure 12. 5 Figure 14 illustrates yet another seal configuration and is a combination of outboard Figure 4 and inboard Figure 7. It is clear that the design can be used with all types of 10 seal faces designs including contacting and non-

contacting designs.

Figure 15a shows an alternate dual seal configuration (80) showing by way of example only, a modular outboard 15 non-contacting seal face design.

From Figure 15a, the barrier chamber (81) is filled with a fluid, which, by way of example only, may be an inhert gas such as nitrogen. The outboard seal face assembly 20 (82) comprises of a stationary member (83) and a rotary member (84). At least one of the seal faces is axially biased to the other. Said axial biasing is shown as one or more spring like members (85). The sealing interface (86) is designed so that in either static and/or dynamic À À 25 operation, the barrier fluid acts to separate the seal.

faces (83) and (84) apart. Said method of face separation À À.

is very small however said separation allows the seal A.

faces to run cool during dynamic operation. I.

À - 30 Said method of seal face separation could be using À Hydrodynamic principles as shown in Figure 5b where one..

or more grooves in the axial end of one or more of the seal faces (83) and (84). Said groove is shaped to increase the pressure between the seal faces, hence push 35 them apart during dynamic operation.

Furthermore, it is considered that said method of seal face separation could be using Hydrostatic principles as shown in Figure 5c where one or more holes in the axial 5 end of one or more of the seal faces (83) and (84) is connected to the barrier chamber. Fluid, or preferably an inhert gas such as nitrogen, is passed through one or more holes in one or more seal faces (83) and (84) increases the pressure between the seal faces causing 10 them to be pushed apart slightly in both static and/or dynamic operation. It is considered obvious that said holes could connect into a full or partial groove in the axial face of one or more of the seal faces (83) and (84). Said groove would act to evenly distribute the 15 hydrostatic force acting to separate the seal faces (83) and (84).

The invention allows said modular non-contacting seal faces to be arranged in a number of physical 20 configurations. These are shown, by way of example, in Figures 16 and 17.

Figure 16 shows an alternate dual seal configuration showing by way of example only, a tandem design with a 25 modular set of inboard (90) and outboard (9l) non-

contacting seal faces.

Figure 17 shows an alternate dual seal configuration..

showing by way of example only, showing a back to back 30 design with a modular set of inboard (100) and outboard.

(101) non-contacting seal faces....: Àe he It is considered self evident to the experienced reader that the invention may be employed for both Rotary seals 35 and Stationary seals, single, double or triple mechanical

seals, metal or rubber bellows seal as well as pusher seals using contacting or non-contacting seal face technology, whether designed in a cartridge or component seal format.

It is also considered self evident that the invention may be used with metallic components as well as non-metallic components. Some types of equipment rotate the housing and have a stationary shaft. It is considered that the 10 invention can be similarly applied to such designs.

Equally, it is considered self evident that should non-

contacting seal faces be employed, the design can be employed for either hydrodynamic and/or hydrostatic seal 15 face technology, or to that matter, any combination of the two principles.

It can be seen by an experienced reader, that the modularity of the invention offers significant technical 20 and commercial advantage to the holder.

À. À À À. À..- À À Àe L ate À À. À Àer À À À

Claims (17)

CLAIMS:

1. A modular mechanical seal with a gland member, which is common too more than one generic seal format.

2. A modular mechanical seal according to claim l, where a common gland member is employed for both single and double seal formats.

10

3. A modular mechanical seal which can be configured into a multitude of arrangements and seal face orientations, from a minimum set of modular components.

4. A modular mechanical seal according to Claim 3,

15 which allows more than one set modular set of mechanical seal faces to be orientated in such a way that the spring biasing part of the seal faces assemblies may be oriented in a face to face, back to back or face to back orientation.

5. A modular mechanical seal gland, according to any preceding claim, which can accommodate more than one different shaped stationary seat member within the same gland cavity.. -.

. .

6. A modular mechanical seal gland, according to Claim 5, where one or more adapter members are employed to r adapt various stationary seats., .

30

7. A modular mechanical seal according to any preceding À '.' claim, which employs modular set of seal faces, said set. -I..

of seal faces which may be deployed and orientated in a number of ways within a common modular gland member.

8. A modular mechanical seal according to Claim 7, which employs contacting seal face technology.

9. A modular mechanical seal according to Claim 7, 5 which employs noncontacting seal face technology.

10. A modular mechanical seal according to Claim 9, which employs noncontacting seal face using hydrodynamic seal face separation techniques.

11. A modular mechanical seal according to Claim 9, which employs noncontacting seal face using hydrostatic seal face separation techniques.

15

12. A modular mechanical seal according to any preceding claim, which employs modular set of seal faces, said set of seal faces consists of one or more pusher type seals using at least one spring to axial bias one seal face to a corresponding seal face, said modular seal face may be 20 deployed and orientated in a number of ways within a common modular gland member.

-:

13. A modular mechanical seal according to any preceding À..

claim, which employs modular set of seal faces, said set 25 of seal faces consists of one or more metal bellows type..

seals which incorporate an integral spring like member to:.

axial bias one seal face to a corresponding seal face, said modular seal face may be deployed and orientated in..

a number of ways within a common modular gland member. À A

14. A modular mechanical seal according to any preceding claim which employs a combination of pusher and/or metal bellows seal faces, whether of a contacting or non-

contacting nature, or any combination of the above.

15. A mechanical seal according to any preceding claim and substantially as herein described.

16. A mechanical seal according to Figures 3 to

17.

À À À Àe À. À À À.- À.e À À À À . À À À À Àe