GB2270342A

GB2270342A - Manlid for a container tank

Info

Publication number: GB2270342A
Application number: GB9216498A
Authority: GB
Inventors: Edward Sagar Fort
Original assignee: Fort Valve Engineering Ltd
Current assignee: Fort Valve Engineering Ltd
Priority date: 1992-08-03
Filing date: 1992-08-03
Publication date: 1994-03-09
Anticipated expiration: 2012-08-03
Also published as: GB9512998D0; GB2270342B; GB9216498D0; GB2289718B; GB2289718A

Abstract

A securing assembly for a container tank manlid has a threaded bolt 26 rotatably mounted on the manlid 10. A hand nut 56 is threadedly mounted on the bolt and is engageable with the upper surface of the manlid. The bolt has an enlarged head portion 64 and a spring 66 biasses the bolt in the direction of the head portion. The container tank is provided with a slot 66 which allows passage of the bolt when the head 64 is aligned with the slot, and which prevents passage of the bolt when the head is not aligned with the slot. The manlid is mounted on a pivot which is in turn mounted on a hinge assembly secured to the container tank. The locus of the pivot pin 44 is substantially linear, and thus the enlarged heads 64 of the bolts 26 may pass through their associated slots 66 on the container tank without fouling thereon. <IMAGE>

Description

DESCRIPTION MANLID FOR A CONTAINER TANK The present invention relates to manlids for container tanks.

A manlid for a pressurised container tank typically comprises a domed metal lid which is hingedly attached to the pressure vessel. The manlid is typically held in position by means of a plurality of swing bolts. Such swing bolts are screw-threaded and carry a threaded hand nut thereon. The lid is provided with a plurality of slots in its periphery and each bolt is pivotally mounted on the pressure vessel, whereby it can be pivoted into a slot in the closed manlid and secured in position byeans of tightening the hand nut until it abuts the surface of the lid. Releasing the lid involves unscrewing each hand nut and pivoting the bolts out of the slots in the lid, whereupon the lid can be pivoted open.

It is an object of the present invention to provide an alternative securing arrangement for a manlid, in which the securing device is located on the manlid rather than on the pressure vessel.

In accordance with a first aspect of the present invention, a securing assembly for a container tank manlid comprises a bolt rotatably mounted on the manlid having a threaded shank and a nut member threaded thereon by means of which the bolt is axially displaceable, the bolt further comprising an enlarged head portion and biasing means which bias the bolt in the direction of the head portion, the container tank comprising a slot which allows passage of the bolt when the enlarged head is aligned with the slot and which prevents passage of the bolt when the enlarged head is not aligned with the slot.

Preferably, after the enlarged head has passed through the slot the bolt may be rotated to engage the head with a portion of the pressure vessel in order to prevent axial movement of the bolt. Advantageously, there is a plurality of securing assemblies in accordance with the present invention.

In one embodiment the enlarged head of the bolt is generally T-shaped. The biasing means may comprise a spring extending between the lid and the bolt head.

The nut member preferably comprises a hand nut.

The above securing assembly enables a manlid to be fitted to an existing container tank with only minimal alteration to the container tank.

However, in view of the fact that one or more bolt heads have to pass through associated slots in the pressure vessel, it is important that the manlid be displaceable upwardly in order to disengage the bolts from the slots, in order to permit hingeing of the manlid.

Thus, in accordance with a second aspect of the present invention, a manlid for a container tank comprises a pivot upon which it is pivotally mounted, the pivot being mounted on a hinge assembly secured to the container tank, whereby the locus of the pivot pin is substantially linear.

In this way, if the manlid is provided with one or more securing assemblies in accordance with the first aspect of the present invention, the enlarged heads of the bolts may pass through their associated slots on the container tank without fouling thereon.

In one embodiment, the locus of the pivot upon which the manlid is mounted is substantially vertical.

Preferably the hinge assembly is spring-biassed in order to bias the manlid into a preferred, e.g.

open condition.

Preferably, the hinge assembly comprises a parallelogram linkage.

The present invention also includes a manlid for a container tank as aforesaid, fitted with one or more securing assemblies as aforesaid, together with a container tank fitted with a manlid in accordance with the present invention.

By way of example only, a specific embodiment of the present invention will now be described, with reference to the accompanying drawings, in which; Fig.1 is a plan view of an embodiment of manlid for a container tank, in accordance with the present invention; Fig.2 is a cross-sectional side view through the manlid of Fig.1; Fig.3 is a cross-sectional side view through a lid securing bolt used in the manlid of Fig.l, in a locking position; and Fig.4 is a cross-sectional side view through the bolt of Fig.4, in an unlocked position.

Referring firstly to Figs. 1 and 2, a manlid 10 for a container tank 12 comprises a circular domed central portion 14 and a peripheral annular sealing and securing rim 16. The rim 16 is provided with a downwardly open annular seal retaining groove 18 which receives an annular seal 20. The seal is shaped and positioned to abut an upwardly depending annular rim 22 located on the upper end of the container tank 12 when the manlid is in its closed position. The manlid is hingedly attached to the container tank 12 by means of a hinge assembly 24 and may be held in a closed position on the container tank by means of seven securing bolts 26 arranged around the periphery of the manlid.

The hinge assembly is in general terms a biased parallelogram hinge mechanism which is adapted to enable the manlid to be displaced generally vertically upwardly in order to disengage the securing bolts 26 and to enable the lid then to be pivoted to an open position to provide access to the interior of the container tank.

The hinge assembly comprises two parallel planar flanges 28 welded to, and extending from the upper end of the container tank. The planar flanges are provided with upper and lower fixed pivot pins 30,32 extending between the two flanges and secured thereto.

Two L-shaped levers 34 are pivotally mounted at their apexes to the upper fixed pivot 30. Two parallel biasing levers 36 are pivotally mounted at one end to the lower fixed pivot 32 and the opposite ends of the biasing levers are pivotally connected by means of pivot pin 38 to one end of a respective one of two parallel cranked levers 40. A torsion spring 41 located around the pivot 32 bears upon the pivot pin 38 to provide a biassing force.

The opposite ends of the cranked levers 40 are pivotally connected to one end of a respective one of the L-shaped levers 34 and to one end of a respective one of two parallel lid mounting levers 42, the opposite ends of the lid mounting lever being pivotally connected to the lid by means of a pivot pin 44. The lid is thus pivotally connected to the lid mounting levers 42, whose opposite end is pivotally connected to the L-shaped lever 34 and the cranked lever 40.

The positions of the components of the hinge assembly when the lid is in its closed position are illustrated in full lines in Fig.2. The positions of the hinge assembly components when the lid is in its open position are illustrated in dotted lines in Fig.2. It will be appreciated that the torsion spring 41 provides a biasing force which urges the hinge assembly from the position shown in full lines to the position shown in dotted lines, via the levers 36, 40 and 34. The movement of the pivot pin 44 provided by the hinge assembly, upon which the lid is hinged, is essentially vertical for most of its path, which is important for disengaging the securing bolts 26, as will be explained.

As best shown in Figs. 2, 3 and 4, the securing bolts comprise a cylindrical shank 48. The upper end of the shank is screw-threaded and passes through an aperture 50 in the peripheral rim. The aperture 50 is provided with a shoulder 52 for mounting of a compression spring 54, to be explained more fully later. A hand nut 56 is threadedly mounted on the threaded portion of the shank and comprises a body 58 with a complementarily-threaded through aperture and a handle 60 projecting from the body. The hand nut is retained on the shank by means of a retaining washer 62 secured to the upper end of the shank.

The lower end of the shank is provided with an enlarged T-shaped head 64. When the head 64 is suitably aligned (with the axis of the head approximately radial with respect to the vessel, as illustrated in Fig.4), the shank 48 and the head 64 may pass through an associated slot 66 formed in an annular securing rim 68 located on the exterior surface of the vessel. The maximum clockwise rotation of the head 64 is restricted by means of two lugs 70,72.

The bolt is biased downwardly by means of the compression spring 54, which bears on the upper surface of the head 64 and also upon a bearing washer 74 located on the shoulder 52.

The bolt assembly has been described with reference to one bolt only. However, it should be appreciated that the other six bolt assemblies are identical to the assembly described above.

The manlid illustrated in Fig.2 is shown with the bolt assemblies in their locked positions, i.e. with the upper faces of the bolt heads 64 located in a recess 69 in the undersurface of the annular securing rim 68. In order to unlock the lid, the following procedure is adopted. Firstly, each hand nut 56 is rotated anticlockwise. As rotation of the hand nut 56 occurs, the spring 54 displaces the bolt and its head 64 downwardly, out of engagement with the recess 69.

As the hand nut is rotated anticlockwise to its fullest extent it engages the retaining washer 62, whereupon further rotation of the hand nut 56 also causes the bolt to rotate, out of engagement with the lugs 70,72, such that the axis of the head extends radially with respect to the vessel and is aligned with the seat.

The lugs 70,72 thereafter prevent any further anticlockwise movement of the bolt. This procedure is repeated for each of the other six bolt assemblies.

For some of the bolt assemblies, it will be necessary to compress the hinge assembly 24, since if the lid 10 is held on the vessel by only a few bolts, the spring 41 of the hinge assembly tends to displace the lid 10 slightly upwardly, thereby increasing the frictional forces within the bolt assembly.

When all of the bolt assembles have been adjusted to their unlocked positions (as illustrated in Fig.4), the lid is then allowed to rise. As explained previously, the spring 41 of the hinge assembly biases the hinge assembly towards an unlocked position, shown in chain dot in Fig.2. Thus, when the bolts no longer secure the lid shut, the hinge assembly causes the lid to rise. As described previously, the parallelogram linkage causes the motion of the lid to be approximately vertical, at least for a substantial portion of its travel (e.g.

for approximately 2.75 inches or 7 cm). This vertical motion is important, since there is not a great deal of play between the heads 64 of the bolts and the slots 66, and any significant non-vertical movement of the lid 10 would cause fouling of the heads in the slots and would thus interfere with the action of the lid release. Once the bolts are free of the slots, the lid may then be pivoted to any position about the pivot pin 44. The maximum opening position of the lid is limited by a pin 76 extending between the upper ends of the L-shaped levers 34.

In order to close the opened lid, the lid is pivoted back about the pivot pin 44. The lid is then lowered onto the neck of the vessel, and any bolts whose heads are not aligned with the slots 66 are rotated anticlockwise using the hand nut 56 which at that stage abuts the retaining washer 62. The lid is then forced downwardly such that the bolt heads 64 pass through the slots. It may be necessary at this stage to compress the hinge assembly 24 as before. As for unlocking the lid, the motion of the lid during closing is substantially vertical, so that the bolt heads pass easily through the slots 66. The hand nuts 56 are then tightened, the friction between the hand nuts and the threaded shanks 48 being sufficient to rotate the bolts clockwise until the heads 64 engage the lugs 70,72 and are located in the recesses 69 in the undersurface of the securing ring 68.

Claims

1. A securing assembly for a tank manlid comprising a bolt rotatably mounted on the manlid having a threaded shank and a nut member threaded thereon by means of which the bolt is axially displaceable, the bolt further comprising an enlarged head portion and biassing means which bias the bolt in the direction of the head portion, the tank comprising a slot which allows passage of the bolt in the longitudinal direction thereof when the enlarged head is aligned with the slot, and which prevents passage of the bolt in the longitudinal direction thereof when the enlarged head is not aligned with the slot.

2. A securing assembly as claimed in claim 1, wherein the biassing means comprises a spring.

3. A securing assembly as claimed in claim 2, wherein the spring is a compression spring and extends between the manlid and a portion of the bolt.

4. A securing assembly as claimed in any of the preceding claims, wherein after the enlarged head has passed through the slot, the bolt is rotatable to engage the head with a portion of the pressure vessel in order to restrict axial movement of the bolt.

5. A securing assembly as claimed in any of the preceding claims, wherein the nut member, in use, is located on the opposite side of the manlid from the enlarged head portion.

6. A securing member as claimed in claim 5, wherein the nut member abuts the manlid when the securing assembly is in a securing condition.

7. A securing assembly as claimed in claim 5 or claim 6, wherein the nut member comprises a hand nut.

8. A securing assembly as claimed in any of the preceding claims, wherein the enlarged head of the bolt is generally T-shaped.

9. A tank manlid comprising a securing assembly as claimed in any of the preceding claims.

10. A manlid as claimed in claim 1, further comprising a pivot pin which, in use, the manlid is pivotally mounted, the pivot being mounted on a hinge assembly secured to a tank, whereby the locus of movement of the pivot pin is substantially linear.

11. A manlid as claimed in claim 10, wherein the locus of the pivot upon which the manlid is mounted is substantially vertical.

12. A manlid as claimed in claim 10 or claim 11, wherein the hinge assembly comprises a parallelogram linkage.

13. A manlid as claimed in any of claims 10 to 12, wherein the hinge assembly is spring-biassed to bias the manlid into a preferred condition.

14. A manlid as comprising a plurality of securing assemblies as claimed in any of claims 1 to 8.

15. A manlid for a tank, comprising a pivot upon which the manlid is pivotally mounted, the pivot being mounted on a hinge assembly secured to the tank, whereby the locus of the pivot pin is substantially linear.

16. A manlid as claimed in claim 15, wherein the locus of the pivot upon which the manlid is mounted is substantially vertical.

17. A manlid as claimed in claim 15 or claim 16, wherein the hinge assembly comprises a parallelogram linkage.

18. A manlid as claimed in any of claims 15 to 17, wherein the hinge assembly is spring-biassed in order to bias the manlid into a preferred condition.

19. A securing assembly for a tank manlid substantially as herein described, with reference to, and as illustrated in, the accompanying drawings.

20. A manlid for a tank substantially as herein described, with reference to, and as illustrated in, the accompanying drawings.