This application claims priority to US 62/680,801 filed June 5, 2018, the content of which is incorporated by reference herein.

BACKGROUND

This disclosure is in the field of pipeline and vessel closures like those used, for example, to provide access to a pig trap during launch and recovery operations.

By way of example, a pig trap includes a collar adapted to be attached to an end of a pipe, a door for opening and closing the end of the pipe, means for holding the door to the collar, and means for sealing the door to the collar when the door is held to the collar. The holding means may include segmented plates that expand inside the collar barrel or clamps that hold the door against the barrel. US 4,237,936 to Lollis etal. provides an example of a closure that makes use of clamps. SUMMARY

Embodiments of a closure for a cylindrical vessel includes at least one holding means configured to move the closure into a fully closed state, the holding means having a predetermined actuation force or torque to properly close the closure, the closure including one or both of the following failsafe failure detection features:

a mechanical fuse having a predetermined load failure force below that of a load failure force of at least one component of the holding means and above that of the predetermined actuation force or torque; or

a block sized to at least partially overlap a pressure warning lock hole of the closure door when the closure is not in the fully closed state and to fully expose the pressure warning lock hole when the closure is in the fully closed state. The holding means move between an unactuated or open position and an actuated or fully closed position. In embodiments, the holding means may include a pair of clamp rings arranged about a door of the closure so as to hold the door in a closed and sealed condition. The predetermined actuation force is above the weight of the clamp rings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of a prior art closure with holding means properly closing the closure in a fully closed state. The holding means include a handle with a linkage connected to clamp rings.

FIG. 2 is the prior art closure of FIG. 1, illustrating blockage or debris in a bottom portion of the closure prior to actuation of the holding means. None of the pins“P” that hold the closure together are designed as a weak link.

FIG. 3 is an isometric view of an embodiment of a closure of this disclosure including a mechanical fuse capable of preventing a failure of at least one other component of the closure when there is blockage or debris or where excessive force is required to properly close the closure.

FIG. 4 is an enlarged cross section view of the mechanical fuse of FIG. 3.

FIG. 5 is a rear isometric view of a prior art closure and illustrating a pressure warning lock. It may be possible to install the pressure warning lock without the holding means being properly closed.

FIG. 6 is a rear isometric view of an embodiment of a closure of this disclosure including a block that prevents the pressure warning lock from being inserted when the closure is not in a fully closed state. The block may be a bracket sized to at least partially cover the pressure warning lock hole when the holding means have not been fully actuated to properly close the closure. The block is illustrated to show the interference with the pressure warning lock, which cannot be inserted into the pressure warning lock hole, until the closure is fully closed and the block clears the pressure warning lock hole.

FIG. 7 is an enlarged view of the block of FIG. 6.

FIG. 8 is a rear isometric view of an embodiment of a closure of this disclosure including a ratchet-style closing mechanism and a block. The block may include an extended plate that at least partially covers the pressure warning lock hole when the closure is not yet properly closed. The plate is illustrated to show the interference with the pressure warning lock.

FIG. 9 is an enlarged view of the block of FIG. 8.

DETAILED DESCRIPTION

Embodiments of a closure include a mechanical fuse, a pressure warning lock block, or a combination of the mechanical fuse and the pressure warning lock block. The embodiments may be adapted to a closure the same or similar to that as disclosed in US 4,237,936 to Lollis et al. or US 4,515,287 to Baudoux et al ., the contents of which are incorporated by reference herein.

Referring first to FIGS. 3 & 4, in embodiments of this disclosure a closure 10 includes at least one mechanical fuse 20 having a predetermined load failure force below that of a load failure force of at least one component of holding means 30 of the closure and above that of a force to provide a predetermined actuation force or torque to overcome the holding means 30. In some embodiments the mechanical fuse 20 includes a shear pin 21 or its equivalent. The holding means 30 may include one or more clamp rings 31. A handle 33 may be connected to the clamp rings 31 by corresponding lugs 35, at least one of which includes the mechanical fuse 20.

The load failure force of the mechanical fuse 20 is above the predetermined actuation force of the holding means 30 to properly close the closure 10 into a fully closed position but below that of load failure force of another component of the holding means 30. In embodiments, the other component may be a welded component such as, but not limited to, the lugs 35. The predetermined actuation force may be a force to overcome the weight of the holding means 30. The holding means 30 may include a pair of clamp rings 31, the predetermined actuation force being above a weight of the pair of clamp rings 31.

In embodiments, the mechanical fuse 20 may be located on a top end or portion 11 of the closure 10 so as to be visible to an operator. In some embodiments, the mechanical fuse 10 may be located on the top end 11 of the closure 10 in proximity to a pressure warning lock 17. Where the holding means 30 include clamp rings 31, a common pivot point 37 ( e.g . a pin or its equivalent) of the clamp rings 31 may be located toward a bottom end or portion 15 of the closure. When blockage or debris“B” in a bottom portion 15 of the closure 10 causes an increase in force to be applied to actuate the holding means 30 during closure (but still below the failure force of another component such as the common pivot point 37), the mechanical fuse 20 fails. The failed mechanical fuse 20 may be easily detectable and visible to an operator. The planned failure of the fuse 20 protects at least one other component of the closure from failing due to excessive force required to close the holding means 30.

Referring now to FIGS. 6 & 7, in embodiments of a closure 10 of this disclosure, a block 40 interferes with a pressure warning lock 17, thereby preventing insertion or installation of the lock 17 into the pressure warning lock hole 19 when the closure 10 is opened or not in a fully closed state. The block 40 may be sized so that when the closure 10 is in the fully closed state, the pressure warning lock 17 may be installed in the hole 19. The pressure warning lock 17 may include a pin 23. The holding means 30 may be actuated by a handle 33 or by a rachet-style closing mechanism 51 of a kind known in the art. See e.g. FIGS. 8 & 9. Referring now to FIGS. 8 & 9, in some embodiments the block 40 includes a bracket 41 connected to a linkage 37 of the holding means 30. In other embodiments, the block 40 includes at least one plate 43 that aligns the pressure warning lock 17 with the hole 19. The bracket 41 may include alignment means 39 for the pressure warning lock 17. Unlike prior art closures, the plate 43 is extended in length so that when the holding means 30 are opened or not fully closed, the plate 43 at least partially covers the pressure warning lock hole 19 and prevents the pressure warning lock 17 from being inserted into the hole 19. When the holding means 30 are fully actuated and the closure 10 is properly closed, the hole 19 is fully exposed. In some embodiments, holding means 30 includes one or more clamp rings 31.

While embodiments of the closure have been described, the closure may be modified without departing from the scope of the following claims. The claims are entitled to the full range of equivalents to which recited element is entitled.