GB2193291A - Pipe support - Google Patents

Abstract

A constant tension pipe support has load attachment means and spring means connected in counterbalance to a pivoted lever 1 by connections of which at least one is adjustable such that the position of the connection can be moved transversely of the lever to vary the moment of the force applied to the lever at that connection. The moment adjustment may be made to compensate for a variation in the load exerted on the lever 1 by a supported pipe, or by the spring means, and may be made whilst the pipe support is in use. The preferred embodiment has the adjustable connection provided by a pin 22 associated with the load attachment or spring means engaged in registering portions of mutually inclined slots 13, 17 at the lever and in an adjuster 14 movable along the lever by a screw 19 to vary the position transversely of the lever at which the slot portions register. <IMAGE>

Description

SPECIFICATION Pipe supports This invention relates to pipe supports of the constant tension kind used to support pipes subject to movement in use, for example caused by thermal expansion and contraction, and comprising a frame, a lever pivoted to the frame, load attachment means by which in use of the pipe support a load is supported by the lever at a position spaced from the pivot, and spring means which acts between the frame and the lever at a position spaced from the pivot such that the moment of the spring means about the pivot counterbalances the moment of the supported load about the pivot. Such pipe supports are hereinafter referred to as "of the kind described".

Pipe supports of the kind described are intended to return the pipes they support to their original supported positions when they have deviated from those positions, as for example as a result of thermal expansion or contraction. This may not always happen in practice because a pipe may become so distorted that it cannot be returned to its original supported position. The effect of this is commonly that the load moment about the pivot is increased which increases the strain on the counterbalancing spring means, and may result in unsatisfactory support for the pipe. Distortion of a pipe can in some instances reduce the load moment.

Deviation of the spring means of a pipe support from a mean specification or from an initial rating can also occur.

According to the present invention a pipe support of the kind described is provided in which at least one of the connections of the load attachment means and the spring means to the lever is adjustable such that the position of the connection can be moved transversely of the lever to vary the perpendicular distance from the pivot of the lever to the line of action of a force applied to the lever at the connection.

Adjustment of the connection is preferably such that from a normal position for use of the pipe support the connection may be moved to either side of that position, and movement to one side increases the said perpendicular distance whilst movement to the other side reduces the distance. A boost or reduction in the moment on the lever may therefore be provided as appropriate to compensate for a variation in the force exerted on the lever by a supported pipe or by the spring means.

The position of the connection may be infinitely adjustable between extreme positions to which the connection may be moved transversely of the lever. In a preferred em bodiment of the invention this infinite adjustment is achieved by having a pin of the load attachment means or spring means, as the case may be, engaged in and located on the lever at registering portions of mutually inclined slots in the lever and in an element which is movable along the lever by screw means to vary the position transversely of the lever at which there are portions of the slots in register. There may alternatively be a plurality of set locations on the lever at which the connection may be made selectively to the lever to vary the said perpendicular distance.

Typically the adjustment of the position of the connection will be arranged to provide up to 20% variation in the moment, usually 10% above and 10% below the normal operating moment, but higher or lower ranges of variation may be provided for, as required. A scale on the lever preferably indicates the variation resulting from any adjustment of the position of the connection.

An embodiment of the invention will now be described by way of example only with reference to the accompanying drawings in which: Figure 1 is a simplified side view of a lever of a pipe support in accordance with the present invention, and Figure 2 is a section on line 2-2 of Fig. 1.

In the drawings only parts of the pipe support which are necessary for an understanding of the app#lication of the invention are shown.

The remainder of the pipe support may be of a known construction.

The pipe support comprises a frame by which the pipe support is located in position for use, a lever 1, in this embodiment a wideangled bell crank lever, having a spring arm 2 and a load arm 3 and pivotally mounted on the frame by a pivot 4, spring means supported by the frame and connected to the spring arm 2, and load attachment means 5 connected to the load arm 3 by which a pipe to be supported by the pipe support is attached to the lever. The spring means may typically comprise a helical compression spring operating in a housing fixed to the frame and bearing at one end on a fixed end wall of the housing and at the opposite end on a piston or plate connected to one end of a draw bar which extends co-axially through the spring and out of the housing, and is connected at its other end to the spring arm 2 on the central longitudinal axis of the arm.At the spring arm 2 the draw bar may be connected by a pin to a block, clevis or other suitable element which is adjustable longitudinally of the spring arm in a known manner by an adjusting screw 6 for altering the position along the central longitudinal axis of the spring arm at which the draw bar is connected as required for use.

The load attachment means 5 will usually include a turnbuckle for making adjustments to suit the distance at which a pipe is to be supported from the lever in use.

In this embodiment the lever 1 comprises a pair of parallel, spaced channel-section members 7 disposed with their open sides facing.

The pivot 4 extends between the two channel members 7 and is located at its ends centrally in the webs 8 of the members. At the outer end of the load arm 3 the channel-section members 7 are connected by a U-shaped bridge member 9 located in the channels of the members and secured to the webs 8 by screws 10. A similar bridge member, not shown, connects the channel-section member 7 at the outer end of the spring arm 2, being threadedly engaged by the adjusting screw 6.

At a selected intermediate position along the load arm 3 of the lever two plates 11 are fixed opposite one another by screws 12, one against the web 8 of each channel-section member 7. The plates 11 may be fixed at a plurality of positions along the load arm.

There is a closed-ended slot 13 in each plate and the slots of the two plates are of similar lengths and similarly inclined relative to a central plane P perpendicular to the webs 8 of the channel-section members and containing the central longitudinal axis of the load arm.

Slidable along the load arm between the two plates 11 is a U-shaped adjuster 14 which runs on the side flanges 15 of the channel-section member 7. Side limbs 16 of the adjuster 14 are parallel to and are respectively closely adjacent to the plates 11.

Closed-ended slots 17 in the side limbs 16 extend at right angles to and respectively overlap the slots 13 in the adjacent plates so that portions of the two sets of slots are in register. A web portion 18 of the adjuster 14 has a screw-threaded rod 19 rigidly secured centrally to it which extends to the outer end of the load arm and out through a plain bore hole 20 in the bridge member 9, behind which a nut 21 is fitted on the rod. By turning the nut the adjuster is moved longitudinally along the load arm. As the adjuster is so moved the portions of the slots 17 in its side limbs 16 and the slots 13 in the plates 11 which are in register vary.

A support pin 22 which connects the load attachment means 5 to the load arm extends between the side limbs 16 of the adjusting element 14 and is located at its ends in the registering portions of the slots 13 and 17.

The position at which the support pin is located transversely of the load arm is caused to be altered as the adjuster is adjusted and the portions of slots in register varied. The position can be altered from a normal one at which the support pin will usually be set initially for use in which its central axis is in the aforementioned central plane P of the load arm, to positions at differing distances to either side of that plane.

The slots 13 of the plates 11 are so inclined that in the attitude of the lever which it is normally to assume in use they extend substantially vertically, and thus the slots 17 of the adjuster extend substantially horizontally.

An indicator 23 carried by the rod 18 moves with the adjuster 14 along the load arm and it indicates on a scale 24, fixed on the outside of the load arm, percentage increases or reductions in the load moment about the pivot 4 according to the position of the adjuster.

The use of the adjuster 14 and its effect will now be described. For normal operation the adjuster is set such that the support pin 22 is located with its central longitudinal axis in the central plane P of the load arm. In that position the central portions of the respective slots are in register. The load moment about the pivot 4 of the lever resulting from the load of the pipe supported at the load arm by the support pin 22 is equal and opposite to the moment of the spring acting on the spring arm 2 of the lever about the pivot 4.As initially set for use and the lever occupying an initial angular position about the pivot, for example as indicated at A in Fig. 1, the moments may be expressed as: WxR1 =Sxr1 where, as indicated in Fig. 1: W =pipe load R1 = perpendicular distance (from pivot to line of action of pipe load) S =spring load r1 =perpendicular distance (from pivot to line of action of spring load) Under the normally expected range of movement of the supported pipe the lever may turn from position A to a maximum load applied angular position B, for example, and the moment may then be expressed as: WxR2=Sxr2.

Fine adjustment of the moments may be made at the spring arm by altering the position of the connection of the draw bar along the spring arm by means of the adjusting screw 6.

In the event of excessive movement of the supported pipe to the extent that it becomes distorted and cannot return to its initial supported position, so increasing the load on the load arm and increasing the counterbalancing strain on the spring, the adjuster may be adjusted to reduce the effect of the load. This may be done at any angular position of the lever and regardless of where the connection of the draw bar to the spring arm may be positioned along the spring arm; in other words the adjustment provided by the adjuster and the normal load adjustment available at the lever are in direct percentage relationship.

To reduce the effect of an increased load the adjuster is moved, by means of the nut 21, along the load arm towards the pivot pin 4 to a boost position. In doing that portions of the slots 13 and 17 below the central plane P of the load arm are brought into register and so the support pin 22 is located by the slots below that plane and the perpendicular distance from the pivot pin 4 to the line of action of the pipe load is reduced.When the lever is in maximum position B the moment may then be expressed as: W+ xR2-=S > cr2 where W+=increased pipe load R2- reduced perpendicular distance It will be realised that a similar adjustment may be made to reduce the load moment about the pivot pin in order to compensate for weakening of the spring during use, or if the initial rating of the spring is found to be below a required specification.

Should there be movement of the supported pipe which reduces the load it exerts on the load arm, or the rating of the spring is above a required specification, the adjuster may be adjusted to compensate for that by moving it along the load arm away from the pivot so th t the position at which the support pin is loCated by the slots 13 and 17 is moved above the central plane P of the load arm, thereby increasing the perpendicular distance from the pivot to the line of action of the pipe load. When the lever is in the maximum position B the moment may thus be expressed as: W-xR2+=Sxr2 where W-=reduced pipe load R2+ = increased perpendicular distance The adjustments may be made by means of the adjuster whilst the pipe support remains in operation.

An adjuster similar to that described may be provided at the spring arm.

Claims (16)

1. A pipe support of the kind described in which at least one of the connections of the load attachment means and the spring means to the lever is adjustable such that the position of the connection can be moved transversely of the lever to vary the perpendi cular distance from the pivot of the lever to the line of action of a force applied to the lever at the connection.

2. A pipe support according to claim 1 wherein the connection is adjustable transversely of the lever to either side of a normal position on the lever for use of the pipe support, movement of the connection to one side increasing the said perpendicular distance and movement thereof to the other side reducing the said perpendicular distance respectively to boost or reduce the moment on the lever to compensate for variation in the force applied to the lever.

3. A pipe support according to claim 1 or claim 2 wherein the connection is made by a connecting part associated with the load attachment means or spring means, as the case may be, and means on the lever providing a location for the connecting part and being adjustable to vary the position of the location transversely of the lever.

4. A pipe support according to claim 3 wherein the connecting part comprises a pin, and the means on the lever providing the location are registering portions of mutually inclined slots at the lever and in an element movable along the lever to vary the position transversely of the lever at which portions of the slots are in register.

5. A pipe support according to claim 4 wherein screw means acts between the lever and the element and is operable to cause the element to be moved along the lever.

6. A pipe support according to claim 4 or claim 5 wherein opposed plates are mounted on the lever and have registering similarly disposed slots therein with which the pin engages, and the element is movable along the lever between the opposed plates.

7. A pipe support according to claim 6 wherein the lever and plates have interconnecting means whereby the plates can be fixed at a plurality of positions along the lever.

8. A pipe support according to claim 6 or claim 7 as dependent from claim 5 wherein the element is U-shaped having opposed limbs joined by a web, the opposed limbs respectively being disposed adjacent to the plates and formed with registering similarly disposed slots inclined relative to the slots in the plates through which the pin extends into engagement with the slots in the plates, and the web having a screw-threaded rod fixed to it which extends longitudinally of the lever, through a fixed part of the lever and is fitted with a nut which reacts on the fixed part and when rotated on the screw-threaded rod causes the rod, and thereby the element, to move along the lever to vary the position transversely of the lever at which portions of the slots in the plates and lever are in register for location of the pin.

9. A pipe support according to any of claims 4 to 8 wherein the lever comprises connected parallel channel-section members disposed with their open sides facing, and the element is accommodated between, and is guided in its movement along the lever by, the channel-section members.

10. A pipe support according to any of claims 4 to 9 wherein the slots at the lever and the element are so disposed that in the attitude of the lever which it is normally to assume in use they are respectively disposed substantially vertically and substantially horizontally.

11. A pipe support according to claim 1 or claim 2 wherein there is a plurality of set loca tions on the lever at which the connection may be made selectively to the lever to vary the said perpendicular distance.

12. A pipe support according to any preceding claim wherein a scale is provided on the lever which indicates the variation in the moment on the lever resulting from any adjustment of the position of the connection.

13. A pipe support according to claim 12 as dependent from claim 8 wherein the scale is fixed on the lever and is marked with percentage variations in the moment from a normal operating moment, and an indicator is carried by the screw-threaded rod and moves with the element to indicate on the scale the percentage variation in moment resulting from any adjustment of the position of the connection.

14. A pipe support according to any preceding claim wherein the transversely adjustable connection is of the load attachment means to the lever, and the spring means acts on the lever at a connection which is adjustable longitudinally of the lever to vary the distance of that connection from the pivot and thereby adjust the moment of the spring means on the lever.

15. A pipe support according to claim 14 wherein the transversely adjustable connection is adjustable at any position of the longitudinally adjustable connection along the lever, and the moment variation provided by adjustment of the transversely adjustable connection is in direct percentage relationship to the moment resulting from any adjustment of the longitudinally adjustable connection.

16. A pipe support of the kind described substantially as described herein with reference to the accompanying drawings.