JPH0351599A - Water stop construction for pipe body such as water supply pipe and water stopping fitting used therefor - Google Patents

Abstract

PURPOSE:To facilitate the repair work for a pipe body and secure the proper water sealing performance by inserting a water stopping fitting having an annular sealing body into a hole on the side wall of a water stop object pipe body and arranging the annular sealing body at a position inside the pipe body and press-attaching the annular sealing body onto the inner peripheral surface of the pipe body. CONSTITUTION:A hole 22 is drilled on the side wall of a water stop object pipe body 17, and a water stopping fitting 16 is inserted into the hole 22. As for the water stopping fitting 16, an annular sealing body 12 which can be spread and contract in the radial direction is installed in bending/revolution shiftable manners in the lateral direction at the top edge of a supporting rod 1. The annular sealing body 12 of the water stopping fitting 16 which is inserted into the pipe body 17 from the inside of the hole 22 is arranged at a position in the pipe body 17, and the annular sealing body 12 is spread in the radial direction and press-attached onto the inner peripheral surface of the pipe body 17. Therefore, the water stopping work and the repair work after the completion of stopping water can be facilitated. Further, the stop of water in the pipe body can be set into the nearly perfect state.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention is a water stopper for stopping water at an upstream position when repairing existing pipes such as water pipes or adding branch pipes. Concerning the construction method and the water stop equipment used for it.

(Prior Art) Conventionally, as this type of water stop construction method, there is a means shown in FIG. 8.

This conventional means involves cutting the existing pipe 17 as shown in the figure (a), inserting a water stopper 16e of a predetermined structure through the cut opening 4o, and then The annular seal body 12e of the water stop device 16e is expanded in the radial direction to stop water from the pipe body 178. Here, the water stopping device 16e rotates the movable shaft 42 screwed onto the fixed shaft 41 to reduce the distance between the pressure pieces 43, 43a on both the front and rear sides of the annular seal body 12e. 12e is configured to expand in its radial direction.

On the other hand, as other means other than the above, conventionally,
There are also those published in No. 336 or Japanese Patent Application Laid-open No. 186694/1983.

This means attaches the T-shaped outer cover tube 44 to the tube body +7f as shown in FIG. A valve body 46 equipped with an elastic sealing material 45 is then inserted into the tube body 17f from the hole 22 as shown in FIG. It is.

(Problems to be Solved by the Invention) However, in the former method shown in FIG. 8, the annular seal body 12e can be brought into pressure contact with the entire inner circumference of the pipe body 17e, and excellent water leakage properties can be obtained. However, in practical terms, the following problems have arisen.

That is, in the former method, in order to completely cut the tube 17e and insert the water stop device 16e from one end side of the cutting opening, the water stop device 16e is placed in the front position of the tube 17s. It is necessary to secure space for placement and operation. Therefore, when the pipe body 17B is buried underground, the excavation area of the ground must be made very large, which causes problems in workability.

In addition, with the means of completely cutting the pipe body 17e, in order to restore the pipe body to its original state after the construction is completed and there is no longer a need to stop the water in the pipe body, it is necessary to cut the pipe body 17e to another downstream side. Tube 1
It is necessary to connect it with 78'. Here, in order to connect both tube bodies, it is necessary to process threaded portions for connecting pipe joints to the ends of the tube bodies 17B and Tγe'. Therefore, repair work for the pipe body has become complicated and takes a long time.

Moreover, in the former method, a large amount of water leaks from the cutting opening 40 of the pipe during the period from cutting the pipe 17e to stopping water inside the pipe using the water stop device IBe. However, the reality is that no suitable means to solve this problem has been developed so far. Therefore, in the former method, not only is there a lot of water wasted due to water leakage, but also the work site is flooded with water, deteriorating the work environment, and a large amount of water is discharged from the water stopper 16e from the pipe opening 40. Another problem was that the workability of inserting the material into the inside of the material was also poor.

On the other hand, in the latter method shown in FIG. 9, since the hole 22 is bored in the outer circumferential wall surface of the tube body +7f, the hole 22 is formed as shown in the same figure.
By using the integral valve cover 23e for water leakage prevention during the drilling work and the insertion work of the valve body 46 in step 2, it is possible to prevent water from leaking from the hole 22 during the series of work, and also to reduce the excavated area of the ground. can be achieved.

However, with the latter means, simply pressing the valve body 46 against the inner circumferential surface of the tube is not sufficient to stop the water, and the opening position of the hole 22 must also be closed. The inner peripheral edges A, A of the opening are formed in a very sharp position as shown in FIG. Therefore, if the elastic sealing material 45 of the valve body 46 is brought into pressure contact with the sharp portion A, cracks will occur in the sealing material 45 and damage will occur, causing water to leak from the portion, making it impossible to ensure water stoppage. This caused problems that seemed to disappear.

Therefore, the present invention not only facilitates a series of water-stopping operations for existing pipe bodies, but also facilitates the subsequent repair work of the pipe bodies. The purpose is to ensure appropriate water-stop sealing performance without causing water-stop seal failure in the state, and to prevent undue water leakage.

(Means for Solving the Problems) The present invention improves the water-stopping device with excellent water-stopping properties employed in the former conventional means, and the water-stopping device is installed from the side of the cutting pipe body. This structure was designed to solve the above-mentioned conventional problems by inserting the tube into a position where good water stoppage can be achieved within the tube.

That is, firstly, in the present invention, after the hole 22 is bored in the side wall of the water stop target pipe body 17, the annular seal body 12, which can be expanded and contracted in the radial direction, is attached to the tip of the support rod 1. The water-stopping device 16, which is provided so as to be able to bend and rotate in a lateral direction different from the longitudinal direction, is inserted into the tube body 17 through the hole 22, and the annular seal body 12 of the water-stopping device 16 is inserted into the tube body 17 through the hole 22. 22
The annular seal body 12 of the water-stopping device 16 is expanded in the radial direction, and the annular seal body 12 of the water-stopping device 16 is expanded in the radial direction, and the inner circumferential surface of the tube body 17 is The water in the pipe body 17 is stopped by bringing it into pressure contact with the pipe body 17.
This is a water stop bead method for pipes such as water pipes.

Second, the present invention provides a water stop construction method having the above structure, in which the hole 22
Before carrying out the drilling work, an auxiliary pipe 18 consisting of a valved casing 23 equipped with a water stop valve 19 is installed in advance in the pipe body 1.
The hole 22 is drilled in the side wall of the tube body 17 using a punching tool 25 inserted into the valved casing 23 and the auxiliary tube 18. , and inserting the water stop device 16 into the pipe body 17 into the valved casing 23 and the auxiliary pipe 18.
This is a water-stopping construction method for pipe bodies such as water pipes, which is performed by inserting water pipes.

Thirdly, the present invention is a water stopping device for performing the above-mentioned first or second water stopping method, which is inserted into the pipe body 1γ to block water flow in the pipe body 17. In a water stop device for a pipe body such as a water pipe, in which an annular seal body 12 that can be expanded and contracted is provided at the distal end side of a support rod 1, the support rod 1 has an annular seal body 12 attached to the support rod 1. At least one or more portions on the distal end thereof are formed to be bendable so as to be able to bend and rotate in a lateral direction different from the longitudinal direction.
This is a water stop device for pipe bodies such as water pipes.

(Function) In the first and second structural water stop construction methods described above, the water stop equipment 1
6, the annular seal body 12 is provided so as to be able to bend and rotate in a lateral direction different from the longitudinal direction of the support rod 1. Annular seal body 1 of water stop device 16 inserted inside
2 can be bent and rotated within the tubular body 17 to be placed at a predetermined position inside the tubular body where the hole 22 is not bored, thereby making it possible to stop water in the tubular body 17.

Since the water stop device 16 is inserted through the hole 22 formed in the side wall of the tube body 17, the work of inserting the water stop device 16 into the cough tube body 17 is performed at the upper part of the tube body 17. This can be easily carried out from any position such as, and there is no need to provide a large work space for operating the water stop device 16 in addition to the space for drilling the holes 22. Further, since the pipe body 17 to be water-stopped is not completely cut off, there is no need to connect the pipe bodies 17 through complicated work during repair work. Further, by expanding the annular seal body 12 at a position where the hole 22 is not formed, there is no need to seal the hole 22 with the annular seal body 12. The water stoppage of the tube body 17 can be achieved by simply bringing the annular seal body 12 and the inner circumferential surface of the tube body 17 into pressure contact.

Furthermore, in the means for carrying out a predetermined series of operations with the auxiliary pipe 18 having the valve-equipped casing 23 of the second structure connected thereto installed in an inclined manner on the outer surface of the pipe body 17, a hole is provided. 22
The outer end opening of the valve-equipped casing 23 or the valve 1 is
By maintaining the frozen state at position 9, it is possible to appropriately prevent the water flow inside the tube body 17 from unduly leaking to the outside of the tube body. Further, since the auxiliary pipe 1B is inclined, when inserting the water stop device 16 into the pipe body 17, it can be inserted from an oblique direction to the pipe body 17.
This facilitates the operation of inserting the annular seal body 12 into the hole 22 to the non-drilling position. This also eliminates the need to drill holes 22 over a large area.

Furthermore, in the water stop device 16 in which the annular seal body 12 of the third configuration is formed so as to be able to bend and rotate freely in a lateral direction different from the longitudinal direction of the support rod 1, the annular seal body 12 is formed to be able to bend and rotate freely in a lateral direction different from the longitudinal direction of the support rod 1. When the water stop device 16 is inserted through the drilled hole 22, the annular seal body 12 can be bent and rotated 10, so that the annular seal body 12 does not stay at the drilled position of the hole 22, but moves to a predetermined position away from the hole 22. can be appropriately placed and inserted, and the first and second construction methods described above can be appropriately implemented.

(Example) Examples of the present invention will be described below.

[Example of water stop equipment]

In Fig. 1, 1 indicates a plurality of support pipes la, lb, I
Each support pipe Ia, lb,
Each connecting end of the lc is formed with bulging spherical portions 2a, 2b, . . . , 2d that are slidably fitted into each other. 3
a, 3b...3d are mutually fitted bulging spherical parts 2a
, 2b, 2C, 2d with a retaining flange,
The bulging spherical portions 2a+, 2b, . . . , 2d are externally fitted to engage with each other, and are fastened in pairs with bolts and nuts 4, . Due to this connection structure, the support pipes 1a+1b on the tip side of the support rod 1 are connected to the other longest support pipes IC.
It is flexible in the longitudinal direction. In addition, spline grooves 5...r5a... which engage with each other as shown in the figure (opening) are carved on the inner or outer surface of each of the bulging spherical portions 2a...2d, thereby allowing each support pipe to Jar Ib+ l
c is set in a state in which relative rotation is not possible. 6 is a lever handle provided at one end of the support rod 1.

Reference numeral 7 denotes a rotary operation rod that is inserted into the support rod 1 in a relatively loose state, and is connected to the support vibrations 1a. 1b...
A plurality of shaft bodies 7a+7b, 7c corresponding to the support rod 1 are connected so as to be bent as the support rod 1 is bent. As an example of the connecting means, as shown in FIG.
+ Concave grooves 8, 8a carved in the connecting end of 7b + 7c
... Insert the connecting links 28, 288 into the pin 7.
0. 10... may employ a connecting means that prevents relative rotation of each shaft body in the axial direction. 11 is a lever handle of the rotary operating rod 7.

Reference numeral 12 denotes a screw shaft portion 1 screwed onto the tip of the rotation operation rod 7.
4 is an annular seal body that is fitted onto the outside of the ring and is made of an elastic member such as rubber. 13. Reference numeral 13a denotes clamping pressure plates arranged on both sides of the annular seal body 12, and the supporting pipe 1a
One clamping plate 13 fixed to the tip of the screw shaft 1
4 passes through the screw shaft 1l in a screwed state, and the other clamping plate 131 is fixed to the tip of the screw shaft 1l portion 14. As a result, the other clamping pressure plate 13a can freely reciprocate in the direction of arrow b by the forward and reverse rotation of the shaft body 7a of the rotary operation rod 7, and the annular seal body 12 is compressed and decompressed in its axial direction. It can be expanded and contracted in the radial direction.

Reference numeral 15 indicates a conical guide portion formed on the tip side of one of the movable pressure plates I3a.

The water stop device 16 according to this embodiment has the above configuration.

[Example of water stop construction method] Next, the existing water pipe body 1 using the water stop device 16 described above will be explained.
An example of water stoppage construction method No. 7 will be explained.

First, as shown in FIG. 2, the auxiliary pipe 18 is attached to the pipe body 17 to be water-stopped in an inclined state. Here, the auxiliary tube 18 is connected to a pair of holders 19 in the shape of a two-split cylinder. 198, which is integrally connected to the member 19 on one side of the holder 19. Bolts and nuts 20.19a sandwich both upper and lower surfaces of the tube body 17. By tightening both with 20a, the holders 19, 19a and the auxiliary tube 18 can be fixedly attached to the tube body 17. 21. 21 is an O-ring-shaped sealing packing for preventing water leakage 13 .

Next, after installing the auxiliary tube 18, as shown in FIG.
A hole 22 is drilled in the outer wall surface of the tube body 17 facing the hollow interior of the tube body 17. In the drilling operation, first, a valved casing 23 equipped with a valve 19, such as a butterfly valve, which can be opened and closed, is screwed onto the tip side of the auxiliary pipe 18, and a cap 24 is installed to close the outer end opening 26 of the casing 23. A drilling tool 25 is attached to the valved casing 23.

Note that, as an example of the drilling tool 25, a high-pressure water jet nozzle can be applied.

After that, with the valve 19 open, the drilling tool 25 is inserted deep into the auxiliary pipe, and high-pressure water is discharged from the drilling tool 25 to form a circular hole 22 in the outer wall surface of the pipe body 17. Can be drilled. In the drilling operation using high-pressure water jet, the pipe body 17 can be easily drilled in an oblique direction.

Note that tap water flowing through the pipe body 17 flows into the auxiliary pipe 18 and the valved casing 23 through the perforation of the hole 22, but the flowing water is appropriately stopped by the cap 24 and does not leak to the outside. . The operation for removing the punch 25 can be carried out with the tip of the punch 25 pulled up to the upper position 14 of the valve 19 and with the valve 19 closed.

Thereby, water leakage from the auxiliary pipe 18 to the outside can be prevented by the valve 19.

After completing the above-mentioned drilling work, insert the water stop device 16 shown in FIG. 1 into the auxiliary pipe 18 from the outer end opening 26 of the valve casing 23 as shown in FIG. 17. Also, during such insertion work, the cap 24a
By closing the outer end opening 26 and opening the valve 19, this can be done appropriately without causing water leakage to the outside.

Therefore, the tip of the water stopper 16 is not simply stopped at the opening position of the hole 22, but is placed deep inside the tube body 17 at an appropriate distance L from the hole 22, as shown in FIG. have it placed. If the support rod 1 of the water stop device 16 is a simple rod-shaped one, the above-mentioned insertion operation is extremely difficult, but the support rod 1 of the water stop device 16 and the rotation operation rod 7 inside thereof according to the present invention Since it is bendable, the above operations can be performed appropriately. Furthermore, since the water-stopping device 16 is inserted from above the tube body 17, there is no need to separately secure a special space for inserting the water-stopping device 16. Therefore, there is no need to increase the excavation area of the ground.

After the annular seal body 12 of the water stop device 16 is placed in a position where the hole 22 is not bored as described above, the lever handle 11 may be operated to rotate the rotation operating rod 7. . As a result, as shown in FIG. It is compressed by the tube 13a, expands in the radial direction, and comes into pressure contact with the entire inner circumferential surface of the tube body 17. Here, since the entire circumference of the annular seal body 12 is in pressure contact with the inner circumferential surface of the tube body 17 at a position where the hole 22 is not present, its watertight sealing performance is very good. Even if sludge exists on the inner surface of the tubular body 17 or the tubular body 17 is slightly deformed into an elliptical shape, sealing failures caused by this are extremely unlikely to occur. Therefore, the pipe body 17 can be maintained in a substantially completely water-tight state by the water-stopping device 16, and no inconvenience will be caused in the repair work performed on the downstream side.

In addition, when the above-mentioned water stop state is released and the pipe body 17 is repaired, the annular seal body 12 is contracted by rotating the water stop device 16 by operating the operating rod 7, contrary to the above, and the auxiliary pipe is 18 and the valved casing 23. If the annular seal body 12 is pulled up above the valve 19, the valve 19 is closed, and the entire water stop device 16 is removed.
After all, it does not cause unnecessary water leakage.

[Other examples of water stop equipment]

It should be noted that the water stop device 16 of the above embodiment has a rotary operation rod 7.
The rotation of the pair of pressure plates 13. Although the annular seal body 12 is designed to be able to expand and contract by increasing and decreasing the dimensions between the sections 13a, the present invention is by no means limited to such a configuration.

For example, as shown in FIG. 7(a), a guide body 28 having an outer diameter ob larger than the inner diameter Oa of the annular seal body 12 is reciprocated back and forth by operating a control lever 29 on the distal end side of the annular seal body 12 made of an elastic member. It may be provided so that it can move freely. In this means, the guide body 28 is pulled in the direction of arrow C and is forcibly fitted inside the annular seal body 12, thereby expanding the outer diameter of the annular seal body 12 and achieving the same water stop function as described above. can get. Also, as shown in the same figure (mouth),
It is also possible to apply means such as forming the annular seal body 17 and 12 into a tube shape and supplying a fluid such as water or water into the annular seal body 12 with a flexible pressure-resistant hose or the like to expand the annular seal body 17. good. The annular seal body 12 of the water stop device according to the present invention needs only to be able to expand and contract in the radial direction.

Furthermore, the configuration of the support rod 1 is not limited as described above, and the point is that the annular seal body 12 can be bent and rotated in a lateral direction different from the longitudinal force direction of the support rod 1 at least at one or more locations on the tip side thereof. It suffices if the portion is formed to be bendable. Specific structure of the connecting portion 27 or the bulged spherical portion 2a of the above embodiment
, 2b. For example, a plurality of support members may be connected via bellows to be flexible. Further, the specific angle at which the annular seal body 12 bends and rotates does not matter. This may be determined depending on the conditions of use.

In this way, the specific structure or design of each part of the water stop device according to the present invention can be changed as desired.

(Other Examples of Water Stopping Method) 18 The specific structure of the water stopping method of the present invention is not limited to the above embodiments.

In the above embodiment, the holes 22 were drilled using high-pressure water, but instead of this, the holes 22 may be drilled using a drilling tool equipped with a cutter blade, and the shape of the holes 22 may be Nothing is specified.

Further, the present invention provides that the annular seal body 12 of the water supply device 16 is placed in a position inside the tube where the drilled hole 22 is not open, and then the annular seal body 12 is expanded to stop water. It goes without saying that the specific placement position of the water-stopping device 16 is not specified.Furthermore, in the above embodiment, the auxiliary pipe 18 attached to the pipe body 17 to be water-stopped is used to close the hole. 22 drilling work and water stop equipment 1
6, and during the series of operations, the tube body 17 is inserted.
Although a case has been described in which no unreasonable leakage of water to the outside is allowed to occur, it is not necessary to employ such means in the present invention as set forth in the first claim.

In addition, the present invention can be freely modified in the specific configuration of each work step. In addition, the present invention is mainly used for repairing water pipes,
Although it is used for additional work on branch piping, etc., it goes without saying that it is not limited to such use and can be applied to various other types of water shutoff work on piping.

(Effects of the Invention) As described above, the present invention provides a water stop device in which a ring-shaped seal body is provided at the tip of a support rod so that it can be bent and rotated. After the annular seal is inserted into the body and placed at a position inside the tube away from the opening position of the hole, the annular seal is expanded in the radial direction and brought into pressure contact with the inner circumferential surface of the tube to stop water. In order to do this, a large piece of equipment is used to operate the water-stopping device in front of the pipe, such as the conventional method of completely cutting off the water-stopping target pipe and inserting the water-stopping device through the opening at its tip. No work space is required, when water pipes etc. buried underground are to be stopped, there is no need to take a large excavation area of the ground, and when pipe repair work is to be performed after the water has been stopped. In addition, there is no need to reconnect the pipe bodies through large-scale work, and this has the effect of facilitating a series of water works as well as repair work after the completion of the Kitamoto project.

Furthermore, in the method of expanding the annular seal body of the present invention at a position where no hole is formed, the valve body is inserted through the conventional hole in the side wall of the pipe body, and the seal of the valve body is applied to the sharp opening periphery of the hole. The annular sealing body of the water stop device is accurately pressed against the inner circumferential surface of the tube, without causing undue damage to the valve body unlike the method of press-fitting materials, and almost completely shutting off water in the tube body. You can also obtain effects that can be applied to certain states.

In this way, the present invention not only improves a series of work efficiency, but also ensures water stoppage of the pipe body, and solves two problems that could not be solved at the same time with conventional means. The practical value of this solution is enormous.

In addition, in the method of carrying out a series of predetermined operations with the auxiliary pipe in which the casing with a valve of the present invention is attached in an inclined manner to the outer surface of the pipe body, a series of water shutoff operations may be carried out. In some cases, by maintaining a water stop state at the outer end opening of the valved casing or at the position of the valve, it is possible to properly prevent the water flow inside the pipe from improperly leaking to the outside of the pipe. This has the excellent effect of preventing this problem and further improving work efficiency.

Moreover, since the auxiliary pipe is in an inclined state, when inserting the water stop device into the pipe body, it can be inserted from an oblique direction to the pipe body, making it easier to insert the annular seal body into the hole where it is not drilled. This has the advantage that it is easy to do so, and it also eliminates the need to drill holes over a large area.

Furthermore, according to the means of the water-stopping device of the present invention in which the water-stopping device is shaped so as to be able to bend and rotate freely with respect to the support rod, the water-stopping device can be inserted through the hole drilled in the side wall of the pipe body to be water-stopped. The operation of inserting the instrument into the tube body and arranging the annular seal body in the non-drilling position of the hole can be performed appropriately, which contributes to the present invention and to the implementation of the woodworking method and is convenient.

[Brief explanation of drawings]

FIG. 1 shows an embodiment of the water-stopping device according to the present invention, in which (A) is a front sectional view, the opening (opening) is an enlarged sectional view along the x1x line in FIG. Figure (c) is a plan view of the main part. 22 Figure 2 (a), (mouth). FIG. 3, FIG. 4, FIG. 5, and FIG. 6 are main part sectional views showing a series of work steps of the water stop method according to the present invention. FIGS. 7(A) and 7(B) are sectional views of main parts showing other embodiments of the water stopping device. Figure 8 (a), (mouth) and Figure 9 (a), (mouth), (c). (2) is a sectional view showing a conventional example. 1... Support rod 12... Annular seal body 16... Water stop device 17... Water stop target pipe body 18... Auxiliary pipe 19... Valve 22.
... Hole 23 ... Casing with valve 2
5... Punching tool 26... Outer end opening 2
7. 27a...Connection part

Claims (1)

[Claims] 1. After drilling a hole 22 in the side wall of the pipe body 17 to be water stopped,
An annular seal body 12 that can expand and contract in the radial direction is attached to the support rod 1.
A water-stopping device 16, which is provided at the distal end of the support rod 1 so as to be bendable and rotationally movable in a lateral direction different from the longitudinal direction of the support rod 1, is inserted into the pipe body 17 through the hole 22. 16 annular seal bodies 12 are placed away from the opening position of the hole 22 to a position inside the tube where the hole 22 is not bored, and then the annular seal body 12 of the water stop device 16 is moved in the radial direction. A water stop construction method for pipe bodies such as water pipes, characterized in that water is stopped within the pipe body 17 by expanding it and bringing it into pressure contact with the inner circumferential surface of the pipe body 17. 2. In the water shutoff construction method for pipe bodies such as water pipes described in claim 1, before drilling the hole 22, a valved casing 23 equipped with a water shutoff valve 19 is connected. The auxiliary pipe 18 is installed in advance on the outer surface of the tube body 17 in an inclined state with respect to the tube body 17, and the hole 22 in the side wall of the tube body 17 is inserted.
The drilling work is performed using the drilling tool 25 inserted into the casing 23 with a valve and the auxiliary pipe 18, and the work of inserting the water stop device 16 into the pipe body 17 is performed into the casing 23 with a valve and the auxiliary pipe 18. A water-stopping method for pipe bodies such as water pipes, which is performed by inserting a water-stopping device 16. 3 An annular seal body 12 that can be expanded and contracted to be inserted into the pipe body 17 to be water-stopped to block the flow channel within the pipe body 17
In a water stop device for a pipe body such as a water pipe, in which a support rod 1 is provided at the distal end side of the support rod 1, the support rod 1 has an annular seal body 12 in a lateral direction different from the longitudinal direction of the support rod 1. A water stop device for a pipe body such as a water pipe, characterized in that at least one or more portions on the distal end thereof are formed to be bendable so as to be able to bend and rotate.