DEVICE AND METHOD FOR REMOVING ELASTOMERIC POLYMER LINER MATERIAL FROM INSIDE A PIPE

In one aspect, a device for facilitating removal of elastomeric polymer liner material from inside a pipe comprises a knife having an axial blade portion and a radial blade portion joined to form a heel with respective cutting edges of the axial and radial blade portions facing in the same direction. The knife has a working orientation in which the axial and radial blade portions are oriented axially and radially, respectively, relative to the pipe and the axial blade portion is further from the pipe axis than the radial blade portion. Rotation of the knife about the pipe axis in the working orientation with the cutting edges leading and the knife contacting the elastomeric polymer liner material causes the cutting edges of the radial and axial blade portions to cut through the elastomeric polymer liner material in the radial and axial dimensions, respectively, of the pipe.

TECHNICAL FIELD

The present application pertains to pipe having an elastomeric polymer liner, and more specifically to a device and method for removing elastomeric polymer liner material from inside a pipe.

BACKGROUND

Cylindrical metal pipes, such as 30-inch inner diameter steel pipes commonly used for oilsands and mining tailings pipelines, may have a liner bonded to an interior surface of the pipe wall. The liner may be made from an elastomeric polymer, such as polyurethane or urethane. Examples of commercially available polyurethane products from which pipe liners may be made include RoPlasthan™ and RoCoat™ products from ROSEN™ Swiss AG and Irethane™ products (e.g., Irethane™ 2855) sold by ITW Performance Polymers. The liner protects the metal pipe from abrasion by hard particulate matter that may be mixed in with liquid being carried through the pipe (e.g., quartz sand). A metal pipe having an elastomeric polymer liner may be referred to as a “lined pipe.”

An elastomeric polymer liner may have substantial thickness, e.g., approximately 1.5 to 2.0 inches for a 30-inch inner diameter metal pipe. The durometer (hardness) of different elastomeric polymer materials may vary, but the materials all generally have a degree of resiliency. This characteristic contributes to the abrasion-resistance of the liner, even as compared with harder materials of lesser resiliency.

Lined pipes are commonly sold in predetermined lengths or “spools,” so called because of the annular flange at each end of the pipe. For example, 30-inch inner diameter pipes are commonly sold in 60-foot lengths, among others. A pipeline project may necessitate the purchase of many modular lined pipe spools of various lengths, depending on the planned pipeline layout.

Dynamically changing circumstances in the field may render a purchased lined pipe spool too long for its intended purpose. This may occur, e.g., if environmental considerations force re-routing of an oil pipeline from a planned layout. In such circumstances, shorter lengths of lined pipe may be needed to facilitate a new pipeline layout. Although shorter spools of lined pipe could possibly be ordered from a manufacturer, the associated additional cost and delivery delay may be undesirable.

Severing a spool of lined pipe into shorter lengths for re-use in the field may be viewed as a lower cost and timelier alternative. Severing may be performed using a known annular pipe machining lathe, also known as a split-frame lathe, clamshell lathe, or simply annular lathe. This type of lathe has the appearance of a ring that is clamped to a pipe exterior substantially coaxially therewith. The ring comprises two adjacent annular parts: a stationary part and a rotating part. The stationary part surrounds the pipe and is clamped to the pipe exterior. The rotating part also surrounds the pipe and is rotatable about the pipe relative to the stationary part. The rotating part has a tool mount that can be fitted to carry a tool bit having an extremely hard tip that points radially inwardly towards the pipe axis. Rotation of the rotating part of the lathe causes the tool bit to orbit the pipe. Simultaneously, the lathe can be made to advance the tool bit radially inwardly so that its tip progressively cuts into and through the pipe wall, from the outside in, over the course of multiple orbits of the pipe.

The severed ends of a pipe may lack any brackets or flanges to facilitate interconnection with adjacent pipe spools. Welding of brackets or flanges onto the ends of a severed lined pipe may expose the pipe wall to extremely high temperatures that may be conducted through to the liner. This may be unsafe for workers, e.g., when the liner is made from an elastomeric polymer material such as polyurethane. The reason is that heating of the elastomeric polymer liner material above a threshold temperature may release dangerous gases, such as hydrogen cyanide.

SUMMARY

In one aspect, there is provided a device for facilitating removal of elastomeric polymer liner material from inside a pipe, the device comprising: a knife having an axial blade portion and a radial blade portion joined to form a heel with respective cutting edges of the axial and radial blade portions facing in the same direction, the knife having a working orientation in which the axial and radial blade portions are oriented axially and radially, respectively, relative to the pipe and the axial blade portion is further from an axis of the pipe than the radial blade portion; wherein rotation of the knife about the axis of the pipe in the working orientation with the cutting edges leading and with the knife in contact with the elastomeric polymer liner material causes the cutting edge of the axial blade portion to cut through the elastomeric polymer liner material along an annular trajectory and additionally causes the cutting edge of the radial blade portion to simultaneously cut through the elastomeric polymer liner material in a radial dimension of the pipe.

In another aspect, there is provided a method of facilitating removal of elastomeric polymer liner material lining an inner surface of a pipe, the method comprising: orienting a knife in a working orientation with respect to the pipe, the knife having an axial blade portion and a radial blade portion joined at a heel with respective cutting edges of the axial and radial blade portions facing in the same direction, wherein the axial and radial blade portions are oriented axially and radially, respectively, relative to the pipe, with the axial blade portion being further from an axis of the pipe than the radial blade portion; and rotating the knife about the axis of the pipe in the working orientation with the cutting edges leading and with the knife in contact with the elastomeric polymer liner material to cause the cutting edge of the axial blade portion to cut through the elastomeric polymer liner material along an annular trajectory and to simultaneously cause the cutting edge of the radial blade portion to cut through the elastomeric polymer liner material in a radial dimension of the pipe.

In a further aspect, there is provided a device for facilitating removal of elastomeric polymer liner material from inside an end section of a pipe, the device comprising: a knife having an axial blade portion and a radial blade portion joined to form a heel with respective cutting edges of the axial and radial blade portions facing in the same direction; a knife support structure configured to support the knife inside the end section of the pipe from an exterior periphery of the pipe with the knife in a working orientation in which the axial and radial blade portions are oriented axially and radially, respectively, relative to the pipe and the axial blade portion is further from an axis of the pipe than the radial blade portion; a radial feed mechanism operable to, upon rotation of the knife support structure about the axis of the pipe with knife held in the working orientation and the cutting edges leading, progressively advance the knife radially outwardly from an inboard position in which the cutting edge of the axial blade portion is radially inward of the elastomeric polymer material lining the inner surface of the pipe to an outboard position in which the cutting edge of the axial blade portion is adjacent to the inner surface of the pipe; and an axial feed mechanism operable to, upon rotation of the knife support structure about the axis of the pipe with knife held in the working orientation and the cutting edges leading, progressively move the knife, in the outboard position, axially and heel-first along the end section of the pipe.

In another aspect, there is provided a method of facilitating removal of elastomeric polymer material lining an inner surface of an end section of a pipe, the method comprising: securing an annular rotary drive mechanism about an exterior periphery of the pipe; attaching a knife support structure to the annular rotary drive mechanism, the attached knife support structure being configured to support a knife inside the end section of the pipe in a working orientation, the knife having an axial blade portion and a radial blade portion joined at a heel with respective cutting edges of the axial and radial blade portions facing in the same direction, the axial and radial blade portions being oriented axially and radially, respectively, relative to the pipe with the axial blade portion being further from an axis of the pipe than the radial blade portion when the knife is in the working orientation; while the annular rotary drive mechanism rotates the knife support structure about the axis of the pipe with the knife in the working orientation and the cutting edges leading, progressively radially outwardly shaving away an annular portion of the elastomeric polymer material from the end section of the pipe by progressively advancing the knife radially outwardly from an inboard position in which the cutting edge of the axial blade portion is radially inward of the elastomeric polymer material lining the inner surface of the pipe to an outboard position in which the cutting edge of the axial blade portion of the knife is adjacent to the inner surface of the pipe; and then while the annular rotary drive mechanism rotates the knife support structure about the axis of the pipe with the knife in the working orientation and the cutting edges leading, progressively axially cutting away a substantial remainder of the elastomeric polymer material from the end section of the pipe by progressively moving the knife axially along the end section of the pipe heel-first.

In a further aspect, there is provided device for facilitating removal of elastomeric polymer liner material from inside an end section of a pipe, the device comprising: knife means having an axial blade portion and a radial blade portion joined to form a heel with respective cutting edges of the axial and radial blade portions facing in the same direction; knife support means configured to support the knife means inside the end section of the pipe from an exterior periphery of the pipe with the knife means in a working orientation in which the axial and radial blade portions are oriented axially and radially, respectively, relative to the pipe and the axial blade portion is further from an axis of the pipe than the radial blade portion; radial feed means operable to, upon rotation of the knife support means about the axis of the pipe with knife means held in the working orientation and the cutting edges leading, progressively advance the knife means radially outwardly from an inboard position in which the cutting edge of the axial blade portion is radially inward of the elastomeric polymer material lining the inner surface of the pipe to an outboard position in which the cutting edge of the axial blade portion is adjacent to the inner surface of the pipe; and axial feed means operable to, upon rotation of the knife support means about the axis of the pipe with knife means held in the working orientation and the cutting edges leading, progressively move the knife means, in the outboard position, axially and heel-first along the end section of the pipe.

DETAILED DESCRIPTION

In this document, any use of the term “exemplary” should be understood to mean “an example of” and not necessarily to mean that the example is preferable or optimal in some way. Terms such as “top,” “bottom,” “left,” “right,” “side,” and “front” may be used to describe features of some embodiments in this description but should not be understood to necessarily connote an orientation of the embodiments during manufacture or use.

Referring toFIG.1, a lined pipe spool100is depicted in perspective view. The lined pipe spool100comprises a substantially cylindrical metal (e.g., steel) pipe102. The metal pipe102has annular flanges103at either end to facilitate interconnection with adjacent pipe spools. The flanges103may have through holes spaced about the circumference of each flange (not expressly depicted inFIG.1) to receive bolts for interconnecting aligned flanges of adjacent pipe spools. In the illustrated example, the inner diameter of the pipe102is 30 inches, and the thickness of the liner104is 1.5 inches. Alternative embodiments may be used with lined pipes of other diameters and liner thicknesses.

The lined pipe spool100further comprises a substantially cylindrical elastomeric polymer liner104bonded to an inner surface of the pipe102. In this example, the liner104is made from polyurethane, such as RoCoat™ products from ROSEN™ Swiss AG. The durometer of the polyurethane in this example may be approximately 87 Shore A. The durometer of the elastomeric polymer liner material may differ in alternative embodiments.

The lined pipe spool100may for example be intended for use in constructing a pipeline for carrying oil sands or mining tailings that may comprise solid particulate matter such as sand. The liner104may be intended to prevent damage to the pipe102from the solid particular matter and to thereby extend its working life.

At a pipeline construction site, it may become necessary or prudent to sever the lined pipe spool100into two shorter lengths, e.g., so that at least one of the lengths can be used for interconnection with other lined pipe spools. Severing may be performed in the field using an annular lathe, as depicted inFIG.2.

FIG.2is a simplified perspective view of an annular lathe200, a form of annular rotary drive mechanism. The annular lathe200comprises two adjacent, coaxial annular parts: a stationary annular part202and a rotatable annular part204.

The stationary annular part202is securable (e.g., clampable) to a pipe exterior. Multiple locator feet206(four illustrated) may project radially inwardly from an inner face of the stationary annular part202. These may serve as the point of contact between the pipe exterior and the annular lathe200.

The rotatable annular part204is rotatable about axis AA relative to the stationary annular part202. The rotation may be driven by a motor, such as a pneumatic motor, that may be mounted to a motor mount (not depicted) in the stationary part202. The motor is typically capable of generating significant force, e.g., sufficient to drive a cutting tool bit mounted to the rotating annular part204as it cuts through the metal wall of the pipe. A tool mount208, which may be a plate fixedly attached to a face of the rotatable annular part204(e.g., by welding or bolts), may serve as the mounting location for such a cutting tool bit.

The annular lathe200is depicted inFIG.2in an assembled annular state. The lathe200is also separable along a bisecting joint210into two semi-annular (C-shaped) halves to facilitate its installation onto a pipe. This is depicted inFIGS.3and4.

FIGS.3and4are simplified perspective views depicting the annular lathe200ofFIG.2during and after installation onto the lined pipe spool100ofFIG.1, respectively. InFIG.3, the annular lathe200has been separated into two C-shaped, semi-annular halves220and222to facilitate installation. The top semi-annular half220of the annular lathe200comprises a semi-annular half of each of the stationary part202and the rotating part204and two connector brackets224. The bottom semi-annular half222of the annular lathe200comprises a complementary semi-annular half of each of the stationary part202and the rotating part204. For clarity, the locator feet206are omitted fromFIG.3.

Referring toFIG.4, the top and bottom semi-annular halves220and222of annular lathe200have been joined in a conventional manner, e.g., using brackets224and/or other connectors. The assembled annular lathe200has been secured about an exterior periphery of the lined pipe spool100at a desired pipe severing location, with locator feet206(not visible) holding the stationary part202of the annular lathe200substantially coaxially with the pipe spool100. The lengths of the locator feet206may be adjustable to facilitate centering of the annular lathe200on the cylindrical lined pipe spool100.

InFIG.4, a tool slide block assembly226(also referred to simply as tool slide226) having a base228and a slidable block230holding a cutting tool bit232is mounted to the tool mount208of rotatable annular part204. The cutting tool bit232is oriented so that its tip234points radially inwardly toward the pipe spool100.

The annular lathe200may be used to sever the lined pipe spool100in a conventional manner, as follows. Firstly, the rotatable annular part204is made to rotate relative to the stationary part202. This will cause the tool mount208, and the attached tool slide block assembly226, to orbit the pipe102. The tip234of tool bit232will initially be radially clear of the pipe102.

As the tool slide block assembly226continues to orbit the pipe102, the tool block230holding tool bit232may be made to slide radially inwardly relative to base228. This may be achieved by causing a threaded rod (not illustrated) that is in fixed radial relation to base228and which engages a radially oriented threaded bore (not illustrated) through block230to rotate. Rotation of the rod may be caused by a stationary trip engaging a star wheel (not illustrated) disposed at a radially distal end of the rod. The trip may rotate the star wheel and threaded rod through a predetermined angle with each orbit of the tool mount226, causing the tool mount226to slide incrementally radially inwardly with each orbit of the tool mount226about the pipe102. When the tip234of the tool bit232reaches the pipe102, it will begin to progressively cut through the pipe102from the outside in. Thereafter, the same tool bit232will continue to cut through the elastomeric polymer liner104, also from the outside in.

A severed part of the lined pipe spool100may be removed, leaving the other severed part of the lined pipe spool100, i.e., the part to which the annular lathe200has been clamped. The latter severed part, referred to as lined pipe150, is shown in simplified perspective view inFIG.5.

Referring toFIG.5, it can be seen that the open end160of lined pipe150, where severing has just been completed, lacks a flange to facilitate interconnection of that end160of the pipe150with an adjacent pipe spool. It may accordingly be desired to weld a number of brackets to an exterior of the pipe102about the open end160to facilitate such interconnection. To limit exposure of welders to dangerous gases that may be emitted by the elastomeric polymer liner104upon exposure to heat from welding or possibly even combustion of the liner104, it may be considered prudent or necessary to remove the liner104from an end section162of the lined pipe150before any such welding is performed. The end section162may for example be 18 inches long.

However, conventional methods of elastomeric polymer liner removal may be considered impractical in the field. Perhaps the most common approach for removing an elastomeric polymer liner bonded to the inner surface of a metal pipe is using high-pressure water jets, which is conventionally done in a factory setting. Robotic arms carrying nozzles capable of spraying high-pressure (e.g., one hundred thousand PSI) water jets may be extended into a lined pipe. The water jets may be controlled so as to cut away the liner material, including any bond that may be formed between the material and the pipe wall (which may be very strong), without damaging the steel pipe. The temperature of the water may be kept cold to prevent the elastomeric polymer liner from undergoing an exothermic reaction that may release dangerous gases during liner removal.

The equipment required for liner removal using high pressure water jets may be considered impractical for liner removal in the field. The lined pipe150could be shipped to the factory for liner removal using water jets. However, this may necessitate the use of heavy equipment, such as a crane, to load and unload the lined pipe onto and from a flatbed truck for delivery. Undesired delay and shipping costs may result.

The applicant considered various alternative approaches for elastomeric polymer liner removal in the field. However, the very characteristics of the elastomeric polymer material that serve to protect the metal pipes that have been lined with the material—including the durability and resiliency of the material—can also make liner removal difficult.

For example, one approach attempted by the applicant was using a milling bit to mill away the liner in the manner of a router. However, it was found that milling tends to shred the elastomeric polymer material in unpredictable ways and to leave an irregular surface texture. Moreover, there may be a risk of metal pipe damage when a milling bit approached the inner surface of a metal pipe. For some industries (e.g., the petroleum pipeline industry), even a comparatively small degree of damage to a metal pipe, such as a 1/16″ deep cut, can render the pipe unusable in view of strict standards for environmental safety.

The applicant has therefore developed the below-described device to facilitate elastomeric polymer liner removal. In overview, the device utilizes a sharp knife having two blade portions to cut away the elastomeric polymer material from an end section of a lined pipe in ribbons or strips. The cutting is performed in two operational stages, which may be followed by a stripping phase, as will be described below. The device can be used in the field to remove the elastomeric polymer liner from an end section of a lined pipe relatively quickly and with limited risk of damage to an inner surface of the metal pipe. Moreover, the device can be actuated (at least in part) by a commercially available annular lathe. Conveniently, for at least some embodiments, the device may be utilized to facilitate elastomeric polymer liner removal from an end of a severed pipe using same annular lathe that severed the pipe. In some embodiments, such an annular lathe may conveniently remain continuously clamped to the pipe during both pipe severing and elastomeric polymer liner removal, which may promote efficiency in performing these operations quickly.

An example device300for facilitating removal of elastomeric polymer liner material from inside an end section of a pipe is depicted inFIGS.6,7, and8.FIG.6is a top left perspective view of the device300also showing a portion of the annular lathe200to which the device300may be attached during use.FIG.7is a bottom right perspective view of the device300ofFIG.6after its attachment to the annular lathe200.FIG.8shows the device300in isolation in exploded view. For clarity, the lined pipe150is omitted from each ofFIGS.6,7, and8.

In each ofFIGS.6and7, the device300is depicted in a first configuration as it may appear during a first stage of cutting, which may be referred to as a radial “plunge cutting” stage. The device300also has a second configuration that is used during a second stage of cutting operation, which may be referred to as the “axial cutting” stage, as will described.

As illustrated inFIGS.6-8, the device300includes a knife support structure302. In the present embodiment, the knife support structure302includes a knife carriage arm304and a mounting bracket306extending substantially orthogonally from the knife carriage arm304. The knife carriage arm304supports the knife340(described below) that is used to cut the liner104inside the pipe. The mounting bracket306serves as a point of attachment of the knife support structure302to the annular lathe200via tool slide226. The knife carriage arm304and mounting bracket306are rigid, e.g., being formed from a unitary piece of strong metal such as steel.

The knife support structure302of the depicted device300further includes a knife holder308, which is perhaps best seen inFIG.8. The knife holder308is a rigid block having a recessed upper surface310shaped to mate tightly with a complementary surface312of the knife340. These mating surfaces may help to maintain the knife340in a working orientation, described below.

In the present embodiment, the knife holder308is configured to slidably engage a rail314defined along the knife carriage arm304. InFIG.8, the rail314is depicted as a pair of parallel upstanding guides at either side of the knife carriage arm304. The rail314may be designed to prevent the knife holder308from lifting away from the knife carriage arm304, e.g., via a slidable interlocked relationship.

The knife holder308has a threaded bore316therethrough that is parallel to the rail314(seeFIG.8). The threaded bore316engages a threaded rod318that is also parallel to the rail314. The threaded rod318is axially fixed relative to the rail314while remaining rotatable, e.g., by virtue of being held by a bearing319in bracket306. As a result, rotation of the threaded rod causes axial movement of the knife holder308along the rail314.

Rotation of the threaded rod318may be actuated by a DC motor320(a form of rotary actuator), which may for example be a 12V DC motor of the type used in portable electric drills. As illustrated, the motor320has a rotary shaft321terminated by a socket322(a form of mechanical connector). The socket322of the present embodiment is suitable for mechanically engaging either of a star wheel324at the end of threaded rod318and a star wheel231at the end of a threaded rod229of the tool slide226.

A motor support bracket326on an opposite side of mounting bracket306is configured to support the DC motor320with socket322mechanically engaging star wheel324. The DC motor320will so occupy the motor support bracket326during a second, axial cutting stage of operation, described below. Collectively, the rail314, threaded bore316, threaded rod318, and DC motor320may be considered to comprise an axial feed mechanism332.

The knife340component of device300is shown in more detail inFIGS.9-13.FIGS.9and10illustrate the knife340in bottom left isometric view and top right isometric view, respectively.FIGS.11,12, and13illustrate the knife340in bottom view, left side elevation view, and front elevation view, respectively.

As illustrated, the knife340has an axial blade portion342and a radial blade portion344joined to form a heel346. The axial and radial blade portions342and344are so named by virtue of their intended orientation during use, as will be described. In the present embodiment, the axial blade portion342forms a right angle with the radial blade portion344, as perhaps best seen inFIG.12. In alternative embodiments, the angle K between the axial and radial blade portions342,344may be greater than or less than 90 degrees. It will be appreciated that, in cases where K is greater than or less than 90 degrees, the axial orientation of the axial blade portion342when the knife340is in the working orientation will be unchanged from the case where K is 90 degrees. However, the radial blade portion344will to some extent be inclined away from a purely radial orientation.

Each of the axial blade portion342and radial blade portion344of the present embodiment has a substantially trapezoidal cross-sectional shape, which is perhaps best seen inFIG.9. In some embodiments, the knife340may be made from a chipper knife, such as a Vermeer® Model BC1000 Compatible Brush Chipper Knife. For example, such a chipper knife may be cut into two portions, e.g., using a water jet, and the two portions may be welded together at an angle to form the depicted knife340.

The axial blade portion342has a primary cutting edge352A, and the radial blade portion344has a primary cutting edge354A. These cutting edges352A and354A face in the same direction and meet at heel346(see, e.g.,FIG.10). The axial and radial blade portions342and344also have alternative cutting edges352B and354B, respectively, each facing in an opposite direction from, and parallel to, its respective primary cutting edge352A and354A. The alternative cutting edges352B and354B similarly meet at heel346(see, e.g.,FIG.9). The axial blade portion342has flat cutting faces356A and356B adjacent to cutting edges352A and352B, respectively.

It will be appreciated that, when the knife340is being used to cut away elastomeric polymer liner material104from an end section of a pipe, only one of the two pairs of cutting edges-either the primary pair352A and354A or the alternative pair352B and354B-will be used at any given time. The alternative cutting edges352B and354B are provided to extend the useful life of the knife340. In particular, the primary cutting edges352A and354A of a new knife340may be used until they have become dull. Thereafter, the alternative cutting edges352B and354B may instead be used for cutting. This may conveniently be done by reversing a direction of rotational movement of the knife, e.g., by reversing the direction of rotation of the rotatable annular part204of the annular lathe200from clockwise to counter-clockwise. Alternative cutting edges are not strictly required, but their absence may necessitate more frequent replacement of the knife340.

In the present embodiment, the width W of the axial blade portion342of the knife, as measured between the primary cutting edge352A and the alternative cutting edge352B, is 4.5 inches (seeFIG.11). This width is approximately 6.65 times smaller than the 30-inch inner diameter of the example pipe102of the present embodiment. In general, the width W of the axial blade portion342may be six to seven times smaller than an inner diameter of the pipe102. This ratio may differ in alternative embodiments.

In the present embodiment, the axial blade portion342has a length L1of 4.5 inches, and the radial blade portion344has a length L2of 2.5 inches (seeFIG.12). In general, the length L2of the radial blade portion344should be slightly longer (e.g., 0.75 inches longer) than the maximum thickness (depth) of the portion of the liner104to be removed from the end section of the pipe. In some embodiments including the present one, L1is at least 1.5 times L2. This may help to reduce a weight of the knife340.

The axial blade portion342of the present embodiment has a pair of bores348therethrough (seeFIG.11). These may be used to facilitate removable attachment of the knife340to the knife holder308, e.g., using threaded fasteners such as bolts.

Referring again toFIGS.6-8, the device300further includes a tool slide block assembly226. In the present embodiment, this component is the same tool slide block assembly226as was used for severing the pipe spool100(seeFIGS.4and5). The tool slide block assembly226serves as an indirect point of attachment of the knife support structure302to the annular lathe200.

As noted above, operation of the device300for facilitating removal of the liner104from the pipe150occurs in two phases: a cutting phase and a stripping phase. The cutting phase is intended to remove substantially all the liner material from the end section162of the pipe150using the knife340. The stripping phase is intended to remove any remnants of liner material that may remain clinging to the inner surface of the pipe after the cutting phase.

The cutting phase occurs in two stages: a radial plunge cutting stage and an axial cutting stage. The radial plunge cutting stage is depicted inFIGS.14to17. The axial cutting stage is depicted inFIGS.18and19.

For the radial plunge cutting stage, the device300is configured as shown inFIG.7. More specifically, the mounting bracket306of the knife support structure302is attached to the tool block230of the tool slide226, and the base228of the tool slide226is attached to the tool mount208of the annular lathe200. The knife support structure302may thus be considered indirectly attached to the annular lathe200by way of the tool slide226.

During the radial plunge cutting stage, the DC motor320is held by a motor support bracket360similar to motor support bracket326, described above. The motor support bracket360is oriented radially and is attached to the rotatable annular part204of the annular lathe200either directly or indirectly. The motor support bracket326holds the DC motor320so that the socket322mechanically engages the star wheel231of tool slide226. The DC motor320may be secured to bracket360in that configuration, e.g., using a removable strap or ties (not depicted).

The configuration of device300at the commencement of the plunge cutting stage is shown inFIG.14.FIG.14is a not-to-scale schematic side view of the device300attached to the annular lathe200with the lined pipe150shown in cross section. The annular lathe200is secured to the exterior of the pipe150so that the axis of rotation of rotatable annular part204(not depicted) is substantially coaxial with the pipe axis PA.

InFIG.14, the device300is shown at the twelve o'clock position of the annular lathe200. This may be for convenience of installation of device300onto annular lathe200. The rotatable annular part204may be locked relative to the stationary annular part202during the installation. It will be appreciated that the rotatable annular part204of annular lathe200could be rotated so that the installation of device300takes place at another position about its circumference.

As shown inFIGS.7and14, the knife support structure302of the installed device300is configured to support the knife340in a working orientation. The working orientation of the knife340is one in which the axial blade portion342and the radial blade portion344are oriented axially and radially, respectively, relative to the pipe102, and the axial blade portion342is further from an axis of the pipe than the radial blade portion. Keeping the knife340in this orientation throughout cutting may limit a risk of damage to an inner surface of the pipe102from a corner of the axial blade portion342(e.g., heel346). Features of the device300that may help to keep the knife340in the working orientation during cutting may for example include rigid construction of knife support structure302, tight mating of knife340with knife holder308, and avoidance of excessive wear in wear parts such as bearing319, among others.

In the present embodiment, the knife340is oriented for heel-first axial entry into the open end160of the pipe102. In other words, the knife support structure302supports the knife340so that the radial blade portion344is axially further (deeper) in the pipe that the axial blade portion342. This is not strictly required but may be advantageous in certain respects. For example, as will become apparent, an operator standing at the open end160of the lined pipe150during liner removal may be able to better see cutting progress with the knife340oriented as described, particularly when the knife340is in the outboard position.

At the commencement of plunge cutting, the knife340is placed in an inboard position (see, e.g.,FIG.14). The term “inboard” as used herein refers to a radial position of the knife340in which the cutting edge352A of the axial blade portion342is inwardly (radially) clear of the liner104. In the present embodiment, the knife340may be placed in the inboard position by appropriately adjusting the tool slide226, i.e., by turning star wheel231(FIG.8) to suitably adjust a radial position of the tool block230relative to base228. This adjustment may for example be made before the mounting bracket306is attached to the tool block230.

In the present example, the knife340is initially axially positioned so that the end343of the axial blade portion342furthest from the heel346is flush with an end of the pipe (seeFIG.14). As will be appreciated, the result is that the annular portion of the liner104that will be removed by the first, plunge cutting stage will be at the open end160of the pipe102.

Referring again toFIG.7, it can be seen that a rotation sensor328is attached to the rotatable annular part204of the annular lathe200adjacent to the tool slide226. The sensor328has a complementary trigger330, which in this embodiment is attached to the stationary annular part202of the annular lathe200. The rotation sensor has two modes of operation: active and inactive. In the active mode, the rotation sensor328is configured to generate a signal when it comes into contact or close proximity with the trigger330. In the active mode, the rotation sensor328is prevented from generating this signal. The rotation sensor328and trigger330may take various forms in different embodiments. In one example, the sensor328may be a mechanical switch, and the trigger330may be an object that physically contacts the mechanical switch. In another example, the sensor328may be an optical sensor, and the trigger330may be a light source. In some embodiments, multiple triggers may be situated about the periphery of the stationary annular part202, e.g., to sense a finer granularity of rotation.

The rotation sensor328is electronically coupled to a switch (e.g., a relay—not expressly depicted) for activating the DC motor320. The electronic coupling may for example comprise suitable wiring (not depicted).

With device300securely mounted to the annular lathe200, rotation of the rotatable annular part204of the lathe200may be commenced, e.g., by activating a pneumatic motor (not illustrated). The direction of rotation is with primary cutting edges352A and354A of knife340leading the rotational movement, i.e., clockwise as viewed from the open end160of the pipe150. With the rotation sensor328in operational mode, an electronic signal (e.g., pulse) will be generated whenever the rotation sensor328rotates past trigger330. It will be appreciated that each pulse after the first will be indicative of a predetermined extent of rotation (here, a single revolution) of the knife support structure302about the axis PA of the pipe102.

In the present embodiment, each pulse from the active rotational sensor328activates a switch (not illustrated), causing the shaft321and socket322of the DC motor320to rotate for a predetermined time interval. The rotation of the socket322in turn rotates the star wheel231. The direction of rotation is chosen to cause the tool block230to advance radially outwardly towards the wall of the pipe102. Each rotation will accordingly move the knife support structure302radially outwardly, bringing the knife340progressively closer to the liner104.

When the cutting edge352A of the axial blade portion342reaches the liner104, it will “plunge” into the liner104and begin cutting it along an annular trajectory. With each revolution of the annular lathe200, the knife340will shave away a ribbon of the elastomeric polymer material from liner104.

FIG.15is a schematic side view of the device300partly through the plunge cutting stage of operation. The conventions ofFIG.15are similar to those ofFIG.14. The upward arrow R denotes advancement of the knife340axially outwardly from the inboard position ofFIG.14. InFIG.15, the knife340has cut an annular groove190into the liner104over the course of multiple orbits about pipe axis PA. It will be appreciated that the width G of the groove matches the length L1(FIG.12) of the axial blade portion342.

FIG.16is a perspective view of the knife340, as viewed from the open end160of the pipe150, partly through the plunge cutting stage of operation.FIG.16illustrates the manner in which the knife340cuts a single ribbon194of elastomeric polymer material from liner104during the plunge cutting stage. To avoid visual obstruction, only the knife340component of device300is depicted inFIG.16. The rotational movement of the knife340is in direction M, i.e., clockwise.

As illustrated, most of the cutting or “shaving away” of the ribbon194during the plunge cutting stage is performed by the axially oriented primary cutting edge352A of the axial blade portion342. However, the radially oriented primary cutting edge354A of the radial blade portion344closest to the heel346of the knife340also simultaneously cuts the ribbon194radially, away from the remainder of the liner104. The thickness T of the ribbon194is determined by the extent of outward radial advancement of the knife340since its previous cutting pass. For example, the thickness T may be approximately one-sixteenth of an inch in some embodiments. This thickness may be adjusted as appropriate for different embodiments, e.g., by adjusting the duration of activation of the DC motor320for each revolution of the annular lathe200. It will be appreciated that the width of the ribbon194matches the length L1of the axial blade portion342(seeFIG.12).

FIG.17is a schematic side view of the device300at the conclusion of the plunge cutting stage of operation.FIG.17adopts similar conventions to those used inFIGS.14and15. As illustrated, an annular portion of the elastomeric polymer material has been shaved away from the end section of the pipe. InFIG.17, the knife340, still in its working orientation, has reached an outboard position. In the outboard position, the cutting edge352A of the axial blade portion342is adjacent to the inner surface101of the pipe102. In this position, the flat cutting face356A immediately adjacent to the primary cutting edge352A forms an angle J with the inner surface101of the pipe wall (seeFIG.13). In one embodiment, the angle J is approximately 30 degrees. This angle may be suitable for effectively shaving away elastomeric polymer material having a durometer of approximately 87 Shore A. If the angle is too small, the cutting edge may not be able to effectively “bite” into the elastomeric polymer material. If the angle is too large, the knife340may chatter. The optimal angle may differ for elastomeric polymer materials of different durometers. Device300may be used with multiple swappable knives, each forming a different angle J that is optimal for a cutting a respective type of elastomeric polymer material.

At the conclusion of the plunge cutting stage, rotation of the rotatable annular part204of annular lathe200may be halted. In preparation for the axial cutting stage of operation of device300, the DC motor320may be removed from the motor support bracket360and placed into the other motor support bracket326. The socket322of the DC motor320may be mechanically engaged with the star wheel324, and the DC motor320may be secured to the motor support bracket326.

In some embodiments, the end of the knife carriage arm304furthest from the mounting bracket306may be stabilized prior to commencement of the axial cutting stage. This may be intended to reduce a risk that the knife340will deviate from its working orientation upon being subjected to the forces inherent in this stage. Stabilization may for example be achieved by attaching additional support structure or bracing between that end of the knife carriage arm304and the rotatable annular part204of the annular lathe200. The support structure may take the form of an A-frame member that is anchored to, and spans between, the annular lathe brackets226(not expressly depicted).

To commence the axial cutting stage, clockwise rotation of the rotatable annular part204of the lathe200may be resumed with the knife340still in the outboard position and in the working orientation. With each revolution, the rotation sensor328(when in its active mode) generates a signal that causes the DC motor320to activate for a predetermined time interval. This causes the star wheel324, and thus threaded rod318, to rotate by a predetermined extent. The direction of rotation is such that the knife holder308slides axially along rail314to translate the knife340heel-first. In this case, that direction is away from the mounting bracket306. Each revolution of the annular lathe200of the present embodiment will accordingly cause the knife340to move axially deeper into the pipe150by a predetermined amount without changing the radial position of the knife340.

FIG.18is a schematic side view of the device300during the axial cutting stage of operation. The conventions ofFIG.18are similar to those ofFIG.14. The arrow A denotes progressive heel-first movement of the knife340axially into the pipe150. InFIG.18, the knife340has removed substantially all of the liner104from an axial extent of the pipe102closest to the end160of the pipe over the course of multiple orbits about pipe axis PA.

FIG.19is a perspective view of the knife340partly through the axial cutting stage of operation as viewed from the end160of the pipe150.FIG.19illustrates the manner in which the knife340cuts a single strip198of elastomeric polymer material from liner104during the axial cutting phase. To avoid visual obstruction, only the knife340component of device300is depicted. The rotational movement of the knife340inFIG.19is in direction M, i.e., clockwise.

As illustrated, most of the cutting of the strip198during the axial cutting stage is performed by the radially oriented primary cutting edge354A of the radial blade portion344. However, the axially oriented primary cutting edge352A of the axial blade portion342closest to the heel346of the knife340does simultaneously cut the strip198axially, away from the inner surface101of the pipe102. The thickness TT of the strip198is determined by the degree of axial movement of the knife340since is previous cutting pass. In some embodiments, the thickness TT may be approximately 0.375 inches.

It will be appreciated that, during the axial stage of cutting operation, the radial blade portion344of the knife340cuts through substantially the entire radial thickness of the liner104with each revolution of the annular lathe200. Thus, the height H of the strip198will be substantially equivalent to the thickness of the liner104. The cutting away of the strip198in the radial dimension will leave a clean annular face105on the remaining liner104. In the present embodiment, the face105is orthogonal to the inner surface101of the pipe102. A clean face105may facilitate the splicing of an annular section of replacement liner into the end section of the pipe when the pipe150is eventually joined with another pipe spool.

It will be appreciated that, when the primary cutting edges352A,354A of knife340become dull, the device300may still be used to cut liner104by reversing the direction of rotation of the annular lathe200from clockwise to counter-clockwise. This will result in the alternative cutting edges352B,354B of knife340becoming the leading edges. When the alternative cutting edges become dull, the knife340may be replaced.

With the cutting phase of operation of device300concluded, the knife support structure302may be detached from the tool slide226. To commence the stripping phase, a stripper support structure402may be attached to the tool slide.

FIG.20is a perspective view of a stripper carriage400including stripper support structure402. It will be appreciated that the stripper support structure402is similar in many respects to the knife support structure302described above. For example, the stripper support structure402has a stripper carriage arm404with an axial rail414, a mounting bracket406, a stripper holder408with a threaded bore416, and an axially fixed rotatable threaded rod418engaging the threaded bore and terminated by a star wheel (not visible inFIG.20). Each of these components is analogous to its counterpart component of the knife support structure302, described above. Rotation of the threaded rod418causes the stripper holder408to slide axially along rail414, with the direction of sliding being determined by the direction of rotation.

The stripper holder408holds a rotary stripper490having a wire brush492and an actuator (not visible inFIG.20) for rotating the wire brush492. The rotary stripper may for example be a battery-powered angle grinder, such as a Dewalt™ 60V Flex Volt® Grinder. The wire brush492may for example be a knotted wire brush, such as a Forney™ 72759 Wire Wheel Brush Twist Knot with threaded arbor, 4 inch by 0.02 inch.

In preparation for the stripping phase, the stripper support structure402is attached to the annular lathe200. In the present embodiment, the attachment is indirect via the tool slide226. However, the attachment could be direct in alternative embodiments. The stripper holder408holds the rotary stripper490in a stripping orientation in which at least a portion of the wire brush492will be in contact with the inner surface101of the pipe102.

To commence the stripping phase, the actuator of the rotary stripper490may be activated to cause the wire brush492to rotate. The annular lathe200may then be activated to initiate rotation of the stripper carriage400about the axis of the pipe with the rotary stripper490in the stripping orientation and the rotary actuator rotating the wire brush492. As the stripper support structure402rotates about the pipe, the DC motor320may cause the stripper holder408to progressively move axially along the rail414, using the same mechanism as was used to move the knife340axially along rail314during the axial cutting stage (see, e.g.,FIGS.18and19, described above). Any remaining bits of elastomeric polymer liner material still clinging to the inner surface101of the end section162of the pipe102may thereby be stripped away.

Various alternative embodiments are possible.

It is possible for the orientation of knife340to be reversed so that the heel346enters the pipe150last. In this case, the knife340may be axially aligned at the commencement of the plunge cutting stage so that the annulus of elastomeric polymer material that is removed from liner104by plunge cutting is within the end section162pipe away from the open end160. Thereafter, the knife340may be made to move heel-first axially towards (not away from) the open end160of the pipe150during the axial cutting stage. This approach may be less desirable from an operator visibility standpoint. The reason is that the operator's view of the axial blade portion342of the knife340in the outboard position may be obstructed by as-yet unremoved liner104.

In some embodiments, the axial blade portion of the knife may be shaped differently, with its cutting edges raked radially outwardly from the body of the axial blade portion, i.e., raked in a direction opposite to the direction in which the radial blade portion extends from the heel of the knife. The reason may be to improve cutting performance for certain durometers of elastomeric polymer material during the plunge cutting stage. This is depicted inFIGS.21and22.

FIGS.21and22illustrate an alternative embodiment of knife370in bottom left isometric view and top right isometric view, respectively. The knife370is similar in many respects to the knife340, described above. For example, the knife370has an axial blade portion372and a radial blade portion374joined to form a heel376. The axial blade portion372has a primary cutting edge382A, and the radial blade portion374has a primary cutting edge384A. These cutting edges382A and384A face in the same direction and meet at heel376. The axial and radial blade portions342and344also have alternative cutting edges382B and384B, respectively, each facing in an opposite direction from, and parallel to, its respective primary cutting edge382A and384A. The alternative cutting edges352B and354B similarly meet at heel376. The axial blade portion372has flat cutting faces386A and386B adjacent to cutting edges382A and382B, respectively.

FIG.23is a schematic side view of the knife370in the working orientation upon having reached an outboard position at the conclusion of radial plunge cutting. In the outboard position, the cutting edge382A of the axial blade portion372is adjacent to the inner surface101of the pipe102. In this position, the flat cutting face386A immediately adjacent to the primary cutting edge382A forms an angle JJ with the inner surface101of the pipe wall. In one embodiment, the angle JJ is approximately 45 degrees. It is believed that this angle should be suitable for shaving away elastomeric polymer material having a durometer of approximately 70 Shore A or similar. In another embodiment, the cross-sectional shape of the axial blade portion372may be trapezoidal like that of axial blade portion342, albeit with a 45-degree angle of flat cutting face386A.

Other modifications may be made within the scope of the claims.