Abstract:
A pipe joint between welded exposed metal end sections of coated pipe being formed into a pipeline is cleaned before a corrosion resistant film is applied. A cleaning head of a cleaning mechanism is placed with a mounting frame on the pipe in the area of the pipe ends to be cleaned. The cleaning head moves in a succession of longitudinal cleaning passes in the direction of the longitudinal axis of the pipe area being cleaned. The frame also moves the cleaning head rotatably with respect to the pipe joint to positions for the longitudinal cleaning passes. A control mechanism defines the extent of the longitudinal cleaning passes, and also controls movement of the cleaning head to successive cleaning passes until the pipe joint is cleaned. The control is programmed and automatic, and there is no need for contact with the mechanism while it is in operation. The number of cleaning heads and cleaning material supply and exhaust hoses or tubes, as well as the number of crew required, is reduced.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to cleaning portions of pipe in the areas where adjacent end sections of pipe have been welded together to form a pipeline or the like. More specifically, the present invention provides a new and improved pipe weld cleaner and control mechanism to regulate and control movement of a cleaning head as it moves along and about the welded pipe end portions while cleaning those end portions after they have been welded together. 
     2. Description of the Related Art 
     Pipelines have been for a number of years laid on the submerged floors of bodies of water from pipe laying barges. On the pipe-laying barge, the pipeline length was formed by welding successive lengths or sections of pipe sequentially in an end-to-end fashion to previously welded sections at an end portion of the pipeline. The pipe sections were typically covered with concrete or some other protective coating along their lengths except for the exposed metal end sections. The welded sections extended from the pipe-laying barge into the body of water and were laid or deposited in or on the floor of the body of water. After a length of pipe was welded to the end of the pipeline, and before its entry into the body of water, it has been the practice to clean the areas where the weld occurred so that a corrosion-resistant coating or film of a suitable synthetic resin could be applied. It was also typical after application of the corrosion coating film to apply a protective coating over the corrosion resistant film. U.S. Pat. Nos. 4,909,669; 5,328,648; 5,804,093; 5,900,195 and 6,402,201, owned by the assignee of the present application, are examples of end portion protective covers or coatings for such a purpose. 
     So far as is known, previous machines for pipe cleaning in the area of the welded ends have taken the form of a set of pipe-enclosing collar rings mounted around the circumference of the pipe. The collar rings were longitudinally spaced from each other along the pipe, with the most recently welded section located between them. One or more, usually several, blast material applicator heads and removal heads or evacuators were mounted between the collar rings at selected locations about the periphery of a section of the pipe. 
     The applicator heads and the removal heads were moved in a circumferential arcuate path about an incremental length of the pipe until the full circumferential extent of that section of the length of the pipe has been cleaned. These previous cleaning machines have had problems in movement control. Several crewmembers were required for each machine. In addition to an operator controlling starting and stopping of the machine, typically there were at least two other crew members involved in movement of the cleaning heads to successive sections of the pipe lengths to be cleaned. After a certain length of pipe was cleaned, the mounting rings had to be opened and moved to a new location for additional cleaning. Further, each individual blast material applicator head was provided with a separate supply hose and each individual material removal head with a separate removal hose or tube. 
     Thus, there were several cleaning crew members and a number of hoses in a relatively small area, where a number of applicator heads and removal heads were moving in rotary paths about the circumference of a short length of the pipe section. As a result, movement control was a problem. Also, cleaning operations were time consuming and labor intensive. In addition there were some safety concerns due to the close proximity of some of the work crew to the rotating equipment and supply hoses. 
     SUMMARY OF THE INVENTION 
     Briefly, the present invention relates to a new and improved pipe weld cleaning machine to clean a pipe joint formed at end portions of longitudinally extending joined sections of a coated pipe. A cleaning head of the pipe weld cleaning machine is provided to clean the pipe joint between the coated portions on either side of the pipe joint. A frame mounts the cleaning head in a position disposed for movement with respect to the pipe joint. The frame includes a carriage for repetitive longitudinal cleaning movements along the pipe joint during cleaning. A motor moves the cleaning head on the carriage longitudinally of the pipe joint during the longitudinal cleaning movements. Sensors are provided to detect limits of the longitudinal cleaning movements for movement control purposes. 
     The frame of the machine also includes structure to move the cleaning head and carriage rotatably about the circumference of the pipe to begin cycles of the repetitive longitudinal movements and sensors to detect limits of the rotatable movement of the structure moving the cleaning head and carriage. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A better understanding of the present invention can be obtained when the detailed description set forth below is reviewed in conjunction with the accompanying drawings, in which: 
         FIG. 1  is an isometric view of a pipe weld cleaning machine according to the present invention. 
         FIG. 2  is a side elevation view of the pipe weld cleaning machine of  FIG. 1 . 
         FIG. 3  is a cross-sectional view taken along the lines  3 — 3  of  FIG. 2 . 
         FIGS. 4 and 5  are enlarged isometric views of portions of the pipe weld cleaning machine of  FIG. 1 . 
         FIG. 6  is a functional block diagram of the motors and control system of the pipe weld cleaning machine of  FIG. 1 . 
         FIG. 7  is a functional block diagram of the control system of  FIG. 6 . 
         FIG. 8  is an elevation view of a control panel in the input/output unit of the control system of  FIG. 6 . 
         FIG. 9  is an elevation view of control switches of the control system of  FIG. 6 . 
         FIG. 10  is a side elevation view of a metal pipe joint of the type cleaned according to the present invention 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the drawings, the letter M ( FIGS. 1–3 ) designates generally a pipe weld cleaning machine according to the present invention. The pipe cleaning machine M is adapted to clean a metal pipe joint J ( FIG. 10 ) formed at end portions  10  and  12  of longitudinally extending joined sections  14  of coated pipe P of the type used in pipelines on or in submerged floors of bodies of water. 
     Pipelines have been for a number of years laid on the submerged floors of bodies of water from pipe laying barges. On the pipe-laying barge, the pipeline length was formed by welding end portions  10  and  12  of successive lengths or sections  14  of pipe sequentially in an end-to-end fashion to previously welded sections at an end portion of the pipeline. The pipe section  14  were typically covered with concrete or some other protective coating  14   a  along their lengths except for the exposed metal end sections  10  and  12 . After a length of pipe was welded to the end of the pipeline as indicated at  15 , and before entry of the pipe into the body of water, it has been the practice to clean the areas where the weld  15  occurred and the end sections  10  and  12 . The cleaning was done so that a corrosion-resistant coating or film of a suitable synthetic resin could be applied. It was also typical after application of the corrosion coating film to apply a protective coating over the corrosion resistant film. U.S. Pat. Nos. 4,909,669; 5,328,648; 5,804,093; 5,900,195 and 6,402,201, owned by the assignee of the present application, are examples of end portion protective covers or coatings for such a purpose. The welded sections extended from the pipe-laying barge into the body of water and were laid or deposited in or on the floor of the body of water. 
     The machine M of the present invention is located on a pipe laying barge used in such pipe laying operations. The machine M according to the present invention includes at least one cleaning head H to clean the pipe joint J between the coated sections  14 . Typically, as shown in  FIGS. 1 and 3 , a set or pair of cleaning heads H are mounted in the machine M at positions located on diametrically opposed sides of the pipe joint J. A frame F of the machine M mounts the cleaning head H in a position disposed for successive or repetitive longitudinal cleaning movements in a line parallel to a longitudinal axis  16  of the joined pipe sections  14  along the pipe joint J during such cleaning. One or more motors or power sources S of the machine M move the cleaning head H on the frame F longitudinally of the pipe joint J during the longitudinal cleaning movements. The frame F also moves the cleaning head H rotatably with respect to the pipe joint J at the end of a longitudinal cleaning movement to a new position for the next longitudinal cleaning movement to occur. 
     The frame F includes a first mounting ring  20  and a second mounting ring  22  located at longitudinally spaced positions from each other adjacent to the exposed metal pipe portions  10  and  12  on opposite sides of the area  15  where the pipe joint J is welded. The mounting rings  20  and  22  are generally in the form of inverted U-shaped members and are provided with a suitable number of mounting clips  24  ( FIG. 3 ) which are adapted to receive spacer blocks  26  which rest on appropriate portions of the pipe adjacent the pipe joint J in order to support the machine M on the pipe. 
     Each of the mounting rings  20  and  22  are provided on their respective inner faces  20   a  and  22   a  with a suitable number of support and guide wheels  28  rotatably mounted by bolts or other attachment structure  30 . The mounting rings  20  and  22  are also provided with connector eyelets or openings  25  so that suitable connectors may be attached for lifting, placement and removal of the machine M on the pipe P before and after cleaning operations. 
     The frame F also includes a first support yoke  34  mounted with the first mounting ring  20  to engage the support wheels  28  along an outer peripheral surface  34   a . A gear plate  36  is mounted with the first support yoke  34  between the support yoke  34  and a first mounting ring  20 . The gear plate  36  has a set of gear teeth  38  formed along an outer peripheral portion  36   a.    
     Similarly, a second support yoke  40  is mounted with the second mounting ring  22  to engage support wheels  28  along an outer peripheral surface  40   a . A gear plate  42  is mounted with the second support yoke  40  between the support yoke  40  and the second mounting ring  22 . The gear plate  42  has a set of gear teeth  44  formed along an outer peripheral portion  42   a.    
     The power source or motor P according to the preferred embodiment includes a rotational motor  50  for rotational movement of the support yokes  34  and  40  with respect to the mounting rings  20  and  22 . Preferably, the rotational motor  50  takes the form of a pneumatic or air driven motor mounted with each of the mounting rings  20  and  22 . A suitable motor can be, for example a Model No. 4AM-RV-127-GR20 air gearmotor manufactured by Gast Manufacturing, Inc. of Benton Harbor, Mich. It should be understood that air gearmotors from other sources may be used, and further that other forms of motors than pneumatic or air-driven ones can also be used. The rotational motors  50  are mounted on mounting plates  52  on outer surfaces  20   b  and  22   b  of the mounting rings  20  and  22 , respectively, and may be adjustably located by mounting bolts  54  located in adjustment slots  56 . Each of the motors  50  receives transfer of operating power at inlets  58  and  60  and rotates a shaft  62  mounted extending through associated slots  20   c  and  22   c  of the mounting rings  20  and  22 , respectively. The shaft  62  for each of the motors  50  is rotatable in either of two directions to drive a gear  64 , which engages the gear teeth  38  and  44  to cause the support yokes  34  and  40  to rotate with respect to the mounting rings  20  and  22 . 
     A position encoder mechanism  66  is mounted with one or both of the mounting rings  20  and  22  has a rotatable gear  68  which is engageable with the associated gear teeth  38  and  44  of the gear plates  36  and  42 , respectively. The position encoder or encoders  66  provide indications or signals of relative movement of the support yokes  34  and  40  to a controller C for control of relative movement and position of the support yokes  34  and  40  with respect to the mounting rings  20  and  22 . 
     The support yokes  34  and  40  are rotated with respect to the mounting rings  20  and  22  through the action of the rotational motors  50  on the gear teeth  38  and  44 . It is also to be noted that there is no direct connection between the support yokes and mounting ring at each end of the machine M, eliminating interference between their respective relative movement. If desired, the rotational motors  50  may be provided with a sprocket and the support yokes provided with a chain around their circumference as an alternative. 
     A rotational limit sensor or proximity switch  70  is mounted with one or both of the mounting rings  20  and  22  to sense rotational limits of the cleaning head H with respect to the pipe joint J and provide limit sense signals or movement indications over conductors  71  to the controller C. Such signals indicate that a rotational limit of movement of the support yokes  34  and  40  with respect to the mounting rings  20  and  22  has been reached. The rotational limit sensor  70  may be an optical, metallic, magnetic or other suitable sensor to sense the presence of a corresponding optical, metallic, magnetic or other target located on the support yokes  34  and  40  at the limit of relative rotational travel of the support yokes  34  and  40  in either direction with respect to the support rings  20  and  22 . When the rotational limit sensor  70  detects a limit of relative rotational travel, an indication or signal is provided to the controller C to stop operation of the rotational motors  50  so that the direction of relative rotation can be reversed. 
     The support yokes  34  and  40  are connected together by a suitable number of connector rods or bars  74  extending between inner faces  34   a  and  40   a  of the support yokes  34  and  40 , respectively. A carriage G of the frame F in the form of a number of carriage rods or beams  76  is also mounted between the surfaces  34   a  and  40   a  of the support yokes  34  and  40  for mounting the cleaning head H on the frame F. 
     An upper carriage rod  78  has a rack gear  80  ( FIGS. 1–3 ,  5 ) mounted extending between the mounting rings  34  and  40  on opposite sides of the longitudinal axis of the pipeline and the external surface of the pipe joint J being cleaned. 
     The rack gears  80  ( FIG. 5 ) of the machine M are engaged by gears  82  of a longitudinal motor  84  of the power source P on each side of the pipe joint J. The longitudinal motors  84  each move the cleaning head H on the carriage G longitudinally of the pipe joint J during the longitudinal cleaning movement of the cleaning head H. A suitable motor for the longitudinal motor  84  may be, for example, a Model 31 MR-917 Buckeye® Motor from Cooper Tools of Lexington, S.C. It should be understood that pneumatic motors from other sources may be used, and that other forms of motors than pneumatic or air-driven one can also be used. It should also be understood that rather than a gear drive for longitudinal movement, a chain or wire rope drive mechanism may instead be used. Each longitudinal motor  84  is mounted for adjustable positioning on the motor support plate  86  by suitable mounting structure. An example as shown may take the form of a mounting plate  85  and connector bolts  83  or other suitable attachment devices extending through adjustable slots  87  formed in the motor support plate  86 . 
     A set of movement wheels or rollers, including an upper roller set  88  and a lower roller set  90 , are mounted with the motor support plate  86  for allowing longitudinal movement of the motor  84  along the carriage G. The movement wheels in the roller sets  88  and  90  engage and are supported by upper carriage rod  78  and a lower carriage rod  76  of the carriage G. Preferably, the movement wheels of the roller sets  88  and  90  have grooved surfaces  88   a  and  90   a  formed therein to rest and ride upon rail portions  78   a  and  76   a  of the respective carriage rods  78  and  76 . The amount and direction of movement of the cleaning head H is controlled by signals and power furnished to the motors  84  over conductors or connectors  92  and  94 . 
     The mounting support plate  86  further has a blast applicator head or cover  100  of the cleaning head H mounted at a central portion  96  thereof. The cleaning head H may be one of several conventional, commercially available types, such as a Model PBV08-2 from VacuBlast International of Berkshire, England. The blast applicator head  100  applies abrasive or other suitable cleaning particles provided by the cleaning head H to the pipe joint J being cleaned. The abrasive particles are provided at a connector joint  102  under pressure of air or other suitable gas through a pipe or conduit from a supply source for cleaning purposes. The abrasive particles from the blast applicator head  100  contact the pipeline joint J being cleaned. The cleaning head H may also take other forms to clean and remove rough surfaces and welding by-products or remnant material from external portions of the pipe joint J. The cleaning head H serves to clean the pipe joint surfaces so that a smooth surface is present for subsequent application of a corrosion resistant coating or film of suitable type in the conventional manner. 
     Spent abrasive particles and metal and other waste materials removed by the blast cleaning operation are gathered under suction or partial vacuum in the cover head  100  of the cleaning head H and transported by a return line  106  of the cleaning head H through a conduit or connection. 
     The motor support plate  86  also has arm or lug extensions  110  ( FIG. 5 ) extending outwardly therefrom at suitable locations. The arms  110  serve as limit indicators and are sensed by longitudinal limit sensors  112  mounted at opposite portions on a support rod  114  of the carriage G on each side of the pipeline joint J. The longitudinal limit sensors  112  are mounted at adjustably located positions on the support rod  114  by clamps or other adjustable attachment mechanisms  118  to adjust the longitudinal placement and thus the longitudinal movement of the cleaning head H with respect to the pipe joint J. The longitudinal movement sensors  112  may be optical, metallic, magnetic or other suitable sensors to sense the presences of a corresponding optical, metallic, magnetic or other target located on the arms  110 . The longitudinal movement sensors  112  form an indication or signal indicating that a limit of relative longitudinal travel of the cleaning head H in either longitudinal direction with respect to the pipe joint J has been obtained. 
     When the longitudinal limit sensors  112  sense the limit of relative longitudinal travel, an indication or signal is provided over conductors  115  to the control mechanism C to stop operation of the motor M. At such time, the directional limit of longitudinal travel of the cleaning head H during a longitudinal cleaning movement with respect to the pipe joint J has been achieved. The position of the cleaning head H and the frame F with respect the pipe joint J can then be adjusted so that a new longitudinal cleaning movement may begin. 
     The controller C controls operation of the machine M based on settings provided by an operator at an input/output unit I ( FIG. 8 ) and a control switch panel L ( FIG. 9 ). The controller C may be a programmable logic controller or PLC, of any suitable commercial type, such as a Model D4-450 CPU from Koyo Electronics Industries Co., Ltd. of Tokyo, Japan. The controller C can also take the form of other process control apparatus or computers, such as a personal computer, laptop computer or other form of computer, with appropriate interface or signal conditioning circuits to the encoders, sensors and motors of the machine M. The controller C, unit I and panel L are preferably located in an enclosure for protection from conditions on the deck of the pipe barge. As is conventional, the controller C is provided with an uninterrupted power source or UPS for protection against power transients or surges. 
     The input/output unit I ( FIG. 8 ) includes a control input button  120  which allows an operator to select whether the cleaning head is to be active in cleaning the pipe joint J in only one direction of longitudinal scan or movement of the carriage head H with respect to the pipe joint J, or in both longitudinal directions or scans. An indicator or light  122  in the unit I is energized when bi-directional longitudinal cleaning passes are selected. An indicator or light  124  in the unit I is energized when, in the alternative, only one direction of longitudinal cleaning passes or scans are selected. A screen or display panel or other suitable alphanumeric indicator  125  is provided in the unit I to allow an operator of the machine M to receive messages from the PLC of or the controller C to view instruction codes or settings sent to the PLC. 
     A control input button  126  allows an operator to select the amount or increment of each rotational step of the support yokes  34  and  40  with respect to the mounting rings  20  and  22  between longitudinal scans. As noted above, the longitudinal scans are set to be either one-directional or bi-directional by input button  120 . In this way, the cleaning heads H move in a raster-like scan of longitudinal movements or passes along the pipe joint J in the direction of the longitudinal axis  16 . A control input button or key  128  is provided in the unit I to allow an operator to identify to the controller C the position of a home position or starting position for the support yokes, carriage head and other structure of the frame F is to be provided. The values or codes defining the starting position may then be entered through a keypad  130  with numerical selected keys  132 . 
     Similarly, a control input button or key  134  is provided to allow an operator to notify the controller C of an end point or furthest position the support yokes are to move with respect to the mounting rings. This serves to define final position of the moveable components of the frame F. The values or codes defining the end point are entered thru the selected keys  132  of the keypad  130 . A control input key  136  is provided to notify the controller C of the amount of time which elapses after the machine M is activated for cleaning operations, and before the activation of the blast head B begins. The amount of time can be entered by way of selected key  132 . 
     The control switch panel L ( FIG. 9 ) includes a control switch  140  which has three settings, an OFF position the cleaning apparatus to an off or deactivated position; an AUTO position where blast cleaning operations proceed automatically under the control of the controller C; and a HAND position for allowing the operator to manually control the operation of the blast cleaning head H. The mode control switch  140  must be in the AUTO position before position of the start button  142  is able to begin operation of any cleaning cycle. The control switch panel L also includes a start button  142 , which allows the operator to start the automatic cycle operation when the mode control switch  140  is in the AUTO position. The control switch panel L further includes a stop control button  144 , which stops the machine at any current position of its operating cycle and returns the machine M to the home position. The control switch panel L also includes a blast control switch  146 , which activates the operation of the blast cleaning head. 
     A movement control switch  148  of the control switch panel L allows an operator to move a first of the cleaning heads to the left or right as desired. Similarly, a movement control switch  150  of the control switch panel L allows an operator to move the other of the two cleaning heads to the left or right, as desired. Finally, a control switch  152  of the control switch panel L allows an operator to select the direction of rotation the support yokes  34  and  40  with respect to the mounting rings  20  and  22 , namely either counter clockwise or clockwise, as desired. 
     From the foregoing, it can be seen that the machine M is safe, efficient, reliable and clean in operation. There is no wrapping about the pipe joint J of the supply hoses, due to the raster scan movements of the cleaning heads H. The machine M can be controlled and operated by a single operator and fully automatic. There is also no need for contact with the machine M while it is in operation. 
     In the operation of the present invention, using for example an automatic double pass of the cleaning head H, the mounting rings  20  and  22  are lowered onto the pipe joint J. The mounting rings  20  and  22  are centered on the pipe joint J using the spacer blocks or stand offs  26 . 
     The start button  142  is then pressed. The support yokes  34  and  40  rotate until proximity switch  70  opens, stopping the rotation and resetting the encoder mechanism  66  to zero. The cleaning heads H move longitudinally until limit sensors  112  at one end of the carriage G sense the presence of extensions  110  on the support plate  86  and close. The controller C then stops longitudinal movement of the cleaning heads H on the carriage G. 
     The switch  146  is then activated, starting the flow of blast media from the blast machine. When proximity sensor  70  is open and proximity sensors  112  are closed the blast delay timer begins. At the end of the blast delay, motors  84  are activated by the controller C. The cleaning heads H begin to move longitudinally along the pipe joint J, applying abrasive particles or otherwise cleaning the pipe joint. When the support plate  86  for one of the moving cleaning heads H nears a proximity sensor  112  at the end of a first directional longitudinal scan, the controller C causes the motor  84  for that cleaning head to stop and then reverse direction. The same procedure is followed for the other cleaning head H at the completion of its first directional cleaning scan, although it need not occur at the same time. 
     The cleaning heads H then each begin movement in a return or reverse direction to the first directional scan, moving over the pipe joint J during their reverse travel, cleaning the pipe joint J. For bidirectional cleaning movement, the cleaning heads H clean the pipe joint J in each direction of their longitudinal movement. As noted, the cleaning activity for one cleaning head H may also be set to occur only during one direction of movement, if desired. Movement in the reverse or return direction continues until the proximity sensors  112  inform the controller C that a full cycle of a first directional scan and a return or reverse longitudinal scan is completed. At the end of one full cycle of travel as detected by proximity sensors  112 , the controller C activates the motors  50 . The motors  50  then move the support yokes  34  and  40  with respect to the mounting rings  20  and  22  by an incremental amount of rotational travel which is set into the controller C by step count input switch  126 . After rotation by the established amount, the cleaning heads H perform another cycle of longitudinal scans along the pipe joint J. The cleaning heads H continue cycles of back and forth movements, and rotation between cycles, until the end count set by input switch  134  is reached. At this time, the pressure supply to the cleaning heads H disengages and the support yokes  34  and  40  return to their home position on their respective mounting rings  20  and  22 . The machine M can then be lifted and the pipe advanced to move the pipe joint J for a protective coating to be applied. 
     It should be noted and understood that there can be improvements and modifications made of the present invention described in detail above without departing from the spirit or scope of the invention as set forth in the accompanying claims.