Abstract:
A diverless process of tapping a pressurized subsea pipeline without removing the pipeline from service. The process includes the steps of lowering and landing a measurement tool onto the pipeline in order to check ovality and straightness of the pipeline with the measurement tool. Pipe lift frames are lowered and landed onto the pipeline spaced from a chosen location. The pipeline is lifted by hydraulic actuators or mechanical screws on the lift frames. A hot tap fitting and accompanying orientation frame are lowered and landed on the pipeline between the pipe lift frames. The pipe lift frames are incrementally raised until the pipeline is fully seated in the hot tap fitting and orientation frame. A fitting clamp is secured to the pipeline. A hot tap machine is lowered onto the hot tap fitting and orientation frame. The pipeline is then tapped with the hot tap machine. The pipeline is thereafter lowered by deflating the lift frame bags.

Description:
CROSS-REFERENCE OF RELATED APPLICATION 
     This application claims priority to U.S. Provisional Patent Application No. 60/128,014 filed Apr. 6, 1999, entitled DIVERLESS SUBSEA HOT TAP SYSTEM. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention. 
     The present invention relates to a diverless process for tapping a pressurized subsea pipeline without removing the pipeline from service. This diverless process utilizes specialty clamping equipment, tapping equipment and remote operating vehicles for operating at water depths beyond that accessible by divers. 
     2. Prior Art 
     Various kinds of underwater pipeline work have been carried out using divers equipped with various tools. Deep water conditions entail high subsea pressure and dangerous conditions. Manned or diver equipped operations are not suitable if the pipeline is at a depth which is inaccessible by divers. 
     Remote operating vehicles perform visual and operational functions that are more limited than those functions performed by divers. To compensate for this limitation, processes must be developed to adapt the available technology to the work requirements. These processes are typically referred to as “diverless”. Developed diverless processes are easily adapted for use using divers and/or control from the sea surface in diver accessible water depths. 
     It has been proposed in the past to utilize a diverless underwater pipe tap system. De Sivry et al. (U.S. Pat. No. 4,443,129) discloses an example of a diverless underwater pipe tap system including a lifting device to engage and displace the pipe, a working platform installed vertically above the tapping region and various tools used to carry out operations including concrete stripping, ovality or roundness measurement, and a tapping operation. De Sivry et al. contemplates cutting out a section of the pipeline. There is no disclosure or suggestion of a tap procedure while the pipeline is under pressure and de Sivry would not be suitable for such an operation. 
     Likewise, various hot tap machines for tapping into a pipeline while the pipeline is pressurized have been disclosed. Reneau et al. (U.S. Pat. No. 4,223,925) discloses one example of a hot tap machine for an underwater pipeline. It is advantageous to perform work on the pipeline without interrupting the flow of liquids or gases therethrough. 
     It is also known to provide a remote operated subsea vehicle (ROV) controlled from the surface which includes thrusters or other mechanisms for propelling it through the water in response to a source of power at or controlled from the surface. 
     Brooks et al. (Re27,745) illustrates an example of a submersible wireline robot unit that may be controlled remotely. 
     None of the foregoing would be suitable for deep water conditions where the external subsea pressure is extreme. 
     Given that the life spans of certain deep water oil and gas developments will be coming to an end in the near future, there will be an increasing number of existing pipelines which have excess transport capacity, thereby leaving excess pipeline infrastructure in deep water locations. 
     If production from new fields can be tied into existing pipelines, then the investment in the pipeline can be spread out over more than one development. A diverless hot tap capability would allow the extension of pipelines from new fields to be connected to existing pipelines. This will reduce the overall length of the pipeline required to support a new field. 
     It would also be possible to lay new trunk lines into areas in order to support multiple future field developments which would use lateral pipelines without having to pre-install connection facilities and valves at predetermined locations along the pipeline. 
     Additionally, in deep water oil and gas developments, the cost of the pipeline infrastructure is estimated to be the majority of the cost of all of the installed subsea equipment. 
     As an alternative to diverless hot tap systems, it would be possible to take an existing line out of service, cut a section of the pipeline and bring it to the surface, install a valve, lower the section back to the bottom and reconnect with a suitable jumper. Such an approach is not only time-consuming but requires the pipeline to be out of service. It would also be possible to pre-install blind branch connection facilities in the pipeline for future tie-ins. A disadvantage is that a great number of branch facilities would have to be installed to cover all possible future tie-in locations, a procedure that would be both time-consuming and expensive. 
     Notwithstanding the foregoing, there remains a need for a diverless process of tapping a deep water subsea pipeline under high pressure without removing the pipeline from service. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a diverless process for tapping a deep water, pressurized subsea pipeline without removing the pipeline from service. 
     During the initial stages of the process, a pipeline will be located and a preliminary visual condition inspection will be conducted through use of cameras. Cameras would be incorporated in a remote operating vehicle which is known in various configurations. The pipeline will be inspected in the area of interest and a pipe section will be identified. If the pipe contains a longitudinal weld or seam, the location of the seam will be identified. It is preferred, but not required, to select a location where a weld seam is not cut out with the hole being bored into the pipe during the tapping operation. For seamless pipe, this step is ignored. Additionally, a location will be identified away from any circumferential weld so that no section of the hot tap fitting will be over a circumferential field weld joint. 
     Soil will be excavated from underneath the pipeline at the chosen location to allow unrestricted installation of the tools. The remote operating vehicle will be utilized to remove soil from underneath the pipeline and create a hole or an exposed area. The pipeline will be cleaned using a brush and/or a low pressure water jet powered by the remote operating vehicle. 
     Once the foregoing preliminary procedures have been completed, a measurement tool will be lowered from the surface on to the pipeline in order to check circumferential roundness or ovality of the pipeline while simultaneously checking the straightness of the pipeline. The measurement tool will be powered by the remote operating vehicle. 
     A pair or more of pipe lift frames will be lowered from the surface to straddle the pipeline, the lift frames spaced as appropriate, along the pipeline axis, and on opposing sides of the hot tap location. Each pipe lift frame will include a pair of platforms containing screw or hydraulic mechanisms, located on each side of the pipeline, which are used to position and raise or lower a pipeline lifting tong. 
     Between the pair of platforms is a transverse beam from which extends the pipe tong. Each pipe tong may be positioned transversely to the axis of the pipeline and lowered onto the pipeline using the hydraulic system from the remote operating vehicle or a mechanical screw. Each lift platform may also include a mud mat which is adjustable with respect to the lift frame. 
     The lift frames will position the pipeline to a desired height in an even and incremental sequence by the aforementioned mechanical or hydraulic mechanisms contained in each of the platforms thereby creating an upward net force. The mechanisms are powered by the remotely operated vehicle (ROV) in the same manner as the aforementioned tong and its associated manipulation mechanism. Subsequently, the pipe tongs are mechanically locked onto the pipeline in an elevated position. 
     After lifting the pipeline in preparation for installation of the hot tap fitting clamp assembly, around the pipeline, the measurement tool will again be utilized to check the circumferential roundness or ovality and straightness of the pipeline. 
     In the event the pipeline contains a longitudinal weld and it is deemed necessary to remove the protruding surface of the weld, a weld bead removal tool will be lowered from the surface and landed onto the pipeline. The remote operating vehicle will be docked into the weld bead removal tool and hydraulic and control connections will be made. The weld bead removal tool will remove any protrusion of the longitudinal weld by machining a section of the weld along the pipeline. 
     In the next step of the sequence of the invention, a hot tap fitting clamp assembly and its associated orientation frame will be lowered from the surface and landed on top of the pipeline at the designated location between the lift frames. The hot tap fitting clamp assembly comprises the piping components for the lateral branch connection: a clamp with a branch port and with associated fasteners or studs, a valve having opening and closing features for the branch connection, and a connector hub for connection of the hot tapping machine and subsequently the lateral pipeline. These piping components are preassembled prior to being placed in the fitting and orientation frame. 
     The orientation frame includes a plurality of mud mats to support the hot tap fitting clamp assembly and hot tapping machine in soft soils. These mud mats can be extended and retracted by either hydraulic cylinders or mechanical screws so as to level the frame and support the weight of the equipment. The mud mats may be articulated to aid in the transportation and launching of the orientation frame. 
     Using the remote operating vehicle and its hydraulic system, the diverless hot tap fitting clamp assembly and orientation frame will be leveled. 
     In a preferred embodiment, the fitting and orientation frame includes four uprights, each of which is parallel to the other and each of the uprights are perpendicular to the axis of the pipeline. The orientation frame includes level indicators to measure the tilt, if any, and make leveling adjustments to the frame. 
     The orientation frame houses the hot tap fitting clamp assembly on supports designed to not obstruct the operation of closing the clamp body around the pipeline or rotation of the assembly about the pipeline. The hot tap fitting clamp assembly is made to surround the pipeline, in the closed position, by operating its own hydraulic pistons, or mechanical screws. 
     A plurality of guide posts are lowered from the surface onto the uprights of the orientation frame. The guide posts serve to guide and retain the hot tapping machine to be described herein. The guide posts are different lengths to facilitate the landing of the equipment. 
     The hot tap fitting clamp will be closed to surround the pipeline using hydraulic pistons or mechanical screws attached to the body of the clamp powered and controlled by the remote operating vehicle. The remote operating vehicle will also position the fasteners or studs for securing the body seals of the clamp. A torque tool or stud tensioning assembly will be lowered onto the guide posts, if not preinstalled with the hot tap fitting clamp assembly. The remote operating vehicle will be docked into the torque tool or stud tensioning assembly. Studs on the fitting clamp will thereafter be tightened by said torque tool or stud tensioning assembly. Upon completion of this operation, the torque tool or stud tensioning assembly will be retrieved to the surface. 
     Using a hydraulic piston and pinion arrangement, or other hydraulic mechanism for imparting a rotary motion, the hot tap fitting clamp assembly, which includes a valve and connector hub for the branch connection, is rotated from a side orientation to an upright position with respect to the pipeline. In the upright position, the valve will be vertical and parallel to the uprights and the guide posts. The remote operating vehicle will actuate a grip and seal mechanism in the hot tap fitting clamp to lock the hot tap fitting clamp and to make a seal with the pipeline. Finally, the pipeline will be lowered by the pipe lift frames until the pipeline is supported on the orientation frame. 
     The next operation describes a diverless method to connect the hot tapping machine to the hot tap fitting clamp assembly. The hot tap machine and its accompanying frame will be lowered onto the orientation frame through the use of the guide posts. The hot tap machine will be brought into position above and in approximate alignment with the lateral connection hub that is part of the hot tap fitting clamp assembly. The next operation involves the precision alignment of the connecting hubs (one on the hot tap fitting clamp assembly and one on the hot tap machine) and the landing of sealing surfaces so as to avoid damage in consideration of the weight of the equipment. The connectors are designed with various tapered surfaces to align the sealing faces as they are positioned for contact by the force of the weight of the top connector. An integral part of the connectors are hydraulic cylinders that control the final make-up of the two hubs. Additional hydraulic cylinders are used to latch and unlatch the hubs. 
     An alternate method for lowering the hot tap machine onto the connecting hub would involve a plurality of pistons, or other hydraulic mechanisms, attached to the hot tap orientation frame and the hot tapping machine which will control the height and rate of descent of the hot tap machine with respect to the hot tap frame. Once the hot tap assembly has been set in position using the guide posts, the hot tap machine will be carefully lowered through use of the pistons, or other hydraulic mechanisms, on the hot tap frame and a seal will be made with the hub of the connector on the hot tap fitting clamp assembly. This method would allow for other styles of connectors that do not have the integral controlled landing features to be employed. 
     The hot tap machine will tap the pipeline using its cutter mechanism by passing through the valve, in its opened position, and engaging the pipeline. Thereafter, the cutter of the hot tap machine and pipe coupon will be retracted and the valve will be closed. 
     The pipe lift frames will then lower the pipeline and the accompanying fitting clamp back to the sea floor. 
     A series of steps will be taken to connect a production branch line or extension of another pipeline to the lateral hub of the hot tap fitting clamp assembly on the existing pipeline. With the production branch line terminating in a second production hub and valve assembly, the distance and relative orientation between the hot tap fitting clamp assembly as assembled on the pipeline and with the upright valve and connector hub on the production branch line will be measured. A pipeline jumper which contains mating connector hubs for connection at each end will be built to match the dimensions. The jumper is then lowered and guided by the remote operating vehicle onto the mating hubs at each respective end by the methods previously described in the setting of the hot tapping machine. The jumper will be lowered until the sealing faces meet. After the jumper is connected, the various guide posts and the pipe lift frames will. be retrieved to the surface. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 illustrates an underwater deep sea pipeline residing on a sea floor or sea bed prior to application of the present invention; 
     FIG. 1A illustrates a remote operating vehicle that may be utilized in the process of the present invention; 
     FIG. 1B is a perspective view of a measurement tool which is used as a part of the process of the present invention; 
     FIG. 2 illustrates installation of a pair of pipe lift frames, part of the process of the diverless hot tap system of the present invention; 
     FIG. 2A is an enlarged view of one of the pipe lift frames, which is part of the process of the present invention; 
     FIG. 3 illustrates a weld bead removal tool on the pipeline, which is a part of the process of the present invention; 
     FIG. 4 illustrates installation of an orientation frame containing the assembly of hot tap fitting clamp, valve and connecting hub installed on the pipeline between the pipe lift frames; 
     FIG. 5 illustrates installation of the guide posts on the orientation frame and the use of a torque tool assembly to affix the hot tap fitting clamp on the pipeline; 
     FIG. 6 illustrates the hot tap fitting clamp and its repositioning from a side orientation to an upright orientation; 
     FIG. 6A illustrates an enlarged view of the orientation frame to show movement of its pipe supports. 
     FIG. 7 illustrates the lowering of a hot tap machine and accompanying frame onto guide posts of the orientation frame; 
     FIG. 8 illustrates the initial alignment of the connector hub on the hot tap fitting machine and the hub on the lateral connection of the hot tap fitting clamp assembly; 
     FIG. 9 illustrates the final alignment utilizing hydraulic pistons or other hydraulic mechanism, on the hot tap frame to lower the hot tapping machine onto the hub of the hot tap fitting clamp assembly; 
     FIG. 10 illustrates a production line and terminating production hub which will be connected to the pipeline; 
     FIG. 11 illustrates the attachment of a pig catcher or pig launcher to the production hub prior to connection of the production line to the pipeline; 
     FIG. 12 illustrates lowering of a jumper which is made to span between the production hub and the fitting clamp; 
     FIG. 13 illustrates lowering of the jumper in alignment with the production hub and the pipeline fitting clamp valve for use of the guide posts on the orientation frame and on the production frame; 
     FIG. 14 illustrates the final lowering through use of valves on a jumper frame to brings the jumper into sealing alignment; and 
     FIG. 15 illustrates the final connection of the jumper following which removal of the guide posts and pipe lift frames will be accomplished. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the drawings in detail, FIG. 1 illustrates a section of an underwater deep sea pipeline  12  residing on and supported by a floor  14  of the sea. FIG. 1, thus, illustrates the pipeline  12  prior to application of the process and pieces of the present invention. The pipeline  12  will consist of a number of sections joined together with circumferential welds  16 . Depending on the size of the pipeline and other factors, longitudinal welds (not seen) may also be encountered. Deep water locations (such as depths over 1,000 feet) are known to produce high pressure conditions external to the pipeline, relative to the internal pressure of the line. The present invention is adaptable to various diameter pipelines, where internal pressure is above or below ambient pressure, but is particularly useful for 10″ to 20″ diameter pipelines. 
     A remote operating vehicle or ROV  18 , such as shown in FIG. 1A, will assist in performing many of the steps or operations to be described in the present invention. The remote operating vehicle  18  will be controlled and powered from the surface. During the initial stages of the process of the invention, the pipeline  12  will be located and a comprehensive series of procedures will be performed. A preliminary visual condition inspection will be conducted through use of ROV cameras. The bottom conditions will be reported, the visibility surrounding the pipeline will be reported, the type of soil on the sea floor will be reported, the water current: will be reported and the depth of the pipeline will be reported. Additionally, the location of: circumferential pipeweld seams and longitudinal welds, if any, will be reported. The condition of any coating on the pipeline, such as concrete, polyethylene, fusion bonded epoxy, will also be reported. 
     The pipeline  12  will be inspected in the area of interest and a pipe section will be identified having a weld seam, if applicable, at a suitable position. If the pipe contains a longitudinal weld or seam, the location of the seam will be identified. It is preferred to select a location where a weld seam is not cut out with the hole being bored into the pipe during the tapping operation. For seamless pipe, this step is ignored. Additionally, a location will be identified away from any circumferential weld so that no section of the hot tap fitting installed will be over a circumferential field weld joint. Accordingly, the hot tap procedure to be described will not interfere with any such longitudinal weld. 
     A circumferential field joint  16  will be located and then a location along the pipeline  12  will be located away from the circumferential weld so that there will be no section of the hot tap fitting installed over the circumferential field joint weld. 
     At the outset, soil will be excavated from underneath the pipeline  12  to allow unrestricted installation of tools to be described herein. In one procedure, the remote operating vehicle  18  will employ a pump to create a jet of sea water to remove soil from underneath the pipeline and create a hole or an exposed area. This may be accomplished in several ways such as by pumping away or sucking away the soil. 
     Thereafter, the pipeline  12  in a selected location will be cleaned using a brush or a low pressure water jet powered by the remote operating vehicle  18 . In some instances, external protective pipeline coating, such as fusion bonded epoxy and the like, may be required to be removed prior to proceeding. 
     Lee (U.S. Pat. No. 4,880,335) discloses one system of subsea removal of cement or concrete coatings from pipes. Other types of known coating removal would, of course, be possible within the scope of the invention. 
     Once the foregoing preliminary procedures have been completed, a measurement or metrology tool  19 , as seen in FIG. 1B, would be lowered onto the pipeline  12  at the chosen location in order to inspect the circumferential roundness or ovality of the pipeline while simultaneously checking the straightness of the pipeline. The measurement tool  19  is operated by the remote operating vehicle  18 . The tool  19  moves a probe and camera back and forth axially as well as around circumferentially on the pipe surface to measure ovality and check for surface imperfections. If the pipeline is determined to be within the tolerances of roundness and straightness, the measurement tool may be removed and returned to the surface. Alternatively, the measurement tool might be left on the pipeline  12  for use at a later sequence in the operation. 
     If the pipeline fails the roundness and straightness test, the measurement tool will be axially moved to another location on the pipeline  12  and the measurement test will be re-performed. 
     Once a suitable location on the pipeline  12  has been determined, a plurality of pipe lift frames,  20  and  22 , will be lowered from the surface to straddle the pipeline as best seen in FIG.  2 . FIG. 2A shows an enlarged drawing of one such pipe lift frame  20 . 
     In the present embodiment, at least a pair of pipe lift frames  20  and  22  will be utilized. In some applications, four pipe lift frames (not shown) will be utilized to achieve the desired result. Each pipe lift frame  20  and  22  will include a pair of opposed support platforms  24  and  26  which will be lowered on opposite sides of the pipeline  12 . Each platform contains hydraulic or screw mechanisms. Between the platforms  24  and  26  is a transverse beam  28  from which extends a pipe tong  30 . 
     Each pipe lift platform  24  and  26  may include a mud mat, lift bags (not shown in FIGS. 2 and 2A) or other methods of support. 
     The pipe tongs  30  may be moved transversely or perpendicular to the axis of the pipeline  12  and lowered around the pipeline  12  using the hydraulic system from the remote operating vehicle  19 . The lift frames  20  and  22  will be brought to a desired height in an even and incremental sequence by the lifting device  32  and  34  contained in each of the platforms  24  and  26 . In one preferred method, the hydraulic devices include bags which are actuated with hydraulic power supplied by the remote operating vehicle  18  (not shown in FIG.  2 ). Subsequently, the pipe tongs  30  are mechanically locked onto the pipeline  12  in the elevated position. 
     Once the pipe lift frames  20  and  22  have been installed as described, the measurement tool  19  will then again be utilized to check the circumferential roundness or ovality and straightness of the pipeline. 
     If the measurement tool has not remained on the pipeline  12 , it will be reinstalled on the pipeline  12  between the lift frames  20  and  22 . The remote operating vehicle will be docked into the measurement tool and the hydraulic and electronic control connections will be made. The roundness or ovality and straightness of the pipeline will again be checked in order to determine any effects of the foregoing pipe lifting on the pipe. If the pipeline  12  is within the desired tolerances, the measurement tool  19  will be removed. If the pipeline fails the check, the pipe lifting frames may be readjusted and a new location chosen for the forthcoming hot tap. 
     The next step in the sequence shown in FIG. 3 will only be performed if the pipeline contains a longitudinal weld. If deemed necessary, a weld bead removal tool  40  will be lowered from the surface and landed onto the pipeline  12  as shown in FIG.  3 . The remote operating vehicle  18  (not shown in FIG. 3) will be docked into the weld bead removal tool  40  and the hydraulic and control connections will be made. The weld bead removal tool  40  will remove any protruding longitudinal weld by machining the weld bead from the pipeline  12 . Thereafter, visual inspection through a camera will be made. Finally, the weld bead removal tool  40  will be removed from the pipeline and returned to the surface. The weld bead removal tool will be used in those instances where a longitudinal weld has been found and the tool must be removed prior to the hot tap to be performed. 
     In a step to be performed prior to the tapping of the pipeline, a hot tap fitting clamp will be inspected and prepared for operation. The various seals on the hot tap fitting clamp will be checked. The hot tap fitting clamp will also be rigged for vertical orientation. 
     The next step in the sequence of the invention is illustrated in FIG.  4 . The pipe lift frames  20  and  22  are lowered so that the pipeline  12  will likewise be lowered. A hot tap fitting and its associated orientation frame  48  will be lowered from the surface and landed on top of the pipeline  12  between the pipe lift frames  20  and  22 . The frame  48  may include a pair of opposed mud mats  50  (one visible in FIG.  4 ). The mud mats  50  are movable by hydraulic cylinders between an extended and retracted position. The mud mats will be placed in the retracted position during lowering. The mud mats  50  will be extended and lowered before final touchdown on the sea floor  14 . The mud mats  50  will be operated by the remote operating vehicle hydraulic system. 
     Thereafter, the pipe lift frames  20  and  22  will be raised until the pipeline  12  is fully seated in the saddles of the orientation frame  48 . Using the remote operating vehicle hydraulics system, the orientation frame  48  will be leveled. Thereafter, the pipe lift frames  20  and  22  will be locked in place. 
     In the present embodiment, the orientation frame  48  includes four uprights  42 ,  44 ,  46  and  47 , each of which is parallel to the other. It will be appreciated that while a plurality of uprights is advantageous, the number is a matter of choice. 
     The frame  48  also includes an associated hot tap fitting clamp assembly  54 . The hot tap fitting clamp assembly comprises the piping components for the lateral branch connection: a clamp with a branch port and with associated fasteners or studs, a valve having opening and closing features for the branch connection, and a connector hub for connection of the hot tapping machine. The hot tap fitting clamp assembly  54  is lowered over the pipeline at the selected location. The fitting clamp  54  is initially closed using its own hydraulic pistons and a plurality of fasteners or studs are pushed in. The remote operating vehicle (ROV)  18  will initially be used to hydraulically close the fitting clamp around the pipeline. 
     With reference to FIG. 5, either before or after closing the fitting clamp  54 , a plurality of guide posts  60 ,  62 ,  64  and  66  are lowered from the surface onto the uprights  42 ,  44 ,  46  and  47 , respectively, of the orientation frame  48  to guide and retain. While the guide posts may be of various configurations, in the present embodiment they have frusto-conical shaped, open bases. The guide posts  60 ,  62 ,  64 , and  66  are of uneven length allowing for easy landing of equipment. By stabbing one guide post at a time, the remote operating vehicle can guide the equipment into position. 
     A torque tool or stud tensioning assembly  70  is seen being lowered from the surface into position in FIG.  5 . The remote operating vehicle  18  will be docked into the torque tool or stud tensioning assembly  70  and the hydraulic and electronic control connections will be made. The fasteners or studs on the hot tap fitting clamp  54  will thereafter be tightened by the torque tool or stud tensioning assembly. Once this operation has been completed, the torque tool assembly or stud tensioning assembly  70  will be retracted from the guide posts and returned to the surface. 
     To facilitate the positioning of the hot tap fitting clamp on the pipeline as just described, a lateral connection valve  72  on the fitting clamp assembly  54  will be oriented in a side position. Stated in other words, the connection valve  72  will not be vertical to the sea floor  14 . 
     As shown in FIG. 6, using a hydraulic piston and pinion or rotary actuator arrangement, the fitting clamp  54  will include a connection valve  72  which is rotated approximately ninety degrees (90°) from a side to an upright position. In the upright position, the valve will be vertical to the sea floor and parallel to the uprights and the guide posts. The hot tap fitting clamp and valve assembly will contain level indicators to verify that the valve is vertically oriented. These level indicators may be electronic transponders and/or visual scale measurement devices. 
     Thereafter, the remote operating vehicle  18  will actuate a grip and seal mechanism between the fitting clamp and the pipeline  12 . The remote operating vehicle (ROV) will be capable of monitoring grip displacement indicators and the pressure. The remote operating vehicle  18  will hot stab into a test port and pressurize it to a predetermined pressure to verify a seal between the fitting clamp  54  and the pipeline  12 . Accordingly, the seal integrity is tested. A relative vacuum/pressure test is performed using a remote operating vehicle tool. When the test is; performed with the valve closed, it verifies the integrity of the seal between the pipeline  12  and the fitting clamp  54 , the longitudinal seals along the clamp body, and the seal of the valve for pipeline pressure. In the case of a vacuum test, the external pressure of the water depth is verified. 
     Finally, as illustrated in FIG. 6A, opposed pipe supports  71  rotate about axes  73  (shown by dashed lines) to close to form U-shaped piece  74 , the pipeline  12  will then be lowered by the pipe lift frames  20  and  22  until the pipeline  12  is supported on the orientation and fitting frame  48 . The U-shaped piece  74  receives and supports the pipeline  12 . 
     The next step in the sequence of the present invention is illustrated in FIG.  7 . With the pipeline  12  lowered and supported by the orientation frame  48 , a hot tap machine  90  and accompanying frame  92  (forming a hot tap assembly) is lowered from the surface onto the orientation frame  48  through use of the guide posts  60 ,  62 ,  64  and  66 . The hot tap machine  90  and its frame  92  have been previously rigged together. The same guide post arrangement is used as described previously. The hot tap frame  92  includes receptacles  80 ,  82 ,  84  and  86  which are received on the guide posts  60 ,  62 ,  64  and  66 . While the receptacles  80 ,  82 ,  84  and  86  may take various forms, in the present preferred embodiment, they are frusto-conical with open bases. The hot tap frame  92  may include a plurality of pistons or mechanical screws  94  which control the level of the hot tap machine  90  with respect to the frame. 
     As seen in FIG. 8, the hot tapping assembly will land on the orientation frame  48 . Initially, no seal is made so that the hot tap machine  90  is prevented from accidentally being rammed against the fitting clamp  54 . In FIG. 8, the hot tap machine  90  is aligned with the connection valve  72 . 
     Thereafter, as seen in FIG. 9, the pistons  94  on the hot tap frame  92  will be activated so that the hot tap machine  90  will be carefully lowered and a seal will be made between the hot tap machine  90  and the fitting clamp  54 . The integrity of the seal will then be tested. If the aforementioned pressure test is conducted with the valve open, it tests the integrity of the connection between the hot tap machine  90  and fitting clamp  54  as well. The test medium is not water and is selected to avoid hydrate formation which occurs by a meta-stable combination of natural gas liquids and water at the ambient pressures and temperatures. The test medium utilized could be any of several different methods, such as glycol or methanol. It is introduced to the cavitie(s) by means of a low pressure pump which circulates inhibitor/test medium into the cavitie(s) and takes seawater returns into a holding tank. Once the seawater has been displaced by the inhibitor/test medium, the pressure test is conducted. The test is conducted by connecting a high pressure/vacuum pump to a cavity in the hot tap machine body. The pump will pressurize the cavity between the top of the ball-valve ball and the tap machine. A successful test verifies integrity of the seal between the hot tap machine and the male hub on the hot tap fitting. The ball valve is then opened and the test is repeated. A successful test verifies the sealing integrity of the entire system. The entire process is repeated with the pump in the vacuum mode. This verifies integrity of the sealing system when the hydrostatic (ambient) pressure is greater than the pipeline pressure. 
     After a good test is attained, the tapping will proceed. The remote operating vehicle  18  will be docked into the control panel of the hot tap machine  90  and hydraulic and electronic connections made. The hot tap machine  90  will tap the pipe  12  using its cutter mechanism (not visible). Thereafter, the cutter mechanism and pipe coupon will be retracted through the valve  72  and the valve will be closed. If deemed necessary, the integrity of the seal of the valve will be verified by testing on the external pressure side of the valve (hot tap fitting machine side) with the valve in the closed position. 
     Finally, the hot tap machine  90  and its accompanying frame  92  will be raised and recovered to the surface in a reverse procedure. The entire procedure is performed while the pipeline is operational. The internal pressure of the pipeline may be significantly above or in deep sea conditions, below, ambient pressure. 
     If external pressure exceeds the internal pipeline pressure, it will be necessary to break the seal by pressuring the connection with the valve closed. The internal pressure would be raised to at least the external pressure so that there would be no external forces acting on the seal to prevent disconnection of the hot tapping machine. 
     The hot tap fitting clamp  54  is then released from the uprighting mechanism. Thereafter, the pipe lift frames  20  and  22  will lower the pipe  12  and the accompanying hot tap fitting clamp assembly back toward the sea floor  14 . The weight of the pipeline  12  and the fitting clamp  54  are taken up by the orientation frame  48 . Accordingly, the weight will not be distributed on the hot tap fitting or on the pipeline. The orientation frame  48  is designed with sufficient dimensional tolerances so as to provide the required flexibility for the connection of the lateral pipeline and also provide support for the weight of the connecting pipeline in soft soils. 
     A series of steps will next be taken to connect a production branch or other pipeline to the existing pipeline  12 . In a preferred example to be discussed herein, a new production line  100 , as seen in FIG. 10, is tied in to the pipeline  12 . The production line  100  terminates in a valve or upright production hub  102 . The distance or relative orientation between the hot tap fitting as assembled and the valve hub  102  on the production line is measured. 
     The pipe lift frames  20  and  22  may be removed at this time or, alternatively, may be removed at the end of the procedure. 
     In FIG. 11, a pig catcher  120  is guided onto the production hub so that the production line  100  may be pigged prior to completion, all as known in the art. A pair of guide posts  114  and  116  are lowered on the uprights. 
     With reference to FIG. 12, a jumper  130  is built to match the measured dimensions. The jumper  130  will be filled with methanol or glycol or a hydrate-inhibition fluid prior to being deployed subsea. The jumper  130  is then lowered and guided by the remote operating vehicle  18  using techniques for setting jumpers previously described. As seen in FIG. 12, the jumper assembly  130  is held by jumper frame  132  and is lowered on to male end connectors (one at the connection for the hot tap and one on the lateral pipeline sled structure). The connecting devices on the jumper contain hydraulic pistons to land the female collet connector on the sealing faces in a method to prevent damage to the sealing faces. 
     Finally, as seen in FIG. 13, hydraulic cylinders  136  gradually lower the jumper  130  until the sealing faces meet. Collet connectors then seal off the jumper valve/hub interfaces. FIG. 14 shows the jumper  130  after it has been connected. 
     In a final step, as seen in FIG. 15 the guide posts  60 ,  62 ,  64 , and  66 , and the pipe lift frames  20  and  22  are retrieved to the surface. 
     Whereas, the present invention has been described in relation to the drawings attached hereto, it should be understood that other and further modifications, apart from those shown or suggested herein, may be made within the spirit and scope of this invention.