Abstract:
A clamp system is provided for clamping one tubular to another, such as control lines to a marine choke and kill riser line. The riser clamp comprises a saddle and U-bolt arrangement. The upper surface of the saddle defines a track configured to receive a shoe attached to either the control line clamp or an extension leg attached to the control line clamp. The control line clamp comprises an upper clamp half, a lower clamp half, a hinge pin connecting the halves, a fastener latching the halves, and a support leg having a shoe for receipt by either the saddle structure or the extension leg. The control line clamp preferably contains an elastomeric liner. The elastomeric liner is preferably provided in two halves. The inner surface of each liner half preferably is provided with a non-skid layer to more firmly position the control line.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to clamp assemblies for connecting one member to a support member. In a particularly preferred aspect, the invention relates to an ultra high strength clamp assembly to attach a pipe or line, such as an umbilical line, to another pipe. In a specific embodiment, the invention is particularly adapted for use as a subsea clamp assembly to attach an umbilical line to a choke or kill line of a subsea riser. In the specific embodiment the invention is particularly adapted for use as a variable height stand-off assembly to attach an umbilical line to a choke or kill line in a marine riser assembly. 
     2. Background of the Invention 
     The need often arises for a clamp assembly to attach a cable, hose or pipe to a support member or pipe. The situation often occurs where an umbilical line is required to be secured to a support member or pipe at a certain distance away from the support member, for example, to accommodate insulation, floatation and mechanical barriers. 
     In the offshore drilling and production industry, it is frequently necessary to run umbilical lines hundreds and even thousands of feet below the support vessel or drilling or production platform down to the sea floor and beyond. Typically, the umbilical lines, which may include electric, MUX (fiber optics), and hydraulics, are required to be attached to a support member, such as a choke or kill line, or mud line on a subsea riser system. Due to the high cost of working in such environments, it is critical that the clamp assembly be reliable and dependable to firmly secure the clamped members to prevent costly consequences, such as loss of signal in a fiber optic cable due to slack in an umbilical line which can create a sharp radius in the line preventing signal transmission. Various types of clamp assemblies and stand-off assemblies have been used in these situations. The prior art clamp assemblies and stand-off assemblies have been very costly and time consuming to make, use and install, and many do not clamp the umbilical lines with enough force. 
     SUMMARY OF THE INVENTION 
     In one embodiment of the invention, there is provided a base clamp for a tubular member which forms a mounting base for another clamp or an extension leg. The clamp comprises a saddle structure and at least one U-bolt. The saddle structure has a first end, a second end, an upper surface and a lower surface. The lower surface defines a trough extending from the first end to the second end for mounting the saddle structure to a tubular member. The saddle structure further defines at least one pair of parallel apertures positioned one on each side of the trough for receiving a first U-bolt for fastening the saddle structure to the tubular member. A U-bolt having a first end and a second end is received by the apertures and extends over the trough. The upper surface of the saddle structure defines a track configured to receive a shoe. 
     The track can connect the base clamp via a support leg to a line clamp according to another embodiment of the invention for a tubular hose or cable. The line clamp comprises an upper clamp half, a lower clamp half, a hinge pin connecting the halves, a fastener latching the halves, and a support leg having a shoe. The upper clamp half has a downwardly facing parting line face. The lower clamp half has an upwardly facing parting line face and is positioned in a face to face relationship with the upper clamp half so that the parting line faces are side by side. The hinge pin pivotally connects the clamp halves along a hinge edge. A fastener connects the clamp halves along a latch edge. The support leg extends from the lower clamp half and has an upper end attached to the lower clamp half and a lower end. The shoe is positioned on the lower end of the support leg. 
     Alternatively, the track can connect the base element to an extension leg according to another embodiment of the invention which can be used to connect the base clamp to the line clamp, or, if desired, to another extension leg. The extension leg has a first end and a second end and a longitudinal axis extending between the first end and the second end. A shoe is positioned on the first end of the extension leg. A track is positioned on the second end of the extension leg which is configured to receive the shoe. 
     Preferably, the line clamp employs an elastomeric liner according to another embodiment of the invention to reliably position the clamped line. The elastomeric liner is provided in two halves. Each liner half is formed from an elastomeric material and has an outside wall and an inside wall which defines at least one semi-cylindrical trough. The trough has a longitudinal axis, a first end, and a second end and is sized for closely receiving a hose or cable to be clamped. The outside wall is configured to be to be closely received by an inside surface of a clamp half. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an end view, partly in cross section, of a clamp assembly according to one embodiment of the invention. 
     FIG. 2 is an end view, partly in cross section, of a clamp assembly according to another embodiment of the invention. 
     FIG. 3 is a partially exploded view of the assembly shown in FIG.  1 . 
     FIG. 4 is a partially exploded view of the assembly shown in FIG.  2 . 
     FIG. 5 is a side view of the invention shown in FIG.  1 . 
     FIGS. 6-18 are pictorial representations of certain components of the devices shown in FIGS. 1 and 2. 
     FIG. 19 is a cross sectional view of the component shown in FIG. 18 taken along lines  19 — 19 . 
     FIG. 20 is a bottom view of the device shown in FIG.  18 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     with reference to FIGS. 3-7 there is shown a base clamp  30  for a tubular member  32  which forms a mounting base for another clamp or an extension leg. The base clamp comprises a saddle structure  34  and at least one U-bolt  36 . The saddle structure has a first end, a second end, an upper surface and a lower surface. The lower surface defines a trough  38  extending from the first end to the second end for mounting the saddle structure to tubular member  32 . The saddle structure further defines at least one pair of parallel apertures  40 ,  41  positioned one on each side of the trough for receiving a first U-bolt for fastening the saddle structure to the tubular member. A U-bolt having a first end and a second end is received by the apertures and extends over the trough See FIGS. 3 and 4. The upper surface of the saddle structure defines a track  42  configured to receive a shoe 
     The track forms a panel-shaped chamber  44  which is transversely positioned with respect to a radius drawn from a central section of the trough. The track has a track bottom surface  46  facing away from the trough and a roof structure  48  over the track bottom surface which defines a track top surface  50  which faces the track bottom surface and is spaced from the track bottom surface to accommodate the shoe. The roof structure having a slot  52  sized to accept a leg extending from the shoe. The panel shaped chamber and the slot together form an opening transverse to the longitudinal axis of the leg for transverse receipt of a shoe with attached leg. In use, a safety pin  54  (see also FIG. 9) is positioned across the opening to prevent a shoe with attached leg from becoming accidently dislodged. Preferably, the saddle structure defines a first pair and a second pair of parallel apertures. The first pair is positioned one on each side of the trough adjacent the first end of the saddle shaped structure for receiving the first U-bolt for fastening the saddle structure to the tubular member. The second pair is positioned one on each side of the trough adjacent the second end of the saddle shaped structure for receiving a second U-bolt  37  for fastening the saddle structure to the tubular member. See FIG.  5 . The first U-bolt has a first end and a second end which are received by the first pair of apertures. The second U-bolt likewise has a first end, a second end, is received by the second pair of apertures, and extends over the trough. The saddle structure also preferably further defines a port  56  to permit unobstructed passage of a fastener bolt  58  (see FIG. 4) therethrough positioned between an aperture of the first pair and an aperture of the second pair. 
     The track  42  can connect the base clamp  30  via a support leg to a line clamp according to another embodiment of the invention for a tubular hose or cable. The line clamps illustrated in the Figures are variations of each other and will be described with different reference numerals. The line clamp shown in FIG. 1 will be described with 100 series numerals, while the line clamp shown in FIG. 2 will be described with 200 series numerals. 
     With reference to FIGS. 1 and 2, the line clamp  102 ,  202  comprises an upper clamp half  104 ,  204 , a lower clamp half  106 ,  206 , a hinge pin  108 ,  208  connecting the halves, a fastener  110 ,  210  latching the halves, and a support leg  112 ,  212  having a shoe  114 ,  214  (See FIGS.  10 - 13 ). The upper clamp half has a downwardly facing parting line face. The lower clamp half has an upwardly facing parting line face and is positioned in a face to face relationship with the upper clamp half so that the parting line faces are side by side. The hinge pin pivotally connects the clamp halves along a hinge edge. The fastener connects the clamp halves along a latch edge. The support leg extends from the lower clamp half and has an upper end attached to the lower clamp half and a lower end. The shoe is positioned on the lower end of the support leg. 
     The clamp halves, when positioned in a face to face relationship, form a clamp assembly which defines at least one passage  116 ,  216  therethrough for clamping a cylindrical object, such as line  60  shown in FIG.  5 . The passage has a longitudinal axis and the clamp assembly parts along a parting plane which encompasses the longitudinal axis. The support leg has a longitudinal axis which extends normally to the parting plane. See FIGS. 1 and 2. 
     In a preferred embodiment, the clamp assembly defines a pair of passages extending therethrough in side-by-side relationship. Even more preferred, an elastomeric liner  120 ,  220  lines each of the passages which extend though the clamp assembly  102 ,  202 . 
     Preferably, each elastomeric liner comprises a pair of liner halves  60  (see FIGS. 18-20) positioned in face to face relationship. Each liner half defining at least one trough  62 . One liner half is positioned in each clamp half. Each passage through the clamp assembly is defined by a pair of facing troughs from facing liner halves. In a preferred embodiment, each trough is semicylindrically shaped. A layer  64  of an anti-skid material positioned in each of the semi-cylindrical troughs. Most preferably, the layer of anti-skid material comprises a screen  66  which is coated with abrasive particles. 
     In order that the liner resist dislodging during handling and use, it is preferably provided with a flange  68  on each end. Each of the flanges preferably has a lip  70  which extends toward the opposite flange and retains the liner half in position on the clamp half. 
     Where a low profile is not needed, the preferred assembly employs a fastener as shown in FIG.  1 . The fastener comprises a bolt  158  which extends upwardly and has a wing-nut  160  attached. The head of the bolt is attached to a portion of the lower clamp half and the shaft of the bolt extends through a portion of the upper clamp half and protrudes upwardly. 
     Where a low (or lower) profile is desired, an assembly employing a profile as shown in FIG. 2 can be used. The fastener comprises a bolt  258  having a head which contacts a portion of the upper clamp half and a shaft attached to the head which extends through a portion of the lower clamp half and protrudes downwardly. A port is preferably provided in the base as previously discussed to permit passage of the bolt. 
     As shown in FIGS. 1,  3  and  10 , a flange  170  can be positioned on the support leg between the upper end and the lower end of the support leg which is of the same shape as the shoe. This permits the length of the leg to be easily modified, in the field if necessary. If a longer leg is necessary, the track on the base clamp can connect the base element to an extension leg  172 . See FIG.  8 . The extension leg has a first end and a second end and a longitudinal axis extending between the first end and the second end. A shoe  174  is positioned on the first end of the extension leg. A track  176  is positioned on the second end of the extension leg which is configured to receive the shoe. 
     The shoe is panel-shaped and extends transversely to the longitudinal axis of the leg. The track forms a panel-shaped chamber, preferably identical in configuration to the chamber in the saddle structure, which is transversely positioned with respect to the longitudinal axis of the leg. The shoe has an upper shoe surface facing the leg and a lower shoe surface which faces away from the leg. The track has a track bottom surface facing away from the leg and is configured to fully support the lower shoe surface of the shoe. The track has a roof structure over the track bottom surface which defines a track top surface which faces the track bottom surface and is spaced from the track bottom surface so to contact the upper shoe surface and closely position the lower shoe surface of the shoe against the track bottom surface. The roof structure has a slot sized to accept the leg. The panel shaped chamber and the slot together form an opening transverse to the longitudinal axis of the leg for receipt of a shoe and leg. A safety pin, which can be the same as the pin  54 , is preferably positioned across the opening to prevent the shoe and leg from becoming accidently dislodged. 
     Certain aspects of the liner have been previously discussed. The lips on the liner end flanges combined with its elastomeric construction permit the liner to be snapped onto a clamp half to facilitate handling and reduce the likelihood of accidental dislodging. The anti-skid material can be positioned with a layer of adhesive material positioned between the elastomeric liner half and the layer of anti-skid material, preferably a water-proof adhesive. Suitable anti-skid material is commercially available as sanding screen and can be purchased in rolls. A coarse plastic pipe sanding screen has been used with good results. Such screen is waterproof washable, has an open mesh backing, and is coated with abrasive on both sides. The coated abrasive comprises sharp silicon carbide particles. 
     The elastomer generally has a durometer of between about 70 and 130, preferably a durometer of between about 85 and about 105. Nitrile rubber having a durometer of about 95 has been used with good results. In the illustrated embodiment, the outside wall of the liner half defines half of a side-by-side tubular surface. The inside wall of the liner half defines flats for abutting corresponding flats on an inside wall of an opposed liner half The illustrated and described clamps have consistently provided a clamping force of over 2500 pounds. 
     While certain preferred embodiments of the invention have been described herein, the invention is not to be construed as being so limited, except to the extent that such limitations are found in the claims.