Patent Description:
The device described in the present invention is used to repair pipes, especially in the ones near to connections or fittings. The device is also used to prevent damage caused by the appearance of pits and/or cracks that result in leakage of the fluid conducted in the pipe. Additionally, the device is used to recover the mechanical strength of the pipe, which is usually reduced by corrosion, erosion or accidental deformation. Recovering the mechanical strength of the pipe will prevent an unscheduled plant shutdown or reduction of the flow in the transport of fluids. Therefore, the use of the device will avoid the economic and environmental hazards arising from the leak.

Numerous techniques for closing off the leakage or recovering the mechanical strength of the pipes are available in prior art and can be selected according to the environment where the pipe is, the material in which the pipe is made and the constraints of time and space to the repairment. For a general understanding of the prior art, the techniques with features and methods similar to the present invention are described in the following paragraphs.

The basic technique, applicable also in cases when the pipe is out of operation, consists of welding the parts of the split sleeve or sleeves, forming a second layer in the damaged region.

An example is the <CIT> entitled "Pipeline repair sleeve assembly" which describes seal element and a repair sleeve assembly for sealing and containing a leaking aperture in the wall of an internally pressurized pipeline or other containment member. However, this invention has some limitations, such as its complex design that contributes to high production costs. Maintenance and replacement can also pose challenges due to the integrated nature of the components with the pipeline. There are also concerns regarding durability, pressure resistance, and compatibility with various sizes and types of pipes. Additionally, installation and effective use may require operator skills and specialized equipment.

Another example is the <CIT> entitled "Pipe repair assembly" which describes a pipe repair assembly for sealing leaks in pipelines that transmit oil, chemicals, steam and the like, is disclosed. The assembly is in the form of a two-part sleeve which forms an enclosure or box over a section of leaking pipe. The sleeve includes a pre-fitted sealing jacket to provide a snug fit over the pipe contour. The floating ring, sealant ring and sealing jacket are all compressed when bolts connecting the two parts of the sleeve are secured. However, the American document presents a robust repair set, without the use of a compression unit that guarantees tightness so that welding is carried out in a timely manner, as well as the set is liable to failure due to overload, fatigue, corrosion and/or fragility, since the joints are joined using pins and screws.

As shutting down the operation is cost-consuming, the proposed technique incorporates a compression unit in the system, that allows the sleeves to be heldunited. In this way, a definitive welding can be carried out later, with the pipeline out of operation. Also, the method would be useful when the material carried in the pipeline allows a programmed welding in the tube while in operation. The documents <CIT>, <CIT> and <CIT> filed respectively in <NUM>/<NUM>/<NUM>, <NUM>/<NUM>/<NUM> and <NUM>/<NUM>/<NUM>, illustrate some improvements in the structure of sleeves and in the compression unit.

The documents <CIT> and <CIT> disclose the use of a filling material or adhesive between pipes and sleeves.

When compared to the present invention, the documents in the prior art, even though revealing techniques to close off leaks or recover the mechanical strength of the pipe, are not recommended for several situations because of the proximity of the connections and the dimensions involved. Also, the technique presented in this document allows the user to choose the most efficient sealant material in tightness, with properties that do not deform even after welding.

The documents in prior art do not disclose the filling of solder between the pipes and sleeves, so that the sleeves are completely welded to either the pipe or the connection. Furthermore, the documents describe that the welding among the sleeves must occur prior to the removal of the compression unit. However, the welding is only possible because the length of the sleeves is greater than the width of the chain, or set of chains, of the compression unit that embrace the sleeves.

The present invention has its technical basis in the structural features of the split sleeve that allow its fixation close to the connections and apertures created in the compression unit. These intrinsic characteristics will allow carrying out the welding in the joints of the sleeves as standards PCC2 - "Repair of pressure equipment and piping" and API <NUM> "Standard for Welding Pipelines and Related Facilities".

The structural features, i.e. width, thickness, way of overlapping the parts of the sleeves, and the internal space for accommodating the sealant, associated with the method of welding the sleeves, will allow the choice of a sealant material that is chemically compatible with the pipe material, preventing galvanic or crevice corrosion.

The advantages of the disclosed invention are revealed in basis of its constructive features , wherein the diameter and width of the split sleeve make the split sleeve to be identified as a split ring (<NUM>). These advantageous features are related to the repair methods which use the technique of compression of split sleeves on the surface either with a leakage or requiring mechanical reinforcement.

The split ring (<NUM>) is completely welded to the pipe, in special in the regions near to the connections. However, it is necessary that the split ring be initially attached by the compression unit (<NUM>) for conformance and definitive surface geometry of the ring to the pipe, normalization of the transport of fluids and so that welding can be planned to an opportune moment. To meet the requirements in the standards, which request that the start of the welding be longitudinal, it is necessary that the initiation of the welding for repairment be in the fitting region (<NUM>) of the split ring parts, therefore prior to the removal of the compression unit (<NUM>). The compression unit (<NUM>) is designed with apertures (<NUM>) that allow the longitudinal welding (<NUM>), in the fitting region (<NUM>) of the split ring (<NUM>) parts, with the compression unit (<NUM>) installed and by exerting the compression of the split ring (<NUM>) on the pipe or connection.

The regions near to the pipe connections usually have different roughness when compared to the pipe per se, due to welds either between the connections and the tube, or between tubes. To remedy and close off the leak in these regions, it is necessary that the contact of the ring with the pipe be through a sealant for better accommodation of the surface of the ring to the pipe. The disclosed split ring (<NUM>) is designed with a channel (<NUM>) to accommodating the sealant (<NUM>) preventing future crevice corrosion. The split ring also provides tightness right after its application.

An advantage of the disclosed split ring (<NUM>) and the method of welding the split ring (<NUM>) to the pipe is the possibility of choosing the sealant (<NUM>) material to the best accommodation of the split ring (<NUM>) to the pipe, without damages in the sealant (<NUM>) caused by the increase in the temperature, characteristic of the welding process.

Another advantage arises from the fact that the thicknesses of the split ring (<NUM>), especially in the fitting region (<NUM>) of the ring parts, have been calculated so that damages caused by corrosion or heating do not occur. The split ring (<NUM>) excludes the damage caused by the oxidation of the split ring materials and the pipe, as well as in the connections, even when the heating associated to the welding process is considered. Due to the shape of the split ring's fitting region (<NUM>), there is no need of a backing strip or back plate installation. So, the overlapping of split ring's parts in the fitting region (<NUM>) allows a weld which does not penetrate the region and, at the same time, form a longitudinal weld between the split ring (<NUM>) and the pipe.

Additional advantage of the disclosed invention arises from the suitability of the split ring (<NUM>)'s full width to the curves, reductions and flanges in the pipelines. The split sleeves, also known as double troughs or full encirclement sleeve, available in the prior art have larger dimensions.

The improvements introduced by the disclosed invention in pipe repairment and the methods of fixing pipes while in operation, as well as the definitive welding for the provisional repair will be better understood and clarified with the detailed description and the drawings presented in this document.

The disclosed invention will be described with reference to the accompanying drawings, which show important sample embodiments of the invention and which are incorporated in the specification. A more complete understanding of the invention may be had by reference to the detailed description when taken in conjunction with the accompanying drawings, wherein: <FIG> is a transverse cross section enlarged view of the fitting region (<NUM>) of the parts of the split ring (<NUM>).

<FIG> is an enlarged perspective view of one of split ring (<NUM>) end.

<FIG> is a perspective view of the compression unit (<NUM>).

<FIG> is a perspective view of compressed split rings (<NUM>) or welded (<NUM>)in the pipe and connections regions. <FIG> is an enlarged perspective view of the split ring's welding or fittingregion (<NUM>) and its details.

<FIG> is an enlarged perspective view of welding longitudinal (<NUM>) and circumferential (<NUM>) of the split ring (<NUM>).

One or more exemplary embodiments of the present invention will be described below. The present invention discloses a system for pipe repairment as well as methods of fixing the pipes using such system while in operation and a later definitive welding of the repair in an opportune moment. The invention comprises a split ring (<NUM>) with total thickness corresponding to the sum of the thickness of the channel (<NUM>) of accommodation of the sealant (<NUM>), plus the thickness of the backing strip (<NUM>), which is equivalent to the back plate, and plus the thickness for the welding (<NUM>). The thickness for the welding (<NUM>) must be greater than or equal to the thickness of the pipe to be repaired, as shown in the <FIG>.

<FIG> also shows the two possible embodiments of machining or casting the ends of the split ring parts (<NUM>). For these embodiments, the extension (<NUM>) with
the thickness for the welding (<NUM>) can be either in the two ends of a single part as in the left side ring, or at one of the ends of the two parts as in the right side ring.

The total width (<NUM>) of the split ring (<NUM>) corresponds to the sum of the width ofthe channel (<NUM>) and the two lateral widths (<NUM>) for heat dissipation during the welding. The minimum total width is <NUM> millimeters, allowing the generation of thechannel for the sealant (<NUM>) inside the split ring (<NUM>), as shown in <FIG>.

The thickness of the back (<NUM>), the width of the channel and the lateral widths (<NUM>) for heat dissipation while welding are calculated as a function of the sealant (<NUM>) chosen, and the thermal input during the welding. The expected thickness of the back (<NUM>) is at the minimum the pipe thickness and the lateral widths (<NUM>). In this way, the heat dissipation while welding is at a minimum equal to the thickness of the pipe.

The initial correction of the repair is made without welding, i.e., using a compression unit (<NUM>) that will attach the parts of the split ring to the pipe surface or connection, allowing a later weld to be carried out in the opportune moment.

<FIG> presents the compression unit (<NUM>) according to the present invention with two hollow rectangular pieces, forming apertures (<NUM>). The apertures allow accessibility of the welding area of the parts of the split ring (<NUM>) with the welding unit, exerting the compression on the split ring (<NUM>) to keep it fixedto the pipe or connection. <FIG> shows also that the compression is done by aconnector as a single screw (<NUM>) that will get the chains (<NUM>) near to the compression unit (<NUM>), with the aid of guide pins (<NUM>) so that the compressive forceexerted by the screw (<NUM>) is only in the direction of the tightening, preventing thescrew (<NUM>) from damages.

The compression of the split ring (<NUM>) on the pipe or connection will stop the leakage by the contact of the sealant (<NUM>) with the surface of the pipe or connection. The split ring (<NUM>) assembly and compression unit (<NUM>) will act as reinforcement of the mechanical resistance of the pipe in the site of damage, preventing crack propagation or crevice corrosion and pipe rupture.

The sealant (<NUM>) must be chosen for its capability to adapt to the pipe surface's irregularities. The sealant (<NUM>) is selected among composites, polymers and gaskets, as, for example, but not limited to, Graphite Gasket.

<FIG> illustrates the situation when the split ring can receive a definite welding (<NUM>). In this scenario, the split ring becomes definite part of pipeline or is provisionally fixed (<NUM>), using the compression unit (<NUM>).

<FIG> shows in detail the fitting region (<NUM>) of the parts of the split ring (<NUM>) in condition to be filled with solder, through the apertures (<NUM>), before the compression unit (<NUM>) is removed.

Once joined to the parts of the split ring (<NUM>), carrying out the longitudinal welding (<NUM>), the welding can be made along the circumference of the pipe or connection. The circumferential welding (<NUM>) can start with the compression unit (<NUM>), which must be removed only for the completion of the circumferential welding (<NUM>) in the region of the hollow rectangular parts (<NUM>), as shown in <FIG>.

Welding with heat input control prevents high temperatures in the welding process. The uncontrolled rise of temperatures during the welding can damage the seal and the pipe, already weakened by flaws.

Claim 1:
Pipe repair system by compression of split sleeves with sealant against an outer surface of the pipe, said pipe repair system comprising a split ring (<NUM>) and a compression unit (<NUM>), wherein the split ring (<NUM>) comprises a total thickness corresponding to the sum of the thickness of a channel (<NUM>) of the split ring for accommodation of the sealant (<NUM>), plus the thickness of a back (<NUM>) of the split ring at a first split ring end, which is equivalent to a back plate, and plus an extension (<NUM>) of the split ring at a second split ring end facing the first split ring end with the thickness for welding (<NUM>) said facing split ring ends and
with total width (<NUM>) of the split ring (<NUM>), which is the sum of the width (<NUM>) of the channel (<NUM>) for accommodating the sealant (<NUM>) and of two lateral widths (<NUM>) of the split ring (<NUM>);
the compression unit (<NUM>) comprises two hollow rectangular pieces, forming apertures (<NUM>), the two rectangular pieces being interconnected by chains (<NUM>), the compression unit (<NUM>) comprising a connector configured to perform compression by approximating the chains (<NUM>) of the compression unit (<NUM>) with a single screw (<NUM>) with the aid of guide pins (<NUM>) so that the compressive force exerted by the screw (<NUM>) is only in the direction of the tightening, preventing the screw (<NUM>) from damaging;
the compression unit (<NUM>) is configured to attach parts of the split ring (<NUM>) around the pipe, allowing welding areas that correspond to a fitting region (<NUM>) of the parts of the split ring (<NUM>) to be accessible through the apertures (<NUM>).