Patent Publication Number: US-6656016-B1

Title: Sand blasting apparatus and methods

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to sand blasting apparatus and methods which are especially well suited for directing a spray of relatively fine grit particulates (e.g., sand) toward surfaces that are difficult to access (e.g., pipe surfaces located immediately adjacent a process vessel wall). 
     BACKGROUND AND SUMMARY OF THE INVENTION 
     The technique of abrading a surface by directing a pressurized spray of grit particulates thereagainst is colloquially known as “sand blasting”. Sand blasting is a notoriously well known technique for removing materials from rigid surfaces. Essentially, sand blasting effectively “cleans” undesired materials accumulated on a surface by means of the abrasive action caused by a high pressure stream of grit particulates directed against the surface. Thus, sand blasting is particularly effective for use against mortar or metal surfaces prior to application of coating materials. 
     There are a variety of sand blasting apparatus to accomplish a variety of surfaces. Oftentimes, however, conventional sand blasting apparatus cannot be employed effectively to abrade surfaces with relatively small clearance between the surface to be sand blasted and an adjacent rigid structure. For example, it is sometimes necessary to remove scale from pipes within process equipment, such as coker units employed in the manufacture of hydrocarbon products. One side of such pipes in conventional coker units (especially so-called “single fired” coker units), however, may be located physically close to the refractory wall of the vessel thereby making scale removal by means of sand blasting difficult, if not impossible. 
     It would therefore be highly desirable if apparatus and methods were available which would allow sand blasting of surfaces that are difficult to access. It is toward providing such apparatus and methods that the present invention is directed. 
     Broadly, the present invention is directed to apparatus and methods whereby difficulty accessible sites of a structure may be sand-blasted. More specifically, according to an aspect of the present invention, sand-blasting systems are provide which include a source of pressurized grit particulates, a nozzle for discharging a spray of the pressurized grit particulates, and a flexible supply hose connecting the source of the grit particulates to the nozzle so as to supply the grit particulates from the source thereof to the nozzle. Important to the present invention, a sand-blasting fixture supports the nozzle and a distal portion of the supply hose in such a manner that the spray of grit particulates may be directed against the difficultly accessible site of the structure. 
     In preferred forms, the fixture includes rigid proximal and distal support tubes joined to one another so as to establish an angle therebetween, and a rigid back-lash support member extending outwardly from the distal support tube. In such a manner, the distal portion of the supply hose is movably supported within the proximal and distal support tubes such that the nozzle positioned adjacent to the back-lash support member may be adjustable by means of the distal portion of the supply hose being further advanced into or retracted from within the proximal and distal support tubes. A clamp member is most preferably provided to positionally fix the nozzle to the back-lash support member. 
     These as well as other aspects and advantages of the present invention will become more clear after careful consideration is given to the following detailed description of the preferred exemplary embodiment thereof which follows. 
    
    
     BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS 
     Reference will hereinafter be made to the accompanying drawings, wherein like reference numerals throughout the various FIGURES denote like structural elements, and wherein; 
     FIG. 1 is a schematic depiction of a representative embodiment of a sand blasting apparatus in accordance with the present invention; 
     FIG. 2 is rear perspective view of a preferred sand blasting fixture in accordance with the present invention; and 
     FIG. 3 is a perspective view of the sand blasting fixture depicted in FIG. 2 showing a manner in which structures may be sand blasted thereby. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     An exemplary sand blasting system  10  in accordance with the present invention is depicted in accompanying FIG.  1 . In this regard, the system  10  generally includes a vessel  12  which for containing a quantity of grit particulates to be employed in the sand blasting operation. As is conventional, the vessel  12  is pressurized with air supplied via line  14  through the normally closed ports of a pinch valve  16 . A flexible and compressible depressurizing line  18  communicates between the normally open ports of the pinch valve  16 . 
     The pressure line  14  is also connected via line  14 - 1  to a miser valve  20  at the discharged of the vessel  12 . The miser valve is in turn connected to supply hose  22 . The distal end portion  22 - 1  of the supply hose  22  terminates in a sand blasting nozzle  24 . Thus, in use, the pressurized air passing through the miser valve  20  causes a controlled amount of grit particulates to be entrained in the air flow which is then transported to, and discharged as a spray from, the nozzle  24 . 
     Important to the present invention is the fixture  30  which supports the distal end portion  22 - 1  of the flexible supply hose  22  and its associated nozzle  24 . As is perhaps more clearly shown in accompanying FIG. 2, the fixture  30  is generally comprised of a rigid proximal support tube  32 , and a contiguous rigid distal support tube  34 . The distal support tube  34  is coupled rigidly to the proximal support tube  32  by means of a transition tube section  36  so that the distal support tube  34  is oriented angularly with respect to the proximal support tube  32 . It will be appreciated that virtually any desired angular orientation of the distal support tube  34  relative to the proximal support tube  32  may be provided in dependence upon the individual transition tube  36  that is employed. Thus, it will be understood that the depiction of a generally right angle (90°) orientation between the proximal and distal support tubes  32 ,  34 , respectively, represents a particularly preferred embodiment of the present invention which is exemplary only and thereby non-limiting. 
     As shown, the distal portion  22 - 1  of the supply hose is housed within the fixture  30  and extends sequentially through the proximal support tube  32 , the transition tube section  36  and the distal support tube  34 . A back-lash support member  38  extends outwardly from the terminal end of the distal support tube  34  so as to prevent reactive back-lash of the nozzle member  24  during sand blasting operations. Thus, since the distal portion  22 - 1  of the supply hose  22  is flexible, the support member  38  prevents reactive back-lash of the nozzle from occurring by virtue of the discharge of a pressurized stream of grit particles from the nozzle aperture  24 - 1 . 
     As shown, the support member  38  most preferably establishes a concave surface for accommodating the distal portion  22 - 1  of the hose  22  and its associated nozzle member  24 . The nozzle member  24  may be positionally fixed to the support member  38  by means of a clamp assembly  40 . Most preferably, the clamp assembly  40  is of a type that is capable of being loosened to an extent or removed to allow the nozzle member  24  to be positionally adjusted along the lengthwise dimension of the support member  38  as depicted generally by arrow A 1  in FIG.  2 . Thus, by loosening/removing the clamp assembly  40 , a desired length of the supply hose  22  may be advanced into or withdrawn from the proximal support tube  32  thereby allowing the nozzle member  24  to be moved respectively away from or closer to the distal support tube  34 . 
     Forward and rearward handle members  42 ,  44  are fixed to, and project laterally outwardly from, the proximal support tube  32 . Most preferably, each of the handle member  42 ,  44  are adjustable coupled to the proximal support tube  32  so as to allow for rotation about the support tube&#39;s axis (as depicted by arrows A 2  and A 3 , respectively in FIG. 2) thereby permitting selection of the relative positioning of the handles  42 ,  44  as may be desired by the individual operator. 
     The forward handle  42  may include a removable and support carriage  46  to assist the operator in supporting the fixture  30  against immovable structures during sand blasting operation. The support carriage  30  may also be adjustable along the lengthwise dimension of the handle  42  to allow it to be positioned relative to immovable structures against which it is to be placed. The rearward handle  44  most preferably carries a pneumatic switch  48  which is connected to the pinch valve  16  via pneumatic signal lines  48 - 1 . By manually depressing the switch  48 , the operator will cause the pinch valve  16  to operate so as to open its normally close ports and close its normally open ports. As such, the vessel  12  will become pressurized and will thereby cause the sand blasting operation to begin. Of course, when the operator releases the switch  48 , the pinch valve  16  will revert to its normal conditions thereby depressurizing the vessel  12  and causing the sand blasting operation to cease. 
     Accompanying FIG. 3 depicts one possible use of the fixture  30  to sand blast difficultly accessible exterior surfaces of pipes P 1 -P 4  located closely adjacent to a wall W within a process vessel (not shown). In this regard, pipes P 1 -P 4  may be, for example, process pipes P 1 -P 4  located within a coker unit used in the manufacture of hydrocarbon products. Such coker unit pipes P 1 -P 4  thereby need to be de-scaled periodically. Descaling of the rear portion of the exterior surfaces of pipes P 1 -P 4  located immediately adjacent the wall W may thus be facilitated by the fixture  30  in accordance with the present invention. That is, as shown in FIG. 3, the fixture  30  may be positioned relative to the pipes P 1 -P 4  so that the distal support tube  34 , and hence the nozzle member  24 , are positioned in the space between the process vessel wall W and the rear surface portion of the pipes P 1 -P 4 . A stream of high pressure grit particulates (noted in FIG. 3 generally by GS) issuing from the nozzle aperture  24  is thereby able to be directed against the otherwise difficultly accessible rear external surfaces of the pipes P 1 -P 4  thereby sand blasting the same. 
     While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.