Abstract:
A boiler tube clamp, for securing boiler tubes in an equal-spaced, parallel arrangement, includes a pair of mating half-clamps having multiple opposed recesses sized to snugly cradle boiler tubes of a given diameter. The half-clamps are brought together around the boiler tubes and either welded or bolted together, thereby aligning the tubes in the desired arrangement. The bolts and/or clamps used to secure together the mating half-clamps of each of the embodiments of the invention are unaffected by downward abrasive action that typically occurs in boilers. For welded-together half-clamps, the welds are on top and bottom surfaces where they are shielded from abrasive action. For bolted-together half-clamps, the bolts are protected from abrasive action by recessing the bolt heads and retaining nuts.

Description:
This is a continuation-in-part of application Ser. No. 09/626,390, filed on Jul. 26, 2000, and which is now abandoned. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to clamping mechanisms for securing together multiple tubes together in a mutually parallel arrangement, and a method incorporated for use with such mechanism, and more particularly, provides a new and useful structure that can avoid incorporation of guide protrusions, external C-clamps, and the like and at the same time accommodate single-person installation. 
     BACKGROUND OF THE INVENTION 
     Most power plants use steam turbines to generate electricity. A simple steam turbine power plant consists of a boiler, a steam turbine, and a condenser. Water is heated in the boiler to form steam, which is then ducted to the turbine. The turbine converts the steam&#39;s thermal energy to rotational energy, which is used to power an electric generator. The steam exhausted form the turbine is condensed to water in the condenser, and returned to the boiler where it is again converted to steam. Steam power plants can be fueled by nuclear energy or by any conventional fuel that will supply sufficient heat to the boiler. As petroleum supplies dwindle and the environmental consequences of atomic energy use become increasingly evident, the use of coal-fired power plants will, no doubt, increase. Fuel-burning steam turbine power plants typically feature boilers having an array of metal boiler tubes therein. In order to maintain the tubes in an order arrangement and to prevent them from warping if hot spots occur, or if one or more of the boiler tubes springs a leak, it is common to clamp multiple the tubes in an essentially parallel arrangement. Heretofore, many different types of clamping mechanisms have been utilized. Typically, such clamping mechanisms are comprised of a pair of mating half-clamps, which incorporate guide protuberances and cooperating apertures which aid in bringing the tubes into a proximate, mutually parallel configuration. External C-clamps are sometimes provided to pull the half-clamps together, thereby forcing the tubes into the desired parallel configuration. Installation of such clamps often requires the effort of two or more workmen. 
     U.S. Pat. No. 5,083,372 to Polutnik, et al. discloses a now-common, self-aligning, boiler tube clamp having parallel mating half-clamps. The half-clamps are pulled together with bolts. U.S. Pat. No. 5,060,810 to Jones discloses a similar clamping device for holding load braces on a trailer or truck structure when not in use. 
     Boiler tubes and the clamps which hold them in parallel configurations are subjected to amazingly harsh environments. Both the tubes and the clamps are generally fabricated from stainless steel. The ranks of boiler tubes are generally positioned vertically within a boiler chamber that is at least several stories high. For coal-fired plants, pulverized coal is introduced into an air stream, ignited as it enters the top of the boiler chamber, and exhausted as ash, carbon dioxide, water vapor and other combustion gases at the bottom of the chamber. The coal dust and coal ash are abrasive, and over time, will erode unprotected materials in the boiler chamber. Those portions of the boiler tube clamp assemblies which project a flat surface perpendicular to the air stream become coated with ash and are, thus, protected against abrasion. However, portions of the clamp assemblies which are not coated, and which are directly exposed to the burning coal dust and coal ash will erode. Surfaces of welds, bolts and nuts which are exposed to the air stream are vulnerable. If welds bolts and nuts, which are used to hold the tube clamps together, project laterally from the sides of the clamps into the air stream, they will weaken from the constant erosion, and will eventually fail. 
     What is needed are boiler tube clamp assemblies which are generally immune from the erosive action of the coal dust and coal ash when placed within the air stream of a boiler chamber. 
     SUMMARY OF THE INVENTION 
     The present invention is an improved boiler tube clamp, which has greatly improved immunity to erosion caused by the continual blast of burning coal dust and coal ash in a boiler. Like the boiler tube clamp of Polutnik, et al., the new clamp includes a pair of mating half-clamps having multiple opposed recesses sized to snugly cradle boiler tubes of a given diameter. The half-clamps are brought together around a plurality of boiler tubes, and fastened together either with bolts or welds so as to maintain the tubes in a parallel configuration. Several embodiments of the improved clamp are disclosed. For each embodiment, at least one fastening means is protected from erosion caused by the continual blast of burning coal dust and coal ash. All embodiments feature weldable tabs on generally planar horizontal surfaces which are perpendicular to the flow of the burning coal dust and coal ash. Coal ash, which builds up on the horizontal surfaces, protects the welds from erosion. 
     A first embodiment of the new clamp mechanism includes a pair of non-matching half-clamps, one of which is equipped with a plurality of slots along the upper and lower surfaces thereof. The other half-clamp is equipped with tabs which mate with the slots of the other half-clamp when both halves are brought together by tightening the screw-type fasteners. The mating locations are readily accessible, thereby allowing a weld to be placed at the junction of each slot and its mating tab. When welds are applied to the new clamp, the clamping function is unaffected by vibration. The new clamp also differs from that of Polutnik, et al. in that provision for installation of a screw-type fastener is made between each adjacent pair of tube recesses. In order to reduce the number of personnel required to install the new clamp, one of the mating half-clamps is equipped with bolt head socket at each bolt insertion location, thereby eliminating the need to hold the bolt head with a wrench while tightening a threadably-attached nut. 
     A second embodiment of the new clamp is similar to the first embodiment thereof, with the exception that there are no bolt holes in the half-clamps, and no bolts are used to hold to two halves together. The half-clamps are drawn together using some other clamping means and welds are used to hold both half-clamps together. 
     A third embodiment of the new clamp includes a pair of matching half-clamps, each of which is equipped with a plurality of tabs along the upper surface thereof and a plurality of slots along the lower surface thereof. One half-clamp may be inverted and positioned opposite another so that the tabs of each mate with the slots of the opposing half-clamp. Rather than using a socket recesses on one of the half-clamps to retain the bolt heads of the clamping screw-type fasteners, the head of each bolt may be prevented from rotating by utilizing a locking clip beneath the head of each bolt. A ganged clip may secure all bolts installed in a half-clamp, or individual clips may be employed to lock each bolt to the half-clamp. 
     A fourth embodiment of the new clamp is similar to the third embodiment thereof, with the exception that there are no bolt holes in the half-clamps, and no bolts are used to hold to two halves together. The half-clamps are drawn together using some other clamping means and welds are used to hold both half-clamps together. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     The present invention, both as to the organization and operation of the various embodiments, may best be understood by reference to the following drawings taken in connection with the description which follows, in which: 
     FIG. 1 is an isometric exploded view of a first embodiment of the multiple-tube clamp; 
     FIG. 2 is an isometric view of the clamp of FIG. 1, assembled in connection with multiple cylindrical tubes; 
     FIG. 3 is a cross-sectional view of the assembly of FIG. 2, taken through the plane ABCD, which passes through the longitudinal axes of the five bolts; 
     FIG. 4 is a cross-sectional exploded view of the assembly of FIG. 3; 
     FIG. 5 is an isometric exploded view of a second embodiment of the multiple-tube clamp; 
     FIG. 6 is an isometric view of the clamp of FIG. 5, assembled in connection with multiple cylindrical tubes; 
     FIG. 7 is a top plan view of the assembly of FIG. 6; 
     FIG. 8 is a top plan exploded view of the assembly of FIG. 7; 
     FIG. 9 is an isometric exploded view of a third embodiment of the multiple-tube clamp; 
     FIG. 10 is an isometric exploded view of a fourth embodiment of the multiple-tube clamp; 
     FIG. 11 is an isometric exploded view of a fifth embodiment of the multiple-tube clamp; 
     FIG. 12 is an isometric view of the clamp of FIG. 11, assembled in connection with multiple cylindrical tubes; 
     FIG. 13 is an isometric exploded view of a sixth embodiment of the multiple-tube clamp; 
     FIG. 14 is an isometric view of the clamp of FIG. 13, assembled in connection with multiple cylindrical tubes; 
     FIG. 15 is an isometric exploded view of a seventh embodiment of the multiple-tube clamp; and 
     FIG. 16 is an isometric view of the clamp of FIG. 15, assembled in connection with multiple cylindrical tubes. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The new improved boiler tube clamp, which may be employed to clamp boiler tubes in an equal-spaced, parallel arrangement includes a pair of mating half-clamps having multiple opposed recesses sized to snugly cradle boiler tubes of a given diameter. The half-clamps are brought together around the boiler tubes and fastened together either with bolts or welds or both. The new clamp is disclosed as four primary embodiments, which will be described sequentially in reference to the attached drawings. 
     Referring now to FIG. 1, a first embodiment of the improved boiler tube clamp  100  includes first and second non-matching, elongated half-clamps  101 A and  101 B, respectively. Each half-clamp includes multiple, mutually spaced-apart, inwardly-curved, essentially hemi-cylindrical guides  102 , each adjacent pair of guides  102  on said first half-clamp  101 A being joined together by an integral medial portion  103 A, and each adjacent pair of guides  102  on said second half-clamp  101 B being joined together by an integral medial portion  103 B, each medial portion  103 A of said first half-clamp mating with a medial portion  103 B of said second half-clamp when said half-clamps  101 A and  101 B are brought together in a clamping configuration, thereby forming a series of axially-parallel, spaced-apart, hollow cylindrical guides  202  (see FIG.  2 ). Half-clamp  101 A is equipped with a plurality of slots  105  along the upper surface  106 U and lower surface  106 L thereof. The other half-clamp  101 B is equipped with tabs  107  along the upper surface  108 U and lower surface  108 L thereof, which mate with the slots  105  of half-clamp  101 A when both half-clamps ( 101 A and  101 B) are brought together in an assembled, clamping configuration. Each medial portion  103 A of half-clamp  101 A is equipped with a bolt-shank receiving bore  109 A, which aligns with the bore  109 B of a mating medial portion  103 B of half-clamp  101 B. A bolts  110  may be inserted in each aligned bore pairs  109 A/ 109 B. When a nut  111  is mated to each bolt  110 , the half-clamps  101 A and  101 B may be brought together in an assembled, clamping configuration. A washer  112  may be placed beneath each nut  111 . An mating junction  113  is formed along the perimeter of each slot  105  where it is adjacent a  107 . The mating junctions  113  are exposed and readily accessible, thereby allowing the placement of a weld at each junction  113 . When welds (see FIG. 2) are applied to the junctions  113  of the improved clamp  100 , the clamping function is unaffected by vibration. 
     Referring now to FIG. 2, the two half-clamps  101 A and  101 B of FIG. 1 have been brought together as a clamp assembly,  200  in combination with a series of boiler tubes  201 A- 201 G. The hemi-cylindrical guides  102 A and  102 B of assembled half-clamps  101 A and  101 B, respectively, form multiple cylindrical guides  202 , within each of which a boiler tube  201 A- 201 G is firmly clamped. The bolts  110  and nuts  111  may be employed to fasten both half-clamps  101 A and  101 B together. Once the two half-clamps  101 A and  101 B are brought together, a mating junction  203  is formed along the perimeter of each slot  105  where it is adjacent a tab  107 . The mating junctions  203  are exposed and readily accessible, thereby allowing the placement of a weld  204  at each junction  203 . In this drawing, a weld  204  has been placed on the mating junctions of each of the outer medial portion pairs  103 N/ 103 B and of the two middle medial portion pairs  103 A/ 103 B. When welds are applied to the junctions  203  of the improved clamp assembly  200 , the clamping function is unaffected by vibration. 
     Referring now to the cross-sectional view of FIG. 3, taken through the plane ABCD of FIG. 2, which passes through the axes of bolt receiving bores  109 A/ 109 B. In order to reduce the number of personnel required to install the improved boiler tube clamp  100 , the medial portions  103 B of half-clamp  101 B are equipped with a non-circular, bolt-head receiving socket  301  aligned to a bolt-shank receiving bore  109 B, thereby eliminating the need to hold the bolt head  302  with a wrench while tightening a threadably-attached nut  111 . 
     Referring now to FIG. 4, the assembly of FIG. 3 is shown in an exploded view. Tubes  201 A- 201 F are viewed parallel to their axes. The elements identified in this view have been heretofore described in reference to FIG. 1,  2  or  3 . 
     Referring now to FIG. 5, a second embodiment of the improved boiler tube clamp  500  is identical to the first embodiment clamp  100 , with the exception that there are no bolt shank receiving bores  109 A or  109 B in the medial portions  502  of each half clamp  501 A and  502 B. The half-clamps  501 A and  501 B are drawn together using some other clamping means (e.g., C-clamps) and welds are employed to hold the assembled half-clamps together. 
     Referring now to FIG. 6, the two half-clamps  501 A and  501 B of FIG. 5 have been brought together in an assembled configuration in combination with a series of boiler tubes  201 A- 201 F. A weld  114  has been placed at each mating junction  113 . 
     Referring now to FIG. 7, the top plan view of the assembly of FIG. 6 shows the boiler tubes  201 A- 201 F in an axially parallel and aligned configuration. Welds  114  are also visible in this view. 
     Referring now to FIG. 8, the assembly of FIG. 7 is shown prior to assembly in an exploded view. Of course, no welds are shown in this state of assembly. 
     Referring now to FIG. 9, a third embodiment of the improved clamp  900  includes a pair of matching half-clamps  901 , each of which is equipped with a plurality of tabs  107  along the upper surface  902 U thereof and a plurality of slots  105  along the lower surface  902 L thereof. One half-clamp  901  may be inverted and positioned opposite the other so that the tabs  107  of each mate with the slots  105  of the opposing half-clamp  901 . Because identical half-clamps  901  are employed in pairs, it is desirable to have a bolt-head receiving socket  301  on each medial portion  903 . It will be noted that a washer  904  larger in diameter than the bolt-head receiving socket  301  is placed beneath each nut  111 . The large washer  904  spans, or bridges the socket  301  so that the socket  301  does not interfere with the tightening of the nut  111 . Alternatively, a bolt-head locking clip (not shown) may be placed beneath the head of each bolt. The clips may either be ganged together or each may be shaped so as to lock the bolt head against the medial portion. Using either technique, both of which are common in the mechanical arts, the bolts  110  may be prevented from turning as the nuts  111  are tightened thereon. 
     Referring now to FIG. 10, a fourth embodiment of the improved clamp  1000  is similar to the third embodiment depicted in FIG. 9, with the exception that there are no bolt holes in the identical half-clamps  1001 , and no bolts are used to hold to two halves together. The half-clamps are drawn together using some other clamping means and welds are used to hold both half-clamps together. Welds (not shown in this Figure) are employed to physically join both half-clamps  1001  at mating junctions  113  formed between slots  105  and tabs  107 . 
     Referring now to FIG. 11, a fifth embodiment of the improved clamp includes first and second non-matching, elongated half-clamps  1101 A and  1101 B, respectively. Each half-clamp includes multiple, mutually spaced-apart, inwardly-curved, essentially hemi-cylindrical guides  1102 , each adjacent pair of guides  1102  on said first half-clamp  1101 A being joined together by an integral medial portion  1103 A, and each adjacent pair of guides  1102  on said second half-clamp  1101 B being joined together by an integral medial portion  1103 B, each medial portion  1103 A of said first half-clamp mating with a medial portion  1103 B of said second half-clamp when said half-clamps  1101 A and  1101 B are brought together in a clamping configuration, thereby forming a series of axially-parallel, spaced-apart, hollow cylindrical guides  1202  (see FIG.  2 ). Half-clamp  1101 A is equipped with a plurality of slots  1105  along the upper surface  1106 U and lower surface  1106 L thereof. The other half-clamp  1101 B is equipped with tabs  1107  along the upper surface  1108 U and lower surface  1108 L thereof, which mate with the slots  1105  of half-clamp  1101 A when both half-clamps ( 1101 A and  1101 B) are brought together in an assembled, clamping configuration. Each medial portion  1103 A of half-clamp  1101 A is equipped with a bolt-shank receiving bore  1109 A, which aligns with the threaded bore  1109 B of a mating medial portion  1103 B of half-clamp  1101 B. A bolt  1110  may be inserted through each bolt-shank receiving bore  1109 A in half-clamp  1101 B and secured in a threaded bore  1109 B of half-clamp  1101 B. It will be noted that each bolt  1110  is termed a stretch bolt. That is, the unthreaded part  1113  of the bolt shank  1114  is of reduced diameter, so that when the threaded part  1115  of the shank  1114  is torqued during tightening, the unthreaded part  1113  will stretch. This has a tendency to lock the bolt in the bore. This feature, coupled with a serrated head bearing surface (shown in FIG. 13) which bears against the seat  1116  of a receiving bore  1109 A, ensures that the bolt, when tightened to its specified torque rating, will not vibrate loose. 
     Referring now to FIG. 12, the two half-clamps  1101 A and  1101 B of FIG. 11 have been brought together in clamp assembly  1200  in combination with a series of boiler tubes  201 A- 201 G (see FIG. 2 of the original hand-drawn drawing figures). The hemi-cylindrical guides  1102  of assembled half-clamps  1101 A and  1101 B form multiple cylindrical guides  1201 , within each of which a boiler tube  201 Ak,  201 B,  201 C,  201 D,  201 E,  201 F or  201 G is firmly clamped. The bolts  1110  may be employed to fasten both half-clamps  1101 A and  1101 B together. A mating junction  203  is formed along the perimeter of each slot  105  where it is adjacent a tab  107 . The mating junctions  203  are exposed and readily accessible, thereby allowing the placement of a weld  204  at each junction  203 . When welds  204  are applied to multiple junctions  203  of the improved clamp  1100 , the half-clamps  1101 A and  1101 B become a single unit and will not separate under normal operational conditions. It will be noted that, as a large portion of each weld  204  in on a horizontal surface of the clamp, it will be largely unaffected by erosion caused by the blast of burning coal dust and coal ash against it when installed within a power plant boiler. 
     Referring now to FIG. 13, a sixth embodiment of the improved clamp  1300  includes a pair of matching half-clamps  1301 , each of which is equipped with a plurality of tabs  1302  along the upper surface  1303 U thereof and a plurality of slots  1304  along the lower surface  1303 L thereof. One half-clamp  1301  may be inverted and positioned opposite the other so that the tabs  1302  of each mate with the slots  1304  of the opposing half-clamp  1301 . Because identical half-clamps  1301  are employed in pairs, each medial portion  1305  is alternately equipped with either a bolt-shank receiving bore  1306 A or threaded bore  1306 B, so that when a pair of the half-clamps  1301  are brought together, a bolt  1105  may be inserted into every other medial portion  1305  of each half clamp  1301 . For this arrangement to be successful, an even number of medial portions  1305  and an odd number of tube guides  1307  are required. It will be noted that as with the fifth embodiment of the invention, stretch bolts having serrated head bearing surfaces  1308  are employed to lock the bolts in the bores  1306 A/ 1306 B when torqued to proper specifications. 
     Referring now to FIG. 14 the two half-clamps  1301 A and  1301 B of FIG. 13 have been brought together in a clamp assembly  1400  in combination with a series of boiler tubes  201 A- 201 G. The hemi-cylindrical guides  1307  of assembled half-clamps  1301 A and  1301 B form multiple cylindrical guides  1401 , within each of which a boiler tube  201 Ak,  201 B,  201 C,  201 D,  201 E,  201 F or  201 G may firmly clamped. A mating junction  203  is formed along the perimeter of each tab  107  where it is adjacent a slot  105 . The mating junctions  203  are exposed and readily accessible, thereby allowing the placement of a weld  204  at each junction  203 . When welds are applied to the junctions  203  of the improved clamp  1300 , the half-clamps  1301 A and  1301 B become a single unit and will not separate under normal operational conditions. 
     Referring now to FIG. 15, a seventh embodiment of the improved clamp  1500  includes a pair of matching half-clamps  1501 , each of which is equipped with a plurality of alternating tabs  1502  on the upper and lower surfaces  1503 U and  1503 L of the medial portions  1504  thereof. This embodiment is different from the others in that each bolt-shank receiving bore  1505  is equipped with a nut recess  1506  which can double as a bolt head recess. A serrated head head bear surface  1308  on each bolt  1110  is employed to lock each bolt in its respective bore  1505 . Each nut  111 , of course, is locked in place by the nut recess  1506 . The bolts may be inserted from either direction. 
     Referring now to FIG. 16, the two half-clamps  1501  of FIG. 15 have been brought together in an assembled configuration in combination with a series of boiler tubes  201 A- 201 F (see FIG. 2 of the original hand-drawn drawing figures). The hemi-cylindrical guides  1601  of assembled half-clamps  1501  form multiple cylindrical guides  1502 , within each of which a boiler tube  201  (see FIG. 2) may firmly clamped. A mating junction  1603  is formed along the perimeter of each tab  1502  where it is adjacent a slot  1504 . The mating junctions  1603  are exposed and readily accessible, thereby allowing the placement of a weld  1604  at each junction  1603 . When welds (identical to those in FIG. 1) are applied to the junctions  1603  of the improved clamp  1500 , the half-clamps  1501  become a single unit and will not separate under normal operational conditions. 
     Although only several embodiments of the invention have been heretofore described, it will be obvious to those having ordinary skill in the art that changes and modifications may be made thereto without departing from the scope and the spirit of the invention as hereinafter claimed.