US2029712A - Ship construction - Google Patents

Description

A Feb. 4, 1936. H. P'. FREAR 2,029,712

SHIP CONSTRUCTION Y Filed Jun 19, 1934 3 sheets-sheet 1 5 Sheets-Sheet 2 H. P. FREAR SHIP CONSTRUCTION Filed June 19, 1954 Feb. 4, 1936.

Feb. 4, 1936. H. P. FREAR SHIP CONSTRUCTION Filed June 19, 1954 3 Sheets-Sheet 3 Patented Feb. 4, 1936 ICE SHIP CONSTRUCTION Hugo P. Fear, New York. N. Y., assigner to Bethlehem Shipbuilding Corporation, Ltd., a corporation of Delaware Application June 19, 1934, Serial No. '131,239

11 Claims. (Cl. 114-79) My invention has reference to improvements in the design ofthe structural arrangement for stiffening and supporting the wall of a tank in a vessel especially designed to carry liquid cargo in bulk. Vessels of such design have a mu1tiplic ity of tanks usually having a deck wall attached to opposite vertical transverse walls and opposite vertical 1ong1tudina1 or side walls. said waus l the industry today is the rapid deterioration of the structure of tankers due to corrosion caused by acids resulting from the reaction of the cargo content and salt water ballast, or salt air. Some parts of the structure due to location are more susceptible to corrosion than others, and sumclent experience has now been gained to determine said parts. The best known method of combating the corrosion diiliculty at present is the defensive one of increasing the thicknesses of the parts of the structure that have been found vulnerable to corrosive action. In this way it is hoped to delay expensive renewals and repairs, besides prolonging the life of the vessel as a whole.

While the need for increasing the thickness of certain parts in order to combat corrosion is recognized there is a, consequent urgent demand to save in weight if possible in the balance of the ships structure. This is demanded in order to keep initial costs down and to benefit by future savings in toll charges and carrying capacity.

. It is the object of my invention to increase the eilciency of the stiflening of the walls of a. ship whereby a considerable saving in weight of structural material is made over heretofore practice.

The principle involved in my improvement, briefly stated, comprises the sub-dividing of the area of a wall subject to fluid pressure, and to support the so divided areas independently. For example, assume a deck wall that is designed to withstand a predetermined test head of water. In my improvement the deck wall, as usually is the case, is attached to two pairs of oppositely facing vertical Walls. The middle portion of the deck wall area with its assumed load is supported .entirely from one pair of said oppositely facing tem of framing in my design.

walls, and the remaining portions on each side of the said central portion are supported each by its adjacent one of the second pair of oppositely facing walls. With this arrangement I am able to design my supporting members with the desirable advantage of a reduction inweight for the same eiiciency over previous practice.

The novel features will be more fully under stood from the following description and claims taken with the drawings, in which:

Fig. 1 represents a diagrammatic part section taken along the line I-I of Fig. 2 of a bulk liquid carrying vessel to illustrate a deck wall attached to a transverse vertical wall;

Fig. 2 is similar to Fig. 1 but in plan view, and illustrates a portion oi' a. deck wall supported by four vertical walls beneath in the manner embodied in my invention;

Fig. V3 is a cross section taken along the line 3-3 of Fig. 2;

Fig. 4 is a cross section taken along the line 4-4 of Fig. 5; g

Fig, 5 represents diagrammatically in elevation a transverse vertical end wall in said vessel which embodies my invention; y

Fig. 6 is a cross section taken along the line 6 6 of Fig. 5;

Fig. '7 is a cross section taken along the line l-'I of Fig. 9;

Fig. 8 is a cross section taken along the line 8-8 of Fig. 9; and

Fig. 9 represents diagrammatically in elevation a transverse vertical wall of a side tank in said vessel which embodies my invention.

Referring now to Figs. 1, 2, and 3 which illustrate the embodiment of my invention as applied to a deck oor III supported on two opposite transverse vertical walls II and two longitudinal walls I2. Supporting girders I3 are attached to the deck wall I and extend between and are supported at the ends by the walls Il. The girders I3 constitute the main supporting and stiffening members of the interlocking sys- The girders I3 support the stiiening beams I4 having their ends jutting beyond the girders I3. The beams I4 are attached to the deck wall I0 and to the girders I3. Stiffeners I are continuous through, supported by, and attached to the beams I4 and are attached to the deck wall I0. Stiifeners I E are parallel to the girders I3 and stiffeners I5, and are attached to the deck wall I0 in close proximity to the ends of the beams I4 and by -or from which they are supported. Stiffeners I1 are parallel to the side walls I2 and girders I3, and are attached tothe deck wall I0, and are supported from the side walls I2 preferably by the struts I8.

From the description just given it is readily seen that a reduced load is carried by the described interlocking system of framing, Supporting the middle portion o1 the deck wall III from two opposed walls by virtue of a part of the total load on the wall being carried independently from the other two opposed walls I2 by the struts I 8. For this reason a saving in weight can-be made over the usual structure without impairing the strength of the deck'wall I0. It will also be readily understood that Figs. 1, 2, and 3 are designed to illustrate more the principle of the divided loading and respective means of supporting the same rather than indicating a limitation, or xed ratio, between the divisions of the loadmg.

Furthermore, a beam stiftener |4 of the type shown, supported by the spaced girders I3, em-

bodies two distinct advantages by reason of the free and unsupported ends on each side jutting beyond the girders I3. The rst of these advantages lies in the fact that the space between the girders I3 can be adjusted in relation to the total length of the beams I4 so that the bending moment at the middle of the space will be equal to the bending moments in Way of said girders, on

which account the beams I4 can be designed with a minimum of waste material, resulting in a saving of weight independently of the saving made possible by dividing said load. Theother advantage lies in the fact that a reduction is made in the shearing stresses existing in the attachment of the ends of the beams to the plating or. wall where it has been found difficult and in most cases impossible to prevent leaky rivets at these points. It is a well known fact that the shearing stress normal to abeam at any point is equal to the shearing stress in the attachment ff said beam to the wall at or opposite the same point. We also know that the maximum shearing stress in beams supported as in my design (b 'ms I4) is in way of the said girders, and that it gradually and uniformly reduces to approximately zero at the ends of the beams by reason of the ends being free and unsupported.

Referring now `again to Fig. l, in which II is a transverse vertical wall between two `adjacent tanks I9 and 20, and 2| is a vertical girder (not shown in Figs. 2 and 3) facing in tank I9. The girders 2| are spaced the same as are the girders I3 in Figs. 1 and 2. The opposite wall (not shown)I in tank I9 also has girders similar to 2|, whereas the inside faces of the walls II in tank 20 are smooth (according to a trade expression). This difference where possible is adopted in alternate tanks, the object being to carry salt water ballast in the smooth tanks which have a reduced number of parts subject to corrosive action, which action is accelerated by salt water ballast.

Referring now to Figs. 4, 5, and 6 I illustrate the embodiment of my invention as applied to a transverse vertical end wall 22 which corresponds to the end walls II of Fig. 2. Side walls 23 correspond to the side walls I2 of Fig. 2, and` the deck wall 24 correspondsito the deck wall I0 of Fig. 2. Vertical spaced girders 25 are attached to the Wall 22. Horizontal spaced' stiflening beams 26 are also attached to the wall 22. and are continuous through the girders 25 with ends jutting beyond the girders 25 on each side, the said beams 26 being attached to and supported I do not wish it to be by the girders 25. Continuous vertical stiieners 2l are in close proximity to the ends of the beams 26, and are supported by the ends of the beams 26 but not necessarily attached thereto. 'I'he framing or stiiening thus far described for the wall 22 constitutes the interlocking system of framing supporting the main middle portion of a, loading applied to the wall 22 as supported by the deck Wall 24, the side walls 23, and the bottom wall 28. Continuous vertical stiieners 29 are on each side between the ends of the beams 26 and the side walls 23. 'I'hese stiieners 29 are supported from the side ably by struts 30 as shown.

From the description applying to Figs. 4, 5, and 6 it is seen that the embodiment of my invention therein is practically identical and has the same advantages as that described and explained as applying to Figs. l, 2, and 3. In Figs.

4, 5, and 6 the girders are vertical but spaced the same as in Figs. 2 and 3, while the beam stiffeners 26 are spaced horizontally. Furthermore, the beams due to their changed condition of loading are more closely spaced, and their size is chosen with due regard to their subjection to a hydrostatic head varying with their position. Also the stiieners corresponding to the continuous stilleners I5 of Figs. 2 and 3, are in this case omitted.

, Coming now to Figs. 7, 8, and 9 I illustrate the embodiment of my invention as applied to a transverse vertical end wall 3| of a wing tank. 'I'he deck wall 32, the ships side-wall 33, the longitudi/nal side Wall 34, and the bottom Wall are the surrounding supporting walls of the `vertical end wall 3|. Although an end wall of this type is of relatively small width, I retain the principle of dividing the assumed load on the wall area into three parts and of supporting the middle portion of an interlocking system of framing. The framing supporting the middle portion of the assumed load comprises the spaced horizontally disposed girders 36 extending between the side walls 33 and 34 and attached thereto and supported thereby and attached to the wall 3|, and

Athe spaced vertical stiifeners 31, which are continuous through thergirders 36, and are attached to the wall`3| and the girders 36 with the ends jutting beyond the girders 36 above and below and supported at the ends by the walls 32 and 35. The framing supporting the side components of the assumed load are the vertical stiifeners 38 nearest the side walls 33 and 34. These stiiieners 38 are continuous through the girders 36, but are not attached thereto, passing through open slots therein, and are supported from the side walls 33 and 34 respectively, preferably by means of struts 39, and are attached to the wall 3|.

It is obvious that both the girders 36 and the sti'ieners 38 may be made smaller and lighter without reducing thickness, than if the stiffeners 38 were supported by the girders 36 the same as are the stiifeners 31.

From the foregoing description it will be readily recognized by those skilled in the art that I have a novel method of ship construction which is particularly economical of weight without'any sacrifice in elciency or strength.

above`V described methods are limited in their applicationtogvessels of thetype described and it is manifest tl`at\theprinciple of design herein set forth could be utilized with other well known types of ship construction.

` The terms and expressions which I have employed are used as terms of description andnot walls 23, prefere understood that my n A En claim as new and desire to secure by Letters Patent is: V

1. In a ship structure, a load sustaining wall, boundary walls normal to said loadsustaining wail, spaced girders supported by and attached to two oppositely disposed of said boundary walls and attached to said load sustaining wall, spaced stiffening beams continuous through supported -by and attached to said girders and attached to said load sustaining wall, the ends of saidstiffening beams jutting beyond said girders respectively and terminating short of the two remaining of said boundary walls respectively, stiffening members attached to said'load sustaining wall parallel to said girders and in close proximity to and supported by the ends of the said stiffening beams respectively, and other stiffening members attached to said load sustaining wall parallel to said girders and parallel to and directly supported 'by the said two remaining of said boundary walls respectively.

2. In a ship structure, a wall structure, and four boundary walls supporting said wall structure, the said wall structure comprising a wall member, an interlocking system of framing attached to said wall member and acting to reinforce a limited transverse central portion of the said wall member, the said interlocking system of framing being supported by the two oppositely disposed boundary walls adjacent the ends of said transverse central portion, and stiffening means attached to each of the remainingA portions of said wall member, each of said stiiening means being supported independently by it's adjacent one of the two remaining boundary walls.

3. In a' ship structure, a load sustaining wall, four boundary walls, an interlocking system of framing attached to a transverse central portion of said load sustaining wall and supported by the two oppositely disposed boundary walls adjacent the ends of said transverse central portion, and stifening means attached to each of the remainlingtransverse portions of the said load sustaining wall, each of said stiffening means being supported independently by its adjacent one of the two remaining boundary walls.

4. In a ship structure, a rectangular load sustaining wall, four boundary walls normal to said load sustaining wall, spaced girders support-edV at their ends by two oppositely disposed of said boundary walls, a plurality of stiffening beams supported by saidrgirders transversely thereto having their ends jutting beyond their respective points of support on their adjacent girder but substantially short of the two remaining boundary walls respectively, all the ends adjacent the same girder being in alignment parallel to said girders,

and two stiffening members attached lengthwise .tosaid load sustaining wall in close ,proximity bythe said aligned ends reto and supported spectively.

5. In a ship structure, a rectangular load sustaining wall, four boundary walls normal to said load sustaining wall, spacedgirders having their ends supported by and attached to two oppositely disposed of said boundary walls and attached lengthwise to said load sustaining wall, spaced stiffening beams continuous through supported by and attached to said girders transversely thereto and attached lengthwise to said load sustaining wall, the ends of said stiiening beams jutting beyond their respective points of support on their adjacent girder and terminating substantially short of the two remaining oppositely disposed boundary walls respectively and being in alignment parallel to said girders, and a plurality of closely spaced continuous stiffeners attached lengthwise to said load sustaining wall parallel to said girders, some of said stifleners being continuous through supported by and attached to said stiffening beams transversely thereto, two of said stiffeners being supported by the said aligned ends respectively, and two remaining of said stieners being independently supported by the last mentioned oppositely disposed boundary a pair of oppositely disposed fore-and-aft walls,

spaced girders horizontally disposed in a foreand-aft direction of the ship attached lengthwise to said deck wall and at the ends to said athwartship walls, spaced beams horizontally disposed athwart the ship continuous through supported by and attached to said girders and attached lengthwise to said'deck wall, the ends of said beams jutting beyond their respective points of support on their adjacent girder and terminating substantially short of said fore-and-aft walls respectively and in alignment parallel to said girders, and a plurality of closely spaced continuous stiieners horizontally disposed parallel to said girders and attached lengthwise to said deck wall, some of said stiiieners being continuous through supported by and attached to said beams, two of said stiffeners being supported by the said aligned ends respectively, and two remaining of said stiieners being independently supported by the said fore-and-aft walls respectively.

7. In a ship structure, a vertically disposed athwart` ship Wall panel, four boundary walls attached to said athwartship wall comprising a pair of vertically and oppositely disposed foreand-aft walls and horizontally and oppositely disposed deck and bottom walls, spaced girders vertically disposed attached lengthwise to said athwartship wall and at the ends to said deck and bottom walls, spaced beams horizontally disposed athwart the ship continuous through supported by and attached to said girders and atsaid stiifeners being independently supported. by

the said yfore-and-ait walls respectively.

8.111 a ship structure, a vertically disposed athwartship wall panel, four boundary walls attached to said athwartship wall comprising a pair of vertically and oppositely disposed foreand-aft walls and horizontally and oppositely disposed deck and bottom walls, spaced girders horizontally disposed athwart the ship attached lengthwise to said athwartship wall and at the ends to said fore-and-ai't walls, and a plurality of closely spaced stieners vertically disposed transverse to and continuous through said gird'- ers and attached lengthwise to said athwartship Wall and supported at their ends by said top and bottom walls, the stifleners next adjacent said fore-and-aft walls being unattached to and unsupported by the said girders and each being supported by one of said fore-and-aft walls respectively, and the remaining of said stiil'eners being attached to and supported by said girders,

9. In a vessel to carry liquid cargo in bulk constructed on the quasi longitudinal system oi framing, ahorizontally disposed deck wall panel, four vertically disposed boundary walls 'attached to said deck Wall comprising a pair of oppositely disposed athwartship walls and a pair of oppositely disposed fore-and-aft walls, spaced girders horizontally disposed in a fore-and-aft direction of the ship attached lengthwise to said deck wall and at the ends to said athwartship walls, spaced beams horizontally disposed athwart the vship continuous through supported by and attached to said girders and attached lengthwise to said deck wall, the ends of said beams jutting beyond their respective points of support on their -adjacent girder and terminating substantially short of said fore-and-aft walls respectively and in alignment parallel to said girders, and a plurality of losely spaced continuous stiileners horizontall disposed parallel to said girders and attached lengthwise to said deck wall, some of said stiffeners being continuous throughsupported by and attached to'said beams, two of said stifteners being supported by the said aligned ends rey spectively, and two remaining of said stiifeners being independently supported by the said foreand-aft walls respectively.

10. In a vessel tocarry liquid cargo in bulk .constructed on the quasi longitudinal system of 1 framing, a vertically disposed athwartship wall,

panel,v four boundary walls attached to said athwartship wall comprising a pair of. vertically and oppositely disposed fore-and-aft walls and l and two remaining oi said stiieners vsupported at their ends by horizontally and oppositely disposed deck and bottom walls. spaced girders vertically disposed attached lengthwise to said athwartship wall and at theends to said deck and bottom walls, spaced beams horizontally disposed athwart the ship continuous through supported by and attached to said girders and attached lengthwise to said athwartship wall, the ends of said beams jutting beyond their respective points of support on their adjacent girder and terminating substantially short of said fore-and-aft walls respectively and in alignment parallel to said girders, and a plurality of spaced stiifeners vertically disposed between the aligned ends of said beams and each of said fore-and-aft walls respectively parallel to said girders and attached lengthwise to said athwartship wall, two of said stiieners being supported' by the said aligned ends respectively,

being independently supported by the said fore-and-aft walls respectively.

11. In a vessel to carry liquid cargo in bulk constructed on the quasi longitudinal system of framing, a vertically disposed athwartship wall panel, four boundary walls attached to said athwartship wall comprising a pair of vertically and oppositely disposed fore-and-aft walls and horizontally and oppositely disposed deck and bottom walls, spaced girders horizontally disposed athwart the ship attached lengthwise to said athwartship wall and at the ends to said fore-and-aft walls, and a plurality of closely spaced stieners vertically disposed transverse to and continuous through tached lengthwise to said athwartship wall and said top and bottom walls, the stineners next adjacent said fore-andaft walls vbeing unattached to and unsupported by the said girders and each being supported by one of said fore-and-aft walls'respectively, and

said girders and at-I the remaining of said stileners being attached girders.

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