GB2293391A - Wire strand:sacrificial wires:corrosion resistance - Google Patents

Description

9 9 Q.9% 9R Q 1

BACKGROUND OF THE INVENTION

This application contains subject matter common to U.S. Patent 3,972,175, which patent is hereby inc orporated by reference. This invention relates in-general to wire strands comprised of multiple layers of wire which strands are used alone or formed into wire ropes for use as guys for stabilizing or anchoring large objects such as offshore drilling platforms. This invention relates more particularly to the expeditious production of various strand sizes from a production facility with a minimum of excess inventory of wire and especially to such strands and ropes which are designed for use in highly corrosive environments such as that encountered when such guys are submerged in sea water. In such an environment it is desirable to protect the strands as far as is practical in order to prolong the life of the strand and to improve reliability during its service life.

Most strand is ordered by size, such as one and three quarters inch strand, two inch strand and so forth. Since there are many different sizes of strands and many manners in which wires of various sizes may be combined togetheT to make a strand of a given size, it has been customary for the wire of a particular size suited for each specific strand to be especially ordered for each strand. Special order wire must, of course, be especially made and it is necessary to fit such orders in between other orders for wire so that often there is a significant and even a considerable time interval involved in supplying the wire. It is often the case if the fabrication has gone well that a considerable length of excess wire is left over. This wire is then held in inventory until another use, 1 usually in the making of a strand of the same type, is found for the wire. Since there are a number of different sizes of wire used in various strands, it is frequently some time before the same size and type of wire is required again. The amount of wire held inventory thus tends to become greater and greater, often building up to a completely impractical amounts, It is not unusual for the wire inventory in a strand and/or wire rope shop to amount to three or four hundred tons or even more. All this excess wire held in inventory is a drain on working capital since it ties up money in unused wire supply and also is a waste both of storage space and of the labor necessary to keep track of wire in inventory and to find inventory stock when it is required for the making of a new order of strand.

is To provide corrosion protection to such strands in the prior art, the interstices between t.he individual wires are filled with a lubricating compound or a semi-solid material. In addition, it has been a common practice to encase the entire strand in a plastic tubing to protect it from sea water. These solutions, while partially effective, add considerable weight to the assembly and, if in a highly abrasive environment such as that found in near shore installations,the tubing may began to leak due to sand abrasion and the corrosive water is allowed to enter the strand.

Another solution has been to incorporate anodic material in the strand assembly which will serve as sacrificial electrode which is lost during the life of the strand but provides the steel strands with a measure of corrosion protection. The problem with this solution is that metals suitable as sacrificial electrodes are generally soft with little tensile strength and generally unsatisfactory elongation 2 properties. Thus, when the strand is strained within the elastic limit of the steel wires in the strand by the mooring force, the steel strands return to their original length when the force is removed. However, since the anodic material generally has a much lower elastic limit, it does not return to its original length. Rather it is elongated and tends to bow out of alignment with the steel strands forming "suitcase handle" loops in the outer layer of the strand. One solution for this problem has been to manufacture the anodes from alloys of steel and an anodic material to increase the elastic limit and prevent the problem described above. However, since a minimum amount of anode material is required to provide the desired protection, a greater number of anodic wires are required than with a pure material thus increasing the cost and weight of the strand. Such a system is described in British patent 1,599,410.

SUMMARY OF THE INVENTION is The foregoing difficulties and problems associated with prior art methods of producihg wire strand of various sizes which is resistant to corrosion are obviated by the present invention. In the U.S. patent 3,972,175, it was disclosed that due to the peculiarities of wire sizes and particularly the unique relationship which exists between certain combinations of two wire sizes such as, for instance three-sixteenths and one-quarter inch nominal diameter wire, it is possible to make a whole series of stock type wire strands having size increments of only fractions of an inch or centimeter between strands and such that a suitable strand can be supplied from the series to fulfill almost any order for strand, using 3 only a limited number of wire sizes. In this manner only a limited amount of wire need by kept in inventory since any excess wire left over from the production of one strand size can be easily applied to the production of another strand size. In addition, the limited number of stock sizes of wire can be more quickly supplied from a wire production facility. Alternatively, it is alsimple matter to maintain a small permanent inventory of the limited number of stock wire sizes required to make strand according to the present invention so that each order of strand can be made up as soon as a stranding machine is available and without having to order the requisite wire from a wire production facility. As the stock wire is used immediately from inventory, it is a simple matter for a stock clerk to reorder as necessary to maintain the desired level of inventory. Reordering can be accomplished either as wire stock is actually used or as the order for strand is received, but before the strand on order is actually fabricated. In either case no waiting is required for the arrival of the requisite wire before the order for the is strand can be fulfilled by stranding the order, yet the inventory level can be kept low, avoiding the tying up of capital in excess inventory, possible deterioration of the wire held in inventory and the inevitable costs and inefficiencies inherent in the maintenance of a large inventory of many different sizes of wires. Furthermore, in the event that difficulty is encountered in stranding a product with the wire ordered, additional wire can usually be drawn from the inventory stock wire sizes to complete the order without delay.

The predetermined series of wire strands sizes is preferably in accordance with the invention made in one of two manners. In one variation of the invention the wire is stocked in three wire sizes in which wire of the first size, which is used 4 only as the center wire of the strand, is the largest wire, the second wire is slightly smaller than the first wire size and the third wire size is smaller than the second wire size by approximately one half of a predetermined interval between the stock sizes of strand which it has been determined to customarily supply to customers.

In the English system of measurementthis series of strands may be conveniently made with one eighth inch intervals between the predetermined strand sizes.

In the other preferred variation of the strand supply system of the invention only two wire sizes are used to make a series of strands in which the size interval between nominal strand sizes may be desirable be one-sixteenth of an inch. Both variations will normally make use of substantially the same wire sizes.

The present invention also overcomes the disadvantages of the prior art methods of manufacturing corrosion resistant strands described above by interspersing anodic yvires of nearly pure elementary material in the outer or in the penultimate layer of the strand. The pure element, for example Zinc of at least 99% purity, is formed in a semi-locking "H" shape having its outer surfaces of a contour to match the shape of the outer surface of its adjacent wires. By locking the anodic wire tog6ther with its adjacent structural wires, the anodic wires remain in place in the strand even after the strand has been subjected to substantial strain. The thinner web portion of the H is sized to have a thickness approximately equal to the radius of the wires in the same layer. Thus, in the stranding of the assembly, two H anodes are equal to the diameter of one wire. To further insure the integrity of the strand, a flat outer wire may be loosely spirally wound around the outer surface of the strand to contain the structural and anodic wires in the proper relationship thus further insuring the structural integrity of the strand. The interstices of the strand can be filled with lubricating or semi-solid material such as amorphous polypropylene to help maintain the strand shape. The amount of anodic material can be accurately calculated depending on the galvanic efficiency of the anodic material and the total ampere-hours of polarization current required to mainiain the structural integrity of the strand for its specified useful life.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a cross-section of a strand which can be made according to Table 1 wherein three wire sizes are provided; Figure 2 is a cross-section of another strand which can be made according to Table 1 wherein three wire sizes are used; and Figure 3. is a cross-section of a strand which is formed from two wire sizes according to Table 2.

Figure 4a is a cross sectional view of a corrosion resistant strand made according to Figure 3.

Figure 4b is a cross sectional view of a corrosion resistant strand made acording to Figure 1.

Figure 5 is a cross sectional view of an alternate embodiment of Figure 4a.

Figure 6 is a cross sectional view of another alternate embodiment of the invention.

Figure 7 is a cross sectional view of yet another alternate embodiment of the invention having an outer flat wire wrapping.

6 Figure 8a is a cross sectional view of one of the anodic wires according to the invention.

Figure 8b is a cross sectional view of a structural wire intended to lie adjacent the cathodic wire of Figure Sa.

DETAILED DESCRIPTION OF THE INVENTION

In accordance with the present invention, a conventional stranding apparatus for the stranding of wire strand is used to strand orders for strand in a predetermined series of strand sizes having constant size intervals between the nominal sizes of strand to be produced.

The following describes a system of supplying wire strand from a production facility, that is to say a shop in which the strand is stranded in any type of suitable production stranding equipment known to those skilled in the stranding art, in which only a limited number, i.e. two or three, wire sizes need to be used in order to form an entire series of strands having uniform predetermined small intervals in size between the strands of the series. One convenient size interval to use is dne-eighth inch intervals between strand sizes will result in a series of readily producible strands which will fulfill the requirements of most strand users for different size strands.

In the production of wire strands in accordance with the present invention it is initially necessary to determine the smallest size strand which it will be desired to make in the series of predetermined strand sizes and also the size interval which it is desired to have between the uniformly increasing strand sizes iri the series.

7 The smallest strand size to be produced will be herein referred to as a strand having a diameter of "unity". Every strand in the series is then based upon the unity size strand.

In one method of carrying out the invention there are three stock wire sizes, and only three, used to product all strand sizes in the strand production system.

The first stock size of wire, which is the largest size, is used at the center wire of the strand and is only a little larger than the second stock size of wire. The third stock size of wire is smaller than the second stock size wire by about one half the predetermined interval which has been selected as the proper interval between the strand sizes to be produced. The third stock size of wire also has a diameter of 75% of the second stock size of wire.

In stranding a strand according to the first method of the invention, in order to fulfill an order for strand the largest stock wire is used as the center wire of the strand and a series of other wires selected from the other two stock wire sizes are used in the outer layers of the strand, which when a single wire size is used in each respective operation or layer of the strand, will build up a strand with the correct outer diameter within the predetermined series of sizes of strands. For example, if it is desired to make a strand of unity the largest stock wire is used as the center wire of the strand and two outer layers of the smallest, or third stock size wire, are stranded about the center wire. The stranding of two layers of these wires about the center wire will increase the effective size of the wire core to make a strand having a size equal to unity, the smallest strand of the series which can be made. The first layer of wires will contain seven of the outer third size wires and the outer layer of wires will contain 13 of the third size wires.

8 When a strand having a diameter of unity plus one interval is desired, the strand will be made from one large center wire with six second diameter wires stranded about it and fifteen third diameter wire stranded about the first layer of wires. The change from a layer of third diameter or size stock wires to a layer of second diameter or size stock wires serves to increase the overall diameter of the strand by one predetermined interval since the second diameter stock wires are each one half of an interval larger than the third diameter stock wires. Since there are two wires in each layer of strand positioned on an axis or diameter through the strand, the strand, the strand diameter is rendered one interval larger by a change in wire size from the third stock wire to the second stock wire size.

When a strand having a diameter of unity plus two intervals is desired it may be made with one large central core wire, a first layer of six second diameter stock wires and a third layer of twelve outside second stock size wires. The additional change from a layer or operation of third diameter wires to a layer of second diameter wires again increases the diameter of the strand by one full interval.

When a strand having a diameter of unity plus three intervals is desired, one large central core or center wire will be used with the seven third stock diameter wires stranded about the center wire, thirteen third stock diameter wires stranded about this inner layer and nineteen third stock diameter wires stranded about the center layer. Then the two wire layers formed from second stock diameter wires are replaced with two layers of third stock diameter wires the diameter of the inner section of the strand is decreased by two intervals since each third diameter wire is one half of an interval smaller than a second stock diameter wire. The addition of a third layer of third stock diameter wires to the outside of the strand will then 9 increase the overall diameter of the strand by three intervals for a net increment of one additional interval. This increment arises because each third diameter stock wire is three quarters of the size of a second stock diameter wire or, in effect, one and one half intervals in diameter.

When a strand having a diameter;f unity plus four is desired, one large center wire will be used with six second diameter stock wires stranded about the center wire, fifteen third diameter stock wires stranded about this first layer and twenty-one third diameter stock wires stranded about the second layer.

This same pattern is continued from one strand of the series to the next until a strand having a diameter of unity plus twenty-four or even more intervals is achieved. As will be seen from an analysis of the above described strand wire patterns, the sequence of addition is generally to start with a strand of unity, add a layer of third diameter wires to this basic strand to obtain a strand of unity plus 1 diameter and then to successively change each layer beginning on the inside of wires of the second diameter until all the layers are composed of wires of the second diameter, at which time, in order to obtain a strand of one additional incremental interval diameter, all of the layers are changed or switched back to third di6meter wires again an additional layer of third diameter wires is added to the outside of the strand. The third diameter wire layers are then gradually replaced by second stock diameter wires until a total of three second diameter wires is being used.

At this point the sequence again changes and a layer of third diameter wires is next added on to a base composed of a strand having a diameter of unity plus four intervals. This makes a unity plus 7 interval diameter stand. The next strand size (unity plus 8) is then made from a base strand having the same diameter of unity plus four with an additional layer of third stock diameter wires stranded bout the base strand. The next strand size (unity plus 9) is made from a base strand having the next base diameter and construction (unity plus 5) with a layer of the second stock diameter wires laid about it. The next size strand (unity plus 10) will then be made from a base strand having a diameter and construction of unity plus 6 with an outer layer of second diameter stock wires laid about it. Each succeeding strand then for as far as one wishes to go, for example to unity plus 36 or more intervals in diameter will be constructed of an outer layer of second diameter wires laid over a base of unity plus four intervals less than the diameter of finished strand to be made. For example a strand having a diameter of unity plus 14 will be constructed of a layer of second diameter wires over a unity plus 10 base, a unity plus 16 strand will be constructed of a layer of second diameter is strands over a base of unity plus 12, a strand of unity plus 29- will be constructed of a layer of second stock diameter strands over a base strand diameter of unity plus 25 and so forth. The outer layer of second diameter wires of each successive strand fter unity plus eight is either one or two more wires than the last successive strand. The following is a listing of the various strand sizes and constructions according to this first principal method of carrying out the invention.

Diameter of Strand to be made (Unity plus 1 interval. 2 intervals. etc.

Construction unity unity + 1 unity + 2 unity + 3 unity + 4 unity + 5 unity + 6 unity + 7 unity + 8 unity -l- 9 unity + 10 unity -;- 11 unity + 12 unity + 13 unity + 14 unity + 15 unity 16 unity 17 unity + 18 unity + 19 unity 20 unity 21 unity + 22 unity + 23 unity 24 unity 25 unity + 26 unity + 27 unity 28 unity 29 unity + 30 unity + 31 unity + 32 unity + 33 unity 34 unity - 35 unity.i- 36 13-3rd wire size/7-3rd wire size/1 A st wire size 1 5-3rd w.zA-2nd w.s. /Mst w.s. 12-2nd w.s./6-2nd w.s./1-lst w.s. 1 9-3rd w.sA 3-3rd w.sd7-3rd w.s./1-lst w.s. 21-3rd w.s./1 5-3rd w.sJ6-2nd w.s./1 -1 st w.s. 23-3rd w. sA 2-2nd w.s./6-2nd w.sA - 1 st w.s. 18-2nd w. sd12-2nd w.sd6-2nd w.s.11- 1st w.s. 27-3rd W. S. + unity plus 4 base 21-2nd w.s 22-2nd W. S 24-2nd w.s 25-2nd w.s 27-2nd w.s 28-2nd w.s 30-2nd w.s 31-2nd W. S 33-2nd w.s 34-2nd w.s 36-2nd w.s 37-2nd w.s 38-2nd w.s 402nd w.s 42-2nd w.s 43-2nd w.s 44-2nd w.s 46-2nd w.s 48-2nd w.s 49-2nd w.s. 50-2nd w.s. 52-2nd w.s. 54-2nd w.s. 55-2nd w.s. 56-2nd w.s. 58-2nd w.s. 60-2nd w.s. 61-2nd w.s. 62-2nd w.s.

unity plus 4 base unity plus 5 base unity plus 6 base unity plus 7 base unity plus 8 base unity plus 9 base unity plus 10 base unity plus 11 base unity plus 12 base unity plus 13 base unity plus 14 base unity plus 15 base unity plus 16 base unity plus 17 base unity plus 18 base unity plus 19 base unity plus 20 base unity plus 21 base unity plus 22 base unity plus 23 base unity plus 24 base unity plus 25 base unity plus 26 base unity plus 27 base unity plus 28 base unity plus 29 base unity plus 30 base unity plus 31 base unity plus 32 base 12 A particularly convenient interval to adopt between strand sizes is one- eighth of an inch in the English system of measurement. The requirements of many, if not most, customers for strand can be supplied from a system which adopts an interval of one- eighth of an inch between strand sizes. With a one-eighth inch interval the proper wires to use in the strand are a normal 0.261 inch wire as the initial shock wire size, a 0.250 inch wire as the second stock wire and a 0. 188 inch wire as the third stock wire size. A wire of 0. 188 inch diameter is just three-quarters of the diameter of a wire 0.250 inches in diameter. Using wires of these diameters and a one- eighth inch interval between the strand sizes the strands made in conformance with the present invention can be illustrated by the following table.

TABLE 1 SEQUENTIAL SIZE WIRE STRAND DIAMETER MACHINE INTERVAL (IN.) CONSTRUCTION DESIGNATION OPERATIONS DIAMETERS 0 1 13/.188"7/.188"11.261 " b2 2 1.0131637 1 1 118 13/.188'61.250"11.261 " bl 2 1.1371.761 2 1 1/4 121.250" 61.25W 1/.261" bO 2 1.2611.761 3 1 318 191.188,' 131.188 71.188" 1/.261"b3 3 1.38911.0131.637 4 1 1/2 21/.188" 15/.188" 6/.25W 1/261b2 3 1.513/1.1371.761 1 518 23/.188" 121.250 61.25W 1/.261bl 3 1.637/1.2611.761 6 1 314 181.250" 121.250" 61.250" 1/.26lbO 3 1.761/1.2611.761 7 1 7/8 271.188" 1 1X Base b3 4 1.889 8 2 21/.250" 1 112" Base b2 4 2.013 9 2 1/8 221.250 1 51W Base bl 4 2.137 2 1/4 241.250" 1 3/4" Base bO 4 2.261 11 23/8 25/.250" 1 71W Base b3 5 2.389 12 2 1/2 271.250" 2 Base b2 5 2.513 13 2 51,8 28/.250" 2 1/8 Base bl 5 2.637 14 2 3/4 301.250" 2 1/4" Base bO 5 2.761 2 7/8 31/.250" 2 3/8" Base b3 6 2.889 16 3 331.250" 2 1/2" Base b2 6 3.013 17 3 1/8 34i.250" 2 5i8" Base bl 6 3.137 18 3 1/4 36i.250" 2 W4" Base bO 6 3.261 19 3 3/8 37/.25W 2 7/8" Base b3 7 3.389 13 3 1/2 381,25W Y Base b2 7 3.573 3 518 401.25W 3 118,' Base bl 7 3.637 42 3 314 421.250 " 3 114" Base bO 7 3.761 23 3 718 431.250" 3 318 " Base b3 8 3.889 24 4 441.25W 3 1/2' Base b2 8 4.013 4 118 461.2 5 0 " 3 SiC Base b 1 a 4.137 26 4 114 481.25W 3 314" Base bO 8 4.261 27 4318 43/.250" 3 718 " Base b3' 9 4.389 28 4112 50/.250" 4 Base U 9 4.513 29 4518 521.250" 4 118 Base bl 9 4.637 43/4 541.250" 4 114" Base bO 9 4.761 31 4718 55/.25W 4 3/C Base b3 10 4.889 32 5 561.25W 4 1/2" Base U 10 5.013 33 5 1/8 581.25W 4 5W Base bl 10 5.137 34 5 1/4 601.25W 4 314" Base bO 10 5.261 5 318 61/.250" 4 7/V Base b3 11 5.389 36 5 112 621.25W 5" Base b2 11 5.513 The above table indicates in the column at the left the number of intervals from unity, in the second column from the left the nominal or ordering size of the strand, and in the third column the construction of the strand. The fourth column is a convenience designation indicating the number of layers of 0. 188 inch or third size wire which will occur in the final strand. In this column bl stands for one layer of 0. 188 inch wire, b2 for two layers of 0. 188 inch wire and so forth. This information is convenient in ordering sufficient wire to make any given order of strand or in keeping track of any amount of wire drawn from the inventory. The fifth column of the table shows the, number of stranding machine operations, or layers, through a stranding machine necessary to make the particular strand in a case where the stranding machine available is a maximum of 26 bobbins of wire for one normal operation and a maximum of 72 available bobbins on a single pass through the stranding machine. Naturally if the particular stranding machine or machines which are available in any given shop or upon which the strand is to be made are larger of smaller with respect to the number of bobbins and the like, the number of operations or passes through the stranding apparatus will vary from the particular designation of 14 indicated on the table. The last column of the table shows in inches to the third decimal place the actual or theoretical diameter of each strand made according to the invention plus in the case of the first few strands the theoretical diameter of the intervening strands made in each of the operations.

While it is much preferable for the central wires of the ihitial strand to have a diameter slightly greater than the second diameter wire, for instance, as shown on the table, having a normal diameter of 0.261 inches rather that 0.250 inches, it is possible for the two wire sizes, or, in other words for the first and second stock wire sizes to be the same. In this case a 0.250 inch wire will be substituted for the 0.261 inch center wire. The 0.261 inch wire is actually considered to be a nominal 0.250 inch wire, but is preferable as a center wire of a strand in order to prevent too close a clearance between the wires stranded about the center wire. It is advantageous to have at least a slight clearance between the outer wires to avoid "popping" of the wires out of position. Adjustments of the length of lay of the wires about the center wire may also serve to make some adjustments as to packing of the wires.

A second principal method of making a predetermined strand series according to the present inven'tion may be used to produce strand made with a smaller interval between'stock strand sizes of the predetermined series of strands. The second principal method is accomplished by stocking just two stock wire sizes, the first wire size being a predetermined size smaller than the second wire size. The predetermined size by which the wires differ in diameter is equal to the interval which is desired to have between the strand sizes in the system of strands. As in the first principal method of the invention, the smaller of the two wires is three-quarter of the diameter of the larger of the two stock wires used in the series.

In the second principal method of producing the wire strand system of the invention an initial wire core having a diameter of unity will be constructed by stranding a first strand composed of a center wire of the first diameter having a operation of first diameter wires stranded about it. In this second method according to the invention of a strand havi-ng a diameter of unity plus one interval will then be composed of a center wire of the second or larger wire stock wire size (which is one interval larger than the first wire size) with an outer operation of layer of the first (or smaller wire size) wire size. A strand having a diameter of unity plus two intervals will then be constructed from a center wire of the first or smaller wire size plus one operation or layer of the second or larger wire size. By decreasing the single center wire size one interval and increasing the outer wire size one interval, the effective diameter of the strand is increased one full interval since there are two outer wires across the diameter of, the strand but only one center wire across the diameter of the strand. Thus one interval is subtracted as two intervals are added to the diameter resulting in a net increment in diameter of one interval. The net'strand diameter of unity plus three intervals is constructed of a center wire of the second or larger size plus an outer operation or layer of second diameter wires. It will be recognized that by incredsing the size of the center wire one interval the overall diameter of the strand is increased by one interval.

The next two intervals of strand diameter, i.e. unity plus four and unity plus five, are, because of the peculiarities of wire sizes and packing arrangements, not manufacturable by the use of the two primary stock wire sizes and thus do not exist in the predetermined system of strands according to the invention. A strand having a diameter of unity plus sixintervals, however, would be composed of a center 16 comprised of a first or smaller center wire plus two operations or layers of first wire size stranded consecutively about the center wire. A strand of unity of seven would then be constructed by using a center wire composed of second stock size wire, or the larger wire size, plus the same two operations or layers of first, or smaller, wire size stranded abouFthe center wire thus effectively increasing the diameter of the strand by one interval of diameter. A strand of unity plus eight diameters would be constructed by using a first or smaller center wire plus one operation of second or larger wire size effecting a net increment of diameter of the strand of one interval. A strand of unity plus nine intervals would be comprised of a center wire of the second or larger stock wire size plus one second wire size and one first wire size operation or layer about the center of the strand. A strand of unity plus ten intervals would be composed of a first wire center and two outer operations of second, or larger, stock wire giving a net incr--.Ment again of one interval in diameter for the overall strand. A strand of unity plus eleven would be composed of a second or larger wire size plus two operations of second wire size. A strand having a diameter, on the other hand, of unity plus twelve intervals would have a center wire of the first wire size plus three outer operations of first wire size. Thus, by subtracting one interval from the size of the center wire and two intervals each from the size of the two outer layers of the strand, or a total decrease of five intervals, and at the same time adding one extra layer of first diameter wires, there is a net increase of one interval to the outside diameter of the strand.

The next strand size, namely unity plus thirteen intervals, is composed of a center wire composed of a second or larger wire size plus three operations or layers of first size wire. A strand having a diameter of unity plus fourteen intervals on the 17 other hand is composed of a first wire size center wire plus two operations of first wire size and one operation or layer of second wire size. The strand series can be almost indefinitely extended beyond this point by alternating the size of the center wire between the first wire size and the second wire size while simultaneously, each time the center wire returns to the smaller first wire size, increasing the size of the wires in one of the outer layers of the strand. When all of the layers plus the center wire are composed of second wire sizes then the size of all the wire in the first two layers and the center wire of the strand are returned to the first or smaller wire size and an additional layer of outer first or smaller wires is added to the outside of the strand.

One very satisfactory embodiment of the invention using two sizes of stock wires in accordance with the above is one in which the first smaller size wire is 0. 188 inches in diameter and the second larger size wire is 0.250 inches in diameter.

It will be noted that these are the same two principal wires as are so effectively used in the first principal method of the invention as a preferred embodiment except that in the first principal method the smallest or 0. 188 inch wire was referred to as the third wire of the series, while in the second principal method the 0. 1 8 inch wire is referred to as the first wire of the two wires in the series.

This is because it is convenient to designate the center wire of a strand of unity as the first wire of the particular series and the center wire in the first series is always a larger wire, while in the second series the initial center wire is a in a strand of unity is the smaller of the two wires. It is usually advantageous in production time to use the largest sizes of wire possible or permissible while still maintaining the necessary properties of the wire. A 0. 188 inch wire is, furthermore, just seventy- five percent of 18 the diameter of the 0.250 inch wire making the wire geometry proper for the fabrication of both series of the strands of the invention. The use of larger rather than smaller wires in a strand is, other things being equal, desirable in order to have as few wires as possible in the strand in order to cut down on the operations necessary to both make the wire and to strand or lay the wire into a wire strand The addition of a few extra wires in the strand may often be enough to require passage of the strand through another operation or pass in the stranding apparatus if the capacity of the strand is exceeded by the number of wires in the strand. Each extra operation means additional handling and time for production with resultant increase in manufacturing expense.

It will be evident from the foregoing that the two principal embodiments of the present invention are closely related in that when a 0.250 inch wire is used in the first described embodiment, which normally uses three wire sizes, some of the strands made by both systems correspond. For example the strand conforming to unity plus nine intervals in the second embodiment would then be substantially identical to a strand of unity plus two intervals in the first principal embodiment and a strand of unity plus thirteen in the second principal embodiment would be the same as unity plus three in the first principal embodiment. It would then be recognized that there are also other structures of strands made in the two principal embodiments which are substantially identical.

A chart may be constructed to illustrate the use of 0. 188 inches and a second wire size of 0.250 inches in the present invention as described above with respect to the second principal method of the invention. Such a chart or table is shown in the FIG. 1 attached hereto. The table shown in FIG. 1 is designed to quickly indicate the 19 general construction of wire strands using the 0. 188 inch and 0. 250 inch wires in accordance with the invention.

This chart or table is read down along the left edge to find the size of strand which will be made by various numbers of 0.250 inch wires across the diameter of the strand and along the top edge to find the size or diameter oi strand which will be made by various numbers of 0. 188 inch wires across the diameter of the strand.

Strands composed of mixtures of the two wire sizes can be found in the body of the chart. The nominal sizes in inches and fractions of an inch as shown in the body of the chart the actual theoretical size in whole and decimal parts of an inch are shown in the body of the chart. When ordering the strand the size of the strand is found in the body of the chart and the number of layers of both 0. 188 inch and 0. 259 inch wires are read off from the top and side of the chart respectively. Lines pass through non-existent strand cornstructions. The diagonal lines also enclose within their boundaries all of the strands of the series constructed of the same number of wires.

The total number of wires in each respective strand can be read off the top and side of the table respectively. The center wire diameter is always the odd number at the edge of the chart corresponding to the coordinates of the strand diameter and the number at the other end of the chart is always an even number indicating full outer layers of wires about the strand each of which layers contributes two wires to the strand diameter. The sequence of progressively larger numbers of wires can be read off from the chart from the top and the left. The sequence of strand sizes progressing from the largest to the smallest size can be read consecutively along the diagonals progressing from the top down across the page to the left and then beginning again at the top of the chart or to the left of the line designated as the "repetition line" or the limit.

The vertical line designated repetition line down the center of the chart indicates the limit of repetition of the predetermined system of wire strands. It will be noted that the first strand size to the left of the line is in each case the next continuing size strand in the series continued from the diagonal series directly above.

The strand size immediately to the right of the line is, however, a repetition of the last strand size in the immediately preceding diagonal column,constructed, however, of more 0. 188 inch wires and less 0.250 inch wires. In each case the actual size of the size as compared with the nominal size is slightly greater in the strands to the right of the repetition line than to the left of the line.

Since the use of increasing numbers of smaller wires in place of larger wires requires the use of more total wires to attain the same diameter strand, it is advantageous to use more of the of the larger size wires since the wire is then not only subjected to fewer drawing operations, but the number of wires to also be handled is also less. It will be recognized furthermore, that is often a serious disadvantage to use more wires than necessary in a construction since a few more wires in a construction may result in having to pass a strand through a stranding apparatu additional times. Therefore, the preferred strand constructions to left of the repetition line will normally be used in the series. If, however, alternate constructions using proportionately more of the smaller wires are designated for one application or another the alternative constructions to the right of the line may also be used and are encompassed in the present invention.

This invention is useful for the production of wire strand such as bridge strand, strand for use with boom pendants and other types of structural and semi-structural 21 strands such as the strand used for roof supports and guy lines and the like, and also working strands such as used for drag lines and the like, and even strand used in making wire rope and the like.

SPECIFIC EXAMPLE Referring to Table 2, it is desired to determine the construction of a 2 7/8 inch diameter strand is located. The number of 0. 188 diameter wires across the strand center line is noted as 6 at the top of the column directly above the 2 7/8 inch diameter designation. Going horizontally to the left edge of the table the number 7 is noted for the number of 0.250 diameter wires across the strand center line.

Following up the channel to the upper end thereof the strand construction is noted as being 1 X1 27. Since there are an odd number of 0.250 diameter wires across the centerline, the core wire diameter will be 0.250 inch.

As mentioned above, the two principal embodiments of the invention using 0.250 inch wires in place of the preferred 0.261 inch wires for the center wire of the strand are closely related in that in this instance many of the constructions of strands in the two embodiments are in fact identical. Close inspection of the two principal methods of the invention will show that the two principal methods are in fact variations of a single broad method in that the first method is actually a simplification or abbreviation of the second method using a preferred wire size for the center wire of the strand. Thus it will be noted that when only the strand constructions occurring at one-eighth intervals and beginning at one inch strand are considered in 22 1 WIRES ACROSS STRAND NUMBER OF.188 WIRES CENTER Ll". 2. 3. 4. 5. 6. 7.

RAND CONSTRUCTION --- lX7 IX19 IX37 9/16j 15/16j 1 1 5/16j 113/8 1 1/16_1 7/161 - ' 1 13/16 1 1/2 -- -- -- 1 7/8 --, - 1 9/16 1 15/16_ -, 2 5/16_ -- -- 21 2 --:3/8 -- 2-1/16, - -- 2 7/16 t - -2 13/16 -- -2 112 - -7. - 217/8 --, - - 2 9/16 2 15/16 3 5/16 3 3 3/8 3 1/16__, - -- 3 7/16, - -' 3 13/16 3 112, - 3 7/8_, - ' 3 9/16__ 3-- 15/16, - 4 5/16_ 4 4 3/8_, 4 1/16_-, ' -- 4 7/16,, ' 4 13/16_ 4 1/2 - 4 7/8, - ' 4 9/16_- 4 15/16, 5 5/16 -- 5 -- 5 3/8--, - 1/ 1 6__ 5 7/16 5 13/16 112 5 7/8 - LINE 9/16, 5 15/16, - +3/8" 6 6 1/16, 8 --1- Ll 5/8 2.

3. - 3/4 1/8 4., - -- 1 3/16-- - - 5. 1 1/4 ' -, 1 5/8 6. - 1 11/16, - ' 7. -1 3/4 - - - - 2 1/8 8. --, 2 3/16, - ' 9. 2 1/4 __, - -- 2 5/8 10. - -- 2 11/16 ' - 11. 2 3/4 -- - ' 3 1/8 12,-' 3 3/16 ' - ' 13. 3 1/4 __, - 3 5/8 14., - ' 3 11/16 ' - ' 15. 3 3/4, - 4 1/8 16., - ' 4 3/16 - - - 17 4 1/4 -- - 4 5/8 18.,-- 4 11/1, - -- 19. 4 3/4 ' - ' 5 1/ ' 8 20., - -- 5 3/16 21. 5 1/4 ' - ' 5 5/8 22., - -- 5 11/16 ' - ' 23. 5 3/4 -- ' ' 6 1/ 24.,- 6 3/16 -- 25. 6 1/4 __, - -- 8. 9.

10. 11.

STRAND 12. 13. CONSTRUCTION 1X61 1X91 1X127 1 11/16 2 1/16 1 2 7/16 1 3/4 --- 2 1/8--, -- j 2 1/2 -- -- - -- -- ' 2 3/16 -- - 2 9/16 12 15/16 2 1/4__ 2 5/8 3 -- -- 2 11/16 -'3 1/16 -1 7/16 2 3/4 __, ' 3 1/8,, - '3 1/2 __, -- - ------3 3/16,, - 3 9/16 ' - -- 3 15/16 3 1/4 __, - 3 5/8_, - -- 4 -- -- - - ' 3 11/16, - ' 4 1/16 -' 4 7/16 3 3/4, - -- 4 1/8 --, - 4 1/2 -- ' -- -- 4 3/16,, - 4 9/16 __, - __4 15/16 4 1/4--,--- 4 5/8,, - -- 5 4 11/16,, - 5 1/16 _ ' - 5 7/16 4 3/4__, - ' 5 1/8, - 5 1/2 3/16__, - _ 5 9/16 114__, - ' 5 5/8 11/16 3/4 REPETITION NO 13/1 OR 7/8 DIA. EXISTS IN THIS SERIES +1/2 +1/1 C INCREMENTS OF DIAMETER CHANGE 1X169 1X217 1X271 1 X331 1X397 1 X469 --f:X> m rm t..i Wires ^crust Strand Centetfine Q-t- i NUMBER OF.5111111. WIRES 0 1 2 3 4 5 6 7 0 9 10 11 12 13 14 is 16 17 16 19 20 21 - 0 0 30 42 54 66 70 90 102 1 - - 19 31 43 - 55 -- 67 79 91 103 115 127 7 20 - 32 4-1 00 92 104 116 1.10 --- --- ---- - -- - 1213.

3 21 - 33 45 57 81 93 lots 117 - 141 129 - - 34 46 58 70 02 94 106 110 130 142 47 59 71 03 95 107 119 131 143 G 48 60 72 04_ 96 100 120 132 144 7 49 - 61 73 85 97 109 121 133 145 62 74 86 90 110 122 134 145 9 63 75 07 99 ill 123 135 147 76 on 100 112 12-1 136 140 11 77 09 A 101 113 125 137 149 - 12 90 102 114 126 1 130 1 so -- liel)(,1;1iogl 13 91 103 115 127 139 151 14 104 116 128 140 152 105 117 129 141 153 7110 follovviy)u sizes do Ilot exist Irl this series:

16 110 130 142 154 22, 23, 24, 25, 26, 27, 28, 29 17 119 - 131 143 155 36, 37, 39, 39. 40, 41 18 - 132 144 156 50, 51, 52, 53 19 133 145 157 64, 65 146 150 12mni 21 147 159 22 160 + Imm 23 161 q -r.404- F- 3- -1 (N the chart shown in the Table 2, the constructions are similar to the constructions in Table 1. That is to say that, if one inch cable in the chart in the Table 2 is taken as unity and one-eighth intervals of strand only are read from the chart, then the construction of strand would be substantially the same as in as in Table 1 if a 0.250 inch wire is substituted for the preferred 0.261 inch center wire in Table 1. It-will be clear from this that the strand constructions of the first principal method of the invention are actually selected intervals or constructions of the second principal method of the invention using as unity a strand size which occurs beyond the missing or non-existent strand sizes in the second series of strands. It will additionally be clear from this that it would also be advantageous to use 0.261 inch in place of the 0.260 inch wire size for the center wires of the strands in the second embodiment and that it would also be advantageous to use as a somewhat larger size wire in place of the 0. 188 inc.h wire in the second embodiment when this wire is to be used as the center wire of the strand. Such a wire size might be a 0. 195 inch or more diameter wire. It will be clear also that in both instances the amount by which the actual size of the center wire of the strand exceeds its nominal size is not critical and a large number of sizes of slightly enlarged wires with respect to nominal size may be used so tong as the wire is sufficiently enlarged to provide some clearance between the wires stranded about the enlarged wire, but not so large as to provide excessive clearance between the outer wires. A range of ten to fifteen thousandths of an inch increase in the center wire size is very satisfactory in most instances. Thus an oversize 0.250 inch wire would desirably be from 0.261 to 0.266 inches in diameter and an oversize 0. 188 inch wire would desirably be f rom 0. 198 to 0. 203 inches in diameter. Because of wire geometry it is more desirable that 0.250 inch wire be oversize when used as the center wire than that 0. 188 inch wire be oversize. It will be evident also that when other actual wire sizes are used in place of the 0. 188 inch and 0.250 inch wire for the outer wire layers of the strand the same general additional size increment for the center wire is also desirable, but. in the same manner, not critical. The use of an ovetsize wire for the 0. 188 inch center wire does, of course, involve the stocking of an extra wire size so that the second principal method of the invention would require in actuality, if practiced with desirably oversized center wires, four stock wire sizes rather than two. However, since there is only a single relatively short length of center wire in each strand, the inventory involved is not great.

The invention is not restricted, of course, to the use of 0. 188 inch and 0.250 inch wires in either the outer or inner layers of the strands, but only to the stocking, basically, of the two wire sizes which differ from each other in diameter by a predetermined even fraction, including one, of the predetermined desired interval between strands in the series of strands to be made and in which the smaller of the two wires is three-quarters of the size of the larger of the two wires. Any strand diameter conforming'to the predetermined interval between strands, or multiples of this interval, can then be built up by using the two wire sizes. The measurement of the wires and strands may be in either the English system as illustrated in Table 2 or the metric system as illustrated in Table 3, so long as the basic size relationships and constructions remain the same.

Referring now to Figure 4, there is shown another embodiment of the invention.- The strand illustrated is composed of multiple structural wires of different sizes as described above. The number and size of the individual wires used is 26 dependent on the diameter of the strand required.

Referring again to Figure 4, there is show a first wire size 2 which is used to form the outer layer of the strand and several of the inner layers as required by the final strand diameter specified. A layer of a second wire size, shown at 4, is used between the layers df the wire 2. In the example illustrated, there are two layers of wire 2 as the two outer layers. Next, a layer of wire 4 is inserted and this is followed by four additional layers of wire 2. The next two layers and the center wire 8 are of the size of wire 4.

Referring now to the outer layer of the strand illustrated in Figure 4, there are interspersed between selected structural wires 2, anodic wires 6. These anodic wires are formed in an approximate "H" shape which allows them to be locked to their adjacent structural wires 2 to form a mechanical bond between them. A detail drawing of the qross section of wire 2 and the anodic wire 6 are illustrated in Figures and 9b. The intersticial space 12 between the individual wires and between is filled with a semi-solid material such as amorphous-polypropelene Referring now to Figure 8a, there is shown an enlarged illustration of the anodic wire 6. This wire is made of a pure metallic element having a high galvanic efficiency, for example, pure Zinc. Other similar metals such as Aluminum and Aluminum Alloy may also be used. The best results are obtained if the Zinc is of a purity of at least 99 %. Such a material is defined by the composition of Zinc anode material of ASTM-13-41 8 Type 11. This material is pure Zinc except for approximately 017% of other metallic elements. As shown, this anodic wire is designed to be assembled in a layer of structural wires illustrated in Figure 5. The anodic wire is formed in an approximate "H" shape having a generally flat top and bottom surface 27 and concave surfaces on both sides. The radius R of the concave shape of the side walls is dimensioned to be the same as the radius of the cross section of the S structural wires to be assembled in the same layer. In addition, the thickness of the web portion of the "H" is made equal to the radius R of the structural wire. Thus, in the assembled strand, each two anodic wires occupies the same portion of the circumference of a layer of the strand as one of the structural wires. Also, the upper portion A of the anodic wire is slightly larger than the bottom surface B. This dimensioning allows the anodic wire to engage the adjacent structural wire snugly in the assembled strand to insure the mechanical integrity of the strand.

Various methods may be used to determine the amount of anodic material required to support cathodic protection during the design life of the strand. These methods may vary from using a simple ratio of anode area to gross steel area (say 40110 zinc for 10 years life), or an engineered approach where the amount of anode is determined from the "current density" produced in sea water between specific anode/cathode combinations, with allowances for galvanic efficiency and differentiation between initial and maintenance current conditions.

Referring now to Figure 5, there is shown an alternate embodiment of the invention of Figure 4. In this embodiment, the anodic wires 6 have been places in the penultimate layer of the strand instead of in the outer layer illustrated in Figure 4. This style may be desirable when the strand is to be subjected to a highly abrasive environment such as that found in near shore installations where the scrubbing effect of the sand in the turbulent sea water could cause rapid deterioration of the soft anodic wires assembled in the outer layer. Otherwise the same method of calculating the number of anodic wires and the selection of structural wire sizes are the same as 28 that applied to the embodiment of Figure 4. In Figure 6, the anodic wires are applied to both the outer layer of the strand as well as the penultimate layer. This configuration may be used when more anodic wires are required than can be safely incorporated in a single layer. Referring now to Figure 7, there is shown yet another embodiment of the invention in which a flat structural wire 10 is loosely wrapped in a spiral fashion around the outer layer of the strand. This additional wrapping helps to maintain the wires of the strand in their proper position and also provides some mechanical protection for the outer wires from physical damage. Thus it can be seen that there is disclosed herein a corrosion resistant strand composed of several types of wires selected to provide the finished strand size required while also providing a highly corrosion resistant strand which will maintain its structural integrity in a corrosive environment and also resist physical damage.

29

Claims (15)

CLAIMS: -

1 2 3 4 6 7 8 9 10 1 2 1 1. A wire strand comprising:

a plurality of metallic first wires arranged in layers to form a multi wire strand, said first wires forming the structural portion of said strand; a plurality of metallic second wires interspersed between certain of said first wires in at least one of said layers of said first wires and spaced approximately equally about the circumference of said layer, said second wires being of a metal higher in the electropotential series than said first wires and formed in a generally H shape having a top and a bottom surface and opposing side surfaces forming a web portion therebetween, said top and bottom surfaces being substantially flat and said side surfaces being of concave shape, the radius of the concave surface being approximately of the same radius as the cross section of said first wires and said web portion being of a thickness approximately equal to the radius of the cross section of said first wires.

2. The strand according to claim 1 where said second wires are made of 2 at least 99% pure element metal.

3. The strand according to claim 2 wherein said. second wires are made of pure Zinc.

4. The strand according to claim 3 wherein said second wires are interspersed between said first wires in the outermost layer of the strand.

5. The strand according to claim 3 wherein the second wires are interspersed between the penultimate outer layer of said first wires.

6. The strand according to claim 3 wherein said second wires are 1 2 1 2 1 2 1 4 6 7 8 9 10 11 12 interspersed between the first wires in the outer and the penultimate outer layers of 3 said strand.

7. The strand according to claim 3 and further comprising a third wire of flat cross section wrapped in a spiral manner around the periphery of the strand.

8. The strand according to claim 3 and further omprising a third wire of flat cross section w rapped in a spiral manner around the periphery of the strand.

9. The strand according to claim 4 and further comprising a third wire of flat cross section wrapped in a spiral manner around the periphery of the strand.

10. The strand according to claim 3 and further comprising a third wire of flat cross section wrapped in a spiral manner around the periphery of the strand.

11. The strand according to claim 3 and further comprising a third wire of flat cross section wrapped in a spiral manner around the periphery of the strand.

12. A wire strand having a diameter range from 1 inch to 5 1/2 inches in which range the difference in diameters between any two successive strands is a constant and said wire strand is formed from no more than three wire sizes which include:

a first wire; a second wire with a size smaller than said first.wire; a third wire with a size which is: i. smaller than said second wire by one-half the constant difference in diameters between successive strands, and ii. equal to 75% of the size of said second wire, and said wires are arranged according to the construction set forth in Table 1 of the specification, whereby said three wire sizes allow all sizes of strand within said 31 14 15 16 17 18 19 20 21 22 23 1 4 diameter range to be manufactured.

a fourth wire interspersed between certain of the wires in the outer layer of said strand, and spaced approximately equally about the circumference of said layer, said fourth wires being of a metal higher in the electropotential series than said first, second and third wires and formed in a generally H shape having a top and a bottom surface and opposing side surfaces forming a web portion therebetween, said top and bottom surfaces being substantially flat and said side surfaces being of concave shape, the radius of the concave sur-face being approximately of the same radius as the cross section of said wires of said outer layer and said web portion being of a thickness approximately equal to the radius of the cross section of said wires of said outer layer.

13. A wire strand according to claim 12 wherein said first wire has a diameter of 0.261 inch, said second wire has a diameter of 0.250 inch, said third wire has a diameter of 0. 188 inch, and said difference in diameters between any two successive strands is 1/8 inch.

14. A wire strand having a diameter range from 9/16 inch to 1/4 inch and from 15/16 inch to 6 1/4 inches in which range the difference in diameters between any two successive strands is a constant and said wire strand is formed from no more than two wire sizes which include:

a first wire, a second wire, said first wire is, i. smaller than said second wire by the difference in diameters 32 11 12 13 14 16 17 18 19 21 22 23 1 2 3 4 inch.

between any two successive strands, and ii. equal to 75% of the diameter of said second wire, and said wires are arranged according to the construction set forth in FIG. 1 of the specification, whereby said two wire sizes allow all sizes of strand within said diameter range to be manufactured: a third wire interspersed between certain of the wires in the outer layer of said strand, and spaced approximately equally about the circumference of said layer, said third wires being of a metal higher in the electropotential series than said first and second wires and formed in a generally H shape having a top and a bottom surface and opposing side surfaces forming a web portion therebetween, said top and bottom surfaces being substantially flat and said side surfaces being of concave shape, the radius of the concave surface being approximately of the same radius as the cross section of said wires of said outer layer and said web portion being of a t6ickness approximately equal to the radius of the cross section of said wires of said outer layer.

15. A wire strand according to claim 14 wherein said first wire has a diameter of 0. 188 inch, said second wire has a diameter of 0.250 inch,. and said difference in diameter between any two successive strands is 1/16 33