Page 24 AC 43.13-1 197 Section 2. FINISHING WOOD STRUCTURES
37. GENERAL, Any repair to spars, ribs, skin surfaces, or other structural parts of the airframe involves finishing as the final step of the job. The time and effort spent during the preparatory phase of the refinishing process will be reflected in the appearance of the finished surface. Adherence to the instructions issued by the finish manufacturer is necessary to obtain the appearance desired and protective characteristics for the product used.
38. PRECAUTIONS TO BE OBSERVED. When making repairs, avoid excessive contamination of surfaces with glue squeezeout at joints and on all surfaces. Excess glue should always be removed before applying finish. Because paints and glues are incompatible, even a slight amount of glue underneath the finish may cause premature deterioration.
a. Soiling substances, such as oil and grease, should be removed as completely as possible.
Naphtha may be used to sponge off oil and grease. Markings that are made by grease pencils or lumber crayons containing wax are harmful and should be removed, but marks made by ordinary soft graphite pencils and nonblotting stamp pad inks may be safely finished over. All dust, dirt, and other solid particles should be cleaned off.
b. Sawdust, shavings, and chips must be removed from enclosed spaces before they are sealed off by replacement of akin. A vacuum cleaner is useful for such cleaning.
6. Since no satisfactory gluable sealer has yet been developed, it is necessary to avoid applying sealer over the areas where glue will be applied. Mark off areas to receive glue, allowing an additional 1/4 inch on each side of the glue area to provide for misalinement when mating the parts. It is preferable to leave some unsealed areas rather than risk weakening the glue joint by accidental overlap of the seale into the glued areas.
d. Finish is likely to crack when applied oven fush-driven nails and screws. To avoid this, a strip of tape may be applied over the heads finish is applied. after application of sealer and before the finely
e. Fill all holes left from nail-strip gluing or countersunk nails and screws with a wood filler before finishing the surface. It may be necessary to cover with a patching putty the slight depressions left after applying filler, if a completely smooth surface is desired; but, as rule, patching putty may be dispensed wit safety.
f. Treat surfaces which are likely to come i contact with fabric during the doping proces with a dope-proof paint, cellophane tape, etc to protect them against the action of the so vents in the dope.
39. FINISHING OF INTERIOR SURFACES. Finig repaired ribs, spars, interior of plywood ski and other internal members, including areas c contact between metal and wood, by applyi at least two coats of spar varnish. Prot built-up box spars and similar closed stru tures on the interior by at least one heavy cor of spar varnish or lionoil. Where better protection is required, as on the surfaces of wheel wells and the bottoms of hulls below the foo boards, an additional coat of aluminized sea consisting of 12 to 16 ounces of alumir paste per gallon of sealer may be applied.
40. FINISHING OF EXTERIOR SURFACES. Exteri surfaces should first be sealed with at least t coats of sealer or spar varnish. The surfa finish should then be completed by the applid tion of enamel, aluminized varnish, or oth special finish as required to duplicate the orig Par 37 Chap
AC 43.13-1A 1972 nal finish. If dope or lacquer is used to complete the finish, the sealer coats should be dope-proof. Spar varnish or sealer conforming to Specification MIL-V-6894 is satisfactory.
41. FINISHING OF END GRAIN SURFACES. End grain surfaces, such as edges of plywood skins and holes in spars and other primary structural members, require careful protection.
Sand these surfaces smooth. Apply two coats of a highly pigmented sealer, or one coat of wood filler, and one coat of clear sealer to end grain interior surfaces and cut holes. Exterior end grain surfaces (except those covered with doped fabric) require an additional (third) coat of clear sealer. A final coat of aluminized varnish may be applied to end grain surfaces.
If the surfaces are to be finished with dope or lacquer, a dope-proof sealer similar to Specification MIL-V-6894 should be used.
Exposed end grain includes such surfaces as those around ventholes, inspection holes, fittings, and exposed scarfed or tapered surfaces such as those of tapered blocking.
42. FINISHING WITH FABRIC OR TAPE. To refinish with fabric or tape, it is first necessary to insure that paint has been removed from an Chap 1 Page 25 area greater than that to be covered by the fabric.
a. Apply two brush coats of a dope-proof sealer similar to Specification MIL-V-6894, allowing the first coat to dry 2 hours and the second coat at least 6 hours. Follow with one coat of clear dope, and allow it to dry 45 minutes.
Apply a second coat of clear dope and lay into the wet film a piece of pinked-edge airplane cloth. All air bubbles should be worked out by brushing to insure maximum adherence. Allow this to dry 45 minutes. Apply one brush coat to insure proper penetration, and at least one spray coat of clear dope, allowing each to dry 45 minutes. The dried spray coat may be sanded with fine sandpaper to obtain a smoother finish. Complete the refinishing of the surface by application of lacquer, enamel, or aluminized varnish as required to match the adjacent area.
b. The size of the fabric patch should be such as to extend at least 1/2 inch on each side of any crack or group of cracks, at least 1 inch on each side of & scarfed joint glue line, and at least 2 inches beyond any edge of a skin patch to insure proper adhesion.
43.-53. RESERVED.
Par 40
C 43.13-1A Page 27 972 Chapter 2. AIRCRAFT METAL STRUCTURES Section 1. REFERENCES AND PRECAUTIONARY MEASURES I. REFERENCES. The following chapters of this aC should be referred to when accomplishing repairs to aircraft metal structures:
a. Identification and Inspection of Materials.
(dentification and inspection of materials should be conducted in accordance with Chaper 7.
b. Corrosion Protection. Corrosion protection reatment, cleaners, and paint removing should e accomplished in accordance with Chapter 6.
c. Aircraft Hardware. Acceptable means of ttachment are listed in Chapter 5.
b. Materials and Construction Techniques. The development of new materials and techniques has made possible the use of control surfaces of less mass weight for a given area than some aircraft of older design. The effect of repair or weight change on the balance and center of gravity is proportionately greater on lighter surfaces than on the older designs. Since control surfaces on some models are balanced for flutter-free operation up to maximum speed for which the aircraft was originally designed, special attention, therefore, must be given to such surfaces relative to the effects of structural repairs and rework on their balance con- 5j. FLUTTER AND VIBRATION PRECAUTIONS. To revent the occurrence of severe vibration or utter of flight control surfaces during flight, recautions must be taken to stay within the esign balance limitations when performing aintenance or repair.
a. Balance Changes. The importance of retainr the proper balance and rigidity of aircraft entrol surfaces cannot be underestimated. As reneral rule, repair the control surface in ch a manner that the structure is identical to : original so that the weight distribution is t affected in any way. In order to preclude he occurrence of flutter of the control surface n flight, a degree of static and/or dynamic balnce is established for each model of aircraft.
certain conditions, counter-balance rht is added forward of the hinge line to tain balance. Remove or add balance ught only when necessary in accordance h the manufacturer's instructions, or obtain A approval. Flight testing may be required.
filure to check and retain control surface bale within the original or maximum allowavalue could result in a serious flight haz-
directed to the effect indiscriminate application of extra coats of dope or paint has on the balance of control surfaces. Proper maintenance of control surface balance may require removal of dope or paint, down to the base coat, prior to application of finish coats. Consult the aircraft manufacturer's instructions relative to finishing and balance of control sur-
have occurred from unbalanced conditions caused by the collection of water or ice within the surface. Therefore, ventilation and drainage provisions must be checked and retained when maintenance is being done. Certain construction designs do not provide for ventilation and may collect moisture through condensation which will affect balance. In the event this condition is found, refer to the manufacturer's instructions for moisture removal.
e. Trim Tab Maintenance. In addition to unbalanced control surface, loose or vibrating trim tabs will increase wear of actuating mechanisms and hinge points which may de- Par 54
velop serious flutter conditions. Most trim tabs are not balanced separately from the control surface. Minimum tab flutter is maintained through rigid actuating mechanisms. Trim tabs and their actuating mechanism are constructed as lightly as possible to keep the weight aft of the hinge line of the control surface as low as possible. Actuating mechanisms are highly susceptible to wear, deformation, and fatigue failures because of the buffeting nature of airflow over the tab mechanism.
Trailing-edge play of the tab may increase, through wear of the mechanism, to an unsafe condition. Careful inspection of the tab and its mechanism should be conducted during overhaul and inspection periods. Compared to other systems on the aircraft, only a minor amount of tab-mechanism wear can be tolerated. In the absence of a specified limit for tab trailing edge movement in the manufacturer's manual, it is acceptable to use a limit of 2 1/2% of the chord, measured at the trailing edge of the tab.
For example, a tab that has a chord of 4" would have a maximum permissible free play of 4" x .025 or 0.100 inches (total motion up and down) measured at the trailing edge. Correct any free play in excess of this amount.
Care must also be exercised during repair or rework to prevent stress concentration points or areas which could increase the fatigue susceptibility of the trim tab system.
Par 55 AC 43.13.
56. BRAZING, Brazing may be used for repa to primary aircraft structures only if brazi was originally approved for the particular & plication. Brazing is not suitable for repair welds in steel structures due to lower streng values of the brazed joint as compared welded joints. Brazing may be used in the 1 pair of secondary structures.
Due to the large number of brazing allo used, it is difficult to be certain that the mai rial selected for repairing a brazed joint w result in a joint having the same streng characteristics as the original. In cases whe it is necessary to apply copper alloy brazil material, more than once on a steel surfa‹ and particularly if temperatures over 2,000° are reached, there is a possibility that brazi!
metal may penetrate between the grains in t steel to an extent that may cause crackin Copper brazing of steel is normally accor plished in a special furnace having a controlk atmosphere, and at a temperature so high th field repairs are seldom feasible. If copp brazing is attempted without a controlled a mosphere, the copper will probably not con pletely flow and fill the joint. Therefore, col per brazing in any other than appropriatel controlled conditions is not recommended.
57-67. RESERVED.
Chap
C 43.13-1A Page 29 1972 Section 2. WELDING
8. GENERAL. This section covers weld repairs aircraft and component parts thereof with he exception of welding on powerplants and propellers which is provided in chapters 12 and 14 respectively. Observe the following when using such equipment as tungsten inert gas (TIG), metal inert gas (MIG), plasma arc, shield carbon arc, and oxygen-acetylene gas.
a. Equipment Selection. Use the welding equipment manufacturers' information to determine if the equipment will satsify the requirements lor the type of welding operation being underaken. Disregarding such detailed operating intructions may cause substandard welds. For xample, when using TIG equipment, a weld an be contaminated with tungsten if the proper size electrode is not used when welding with lirect current reverse polarity. Another example, the depletion of the inert gas supply below the critical level causes a reduction in the gas flow and will increase the danger of atmospheric contamination.
(1) Electric welding equipment versatility requires careful selection of the type current and polarity to be used. Since the composition and thickness of metals are deciding factors, the selection may vary with each specific application. Metals having refractory surface oxide films, i.e., magnesium alloys and aluminum and its alloys, are generally welded with A.C., while D.C. is used for carbon, low alloy, noncorrodible, and heat-resisting steels, copper, etc. General recommendations covering current and polarity are shown in figure 2.1.
(2) Oxygen-acetylene gas equipment is suitable for welding most metals. It is not, how- FIGURE 2.1.-Current and polarity selection for inert gas welding.
ALTERNATING DIREO
CURRENT CURREN' With High- Frequency STRAIGHT REVERSE MATERIAL Stabilization Polarity Polarity dagnesium up to 1/8 in. thick 1 N.R. 2 ngnesium above 8/16 in. thick 1 N.R. N.R.
agnesium Castings N.R. 2 uminum up to 8/82 in. thick N.R.
luminum over 8/82 in. thick N.R. N.R.
luminum Castings N.R. N.R.
Stainless Steel N.R.
Brass Alloys N.R.
Silicon Copper N.R.
ilver OUUN: N.R.
ver Cladding N.R. N.R.
d-facing N.R.
st Iron N.R.
w Carbon Steel, 0.015 to 0.080 in. 2** N.R.
w Carbon Steel, 0.030 to 0.125 in. N.R. N.R.
ch Carbon Steel, 0.015 to 0.030 in. 2 * 1 N.R.
eh Carbon Steel, 0.030 in. and up 2 * 1 N.R.
Recommended 2. Acceptable N.R. Not Recommended Where A.C. is recommended as second choice, use approximately 25% higher current than is recommended for DCSP.
Do not use A.C. on tightly jigged part.
ap 2 Par 68
ever, the best method to use on such materials as stainless steels, magnesium, and aluminum alloys because of base metal oxidization, distortion, and loss of ductility.
NoTE: When oxyacetylene is used, all flux must be removed, as it may cause corrosion.
b. Accurately Identify the Type of Material to be Repaired. Reference to chapter 7 may provide this information. If positive identification is not possible, contact the aircraft manufacturer or subject the item to a metallurgical laboratory analysis. Before any welding is attempted, carefully consider the weldability of the alloy since all alloys are not readily weldable. The following steels are readily weldable: plain carbon of the 1000 series, nickel steel of the SAE 2800 series, chrome-nickel alloys of the SAE 8100 series, chrome-molybdenum steels of the SAF 4100 series, and low nickel-chromemolybdenum steel of the SAL 8600 series.
c. Preparation for Welding. Hold elements to be welded in a welding jig or fixture which is sufficiently rigid to prevent misalinement due to expansion and contraction of the heated material and which positively and accurately position the pieces to be welded.
d. Cleaning Prior to Welding. Clean parts to be welded with a wire brush or other suitable methods. When cleaning with a wire brush, do not use a brush of dissimilar metal; for example, brass or bronze on steel. The small deposit left by a brass or bronze brush will materially weaken the weld and may cause cracking or subsequent failure of the weld. In case members were metallized, the surface metal may be removed by careful sandblasting followed by a light buffing with emery cloth.
•. Condition of Complete Weld. Make sure that:
(1) The finished weld has a smooth seam and is uniform in thickness;
(2) The weld metal is tapered smoothly into the base metal;
(3) No oxide has formed on the base metal at a distance of more than 1/2 inch from the weld;
Par 60 AC 43.13-1 197
(4) The weld shows no signs of blowholes porosity, or projecting globules;
(5) The base metal shows no signs of pit ting, burning, cracking, or distortion;
(6) The depth of penetration insures fusion of base metal and filler rod; and
(7) Welding scale is removed by wire brush ing or sandblasting.
f. Practices to Guard Against. Do not file weldi in an effort to make a smooth-appearing job, a such treatment causes a loss of strength. D not fill welds with solder, brazing metal, ol any other filler. When it is necessary to rewel a joint which was previously welded, remov all old weld material before rewelding. Avoic welding over a weld because reheating may cause the material to lose its strength and be come brittle. Never weld a joint which hai been previously brazed.
g. Torch Size (Oxyacetylene Welding). The sizi of the torch tip depends upon the thickness of the material to be welded. Commonly user sizes proved satisfactory by experience are:
Thickness of steel Diameter of Drill size (in Inches) hole in tip
0.015 to 0.031 0.026 71
0.031 to 0.065 .031 68
0.065 to 0.125 .037 63
0.125 to 0.188 .042 58
0.188 to 0.250 .055 Б4
0.250 to 0.875 .067 51
h. Welding Rods and Electrodes. Use weldin rods and electrodes that are compatible wit the materials to be welded. Welding rods anc electrodes for various applications have special properties suitable for the application intended. Figure 2.8 shows the allowable strength for the weld metal. Figure 2.2 lists specifications for corresponding metals, ar the applicable specification will identify t use of A.C. or D.C., straight or reverse polal
1. Rosette Welds. Rosette welds are generali employed to fuse an inner reinforcing tube (liner) with the outer member. Where a ro sette weld is used, drill the hole, in the outside tube only, of a sufficient size to insure fusion o Chap
FIGURE 2.2.-Specifications guide for welding metals.
Material To Electrie Tungaten Inert Metal Inert Shield Be Welded Welding Gas (TIG) Ga• (HIG) Carbon ARC Acetviene Medium & High MIL-1-22200/1 MIL-E-29765/1B MIL-E-23765/1B MIL-R-908A Tensile Steel. MIL-9018 Class Class NONE Class 1 Stress Relieved MIL-E-705-2 MIL-E-705-4 High Carbon Steel MIL-E-7018 MIL-E-23765/1B MIL-D-23765/1B MIL-R-CUS1-A MIL-R-908A MIL-E-22200 Class Class Class 1 MIL-E-705-2 MIL-E-705-6 Low and Medium MIL-E-15599-C: MIL-E-23765/1B MIL-E-23765/1B MIL-R-CUSI-A Carbon Steel Class Class MIL-R-5632 MIL-E-705-2 MIL-E-705-6 Class 1 Aluminum and MIL-E-15997A QQR-566 QQR-566 QQR-566° QQR-566 * Aluminum Alloy MIL-E-16053-K' MIL-E-16053-K' Stainless Alloys MIL-E-6844 MIL-R-5031B' MIL-R-5031B* MIL-R-5081B* MIL-R-5081B* M-L-E-22200• Copper and Nickel NONE QQR-571A * MIL-E-21659* QQR-571A * QQR-571A • Alloys Magnesium NONE MIL-R-6944 MIL-W-18326 NONE MIL-R-6944 Alloys Specify Alloy Specify Alloy Specify Alloy Hard Surface MIL-E-19141 MIL-E-19141 MIL-E-19141 MIL-E-19141 MIL-19141 Filler (Refer to A.W.S (Refer to A.W.S (Refer to A.W.S. (Refer to A.W.S. (Refer to A.W.S.
A5.18 or ASTM-A899) А5.18 or А5.18 ог Аб.13 ог Аб.18 от ASTM-A399) ASTM-A399) ASTM-A899) ASTM-A899) ' Specify MIL Type 6010, 6011, 6012, 6013, 6020, 6024, 6027-Same as A.W.S. Number for type. A.W.S. American Welding Society * Specify Aluminum Alloy by Aluminum Assoc. Number e.g.: Type 1100, 5083, etc. ASTM American Society for Testing Materials
• Specify Alloy by A.IS.I. Number e.g.: 304, 316, 842, etc. A.I.S.I.. American Iron and Steel Institute (SAE).
* Specify type per A.W.S. A5.6-66 or ASTM B-225-66.
Page 32 AC 43.13-14 197" FIGURE 2.3.-Strengths of welded joints.
Materle! Heat treatment Welding rod Ultimate Ultimate subsequent to or electrode atress 11 tenaile welding shear × 1000 atresa X 1000 Carbon and MIL-R-5632, Class I 82 51 Alloy steels None MIL-E-15599, Classes E-6010 & E-6013 32 61 Alloy steels None MIL-R-5632, Class 2 48 72 Alloy steels Stress relieved MIL-E-6848, Class 10018 50 85 MIL-E-18088, Class E-10015 & E-10016 Alloy steels Stress relieved MIL-E-18038, Class 60 100 E-12015 & E-12016 the inner tube. A hole diameter of approximately one-fourth the tube diameter of the outer tube serves adequately for this purpose.
In cases of tight-fitting sleeves or inner liners, the rosettes may be omitted.
I. Heat-Treated Members. Certain structural parts may be heat-treated and therefore could require special handling. In general, the more responsive an alloy steel is to heat treatment, the less suitable it is for welding because of its tendency to become brittle and lose its ductility in the welded area. Weld the members which depend on heat treatment for their original physical properties, using a welding rod suitable for producing heat-treated values comparable to those of the original members (see paragraph 68h). After welding, reheat-treat such members to the manufacturer's specifica-
69. STEEL PARTS NOT TO BE WELDED.
a. Brace Wires and Cables. Do not weld airplane parts whose proper function depends upon strength properties developed by coldworking. Among parts in this classification are streamlined wires and cables.
b. Brazed and Soldered Parts. Do not weld brazed or soldered parts as the brazing mixture or solder will penetrate the hot steel and weaken it.
c. Alloy Steel Parts. Do not weld alloy steel parts such as aircraft bolts, turnbuckle ends, etc., which have been heat-treated to improve their mechanical properties.
Par 68
70. REPAIR OF TUBULAR MEMBERS.
a. Inspection. Prior to repairing tubular members, carefully examine the structure surrounding any visible damage to insure that n secondary damage remains undetected. Second.
ary damage may be produced in some structur remote from the location of the primary dam age by the transmission of the damaging loa along the tube. Damage of this nature usuall occurs where the most abrupt change in dire tion of load travel is experienced. If this dam.
age remains undetected, subsequent norma loads may cause failure of the part.
b. Location and Alinement of Welds. Unles otherwise noted, welded steel tubing may spliced or repaired at any joint along the leng of the tube. Pay particular attention to th proper fit and alinement to avoid distortion.
6. Members Dented at a Cluster. Repair der at a steel-tube cluster-joint by welding a sp cially formed steel patch plate over the dented area and surrounding tubes, as shown in figure
2.4. To prepare the patch plate, cut a section of steel sheet of the same material and thickne as the heaviest tube damaged. Trim the re forcement plate so that the fingers extend o the tubes a minimum of 1.5 times the resp tive tube diameter as shown in the figu Remove all the existing finish on the damag cluster-joint area to be covered by the reinfor ment plate. The reinforcement plate may formed before any welding is attempted, or may be cut and tack-welded to one or more the tubes in the cluster-joint, then heated ar Chap
AC 43.13-1A Page 33 1972 LONGERON DENTED AT A STATION.
Lite 706
THICKNESS OF PATCH-PLATE
SAME AS LONGERON
THICKNESS, PATCH-PLATE BEFORE FORMING AND WELDING.
PATCH-PLATE FORMED AND WELDED TO TUBES.
FIOURE 2.4.-Members dented at a cluater.
Chap 2 Par 70
Page 34 AC 43.13-1 197 DENTED OR BENT TUBE.
CRACKED TUBE
REINFORCEMENT TUBE SPLIT NOTE:
LOCALLY DENTED OR
TINES MEMBERORSHOULD 15811 IN CLAMP.
REINFORCEMENT LEAST THE SAME GAUGE AS TUBE BEING REPAIRED.
WELD
AS ALTERNATIVE TO SPLIT
A TWO PIECE REIN- FORCEMENT ‚MAY
FORMED FROM STEEL
SHEET OF THE SAME MAT-
ERIAL AND AT LEAST THE
SAME GAUGE AS AGED TUBE FOUR ENDS AND THE DAM- ROSETTE WELDS AS SHOWN.
FIGURE 2.0.-Members dented in a bay--repairs by welded sleeve.
Par 70 Chap
AC 43.13-1A 1972 formed around the joint to produce a smooth contour. Apply sufficient heat to the plate while forming so that there is generally a gap of no more than 1/16 inch from the contour of the joint to the plate. In this operation avoid unnecessary heating, and exercise care to prevent damage at the point of the angle formed by any two adjacent fingers of the plate. After the plate is formed and tack-welded to the clusterjoint, weld all the plate edges to the clusterjoint.
d. Members Dented in a Bay. Repair dented, bent, cracked, or otherwise damaged tubular members by using a split-sleeve reinforcement;
carefully straighten the damaged member; and in the case of cracks, drill No. 40 (0.098) stopholes at the ends of the crack.
71. REPAIR BY WELDED SLEEVE. This repair is outlined in figure 2.5. Select a length of steel tube sleeve having an inside diameter approximately equal to the outside diameter of the damaged tube and of the same material, and at least the same wall thickness. Diagonally cut Ithe sleeve reinforcement at a 30° angle on both ends so that the minimum distance of the sleeve from the edge of the crack or dent is not less than 11/2 times the diameter of the damaged tube. Cut through the entire length of the reinforcement sleeve, and separate the halfections of the sleeve. Clamp the two sleeve sections to the proper positions on the affected reas of the original tube. Weld the reinforce- Page 35 ment sleeve along the length of the two sides, and weld both ends of the sleeve to the damaged tube as shown in the figure. The filling of dents or cracks with welding rod in lieu of reinforcing the member is not acceptable.
72. REPAIR BY BOLTED SLEEVE, Do not use bolted sleeve repairs on welded steel tube structure unless specifically authorized by the manufacturer or the FAA. The tube area removed by the boltholes in this types of repair may prove critical.
73. WELDED-PATCH REPAIR. Dents or holes in tubing may be repaired by a welded patch of the same material and one gauge thicker, as shown in figure 2.6 provided:
a. Dented Tubing.
(1) Dents are not deeper than 1/10 of tube diameter, do not involve more than 1/4 of the tube circumference, and are not longer than tube diameter.
(2) Dents are free from cracks, abrasions, and sharp corners.
(3) The dented tubing can be substantially reformed without cracking before application of the patch.
b. Punctured Tubing. Holes are not longer than tube diameter and involve not more than 1/4 of tube circumference.
* TUBE CIRCUM. -NOT GREATER THAN "A" (MAX.)
• 2A -
- DAMAGE FIGURE 2.6.-Welded patch repair.
Chap 2 Far 70
AC 43.13-14 1971 ALLOW 1/8" GAP BETWEEN ORIGINAL AND ROSETTE WELD REPLAGEMENT TUBES FOR WELDING.
INSIDE
ORIGINAL TUBE ISLEEVE TUBE
- UZA
REPLACEMENT TUBE
ROSETTE WELD FORVIPELVISAP
INSIDE SLEEVE TUBE
ORIGINAL TUBE FIGURE 2.7.-Splicing by inner sleeve method.
74. SPLICING TUBING BY INNER SLEEVE METHOD.
If the damage to a structural tube is such that a partial replacement of the tube is necessary, the inner sleeve splice shown in figure 2.7 is recommended, especially where a smooth tube surface is desired. Make a diagonal cut when removing the damaged portion of the tube and remove the burr from the edges of the cut by filing or similar means. Diagonally cut a replacement steel tube of the same material and diameter, and at least the same wall thickness, to match the length of the removed portion of the damaged tube. At each end of the replacement tube allow a 1/8-inch gap from the diago- Par 74 nal cuts to the stubs of the original tube. Select a length of steel tubing of the same material, and at least the same wall thickness, and of an outside diameter, equal to the inside diameter of the damaged tube. Fit this innersleeve tube material snugly within the original tube, wit a maximum diameter difference of 1/16 inc From this inner-sleeve tube material cut 2 se tions of tubing, each of such a length that th ends of the inner sleeve will be a minimum dis tance of 1 1/2-tube diameters from the neares end of the diagonal cut.
If the inner sleeve fits very tightly in the replacement tube, chill the sleeve with dry ice or Chap 3