Manufacturing method of metal pipe with inner anti-corrosion coating
FIELD: machine building.
SUBSTANCE: anti-corrosion coating is applied to inner pipe surface, bushes made from corrosion-resistant metal and having on outer surface the sealing layers in the form of elastic coating are installed inside ends of pipe with covering some part of coating and bushes are fixed by their expansion till they tightly touch inner pipe surface. Sealing layer can be made from elastic polymer material.
EFFECT: reducing labour intensity of production and reducing the cost of products.
6 cl, 3 dwg
The invention relates to pipeline transport and can be used in the manufacture of steel pipes with internal anti-corrosion coating.
A known method of manufacturing a pipe with an internal corrosion-resistant coating comprising securing liners, made from a strip of corrosion-resistant metal, the inside of the pipe ends contact welding over the entire surface of the contact pads with the pipe and applying a corrosion-resistant coating on the inner surface of the pipe and partially inserts (U.S. Pat. Of the Russian Federation No. 2177101, CL F16L 58/04, publ. 20.12.01, bull. No. 35).
The disadvantage of this method is the complexity of the technological process of formation and consolidation of the liners on the inside of the pipe ends from the point of view of its mechanization and automation in mass production. In addition, there are high requirements for precision forming inserts on the outer diameter, since a gap between the sleeve and pipe welding over the entire surface of their contact is impossible.
The closest in technical essence to the present invention is a method of manufacturing a steel pipe with an internal anti-corrosion coating, including the calibration of the ends of the pipe internal diameter up to the largest size limit for this assortment of pipes, application of anti-corrosive treatment is Oia on the inner surface of the pipe, the installation of the sleeves of stainless steel, having on the outer surface of the sealing layers, placed in the annular grooves of the sleeves, the inside of the pipe ends overlapping portion of the cover and attaching the sleeves by hand cornerwise device before contact with the interference fit with the inner surface of the tube (U.S. Pat. Of the Russian Federation No. 2262028, CL F16L 13/02, publ. 10.10.05, bull. No. 28).
The disadvantage of this method is the complexity of manufacturing and the relatively high consumption of stainless steel in the manufacture of bushings due to the necessity of forming annular grooves lathe way that collectively leads to an increase in their value.
The objective of the invention is to reduce the complexity of the manufacturing process and reduce the cost of production.
The problem is solved in that in the method of manufacturing a metal pipe with an internal anti-corrosion coating, including the application of anti-corrosive coating on the interior surface of the pipe, the installation of bushings of corrosion-resistant metal, having on the outer surface of the sealing layers, the inside end of the tube with overlapping portion of the cover and attaching the sleeves by hand until it touches the interference fit with the inner surface of the pipe, according to the invention the sealing layers applied on the outer surfaces of the bushings outside of those areas the economic impact, occurs during welding of pipes, in the form of the elastic coating.
The sealing layer may be made of elastic polymer material.
The sealing coating may be made of thermosetting plasticized polymer compound.
The sealing coating may also be applied in closed or open side of the inner end of each bushing is provided with an annular groove to fill the groove.
Uncovered portion of each of the bushings in the immediate vicinity of the border of the coating can be provided with an annular groove.
In addition, the inner ends of the sleeves can be made with a sloping outer chamfers, equipped with a flexible coating.
In the investigated us patent and technical literature such solutions have been identified that allows to make a conclusion on the conformity of the proposed solutions to the criteria of "novelty" and "inventive step".
The method is illustrated in the drawings, which show longitudinal sections of the upper half of the end portion of the pipe (the lower half is a mirror image of the upper)made by this method.
The method is as follows.
On the inner surface of the grooved pipe 1 (see figure 1), excluding the end zones tube length of 50-100 mm, subjected to a heat treatment welding, UNOSAT anti-corrosive heat-sensitive, for example, polymer, floor 2. Inside the ends of the pipe with an overlap part of the anticorrosive coatings set of thin-walled sleeve 3 from corrosion resistant metal, having on the outer surface of the flexible sealing cover 4. The thickness of the sealing coating is selected with consideration of filling irregularities of the outer surface of the bushing and the inner surface of the pipe and for raw lathe way and unpolished surfaces is 0.2-0.4 mm Length covered area of the sleeve is 10-30 mm
In the case of strong irregularities of the parts which come into contact surfaces of the pipe and the bushing on the outer surface of the sleeves can be made open from the inner ends of the sleeves (see figure 1) or closed (see figure 3) annular grooves, a depth slightly greater than the maximum possible irregularities. The width of the grooves is 10-30 mm In this case, the grooves are completely filled with sealant.
In the case of hand sleeves cornerwise device, when the distribution process begins with the inner end of the sleeve, to avoid displacement of the mandrel excess sealant coating in the weld zone of the sleeve, the uncovered portion of each of the bushings in the immediate vicinity of the border of the coating provide the circular groove 5, which serves as a reservoir for excess sealant (see figure 3). Experiments showed that when injected sealant in the area of welding the welding process becomes much more difficult. With this method of distribution there is also the danger of damage to the corrosion coating of pipes extending inner end of the sleeve so that the inner ends of the bushings carried out with gentle (under an angle of 9-12°) outer chamfers, equipped with a flexible coating 6. In the case of a distribution of calibrating sleeves punch, which starts to give out sleeve with their outer end, these drawbacks are not available, therefore the need for the elements 5 and 6 is eliminated. However, for technological reasons, the method of distribution of the sleeves with the help of the mandrel may be preferable.
Material for sealing coating can serve as a single component (curing in contact with air) or two (with a special hardener) silicone sealants, which can withstand temperatures up to 350°C, which allows to reduce the length of the sleeves without the risk of thermal destruction of the sealing cover when welding pipes. You can also use curing vysokopastavlennye compounds based on epoxy and other resins. In all these cases, the length of the sleeves is selected taking into account short-term (not less than 2 hours) heat resistance of the materials used.
Use as a sealing cover sleeves elastic materials is dictated by the fact that the metal pipes and sleeves, perform their different functions, as a rule, have different coefficients of thermal expansion, which can cause displacement of the inner ends of the bushings relative to the tube and, as a consequence, damage to the protective coating of the pipe when the temperature changes in the case of a rigid bonding of the sleeve to the pipe surface.
Attaching sleeves with simultaneous sealing of the gap between the sleeve and pipe are made by hand (radial strain) bushings with calibrating or cornerwise device before contact with the interference fit with the inner surface of the pipe. Tension occurs when there is some plastic deformation of the pipe end in the process of distribution of the sleeves.
During the pipeline construction is made in such a way pipe butt weld in the welding of two metals: first weld sleeve of corrosion resistant metal with the use of corrosion resistant welding electrodes, then the pipe using conventional electrodes.
Examples of specific performance
Example 1. The ends of the steel pipes with an outer diameter of 426 mm and a wall thickness of 10 mm (on THE 14-3-1128-2000) grooved inner gauge diameter 414 mm (this is the largest inner diameter of the pipe at the specified TC) for a length of 250 mm On the inner surface of the pipe by known techniques caused epoxy coating thickness of 0.35 mm, except for anavah zones tube length 80 mm Sheet stainless steel 08KH18N10T made sleeve outer diameter 412 mm, a wall thickness of 2 mm and a length of 150 mm (see figure 1). Outer ends of the bushings has razvalivali with the formation of the outer flange height of 3 mm from the outer surface of the sleeve). On fat outer surface of the inner ends of the bushings 3 hours before installing them into the pipe struck the floor of the two-component silicone sealant brand Sealers-1-18 width of 30 mm, a thickness of 0.2-0.4 mm, an Inner surface of the pipe in the area of placement of the sleeves also cleaned and degreased gasoline. Set the sleeve into the tube until the stop shoulder on the ends of the pipe and using a punch-caliber diameter 411 mm distributed sleeves along their whole length by using a calibrating device.
In this method of manufacturing a pipe with an internal heat-sensitive anti-corrosive coating consumption, stainless steel, reaching for the manufacture of protective sleeves, is reduced to 1.5-2 times compared with the prototype. No turning of the sleeves and manufacture of thin-walled rubber sealing rings. All this significantly reduces the cost of protective sleeves while maintaining at least the same level of the main functions of the bushing - seal joint area from penetration of aggressive transported product pipeline.
Example 2. It is icy steel pipes with an outer diameter 114 and a wall thickness of 5 mm (according to GOST 8732-78) was calibrated to the inner diameter 106,6 mm length 200 mm On the inner surface of the pipe by known techniques caused epoxy coating thickness of 0.35 mm, excluding the end zones tube length of 50 mm From sheet stainless steel 08KH18N10T produced bushing outer diameter of 104 mm, a wall thickness of 3 mm and a length of 120 mm On the inner end of each sleeve has fulfilled the outer chamfer at an angle of 10° to the axis. All adjacent to the chamfer sharp edges have scrupoli and abraded with fine sandpaper. The inner end of each sleeve has trimmed on a lathe to the outer diameter 103 mm in a length of 20 mm with the formation open at this end of the ring groove (see figure 2). With an interval of 5 mm from the groove is formed with an annular groove 5 of a width of 8 mm, depth 1.5 mm for excess sealant. Outer ends of the bushings prepared for welding standard. On skimmed the surface of the chamfers of the inner ends of the bushings up to 1 day before their installation in the pipe was coated from a one-component silicone sealant brand GED-1 thickness of 0.2-0.3 mm. For 3 hours prior to the installation of the open ends of the grooves of the sleeves filled with sealant Sealers-1-18. The inner surface of the pipe in the area of placement of the sleeves were cleaned and degreased with gasoline. Set the sleeve into the tube and using cornerwise devices distributed bushings by moving the mandrel from the inside of the pipe to its ends.
Hidraulicas what their tests are made in this way pipes after connection butt welding showed no penetration pressing water to the area of the joints.
1. A method of manufacturing a metal pipe with an internal anti-corrosion coating, including the application of anti-corrosive coating on the interior surface of the pipe, the installation of bushings of corrosion-resistant metal, having on the outer surface of the sealing layers, the inside end of the tube with overlapping portion of the cover and attaching the sleeves by hand until it touches the interference fit with the inner surface of the pipe, characterized in that the sealing layer is applied on the outer surface of the sleeve outside the heat-affected zone that occurs during welding of pipes, in the form of the elastic coating.
2. The method according to claim 1, characterized in that the sealing cover is made of elastic polymer material.
3. The method according to claim 1, characterized in that the sealing coating made of a thermosetting plasticized polymer compound.
4. The method according to claim 1, characterized in that the coating is applied in a closed or open side of the inner end of each bushing is provided with an annular groove to fill the groove.
5. The method according to any one of claims 1 to 4, characterized in that the uncovered portion of the sleeve in the immediate vicinity of the border of the coating provide the circular groove.
6. The method according to any one of claims 1 to 4, characterized in that the outer surface of the inner end of the sleeve vypolnyaut sloping outer chamfer, covered with an elastic coating.
FIELD: machine building.
SUBSTANCE: first, before welding end of pipeline, heat-shrinkage clutch-bushing is positioned on pipeline close to joint. Upon joint welding, insulated surface is cleaned with metal brushes and dried from moisture. Prime coating - "liquid" primer and mastic band corresponding to coating with 80…90 degrees C temperature of mastic material softening are applied on this surface. Further, the heat-shrinkage clutch-bushing is pushed to a zone of a welded joint symmetrically to it and is heated to temperature 110…120 degrees C. Simultaneously, layers of the mastic band are heated and melted through the heat-shrinkage clutch-bushing ensuring pressure onto melted mastic of the mastic band and filling interstices with it in a zone of welding joint strengthening (hemi-spherical zones) and places of transition to base coating and overlapped layers of the mastic band. Insulating coating of the welded joint of the pipeline contains prime coating- "liquid" primer, the mastic band made either in from of a polymer-bitumen with base out of polyvinylchloride with mastic of 80…90 degr. C of softening, or in form of a base-less material consisting of polymer-bitumen mastic with softening temperature 80-90 degrees C and glass mesh. Also insulating coating consists of the heat-shrinkage clutch enveloping the pipeline and made in form of a solid bushing out of a sheet of light- and heat stabilised one-layer polyethylene modified by radiation-chemical method. The clutch is installed on the pipeline before pipeline joint welding and can travel along axis of the pipeline.
EFFECT: raised efficiency of anti-corrosion protection due to increased resistance of insulation coating.
2 cl, 2 dwg
FIELD: machine building.
SUBSTANCE: according to procedure surface of isolated coupling is prepared and rolled adhesive material is applied on prepared surface. Material is heated to softening; a section of thermo-contracting polymer band is placed on a softened layer. Ends of the band are connected with overlap, thereby forming a collar. A locking plate is put on the point of ends connection; further, the collar is thermo-contracted.
EFFECT: raised adhesion of insulating collar to surface of coupling and increased period between repair operations for re-insulating coupling of pipeline.
FIELD: oil and gas production.
SUBSTANCE: method for manufacturing a tubing string involves coating formation on its internal surface. The coating represents at least one polyurethane coating layer containing ureal groups with their mass fraction in the coating makes 6 to 14%. Total coating thickness is within the range 10 to 500 microns.
EFFECT: increased service durability of the tubing string ensure by more efficient deposit protection and abrasive, hydroabrasive and corrosive wear.
9 cl, 5 dwg
FIELD: machine building.
SUBSTANCE: procedure for application of coating on internal surface of pipeline consists in inserting tube-shaped sleeve out of fibre material inside pipeline. The sleeve is impregnated with binding and enclosed into a flexible shell. Further, the sleeve is turned out, propelled inside the pipeline, straightened and pressed to internal surface of the pipeline under simultaneous effect of a water column on internal surface of the turned out sleeve and pneumatic pulses pneumatically communicated with a compressor. Then the sleeve is solidificated. Variations of value and frequency of pulses is achieved by changing air pressure at the outlet from the compressor. Also a pulse generator is placed inside the pipeline before the sleeve, as far, as it propels inside the pipeline, so, that exhaust openings in the case of the generator are arranged at acute angle to generator axis in the direction of sleeve motion. In air medium around the generator there is periodically generated circular series of pulses.
EFFECT: prevention of occupational injuries.
FIELD: transport engineering.
SUBSTANCE: branches with bell at free end are welded to ends of pipes connected between them. Anticorrosion polymer coating is applied on internal surface of pipes and branches welded to these pipes. A protecting bush with packing rubber rings on external surface of its end sections is installed into an internal cavity of a bell part of the branch. A projecting end of the protecting bush is inserted into the internal cavity of the bell part of the second pipe branch. Further, the bell ends of connected pipes are welded. Before installation a thin layer of sealant is applied on internal surface of the bell to increase tightness. A threaded opening is made in the bell part of each branch. The threaded openings are capped with threaded plugs after pressure testing and, if necessary, additional sealant insertion.
EFFECT: increased reliability of internal anti-corrosion protection of welded connections of knee-pipe parts in aggressive mediums; maintaining internal pipeline cross section.
3 cl, 1 dwg
FIELD: construction industry.
SUBSTANCE: method of applying protective coating to pipeline involves cleaning of surface, application of rubber mixture with layer 1.5-2 mm, further heating up to temperature of 130-135°C with heating speed of 20-25°C/min when moving heat-radiating device along pipeline; as insulation material, there used is rubber mixture having the following component ratio, wt %: low-molecular oligodien 16-22; sulphur 6-13; thiuram 0.6-1.4; zinc oxide 3-10.0; calcium oxide 0.6-1.2; and filler is the rest. At that, coating is exposed during 20-25 minutes during heating process, then it is exposed, when heating is removed, for 30-35 minutes till it is fully cured.
EFFECT: reducing power and time consumption.
3 cl, 1 dwg
FIELD: machine building.
SUBSTANCE: in method, consisting in plating of pipe surface by ground coat, on which it is applied in the capacity of adhesion layer paste on the basis of petroleum polymer "asmol", and on adhesion layer it is extruded external protective layer on the basis of polyethylene, in the capacity of ground coat it is used 25-35% solution of petroleum polymer "asmol" in organic solvent, paste additionally contains bitumen, bivinyl styrene thermoplastic elastomer and plasticiser at following ratio of components, wt %: petroleum polymer " asmol " - 80-94, bitumen - 5-10, bivinyl styrene thermoplastic elastomer - 2-3, plasticiser - 3-6, herewith asmol paste is applied on ground coat by extrusion.
EFFECT: simplification of plating technology, reduction of power inputs and increasing of adhesion strength of coating.
2 cl, 1 tbl
SUBSTANCE: invention is related to the field of construction and repair of underground pipelines, and may be used for insulation of steel pipelines surfaces with application of insulating tape. In process of method realisation layer of ciacrin glue is applied onto joined surface of at least one tape with further joining of glued insulation tapes, besides, thickness of ciacrin glue layer makes 50-150 mcm, and area of applied ciacrin glue layer is 0.015-0.045 m2.
EFFECT: higher quality of insulation.
FIELD: oil and gas industry.
SUBSTANCE: invention refers to oil producing industry, particularly to preventing asphalt-resin-paraffin sediments (ARPS) on internal surface of flow string (FS). In FS including proper FS with internal coating of a wall there is used polyurethane elastomer of cold moulding as a polyurethane coating; after solidifying coating acquires glossy surface, high adhesion to metal, Shore hardness 50-90 A, uniform thickness of coating, high resistance to wear up to 25 mg, elasticity to 70-75%, and ability to maintain properties of coating within range of temperature from -55 to 100° C. The method of applying coating on internal surface of FS consists in cleaning and de-fatting of internal surface of FS, in injecting material of coating and in its solidifying; injecting of material of coating (polyurethane) is carried out till it fills a circular cavity formed by an internal wall of FS and a puncheon; also roughness of its external surface is not less the 9 surface finish class and should have glossy coating after solidifying; upon final solidifying of polyurethane the puncheon is removed.
EFFECT: preventing asphalt-resin-paraffin sediments.
7 cl, 1dwg
SUBSTANCE: method of constructing a pipeline relates to construction and can be used in constructing and repairing pipelines, particularly those damaged by aggressive action of aggressive transported oil and gas medium and can be used in other industries as well. Connecting elements used are bevelled rings, where bevel edges are made on the outer diametre on the inner side. Bevel edges are also made on the outer diametre of the pipe, after which a plastic cover is stretched, with length greater than the length of the pipe. A heating element is installed between ends of the covers. The ends of the plastic covers are brought to a state of viscous flow. The pipes are connected end to end and welding is done along bevel edges of the outer diametre.
EFFECT: method of constructing pipelines, involving fitting pipe ends with connecting elements, widths of which exceed the thermal breakdown zone of covers, lining pipeline inner surface with a plastic cover.
4 cl, 1 dwg
SUBSTANCE: metal tube has polymer coat with low surface energy. At least a part of said polymer coat is activated. A part of said polymer coat of the mainline constructed by area adjoining each uncoated section has activated surface. Fixation-prone coat with high surface energy is applied on said part with activated surface.
EFFECT: possibility to decontaminate surfaces in-situ prior to erection welding.
25 cl, 8 dwg, 3 tbl, 1 ex
FIELD: machine building.
SUBSTANCE: thin-walled bushings out of corrosion resistant metal are positioned inside ends of pipes so, that external ends of bushings project beyond ends of pipes; projecting ends of bushings are flanged on ends of pipes; bushings are fixed by mutual calibration of bushings and pipe ends by internal diametre; coating is applied and prepared ends of pipes are butt-welded according to process of two-layer metal weld.
EFFECT: raised reliability of pipe connection.
4 cl, 3 dwg
FIELD: machine building.
SUBSTANCE: permanent connection of pipes with internal anti-corrosion coating consists of butt welded pipes with anti-corrosion coating spaced from ends of pipes at distance of thermal effect of welding and of bushing positioned in pipes under butt. The bushing is made out of composite material. Also the bushing has an external central circular groove in the middle of its length with heat resistant composition and fixing devices. Grooves filled with sealant are made symmetrically from the central circle of the groove. The bushing is made out of thermal-plastic material of high adhesion ability to pipe material. The fixing devices correspond to cylinder lugs of the bushing arranged symmetrically on both ends between the circular groove and the grooves. Heat-resistant composition fills whole space between the pipes, circular groove and fixing devices; the latter interact with their external ends with ends of anti-corrosion coating, while with their external surface they interact with internal surface of corresponding pipes and are adhered to them under temperature effect of welding.
EFFECT: increased reliability of connection.
SUBSTANCE: invention is related to the field of polymer pipes butt welding by means of flashing and may be used to weld polyethylene pipes in case of high temperatures of ambient atmospheric air out of regulated interval of welding works performance temperature. Invention provides for identical speed of welded seam cooling along internal surface of polymer pipe along its whole perimetre. On completion of upset forging operation, atmospheric air is supplied to one end of welded pipe under pressure, while the other end of pipe is in open condition.
EFFECT: welded seam produced under such conditions has identical strength properties along the whole perimetre of welded seam.
SUBSTANCE: in the connection on the middle part of inner bush there installed is a rubber gland of T-shaped rectangular section that at the same time is both restricting and sealing. On the ends of inner bush there installed are rubber sealing rings, and to polymeric coating there applied is adhesive composition that, during crimping of outer coupling, forms an adhesive bead on the ends of inner bush and also forms reliable sealing of the joint of the pipes being connected.
EFFECT: invention increases reliability of the joint's sealing of the pipes being connected.
FIELD: machine building, pipelines.
SUBSTANCE: invention relates to pipeline transport and can be used in construction and repair of pipelines with inner polymer antirust coating. A metal sleeve is press-fitted in the end of each pipe to be jointed together between the pipe and inner coating, the sleeve length exceeding the welding thermal effect area. Note that the sleeve features two inner tapered surfaces, widening towards the sleeve ends, and a funnel on its outer end, and an outer diameter is equal or exceeds the pipe ID. Note also that the coating end is extended. Fastening and sealing the coating end is performed by press-fitting the jamming ring into the coating end, within the area of the sleeve inner surface widening towards outside end. Note that the said jamming ring features an outer tapered surface matching the sleeve tapered surface outer end.
EFFECT: expanded performances.
2 cl, 2 dwg
FIELD: construction, pipeline.
SUBSTANCE: plug consisting of two telescopically connected with each other branch pipes, internal surface whereof is made of corrosion-resistant metal, is installed inside the end of the pipe at a depth exceeding length of the heat-affected zone. Sealing ring is preliminary set between the collar and inner face of the external branch pipe, external branch pipe is entered into the pipe at a depth equal or exceeding length of the heat - affected zone and is fixed to the pipe. Sealing ring is pressed between the collar and end face of the external branch pipe by power movement in axial direction of the internal branch pipe, and internal branch pipe is fastened to the external branch pipe.
EFFECT: simplified repairing of active pipelines.
4 cl, 3 dwg
SUBSTANCE: faulty pipeline section is cut out and removed. In free space between opposite-shifted butts of pipeline the repair pipe bushing assembly is installed which has axial retainer and half-rings which length is matched with radial clearances of welds by means of equispaced retainers of repair pipe bushing. At that, on surface of pipe bushing two sections of glass fabric are placed which are equispaced relative to axial retainer. Bushings with opposite conical projections and located behind them circumferential retainers made with possibility to be placed along circumferential perimeter of glass fabric sections are located coaxially and over pipe busing. After that two sections of bushings are shifted along axis with overlapping in opposite direction relative to shifted butts of pipeline pipes. On the most remote from axial retainer conical sections over bushing surfaces ring collars are installed which serve to transfer self-hardening paste along axis inside butt sections of connected pipeline. Glass fabric is laid in a circumferential direction along the length of repaired section of coaxially located bushings. Half-rings are used which diameter and thickness is equal to diameter and thickness of pipeline pipes. These half-rings are installed on glass fabric surface relative to axial retainer interacting with trapezoidal groove relative to axis. Weld joints are made from the side of pipeline pipes butts and on radial cross-sections of half-rings to create monolithic joint of pipeline with repair pipe bushing assembly.
EFFECT: joint reliability enhancement.
1 dwg, 1 ex
FIELD: pipe production.
SUBSTANCE: method involves jointing helical pipe profile and performing following pipe welding along helical perimeter. Helical end profile of one pipe is linearly joined with mating end profile of another pipe. After that the pipes are moved one to another in direction parallel to pipeline axis and pipes are retained in fixed position. Helical pipe joint recesses are connected with each other to create single cylindrical pipeline section formed as full turn.
EFFECT: possibility of permanent air-tight connection of helical pipe joint cavities to create single cylindrical pipeline section.
3 cl, 3 dwg
FIELD: pipeline engineering.
SUBSTANCE: piping unit comprises base and opening that passes through the base and receives the end of the pipe of the flow meter. The opening is filled with a filling material that is distributed around the pipe for the flow meter. The pipe of the flow meter is welded to the base near the second side of the base part.
EFFECT: enhanced reliability.
19 cl, 8 dwg
FIELD: non-disconnectible pipe joints.
SUBSTANCE: pipe is provided with coupling members at its ends. The coupling members are hermetically sealed, overlap the axis and form coaxial ring space near the free end. The length of the wall of the coupling members exceeds the length of the zone of destructive heating of covering during welding. The minimum thickness of the coupling member wall is determined from the formula SCM=STRTDM/RCMDT, where ST and SCM are the thickness of pipe and coupling member, DT and DM are the outer diameter of pipe and coupling member, and RT and RCM are the limiting yield of materials of pipe and coupling member, respectively. The section of outer surface of the pipe adjacent to the face, inner diameter of the coupling member, and the length of ring space allow receiving the aligning unit to provide abutting the faces of coupling members for welding. The aligning unit is made of a bushing which receives the sealing rings for sealing the faces and outer surfaces of the pipe in the ring space.
EFFECT: enhanced operate reliability and service life.
19 cl, 3 dwg