DE102005002618A1 - Process for limiting the temperature during welding of the ends of a pipe pair comprises carrying out welding as one layer welding with an electric arc and non-consumable electrode without using an additive and further processing - Google Patents

Abstract

Limiting the temperature during welding of the ends of a pipe pair in the region of a thin-walled pipe material close to the welding seam comprises carrying out welding as one layer welding with an electric arc and non-consumable electrode without using an additive, continuously determining the temperature distribution over the periphery of the pipe ends (1, 2) in a heat influencing zone, interrupting the welding process when the upper limiting temperature is exceeded and continuing welding after the upper limiting temperature is exceeded. The welding tool (4) experiences a return travel over the periphery of the pipe ends and pre-heating is carried out on the peripheral path assigned to the return travel up to the end of the welding seam. An independent claim is also included for a device for carrying out the above process.

Description

TECHNICAL AREA

The The invention relates to a method for limiting the temperature welding the ends of a pair of tubes in the weld region near a thin-walled Pipe material according to the preamble of the independent claims 1 or 2 and an arrangement for performing of the method according to the preamble of claim 9.

Corrosion resistant steels with fully austenitic structure, for example in the food and beverage industry, Chemistry or pharmacy in the form of pipes are used and welded together Need to become, often experience welding near the weld Area of the pipe material an impermissibly high heating, the a structural change causes in this area in the form of a grain enlargement and thereby the pipes in the area of the weld susceptible to corrosion power. A high heat load in the area of the round weld must therefore be avoided for the aforementioned reason.

At the Circumferential welding these latter tubes, but also in other types of pipes and Pipe materials, are the requirements for seam preparation and for layering to avoid root-side blending strictly observe. This means for example with regard to the temperature during welding the ends of the tube pair in the region of the tube material close to the weld, that this temperature does not exceed a certain permissible limit temperature Otherwise, it may, in addition to the above-mentioned, the corrosion resistance negatively influencing microstructural changes comes.

to Avoiding critical thermal stresses so far Practice that in the course of multi-layer welding of the round seam welding breaks be inserted so that the weld and thus close to the weld Cool down the area of the pipe material can and there a temperature increase over one critical limit temperature that would occur if would be welded multiple layers without time interruption.

A Such welding procedure inevitably leads to the time to produce a complete multi-layered round seam around the duration of the total welding breaks to be inserted extended becomes. It is obvious that such an approach inevitably at a relatively high cost based on a pipe connection leads, as next to the larger temporal Effort for the production of the actual circumferential seam and the other Effort for the production of, for example, one of a plurality of pipe sections existing Pipeline, such as time of provision of facilities for pipe laying and quality assurance, increased accordingly.

The The problem presented above is especially in the case of the circumferential seam welding corrosion-resistant thick-walled tubes of importance, this weld being inevitably in several layers and thus under high thermal stress of the material perform is. Not inadmissible high temperatures near the weld Area of the pipe material was in WO 02/00385 A1 a method for limiting the temperature during welding Ends of a pipe pair in the region of the pipe material near the welding area proposed by gas, in which the welding seam near the area of the pipe material in the field of welding certain heat affected zone subjected to forming gas and cooled at the same time, in which in the pipe material of the heat affected zone a temperature within one by an upper and a lower limit temperature preset temperature range at which the forming gas as a cryogenic liquid bereitge is provided and the application of forming gas in the gaseous state and the cooling of the Heat affected zone dependent on controlled by the temperature.

The However, the above problem is not only with thick-walled pipes, which must be welded in multiple layers and made of corrosion-resistant steel with fully austenitic structure exist, but it also exists in thin-walled pipe materials, the by deposit welding using an arc using inert gas and non-consumable electrode and be joined together without using filler material can.

Related requirements are to be met in particular for round seams of piggable pipes, wherein the welded joint is carried out by means of so-called. Orbitalschweißvorrichtungen. The latter are suitable in connection with the aforementioned arc welding for welding pipe joints up to wall thicknesses of about 4 mm. In the case of piggable pipelines, the design of the welded joints is of crucial importance to the viability and durability of the pig. Sagging weld roots present increased resistance to swaying in the pipeline under a particular radial prestressing pig cause and on the overall system adversely impacting driving pressures. A sagging of the weld root is therefore to be avoided with piggable pipes in any case.

In order to weld satisfactorily the latter pipe joints under the above boundary conditions, is in the EP 0 884 126 A1 proposed a method for the arc welding of a vertically oriented self-contained seam with two-dimensional course using inert gas and non-consumable electrode and without the use of filler material, wherein the seam is made of two stitching stitches, which begin in the region of the lowest point of the seam and in the region of the highest point of the seam, overlapping each other, the first stitching seam being made one piece from the lowest point of the seam over the highest point of the seam, the second stitching seam being made from the lowest point of the seam until the first stitching seam is inserted Piece wide welded, wherein the second stitching seam ends before the highest point of the seam and wherein the second stitching seam is preceded by a preheating, which extends over a lowermost point adjacent the beginning region of the first seam.

It Object of the present invention, the temperature during welding Ends of a pair of tubes in the weld region near a thin-walled Effectively control and limit pipe material and that Welding process like this adapt that the adverse effect of occurring during welding heat attack does not occur on the pipe material.

SUMMARY OF THE INVENTION

These Task is by a method with the features of the independent claim 1 or the additional claim 2 solved. Advantageous embodiments of the proposed method are Subject of the dependent claims. An arrangement for performing of the method according to the invention is characterized by the features of claim 9. An advantageous embodiment the proposed arrangement is the subject of the subordinate Under claim.

The procedural solution builds on the approach known from WO 02/00385 A1, that is that when welding such round seams required forming gas, which prevents the oxidation of the weld and from the inside of the tube to the weld in its root area brought is used at the same time for cooling the welding seam near Area of the pipe material in the area of one determined by welding Heat affected zone so that in the pipe material of the heat affected zone a temperature within one of an upper and a lower limit temperature set temperature range. This looks the well-known Method that the forming gas, such as nitrogen or Argon, as a cryogenic liquefied Gas is provided. This is the total enthalpy of the gas from its boiling temperature at the appropriate supply pressure in the liquid phase up to an upper temperature in the gas phase, due to the necessary Heat transfer at least slightly below the temperature to be maintained, exploitable.

• • als Einlagenschweißung oder alternativ
• • als Zweilagenschweißung

und jeweils mit einem Lichtbogen und nicht abschmelzender Elektrode und ohne Verwendung von Zusatzwerkstoff durchgeführt wird.The per se known feature of the cooling of the heat affected zone by the forming gas is now transferred according to the invention to the welding of the ends of a pipe pair in the weld region near a thin-walled pipe material, wherein the welding

• • as a deposit welding or alternatively
• • as two-layer welding

and each with an arc and non-consumable electrode and without using filler material is performed.

The Decision, whether the thin-walled pipe single-layer or double-layered and in each case with the further features according to the invention is welded, depends i.a. also from to be welded From pipe material. At highest Requirements for corrosion resistance, i. if low or smallest grain enlargements required and / or should be striven for, the decision for the two-layer welding is made in advance. Through this, the whole during the welding process to connect the Pipe end heat to be applied, time and place, in relation to for deposit welding stretched accordingly, so that the specific heat load (heat input / time unit) accordingly reduced and the involved material structure thermally less burdened is. This affects - next to the in this regard in the same direction effective other inventive process engineering Characteristics - positive on the structure near the weld Area off.

The Zweilagenschweißung distinguishes another advantage over the deposit welding, the fact that after introduction of the first welding position and the consequent shrinkage effect on the pipe ends in Result after completion of the second welding position a minor and quite desirable elevation of the Weld both inside and outside results.

One another crucial inventive idea of the present Invention is that in the heat affected zone, the distribution of Temperature over continuously determines the circumference of at least one pipe end will and that welding when crossing the upper limit temperature due to a maximum temperature of current temperature distribution is interrupted. Thus it is possible the Temperature near the weld Area, the heat affected zone, effective to control and limit. To the required quality criteria for the Keep weld to be able to the invention further provides that the welding process after falling below the upper limit temperature due to a maximum Temperature of the now current temperature distribution such continues that first the Welding tool, over the Scope of the pipe ends seen, undergoes a sectoral return and that afterwards on the return to be assigned Circumference to the end of the previously completed weld one Preheating is done. This will ensure that the adverse effect when welding occurring heat accumulation on the pipe material, the overheating - caused grain enlargement in Structure, does not occur. The design of the welding process after a temperature-induced Interruption of the welding process in particular ensures that at no point in the entire seam course a root-side sagging the seam occurs.

The Introduction of the second welding layer can in the process variant "two-layer welding" according to the invention in four procedural events take place, with the respective selection the eligible embodiment of the pipe material, the specific heat stress when welding and the pipe dimensions (diameter / wall thickness ratio) is conditional.

A First embodiment of the inventive two-layer process provides that the second welding position, temporally and locally, immediately at the end of the first welding position followed. This approach is at less critical thermal loads displayed.

A Second embodiment of the inventive two-layer process provides that the second welding position with a time interruption immediately at the end of the first welding position followed. This procedure is for critical thermal loads displayed.

A third embodiment of the inventive two-layer process provides that the second welding position, in terms of time, immediately other than the end of the first welding position begins. These Procedure is indicated if the thermal load less critical is the pipe geometry, however, a change in position of the welding electrode at the transition between the first and second welding position seems advisable.

A fourth embodiment of the inventive two-layer process finally sees before that the second welding position with a time interruption elsewhere than the end of the first welding position it starts. This procedure is indicated when both the thermal load as well as the tube geometry in vorg. Sense critical are.

Around a particularly high cooling capacity provide the Formiergases, sees an advantageous embodiment the method according to the invention both with regard to both deposit and double-layer welding, that the forming gas is provided as a cryogenic liquid.

to variable adaptation to a wide variety of thermal loads be in this regard proposed two variants of the method. The first variant exists in it, the cryogenic liquefied gas from a so-called reservoir and cold evaporator for cryogenic liquid and evaporate in an external evaporator. Of the Saturated steam thus produced leaves for example, with boiling temperature, for example, for an ambient pressure of about 1 bar for Nitrogen at about 77 K (Kelvin) and argon at about 87 K, the evaporator and is at about this temperature also in the proposed Arrangement initiated.

If the thermal load during welding increases in such a way that sufficient cooling with the cryogenic forming gas vapor, which in the best case has saturated steam temperature, is no longer ensured, a second process variant provides, bypassing the evaporator, the storage tank and cold evaporator immediately removed deep cold to supply liquefied gas directly to the arrangement according to the invention. In this way it is possible to use the heat of vaporization of the cryogenic liquefied gas and thus to achieve an even more intensive cooling of the arrangement and ultimately of the area of the tube material which is near the weld region. On the way to the region close to the weld area, the cryogenic liquefied gas will indeed evaporate, but then there is a forming gas available, which in any case has a lower temperature than is the case with a charging of the arrangement according to the invention with forming gas in the gaseous phase. This results from the fact that the cryogenic liquid passed over the evaporator already provides its enthalpy of vaporization there without this could be used for cooling the weld or the welded seam near heated areas of the inventive arrangement.

The to be welded together Pipe ends are on the inside preferably with the so-called inner clamping device stretched and aligned coaxially with each other. One on the outside the piping positioned welding tool and the piping to lead relative to the axis of the pipes relative rotational movement to each other. In the inner clamping device are two so-called Spanner heads provided, the clamping jaws arranged on both sides of the weld circular are and between them form an annular space, the tube side from the root area of the weld (Heat affected zone) is bounded. Such an inner clamping device is for example in the utility model DE-U-90 05 893 or also in EP-B-0 215 868 described. The aforementioned annular space between the jaws within the circumferential weld is known per se Way in the course of production of the round seam with the necessary forming gas acted upon, usually in the region of the longitudinal axis (tube axis) of the inner clamping device fed to the latter is and on both sides of the round seam, each formed via outflow openings of the gas permeable Clamping jaws, can flow out.

The proposed method leads now this annular space described above between the clamping heads, a Cold and Forming gas chamber, the deep-cold forming gas, which here then from welding certain, on either side of the weld in the pipe ends spreading heat-affected zone cool intensively can. The cooling and forming gas chamber becomes outside limited by the heat affected zone and it extends on either side of the weld in Direction of the axes of the pipeline.

Around the cooling the heat affected zone effective and be able to regulate sufficiently is in the area provided a device for measuring temperature, with the temperature of the outer wall a pipe end is detected. In addition, a first control unit provided that over Test leads with the device for temperature measurement and via control lines connected to shut-off valves of a Formiergasversorgung.

to execution the method according to the invention the above briefly outlined arrangement that above the Scope of at least one pipe end more than one temperature measuring point the device is arranged distributed for temperature measurement and that a second control unit is provided, which has a third control line is connected to the welding tool and this controls and the over a line for Signal processing is in communication with the first control unit, to receive the data for controlling the welding tool.

Under the given operating conditions, it is advantageous, like this one advantageous embodiment of the proposed arrangement according to the invention Provides that the temperature measuring realized without contact are.

BRIEF DESCRIPTION OF THE DRAWINGS

One embodiment an arrangement for carrying out the method according to the invention is shown in the drawing and will be described below. Show it

1 a central section through a substantial part of an arrangement according to the invention in the region on both sides of a circumferential weld;

2 a schematic representation of the arrangement according to the invention in conjunction with a part of a Formiergasversorgung;

3 a schematic representation of a cross section through the arrangement according to the invention in the region of the heat affected zone and here to illustrate a device for measuring temperature, wherein the distribution of the temperature measuring points is indicated schematically;

3a a longitudinal section through the pipe ends to be joined together in the region of an in 2 in the area of the round weld with "X" marked detail and

4 in a schematic representation and in the context of a polar coordinate system, the sequence of proposed inventive method steps for producing a circumferential seam before, during and after interrupting the welding process.

1

erstes Rohrleitungsende

2

zweites Rohrleitungsende

3

Innenspannvorrichtung

3*

erster Spannerkopf

3a*

erster Innenteil

3aa*

erster Außenteil

3**

zweiter Spannerkopf

3a**

zweiter Innenteil

3ab**

Verlängerung

3aa**

zweiter Außenteil

3c

erste Antriebsstange

3c*

erster Antriebskolben

3d

zweite Antriebsstange

3d*

zweiter Antriebskolben

3e

erste Druckmittelbohrung

3f

zweite Druckmittelbohrung

3g

Formiergasbohrung

3g*

Querbohrung

3h

Schaf

3i

Versorgungsrohr

3k

Kupplungsvorrichtung

3l

Verteilungskammer

3m

Verteilungsbohrung

3n

feinporig strukturierte Verteilungshülse (Sintermetall)

3o*

erste Abströmöffnungen

3o**

zweite Abströmöffnungen

4

Schweißwerkzeug

5

Gasleitung

6

Leitung für Flüssiggas

7

Sammlerteil

8.1

erste Steuereinheit (Gaszufuhr)

8.2

zweite Steuereinheit (Schweißwerkzeug)

9

erstes ferngesteuertes Absperrventil

10

zweites ferngesteuertes Absperrventil

11

Einrichtung zur Temperaturmessung

11.1a

erste Temperaturmessstelle

11.2a

zweite Temperaturmessstelle

11.ia

i-te Temperaturmessstelle

11.na

n-te Temperaturmessstelle

12

Anzeige- und Umschalteinrichtung

13

Messleitung der Temperaturmessstelle, allgemein

13a

erste Messleitung der Temperaturmessstellen, allgemein

13.1a

erste Messleitung der ersten Temperaturmessstelle

13.2a

erste Messleitung der zweiten Temperaturmessstelle

13.ia

erste Messleitung der i-ten Temperaturmessstelle

13.na

erste Messleitung der n-ten Temperaturmessstelle

13b

zweite Messleitung

14

Steuerleitung, allgemein

14a

erste Steuerleitung

14b

zweite Steuerleitung

14c

dritte Steuerleitung

14d

Leitung für Signalverarbeitung

A

Antriebszylinder

D

Druckmittel (z.B. Druckluft oder Hydrauliköl)

G

Formiergas

K

Kühl- und Formiergaskammer, ringförmig

LG

tiefkaltes verflüssigtes Gas (kryogene Flüssigkeit)

R1

erste Rohrleitung

R2

zweite Rohrleitung

S

Schweißnaht

Z

Wärmeeinflusszone

ϑ_go

obere Grenztemperatur

ϑ_gu

untere Grenztemperatur

1 and 2

1

first pipe end

2

second pipe end

3

Interior fixture

3 *

first tensioner head

3a *

first inner part

3aa *

first outer part

3 **

second tensioner head

3a **

second inner part

3ab **

renewal

3aa **

second outer part

3c

first drive rod

3c *

first drive piston

3d

second drive rod

3d *

second drive piston

3e

first pressure medium bore

3f

second pressure medium bore

3g

Formiergasbohrung

3g *

cross hole

3h

sheep

3i

supply pipe

3k

coupling device

3l

distribution chamber

3m

distribution bore

3n

fine-pored structured distribution sleeve (sintered metal)

3o *

first outflow openings

3o **

second outflow openings

4

welding tool

5

gas pipe

6

Line for liquefied gas

7

collectors part

8.1

first control unit (gas supply)

8.2

second control unit (welding tool)

9

first remote-controlled shut-off valve

10

second remote-controlled shut-off valve

11

Device for temperature measurement

11.1a

first temperature measuring point

11.2a

second temperature measuring point

11.ia

i-th temperature measuring point

11.na

nth temperature measuring point

12

Display and switching device

13

Measuring line of the temperature measuring point, general

13a

first measuring line of the temperature measuring points, general

13.1a

first measuring line of the first temperature measuring point

13.2a

first measuring line of the second temperature measuring point

13.ia

first measuring line of the i-th temperature measuring point

13.na

first measuring line of the nth temperature measuring point

13b

second measuring line

14

Control line, general

14a

first control line

14b

second control line

14c

third control line

14d

Cable for signal processing

A

drive cylinder

D

Pressure medium (eg compressed air or hydraulic oil)

G

forming gas

K

Cooling and forming gas chamber, ring-shaped

LG

cryogenic liquefied gas (cryogenic liquid)

R1

first pipeline

R2

second pipeline

S

Weld

Z

Heat affected zone

θ _go

upper limit temperature

θ _gu

lower limit temperature

W

Wurzelbereich

ϑ

Temperatur in der Wärmeeinflusszone Z

ϑ_a ; ϑ_a*

Temperatur an der Außenwand des Rohrleitungsendes

3 . 3a

W

root area

θ

Temperature in the heat affected zone Z

θ _a ; θ _a *

Temperature at the outer wall of the pipe end

 4

a, b, c,

d, e

Weld seam position of the first stitching seam N ₁

f g, h, i

Weld seam position of the second stitch seam N ₂

N

preheating

N ₁

first Vertical welding

N ₁₁

first part of the first stitching seam N ₁

N ₁₂

second part of the first stitching seam N ₁

N ₂

second Vertical welding

R

returns

DETAILED DESCRIPTION

Via a weld S ( 1 ) to be connected to each other pipe ends 1 . 2 two pipes R1, R2 are on the inside of the pipe ends by means of a so-called internal clamping device 3 mutually concentric aligned and tense. The axis of the inner clamping device depends 3 concentric with the axis of the pipe ends 1 . 2 out. The inner clamping device 3 consists among other things of a first tensioner head 3 * and a second tensioner head 3 ** , The former consists of a wedge-shaped first inner part 3a * , which by axial displacement in a first outer part 3aa * the latter widens in the radial direction. The first outdoor part 3aa * is made up of several distributed over the circumference segments, which are biased by two unspecified, the segments enclosing so-called worm springs in the radial direction. The second tensioner head 3 ** is constructed accordingly and has a second inner part 3a ** and a second outer part 3aa ** on. The inner part 3a ** is in a substantially cylindrical extension 3ab ** on the other hand, and on the other side, the first outer part 3aa * axially supported.

The first tensioner head 3 * is with one on the first inner part 3a * attacking and from a first drive piston 3c * driven first drive rod 3c connected. In the same way, the second inner part 3a ** of the second tensioner head 3 ** via one of a second drive piston 3d * powered second drive rod 3d moved in the axial direction. The first and second drive pistons 3c * respectively. 3d * are arranged in a drive cylinder A and can each side with a via pressure medium holes 3e . 3f supplied pressure fluid D, for example, compressed air, under certain conditions (eg, when reducing the incidence of heat by the cooling of the invention) with an incompressible pressure medium such as hydraulic oil, are acted upon. Thus, the two clamping heads 3 * . 3 ** , each separated, controllable, so that the respective tensioner head 3 * . 3 ** assigned pipe end 1 respectively. 2 , separated and independent of each other, tensioned and concentric with the inner clamping device 3 can be aligned.

The inner clamping device described above 3 initially allows a tensioning and alignment of the pipe end shown on the left side with respect to the weld S 1 , Thereafter, the pipe end shown on the right side can 2 be tense, the left side is used to the right side to form the subsequently produced weld S gap-free. In the first drive rod 3c is a forming gas well 3g arranged in the area between the tensioner heads 3 * . 3 ** in there from the two pipe ends 1 and 2 formed annular cooling and Formiergaskammer K on the way through a transverse bore 3g * , a distribution chamber 3l and a variety of distribution holes 3m opens. A particularly effective distribution of the gas over the entire circumference and the entire length (heat-affected zone Z) of the cooling and Formiergaskammer K provides a fine pored structured distribution sleeve 3n sure, the extension 3ab ** in the area of emerging distribution wells 3m encloses. About the forming gas hole 3g and the above-mentioned further flow path cooling forming gas G, possibly as cryogenic liquefied gas LG, the weld S are supplied during the welding process.

The drive housing A is on his the clamping heads 3 * . 3 ** opposite end face with a shaft 3h connected via the pressure medium holes 3e and 3f and the Formiergasbohrung 3g in the inner clamping device 3 be introduced. The shaft 3h sits down in a supply pipe 3i continued.

The first and the second pipe end 1 . 2 the first and the second pipe R1, R2 ( 2 ) are over the inner clamping device 3 , which, seen in the direction of the tube axis, from the two clamping heads 3 * . 3 ** with two axially spaced rows of individual unspecified jaws and the drive cylinder A is so tight and aligned coaxially with each other, that in the region of the weld S to be produced in the 3a exemplified arrangement of the pipe ends 1 . 2 given is. In the illustration shown ( 2 ) it can be assumed that the first pipe R1, of which only the first pipe end 1 is shown, the second pipe R2 is welded in the form of a piece of pipe of a certain length and that on this second pipe R2, the inner clamping device 3 to the pipe ends to be joined together 1 . 2 is brought in from the inside.

The drive cylinder A terminates in the supply pipe 3i , are passed through the conduit means for energy and gas supply, wherein via a coupling device 3k a collector's item 7 , via which the cryogenic liquefied gas LG or its vapor or gaseous phase G is brought in, with the supply pipe 3i connected is. The collector part 7 combines a gas line 5 and a line for liquefied gas 6 , The gas line 5 finally leads to a first remote-controlled shut-off valve 9 and the line for liquefied gas 6 finally leads to a second remote-controlled shut-off valve 10 ,

When removed via an evaporator, not shown, the Formiergasversorgung the cryogenic gas flows either as saturated steam or, with sufficient heat, as a cold gas G via the gas line 5 , the collector's part 7 and the supply pipe 3i into the cooling and forming gas chamber K between the two tensioning heads 3 * . 3 ** in the area of the heat-affected zone Z (see FIG. 1 ) of the pipe ends to be joined together 1 . 2 , An outflow from this area into the adjacent interior spaces of the pipes R1, R2 is via first and second outflow openings 3o * respectively. 3o ** within the associated tensioner heads 3 * . 3 ** ensured.

The arrangement according to the invention is a first control unit 8.1 associated with the supply of the cryogenic liquefied gas LG and the cryogenic gas G in the cooling and Formiergaskammer K controls. The control unit 8.1 is with the first and the second remote shut-off valve 9 . 10 in each case via a second or first control line 14b . 14a connected. Furthermore, it is over a first measuring line 13a with a device for temperature measurement 11 as well as a second measuring line 13b with a display and switching device 12 (PISL: pressure display and switching below a lower pressure limit) connected in the gas line 5 is arranged and falls below a predetermined pressure or a predetermined, directly measured flow the cooling on LPG removal and thus the supply of the coolant to the line for liquefied gas 6 switches. The monitoring of the pre-pressure at a specific point in the gas line 5 Since the pressure loss coefficients in the downstream line arrangement are fixed, there is sufficiently reliable information about the actual flow in this gas line 5 ,

Furthermore, a second control unit 8.2 provided, on the one hand via a third control line 14c with a welding tool 4 and on the other hand via a line for signal processing 14d with the first control unit 8.1 connected is.

In 3a are the pipe ends 1 . 2 a thin-walled tube shown. The connection of the pipe ends 1 . 2 forms on the inside a root region W of the circumferential weld S, wherein the connection of the pipe ends to be joined together 1 . 2 can be produced by deposit welding or by two-pass welding and in each case with an arc and non-consumable electrode and without the use of additional material. In the weld region near the weld seam S is over the circumference of at least one pipe end 1 . 2 more than one temperature measuring point 11.1a to 11.na the device for temperature measurement 11 arranged distributed (see also 3 ). This may, like this 3a clarified, either on the side of the first pipe end 1 (Temperature value θ _a *) or on the side of the second pipe end 2 (Temperature value θ _a ) take place.

The over the circumference of the pipe ends 1 . 2 distributed arranged temperature measuring points 11.1a to 11.na ( 3 ) transmit their measured values, which represent the distribution of the temperature θ over the pipe circumference, via assigned measuring lines 13.1a to 13.na to the first control unit 8.1 , in turn, over the wire for signal processing 14d this temperature distribution to the second control unit 8.2 transmitted, so that the latter the welding tool 4 according to the inventive method on the way over the third control line 14c can control ( 2 ).

Process variant 1

In the first control unit 8.1 are an upper limit temperature θ _go and a lower limit temperature θ _{gu of} the allowable temperature range θ deposited ( 2 ). When welding the pipe ends 1 . 2 Care must be taken to ensure that these limit temperatures θ _go and θ _{gu are} not exceeded or fallen short of. For this purpose, depending on the required cooling capacity, either gas G via the gas line 5 or cryogenic liquefied gas LG via the line for liquefied gas 6 introduced into the cooling and Formiergaskammer K, there to the interconnected pipe ends 1 . 2 to cool and then over the outflow openings 3o * . 3o ** in the two rows of clamping jaws of the clamping heads 3o * . 3 ** to flow into the adjacent pipe interiors. In the case of excessive cooling (falling below the limit temperature θ _gu ) is the first control unit 8.1 the first remote-controlled shut-off valve 9 or the second remotely controlled shut-off valve 10 close, so that thereby the temperature increases in the area of the pipe material near the weld seam. In the other case, when the upper limit temperature θ _go is exceeded due to a maximum temperature θ of the current temperature distribution passing through the temperature measuring points 11.1a to 11.na is determined continuously, the welding process is interrupted. In the forefront of this interruption, the cooling capacity is first increased with an increase in the temperature θ to the limit temperature θ _go that the first remote-controlled shut-off valve 9 or the second remote-controlled shut-off valve 10 continues to open. Only when it is not possible to prevent the upper limit temperature θ _go from being exceeded by the forcing shown above, the welding process is interrupted.

The welding process briefly described above is in 4 between weld positions a and b (a first part N _{11 of} a first stitch seam N ₁ ). As soon as the upper limit temperature θ _go is undershot due to a maximum temperature of the now current temperature distribution, the welding process is continued in such a way that initially the welding tool 4 , about the circumference of the pipe ends 1 . 2 seen, a sectoral return R undergoes (Welding positions b to c) and that subsequently on the return R attributable circumferential path (between the weld positions c, b) to the end of the previously completed weld S (weld position b of the first part N _{11 of} the first Steignaht N ₁ ) a preheating H takes place. At the end of the previously completed weld S (new weld position d = weld position b) now joins a second part N _{12 of} the first stitching seam N ₁ , which ends, for example, in a weld position e. A remaining round seam, a second stitch seam N ₂ , of the pipe ends to be connected to each other 1 . 2 is in accordance with the from the EP 0 884 126 A1 known processes in such a way that the stitching seams N ₁ , N ₂ begin in the region of the lowest point (welding position g), wherein the second stitching seam N _{2 is} preceded by a preheating line (welding positions f to g) and overlap in the area of the highest point ( Welding positions e, h to i).

The above-described sequence of the described weld sections applies in the Method variant "two-layer welding" for the introduction of the first welding layer as well as the second welding layer In the introduction of the second welding layer, it is possible to proceed according to the above-described four procedural embodiments.

In the first embodiment of the two-layer method according to the invention, the second welding position, seen in terms of time and location, adjoins the welding position e immediately at the end of the first welding position ( 4 ).

In the second embodiment, the second welding position with a time interruption also connects directly to the end of the first welding position to the welding position e ( 4 ), wherein the period of time interruption is arbitrary.

The third embodiment provides that the second welding position, in terms of time, immediately at another point than the end of the first welding position (welding position e; 4 ), where every possible circumferential position comes into question and the time span between the completion of the first welding position and the beginning of the second welding position is determined solely by the method of the welding electrode in the desired new circumferential position.

The fourth embodiment provides that the second welding position with temporal interruption at another point than the end of the first welding position (welding position e; 4 ), where again every possible circumferential position comes into question and the time span of the temporal interruption is freely selectable, but at least according to the temporal premises of the third embodiment.

Process variant II

Represents in the course of carrying out the process variant 1 out that a higher cooling capacity required or from the beginning a higher cooling capacity is necessary, then a non-illustrated reservoir and cold evaporator cryogenic liquefied gas LG is removed and the line for liquefied gas 6 and the collector part 7 on the way over the supply pipe 3i supplied to the cooling and Formiergaskammer K described above. With appropriate dimensioning of the flow rate, the incurable heat on the way into the cooling and forming gas chamber K into the cryogenic liquefied gas LG will cause it to evaporate, so that the pipe ends 1 . 2 in the root area W of the weld S of steam or gas G and not by the much more intense cooling cryogenic liquid LG are acted upon. Depending on the temperature measuring device 11 measured temperatures θ and their respective relation to the limit temperatures θ _go and θ _gu , the supply of LP gas LG via the second remote-controlled shut-off valve 10 controlled.

In both variants of the method it is ensured that in the absence of the forming gas G and thus the cooling of the control of the welding tool 4 serving second control unit 8.2 from the first control unit 8.1 receives the appropriate information and turns off the welding current necessary for welding.

Claims (11)

Method for limiting the temperature during welding of the ends of a pipe pair in the weld region near a thin-walled pipe material, wherein the pipe ends to be joined together ( 1 . 2 ) of two pipes (R1, R2) by an inner clamping device acting on the inside of the pipe ends ( 3 ) are mutually concentrically aligned and tensioned and the axis of the inner clamping device is aligned concentrically to the axis of the pipe ends, wherein the Innnenspannvorrichtung ( 3 ) together with the pipe ends ( 1 . 2 ) an annular Formiergaskammer (K) for acting on the weld (S) with a forming gas (G) forms and limited, wherein the weld near the region of the pipe material in the region of a certain determined by welding heat affected zone (Z) with the forming gas (G) in the gaseous state is acted upon and thereby simultaneously cooled, wherein in the pipe material of the heat affected zone (Z) a temperature (θ) within a predetermined by an upper and a lower limit temperature (θ _go ; θ _gu ) temperature range and the cooling of the heat affected zone (Z) in Depending on the temperature (θ) is controlled and in which a positioned on the outside of the pipes welding tool ( 4 ) and the pipelines (R1, R2) perform a rotational movement relative to one another relative to the axis of the pipelines, characterized in that the welding is carried out as an insert welding with an arc and non-consumable electrode and without the use of additional material, that in the heat-affected zone (Z) the distribution of the temperature (θ) over the circumference of the pipe ends ( 1 . 2 ) is continuously determined, • that the welding is interrupted when the upper limit temperature (θ _go ) is exceeded due to a maximum temperature of the current temperature distribution and • that the welding after falling below the upper limit temperature (θ _go ) due to a maximum Temperature of the now actual temperature distribution is continued in such a way, that first the welding tool ( 4 ), over the circumference of the pipe ends ( 1 . 2 ), undergoes a sectoral return (R) and • that subsequently on the return path (R) to be assigned circumferential distance to the end of the previously completed weld (S), a preheating (N). Method for limiting the temperature during welding of the ends of a pipe pair in the weld region near a thin-walled pipe material, wherein the pipe ends to be joined together ( 1 . 2 ) of two pipes (R1, R2) by an inner clamping device acting on the inside of the pipe ends ( 3 ) are mutually concentrically aligned and tensioned and the axis of the inner clamping device is aligned concentrically to the axis of the pipe ends, wherein the Innnenspannvorrichtung ( 3 ) together with the pipe ends ( 1 . 2 ) an annular Formiergaskammer (K) for acting on the weld (S) with a forming gas (G) forms and limited, wherein the welding seam near the region of the pipe material in the region of a welding determined heat affected zone (Z) with the forming gas (G) in the gaseous state is acted upon and thereby simultaneously cooled, wherein in the pipe material of the heat affected zone (Z) a temperature (θ) within a predetermined by an upper and a lower limit temperature (θ _go ; θ _gu ) temperature range and the cooling of the heat affected zone (Z) in Depending on the temperature (θ) is controlled and in which a positioned on the outside of the pipes welding tool ( 4 ) and the pipes (R1, R2) perform a rotational movement relative to each other relative to the axis of the pipes, characterized in that the welding is carried out as a two-layer welding with an arc and non-consumable electrode and without the use of additional material, that in the heat-affected zone (Z) the distribution of the temperature (θ) over the circumference of the pipe ends ( 1 . 2 ) is continuously determined that the welding is interrupted when the upper limit temperature (θ _go ) is exceeded due to a maximum temperature of the current temperature distribution and • that the welding continues after falling below the upper limit temperature (θ _go ) due to a maximum temperature of the now current temperature distribution in such a way • that first the welding tool ( 4 ), over the circumference of the pipe ends ( 1 . 2 ), undergoes a sectoral return (R) and • that then follows on the return path (R) attributable circumferential path to the end of the previously completed weld (S), a preheating (H). Method according to claim 2, characterized in that that the second welding position, temporally and locally seen immediately adjacent to the end of the first weld. Method according to claim 2, characterized in that that is the second welding position with a time interruption directly to the end of the first weld pass followed. Method according to claim 2, characterized in that that the second welding position, timely, immediately begins elsewhere than the end of the first welding position. Method according to claim 2, characterized in that that the second welding position with a time interruption elsewhere than the end of the first weld pass it starts. Method according to one of claims 1 to 6, characterized in that the forming gas (G) is provided as a cryogenic liquid (LG) becomes. Method according to claim 7, characterized in that that cooling the heat affected zone (Z) with the saturated steam (G) of the cryogenic liquid (LG) takes place. Method according to claim 7 or 8, characterized that in cooling the heat affected zone (Z) the evaporation enthalpy of the cryogenic liquid (LG) partially up Completely is exploited (evaporative cooling). Arrangement for carrying out the method according to one of Claims 1 to 9, having an inner clamping device ( 3 ), which connect the pipe ends ( 1 . 2 ) of two pipes (R1, R2) are each aligned concentrically on the inside of the pipe ends and clamped and concentrically aligned with the axis of the pipe ends, with a between a first and a second tensioner head ( 3 * . 3 ** ) of the inner clamping device ( 3 ) formed annular forming gas chamber (K), which serves to provide the necessary cooling power, on the outside of a particular welding, on both sides of a weld (S) in the pipe ends ( 1 . 2 ) propagating heat-affected zone (Z) is limited and extends on either side of the weld (S) in the direction of the axis of the pipe (R1, R2), with a positioned on the outside of the pipe welding tool ( 4 ), the latter and the pipelines (R1, R2) carrying out a rotation movement relative to each other relative to the axis of the pipelines, with one in the region of Heat affected zone (Z) provided device for temperature measurement ( 11 ), with which the temperature (θ) of the outer or inner wall of the pipe end (R1, R2) is detected, and with a first control unit ( 8.1 ), which are connected via test leads ( 13 ) with the device for temperature measurement ( 11 ) and via control lines ( 14 ) with shut-off valves ( 9 . 10 ) is connected to the Formiergasversorgung, characterized in that • over the circumference of at least one pipe end ( 1 . 2 ) more than one temperature measuring point ( 11.1a . 11.2a , ..., 11.ia , ..., 11.na ) of the device for temperature measurement ( 11 ) and that • a second control unit ( 8.2 ), which is connected via a third control line ( 14c ) with the welding tool ( 4 ) and controls it and • which via a signal processing line ( 14d ) with the first control unit ( 8.1 ) is connected to the data for controlling the welding tool ( 4 ) to recieve. Arrangement according to claim 10, characterized in that the temperature measuring points ( 11.1a . 11.2a . ..., 11.ia . ... , 11.na ) are realized without contact.