CN103909321A - Welding method for under-pressure nitrogen pipeline cracks - Google Patents

Abstract

The invention provides a welding method for under-pressure nitrogen pipeline cracks. The welding method includes twisting and extruding to extend parent metal on two sides of cracks by a hammer and a chisel, twisting and extruding seams after welding until hermetically welding, wherein the twisting length is 10-20mm, and the melting layer is 1.5-2.5mm; if twisting fails in sealing, punching by an electric drill with hole diameter ranging from 2.8-3.2mm; clamping conical welding rods 28-33mm in length and 3.2mm in diameter by tongs, hammering the conical welding rods into the holes by the hammer, and quickly welding after sealing; wherein welding current is 110A, electric arc voltage is 19-30V, twisting electric arc voltage is 25-35V, the hammer weight for seam twisting and extruding is 1.3-1.7 pounds. The welding method is applicable to under-pressure welding of steam pipelines, water delivery pipelines and air pipelines.

Description

A kind of welding method for nitrogen pipeline crackle with pressure

Technical field

The present invention relates to the solder technology of pipeline crack, be particularly useful for the welding method of pipeline crack with pressure.

Background technology

The oxygen that oxyen manutactory produces, argon gas, helium is by pipeline or container transport and use, carry pipeline and the container of liquid nitrogen conventionally to adopt stainless steel or copper and Cu alloy material, and nitrogen pipeline under normal temperature adopts Q235A or 20# steel more, the pressure that pipeline bears is not generally at 0.4MPa to 2.5MPa etc., in nitrogen storage and transportation, during due to liquid nitrogen gasification, the variation meeting of pressure and temperature produces impact to conveyance conduit or container, action of thermal difference, through long-term use, produced fatigue crack, in order not affect production, need under use state, weld, and requirement ensures welding quality.

If nitrogen pipeline leakage difficulty in the time that running status with pressure is welded is very large, the weld seam because the pressure of gas can blow off molten metal before not solidifying, deposited metal cannot be combined with mother metal, secondly nitrogen belongs to inert gas, when concentration is larger, can make welder suffocate, threaten workmen's safety, under air-flow in the time that conveyance conduit is longer and in running and air pressure acting in conjunction, can produce covibration in addition, make pipeline not stop shake, also can affect the extension that deposited metal is combined with mother metal and can be aggravated crackle, bring many difficulties to welding.

The present invention is directed to the nitrogen pipeline of iron company, implement site disposal, adopt the welding repair method that carries out nitrogen pipeline with pressure, under the state that does not affect production, carry out REPAIR WELDING, saved time cost, its effect is splendid, for the energy-saving and cost-reducing of enterprise contributes.

Summary of the invention

The object of the invention is to: the method for welding pipeline providing, save time cost and human resources, there are important production practices and be worth.

The present invention seeks to realize like this: a kind of welding method for nitrogen pipeline crackle with pressure, implement step by step;

Step 1 is twisted with the fingers pressure welding and is connect:

Utilize hammer and chisel by twisting with the fingers to squeeze, they to be extended the base metals on crackle both sides, twist with the fingers and press length 10-20mm, overlay is 1.5-2.5mm, has welded, then has carried out caulking extruding, until welded seal;

Step 2 punching welding: twist with the fingers and press while not reaching sealing effectiveness, adopt electric drill punching, its bore dia 2.8-3.2mm; Adopt long 28-33mm, the sharp cone distal welding rod that diameter is 3.2mm, is clamped with pliers, cone-shaped discard electrode is pounded in hand-hole to welding rapidly after sealing with hammer;

Wherein welding employing electric current is 110A, arc voltage 19-30V, and twisting with the fingers and pressing the arc voltage of use is 25-35V;

Wherein twist with the fingers press tool: according to the shape of crackle and width degree, first the cutting edge thickness of chisel is worn into respectively to 1mm, 2mm, root face that 3mm is thick, then chisel is left to monolateral angle is 60 degree, its edge of a knife angle is 120 degree; First use the chisel compression fissure both sides that 1mm is thick, if do not sealed up, then use the chisel compression fissure both sides that 2mm is thick, if still when unsealing, continue to twist with the fingers and squeeze with the thick chisel of 3mm, twist with the fingers and squeeze by three times, reach temporarily sealing effect; When welding, adopt the welding rod of ZX7-500S type welding machine and E4303 type, the hammer weight of caulking extruding is 1.3-1.7 pound.

Mechanism of the present invention and effect: for nitrogen pipeline crack, implement site disposal, adopt the welding repair method that carries out nitrogen pipeline with pressure, do not affect REPAIR WELDING under the state of production, saved time cost and labor cost, show technological progress.

Brief description of the drawings

The present invention is described further by reference to the accompanying drawings.

Accompanying drawing 1 is nitrogen pipeline crackle schematic diagram;

As shown in the figure: A is crack surface.

Accompanying drawing 2 is twisted with the fingers crowded rear welding schematic diagram for amplifying crackle;

As shown in the figure: 1-crackle is twisted with the fingers and squeezed, 2-welding.

Detailed description of the invention

The present invention is described further in conjunction with the embodiments.

Embodiment

Caulking extruding segmentation welding or boring method:

1) select caulking extruding progressive welding method, utilize hammer and chisel that the base metals on crackle both sides is welded rapidly by twisting with the fingers to squeeze after making its extension reach local temporarily sealing, twist with the fingers and press length 18mm, overlay is unsuitable blocked up, blocked up easy burn-through, overlay is 2.0mm, twists with the fingers again and squeeze, weld, until be soldered to last point after having welded;

2) cannot reach sealing effectiveness by twisting with the fingers to squeeze, last leak source have to be bored to the hole of a diameter 3mm with electric drill, welding rod one end of diameter 3.2mm is worn into cone-shaped, then be cut into 30mm length, so that clamped with pliers, cone-shaped discard electrode is pounded in hand-hole with hammer, when rapidly last this point being welded after temporarily sealing.

3) caulking compression tool:

The chisel of caulking extruding should not be crossed point or excessively sharp, crossing point can shave except base metals, and do not reach the effect of crush seal, therefore the chisel of caulking extruding use wants more blunt, according to the shape of crackle and width degree, the cutting edge of chisel is worn into respectively to 1mm, 2mm, the wide root face of 3mm, first use the wide chisel compression fissure both sides of 1mm, if do not sealed up, use again the chisel compression fissure both sides of 2mm, if also cannot reach temporarily sealing time, continue to twist with the fingers and squeeze with the chisel of 3mm, twist with the fingers and squeeze by three times, reach temporarily sealing effect; The end of chisel is scratch start degree slightly, and chisel is crossed profit can shave off tube metal, crosses round and smooth meeting and makes to twist with the fingers crowded difficulty, and preferably chisel angle being left monolateral is 60 degree, and edge of a knife angle 120 is spent angle; The hammer weight of caulking extruding is 1.5 pounds; Welding machine is selected ZX7-500S type welding machine, and welding material is selected E4303 welding rod.

4) welding operation:

When welding, adopt larger welding current, its objective is the power of blowing that can improve electric arc; to offset the gas pressure of leak source, and can make molten drop be transitioned into accurately soldering place, after droplet metal blocks leak; arc extinguishing at once; blow-out action wants fast, thereby makes the rapid cooling welding that completes of deposited metal drop, and the sth. made by twisting that carries out again next section after it is cooling squeezes seal welding; repeat like this 10 left and right; while being welded to last point, because pressure is excessive, suspend welding; Start cover welding for the second time from bottommost, secondary welding electric current adopts 110A, suitably increase arc voltage, reduce fusion penetration, generally weld the arc voltage of use at 20V, the arc voltage of twisting with the fingers crowded use should be 30V, can make like this fusion penetration reduce, prevent deposited metal refuse and by the air pressure weld seam that blows off, until be welded to last point, the part growing is ground off with angle grinding machine, weld fast and capping.

The present invention adopts welding repair method with pressure, makes the Q235A steel pipe of DN400, and pipeline wall thickness is 6mm, and crackle is 8 points, carries out REPAIR WELDING under the state that does not affect production, has saved time cost and labor cost; Described welding method is also applicable to the welding with pressure of jet chimney, aqueduct, air duct.

The technique effect of the inventive method: 1) carry out pipeline rehabilitation in non-stop-machine situation; carrying out pipeline repair method advantage than shutdown is in the past not affect steel-making, ironmaking; 2) do not need a lot of maintenance, operating personnel, save eight maintenance and operating personnel above.3) and repair quality the same with shutdown welding effect, use more than 10 years.

Claims (2)

1. for a welding method for nitrogen pipeline crackle with pressure, it is characterized in that: implement step by step;

Step 1 is twisted with the fingers pressure welding and is connect:

Utilize hammer and chisel by twisting with the fingers to squeeze, they to be extended the base metals on crackle both sides, twist with the fingers and press length 10-20mm, overlay is 1.5-2.5mm, has welded, then has carried out caulking extruding, until welded seal;

Step 2 punching welding: twist with the fingers and press while not reaching sealing effectiveness, adopt electric drill punching, its bore dia 2.8-3.2mm; Adopt long 28-33mm, the sharp cone distal welding rod that diameter is 3.2mm, is clamped with pliers, cone-shaped discard electrode is pounded in hand-hole to welding rapidly after sealing with hammer;

Wherein welding employing electric current is 110A, arc voltage 19-30V, and twisting with the fingers and pressing the arc voltage of use is 25-35V;

Wherein twist with the fingers press tool: according to the shape of crackle and width degree, first the cutting edge thickness of chisel is worn into respectively to 1mm, 2mm, root face that 3mm is thick, then chisel is left to monolateral angle is 60 degree, its edge of a knife angle is 120 degree; First use the chisel compression fissure both sides that 1mm is thick, if do not sealed up, then use the chisel compression fissure both sides that 2mm is thick, if still when unsealing, continue to twist with the fingers and squeeze with the thick chisel of 3mm, twist with the fingers and squeeze by three times, reach temporarily sealing effect; When welding, adopt the welding rod of ZX7-500S type welding machine and E4303 type, the hammer weight of caulking extruding is 1.3-1.7 pound.

2. according to welding method described in claim 1, it is characterized in that: the method is also applicable to the welding with pressure of jet chimney, aqueduct, air duct.