CN103920967B - Absorption tower welding method - Google Patents

Abstract

The present invention relates to a kind of absorption tower welding method.The invention provides step to comprise: one) welds prepares; Two) weld; Three) post weld heat treatment; Four) postwelding cleaning, finishing and postwelding inspection; Adopt this method can shorten the construction period, increase economic efficiency and ensure welding quality.

Description

Absorption tower welding method

Technical field

The technical program belongs to chemical industry equipment technical field of construction, specifically a kind of welding method of absorption tower.

Background technology

In the work progress of chemical industry equipment, need to carry out on-the-spot segmental hoisting, vertical assembly welding to the large-scale ultra-high overweight such as tower, tank thick-wall equipment.Find in practice of construction, the distance of absorption tower and neighboring devices is little, and density of equipment is large, spatially arranges.Because weld job scene is special, so adopt existing welding method cannot meet the requirement of construction quality and progress.

Summary of the invention

In order to solve the above-mentioned problems in the prior art, the present invention proposes a kind of segmental hoisting, aerial group of adopting to the welding method on the absorption tower of construction method, and step comprises: one) welds prepares; Two) weld; Three) post weld heat treatment; Four) postwelding cleaning, finishing and postwelding inspection;

Described step one) job requirements comprise:

1) groove type is set:

Large V-butt is positioned at equipment outer wall, and little V-butt is positioned at equipment inner wall,

The groove of absorption tower inwall is set to little V-butt, and the groove of absorption tower outer wall is set to large V-butt;

For in the adjacent two sections on absorption tower:

Spacing b between top weldment and bottom weldment is 2mm ~ 3mm; Between at the bottom of the slope of little V-butt and at the bottom of large V-butt slope, spacing P is 1mm ~ 3mm; For little V-butt, the dark H in slope is 28mm ~ 32mm;

For little V-butt, the opening angle α between at the bottom of the Po Bi of top weldment and slope is 40 ° ~ 45 °, and the opening angle β between at the bottom of the Po Bi of bottom weldment and slope is 1 ° ~ 5 °; For large V-butt, the opening angle α between at the bottom of the Po Bi of top weldment and slope is 40 ° ~ 45 °, and the opening angle β between at the bottom of the Po Bi of bottom weldment and slope is 1 ° ~ 5 °;

First weld absorption tower outer wall, after the inwall back chipping of absorption tower, then weld absorption tower inwall;

2) organize right:

Set up scaffold, segmental hoisting, aloft welding are adopted to the tower body on absorption tower; Group to before should by cleaning groove face and groove near the inside and outside wall of weldment 45mm ~ 50mm scope, until send metallic luster; Should accomplish that the unfitness of butt joint of inwall is no more than 3mm during group pair;

3) tack welding:

The wlding that tack welding uses must be consistent with the wlding used when formally welding; Before tack welding, butt-welding fitting is preheated to 130 DEG C ~ 150 DEG C; The number of welds of tack welding is determined according to device diameters, and at weldment surface often distance 280mm ~ 320mm tack welding a bit, the fusion length of tack welding is no less than 50mm, throat depth 3 ~ 5mm;

Described step 2) job requirements comprise:

1) striking

Striking should be carried out in groove face, or adopts run-on tab striking;

2) arc and joint is received

2.1) slowly should mention welding gun when receiving arc, note filling up arc crater, find that crater crack and shrinkage cavity defect should be removed immediately;

2.2) change welding rod when welding should control to complete in 2 ~ 3 seconds;

3) preheating:

The scope of preheating comprises the width of each 270mm ~ 330mm in both sides, welding point center; Temperature measuring point should be selected to be positioned at 48mm ~ 52mm place, weld seam both sides, will remain the monitoring to preheat temperature in welding process; Preheat temperature is 130 DEG C ~ 150 DEG C;

4) welder arranges:

Manual arc welder mode in a center of symmetry is adopted to distribute welding, the speed of welding be consistent and operative orientation; Spacing between adjacent welder is 550mm ~ 650mm;

5) root layer welding:

5.1) root layer throat depth is not less than 3mm, and is not more than 5mm;

5.2) root layer weld seam adopts weave bead welding "the" shape manipulation of electrode;

5.3) root layer weld seam should carry out visual examination and penetrant inspection after being soldered immediately, finds that defect should be removed immediately;

6) packed layer welding:

6.1) packed layer throat depth should not be greater than 4mm;

6.2), when filling ground floor welding, attentional manipulation weld heat input, prevents the arc burn of root layer;

6.3) when filling weldering, adopt multi-pass welding, adopt straight line not swing manipulation of electrode;

6.4) multilayer fill weldering time, every layer be soldered after should check face of weld quality immediately, find defect should remove immediately, the welding of lower floor's weld seam can be carried out;

6.5), during multilayer welding, the strict interlayer temperature that controls is at 130 DEG C ~ 150 DEG C;

7) capping layer welding:

7.1) cover welding adopts multi-pass welding, adopts straight line not swing manipulation of electrode, should fill up weld seam;

7.2) cosmetic welding scoops out attentional manipulation weld heat input, prevents face of weld from producing undercut defect;

7.3) cover welding should be specifically noted that slow blow-out, fills up arc crater;

7.4), after weld seam is soldered, require polishing, weld seam rounding off, absorption tower inner wall surface weld seam answers equating, and crator, welding slag should be removed totally;

8) back root cleaning, welding:

8.1) fillet in normal shear carries out back root cleaning process after being soldered to 30mm;

8.2) back root cleaning will thoroughly remove oxide layer and carburized layer, until expose metallic luster completely;

8.3), after back chipping process, weldquality is checked;

8.4) face of weld after back chipping is detected a flaw, can weld after passed examination;

9) welding is interrupted:

Postheating when weldment that is large for workload, that can not once be soldered interrupts welding, after heat disappear hydrogen treatment measures; The disappear requirement of hydrogen process of after heat heats 300 DEG C ~ 350 DEG C to welding region, is incubated 0.5 hour ~ 1 hour, then Slow cooling; When again welding, confirm flawless, again could weld after preheating 130 DEG C ~ 150 DEG C;

10) welding surroundings

10.1) windproof:

A. welding region uses deep bead and the Polypropylence Sheet closed wind-proof that keeps out the wind;

B. upper and lower 1.3 ~ 1.8 meters of settings of the inherent welding region in absorption tower are kept out the wind layer;

C., time wind speed is greater than 8m/s, forbid to weld;

10.2) rainproof:

A. welding region uses Polypropylence Sheet covering rainproof;

B. when rainy day and relative humidity are greater than 80%, reliable safeguard procedures should be taked, otherwise forbid welding;

Described step 3) job requirements comprise:

Postwelding takes slow cooling measure, and carries out after heat immediately and to disappear hydrogen process; The after heat hydrogen process mode of heating that disappears adopts electric infrared heating mode; The after heat hydrogen treatment process requirement that disappears is, welding region heating 300 ~ 400 DEG C, is incubated 0.5 ~ 1.0 hour, Slow cooling.

First stress analysis is carried out in this welding method:

Aloft during welding, the impact of equipment gravity should be taken into full account;

A, equipment gravity: during aerial group pair, equipment gravity vertically downward, acts on welding point and is mainly compression, during welding, the tensile stress produced when can offset part welding.

B, welding stress: during aerial welding, still can produce welding stress, welding residual stress is solved by the hidden lino removal of subsequent step;

C, Cross Wind Force: during aerial welding, the aerial wind-force surface wind that compares is large, when aerial group to after completing, equipment upper-lower section has been formed as a whole, Cross Wind Force is mainly to Whole Equipment effect, and the shear stress of its Welded Joints is very little, then do not consider;

The solution of welding stress: in welding process, takes weld preheating, rational groove type, size, and strict control group, to quality, uses the welding technology measure such as little heat input, comprehensive above-mentioned measure, reduces welding stress;

Welding residual stress: eliminated by PWHT of stress relieving.

The requirement of post weld heat treatment is as follows:

1, mode of heating and heating plate, heat-insulation layer layout:

1) the every side of weld seam heat treatment width of heating weld seam is not less than 3 times of absorption tower wall thickness;

2) adopt absorption tower inwall one side to arrange mode of heating, need the crawler type far-infrared ceramic electric heating sheets arranging band iron-clad, heating face is of a size of 630 × 330mm, and width of heating is 330mm;

Adopt absorption tower outer wall one side to arrange mode of heating, need to arrange crawler type far-infrared ceramic electric heating sheets, heating face is of a size of 630 × 330mm, and width of heating is 330mm;

3) the two-sided layout mode of heating of the inside and outside wall in absorption tower, need to arrange crawler type far-infrared ceramic electric heating sheets, heating face is of a size of 630 × 330mm, and width of heating is 330mm;

4) arrangement of heating plate in welding process:

4.1) layout of preheating heating plate when absorption tower inwall welds: during the welding of absorption tower inwall, arrange crawler type far-infrared ceramic electric heating sheets at absorption tower outer wall, heating face is of a size of 520 × 430mm, and width of heating is 520mm; During inwall welding, outer wall heating plate electrified regulation always, within ensureing girth joint and both sides 100mm, temperature is under preheat temperature;

4.2) layout of preheating heating plate during back chipping: when absorption tower outer wall back chipping, arrange the crawler type far-infrared ceramic electric heating sheets of band iron-clad at absorption tower inwall, heating face is of a size of 520 × 430mm, and width of heating is 520mm; Preheating 100 DEG C during back chipping;

4.3) layout of preheating heating plate when outer wall welds: during the welding of absorption tower outer wall, arrange the crawler type far-infrared ceramic electric heating sheets of band iron-clad at absorption tower inwall, heating face is of a size of 520 × 430mm, and width of heating is 520mm; During outer wall welding, inwall heating plate electrified regulation always, within ensureing girth joint and both sides 100mm, temperature is under preheat temperature;

4.4) postwelding disappear hydrogen process time heating plate layout: postwelding disappear hydrogen process time, arrange crawler type far-infrared ceramic electric heating sheets at equipment outer wall, heating face is of a size of 520 × 430mm, and width of heating is 520mm; Disappear hydrogen process time, heating plate is electrified regulation always, and Insulation taked by inside and outside wall, and carries out after heat by welding process requirement and to disappear hydrogen process, ensures after-baking temperature and time.

4.5) layout of heating plate during PWHT of stress relieving: during PWHT of stress relieving, arrange crawler type far-infrared ceramic electric heating sheets at absorption tower outer wall, heating face is of a size of 630 × 330mm, and width of heating is 330mm; During post weld heat treatment, heating plate is electrified regulation always, and inside and outside wall all takes Insulation, and carries out PWHT of stress relieving by welding process requirement;

5) heat-insulation layer is inside and outside on absorption tower all lays, and applied thickness must not lower than 120mm; It is outside heating tape 1.5 times that heat-insulation layer lays width;

2, heat treatment point for measuring temperature is arranged:

Point for measuring temperature on absorption tower inside and outside wall respectively divide equally layout 4 point, inside and outside point for measuring temperature arranges difference 45 °;

Point for measuring temperature is fixedly taked: be welded on the inside and outside surface of weld seam by the core wire of absorption tower welding welding rod, thermocouple welding is carried out thermometric on core wire;

3, Technology for Heating Processing:

1) after heat disappears hydrogen treatment process:

Heating-up temperature: the after heat hydrogen process heating-up temperature that disappears is 325 ± 25 DEG C;

Temperature retention time: as the insulation time started when being heated to 325 DEG C, temperature retention time is 0.5 hour ~ 1.0 hours, between soak, holding temperature must not exceed ± and 25 DEG C;

Cooling velocity: during cooling, must not remove heat-insulation layer, Slow cooling under the protection of heat-insulation layer;

2) hidden lino removal technique:

Heating-up temperature: hidden lino removal heating-up temperature is 575 ± 25 DEG C;

Firing rate: when heating-up temperature is more than 300 DEG C, firing rate≤50 DEG C/hr;

Temperature retention time: as the insulation time started when being heated to 575 DEG C, temperature retention time >=4 hour, between soak, holding temperature must not exceed ± and 25 DEG C;

Cooling velocity: more than 300 DEG C when cooling, cooling velocity≤65 DEG C/hr, when being cooled to below 300 DEG C, must not remove heat-insulation layer, Slow cooling under the protection of heat-insulation layer.

In the area that operating environment is severe, adopt this method in practice of construction, satisfactorily resolved the requirement of construction speed and construction quality.

Accompanying drawing explanation

Fig. 1 is stress analysis schematic diagram of the present invention, and in figure, arrow is the compression under the Action of Gravity Field of absorption tower down, is tensile stress towards upward arrow;

Fig. 2 is groove type schematic diagram, in figure:

δ

α

β

b

P

H

Unit

98

40°+5°

1°+4°

2 +1

2 ±1

30

mm

Fig. 3 is that welder arranges schematic diagram; This figure is to overlook the welding of Lai Kan absorption tower, visual angle, and in figure, circle is the cylindrical shell on absorption tower, and arrow direction is weld job direction;

Fig. 4 a and 4b is that under outer wall one side arranges mode of heating, schematic diagram arranged by heating plate, and Fig. 4 a is the sectional view of Fig. 4 b;

Fig. 5 a and 5b is that under the two-sided layout mode of heating of inside and outside wall, schematic diagram arranged by heating plate, and Fig. 5 a is the sectional view of Fig. 5 b;

Fig. 6 a is the stationary state schematic diagram of heating plate at absorption tower inwall;

Fig. 6 b is the stationary state schematic diagram of heating plate at absorption tower outer wall;

Fig. 7 a is that point for measuring temperature arranges schematic diagram at equipment inside and outside wall;

Fig. 7 b is the temperature measurement structure schematic diagram of point for measuring temperature;

In figure, the cylindrical shell 2 on heating plate 1, absorption tower, bracing ring 3, bolt 4, thermocouple 5, diameter 4mm welding rod 6.

Detailed description of the invention

Below in conjunction with specific embodiment, the present invention will be described:

In this example, absorb tower height 79.527m, the heavy 686.9t of void tower, this absorption tower external diameter is 3696mm, and tower wall thickness is 98mm, and main material is SA203GrD (top cylindrical shell, end socket) and SA537CL1 (lower cylinder, end socket).Following difficulty is run into when practice of construction:

1, calculate according to lifting, integral hoisting is in place, must adopt the large-scale crane of more than 1600T, and when installing, domestic market there is no this type of crane; Adopt gate type hydraulic lifting device or mast lifting, occupied ground is too large, is subject to construction site and construction period restriction and cannot implements.

2, because SA203GrD steel is used for-60 DEG C of operating temperatures, conventional welding method cannot ensure the low-temperature flexibility of welding point.

To the stress analysis of aerial welding before weldment:

Aloft during welding, the impact of equipment gravity should be taken into full account.

A, equipment gravity

When aerial group pair, absorption tower gravity vertically downward, acts on welding point and is mainly compression, as Fig. 1.During welding, the tensile stress produced when can offset part welding.

B, welding stress

During aerial welding, still can produce welding stress, welding residual stress is solved by the hidden lino removal of subsequent step;

C, Cross Wind Force

During aerial welding, the aerial wind-force surface wind that compares is large, and when aerial group to after completing, equipment upper-lower section has been formed as a whole, and Cross Wind Force is mainly to Whole Equipment effect, and the shear stress of its Welded Joints is very little, does not consider.

The solution of welding stress

In welding process, take weld preheating, rational groove type, size, strict control group, to quality, uses the welding technology measure such as little heat input, comprehensive above-mentioned measure, reduces welding stress.

Welding residual stress, can be eliminated by PWHT of stress relieving;

3-2) welding procedure program

Welds prepares:

Welding material adopts the wlding of the trade mark identical with manufactory, same manufacturer production.According to related data, SA203GrD steel can select domestic W907Ni, W107 welding rod or Japan to produce NB-3N welding rod; SA537CL1 steel can select W607 welding rod.

Welding rod main chemical contrasts:

Type of electrode

C％

Mn％

Si％

P％

S％

Ni％

Mo％

W907Ni

≤0.12

≤1.25

≤0.6

≤0.035

≤0.035

3.0-3.75

-

W107

≤0.05

0.5-1.0

≤0.3

≤0.035

≤0.035

3.1-3.7

～0.3

NB-3N

0.03

0.94

0.33

0.009

0.010

3.2

0.27

W607

≤0.07

1.2-1.7

≤0.5

≤0.035

≤0.035

0.6-1.0

-

Welding rod welding joint mechanical property and purposes contrast

Must strictly toast before welding rod uses, welding rod baking specification sees the following form:

The granting of welding material and recovery

Carry electrode dryer (in cylinder, temperature is heated to 70-80 DEG C) and receive welding material.Welding material should reclaim and repeat baking, repeats baking and is no more than secondary.

Welding material manages: store: temperature >=5 DEG C, relative humidity≤60%.Baking: normal temperature time >=4 hours, repeat toast number of times≤2 hour.

SA203-GrD, SA537CL1 steel weldability analysis:

SA203GrD welded steel performance:

SA203GrD welded steel better performances, belongs to low alloy ferritic type low-temperature steel.

Its chemical analysis is as follows:

C	Mn	Si	S	P	Ni
						≤0.2％	≤0.8％	0.15-0.40％	≤0.035％	≤0.035％	3.25-3.75％

Notably should prevent cold crack during welding, and contain the Ni of 3.5% due to SA203GrD steel, be also noted that during welding and prevent fire check;

Due to the absorption tower equipment wall thickness thicker (98mm) of this example, welding point simultaneously rigidity is comparatively large, answers preheating 130 ~ 150 DEG C before weldering, and postwelding carries out after heat immediately and to disappear hydrogen process; Hidden lino removal is carried out after nondestructive inspection is qualified;

During low-temperature steel welding, must ensure the low-temperature impact toughness of welding point, under the prerequisite effectively preventing weld defect, select less weld heat input as much as possible, weld heat input is no more than 20000J/cm.Adopt multi-pass welding, during each pass weld, quick non-oscillatory maneuver should be adopted, improve plasticity and the toughness of low-temperature steel welding point.

SA537CL1 welded steel performance

SA537CL1 steel Chinese full name be pressure vessel with through heat treated carbon manganese silicon steel plate, belong to low alloy ferritic type low-temperature steel.

Its chemical analysis is as follows:

C％

Si％

Mn％

P％

S％

Cu％

Ni％

Cr％

Mo％

≤0.24

0.15-.05

1.0-1.6

≤0.035

≤0.035

≤0.35

≤0.25

≤0.25

≤0.08

Notably cold crack must be prevented during welding.Due to absorption tower equipment wall thickness thicker (98mm), welding point simultaneously rigidity is comparatively large, should consider preheating 150-200 DEG C before weldering, and postwelding carries out after heat immediately and to disappear hydrogen process, carries out hidden lino removal after nondestructive inspection is qualified.

During low-temperature steel welding, must ensure the low-temperature impact toughness of welding point, under the prerequisite effectively preventing weld defect, select less weld heat input as much as possible, weld heat input is no more than 20000J/cm.Adopt multi-pass welding, during each pass weld, quick non-oscillatory maneuver should be adopted, improve plasticity and the toughness of low-temperature steel welding point.

Control Welding Process

Welding method: the aerial welding in absorption tower adopts manual electric arc welding method.

1, welds prepares

1.1 groove type

Groove type is as Fig. 2, and large V-butt is positioned at equipment outer wall, and little V-butt is positioned at equipment inner wall, first welding equipment outer wall, after equipment inner wall back chipping, then welding equipment inwall.

1.2 groups pairs

Group carries out magnetic particle testing to front reply groove and neighbouring mother metal, the defects such as groove and mother metal surface flawless, pipe, groove damage and burr.

Group to front should be clean by the foreign bodies removal such as oil, rust, dirt of groove face and the inside and outside wall of neighbouring mother metal 50mm scope, until send metallic luster.

Should accomplish that inwall flushes, and strictly controls unfitness of butt joint during group pair, its unfitness of butt joint should be no more than 3mm.

1.3 spot welding

The wlding that tack welding uses must be consistent with the wlding used when formally welding.

Tack welding welding procedure is identical with the welding procedure of formally welding, and carries out preheating 130 ~ 150 DEG C before weldering by formal welding requirements.

Tack welding quantity is determined according to device diameters, and often a bit, tack welding length is no less than 50mm to distance 300mm tack welding, throat depth 3 ~ 5mm, prevents tack welding weld cracking.

2, welding process

2.1 striking

Striking should be carried out in groove face, or adopts run-on tab striking, strictly forbids, in mother metal surface striking, causing electric arc to scratch.

2.2 receive arc and joint

Slowly should mention welding gun when 2.2.1 receiving arc, note filling up arc crater, prevent crater crack, shrinkage cavity (arc crater pore) defect, find that crater crack and shrinkage cavity defect should be removed immediately.

2.2.2 should be quick during joint, in 2 ~ 3 seconds, more should finish changing welding rod, prevent from not connecting or joint too high.

2.3 preheating

2.3.1 pre-heating mean adopts electric infrared heating mode.

2.3.2 the scope of preheating should comprise the width of each 300mm in both sides, welding point center, and temperature measuring point should be selected to be positioned at 50mm place, weld seam both sides, will remain the monitoring to preheat temperature in welding process.

2.3.3 preheat temperature is 130 ~ 150 DEG C.

2.4 welders arrange (as Fig. 3)

Adopt 6 symmetrical welding manners of manual electric arc welding work, the speed of welding that basic maintenance is identical.

2.5 layer welding

Root layer throat depth is not less than 3mm, and is not more than 5mm; Root layer weld seam adopts little weave bead welding "the" shape manipulation of electrode.

2.6 packed layer welding

Packed layer throat depth should not be greater than 4mm;

When 2.6.2 filling ground floor welding, attentional manipulation weld heat input, prevents the arc burn of root layer.

When weldering filled by thick-walled pipe, adopt multi-pass welding, adopt quick straight line dead beat to move manipulation of electrode; During multi-pass welding, interlayer temperature is at 130 ~ 150 DEG C;

2.7 capping layer welding

Cover welding adopts multi-pass welding, adopts quick straight line dead beat to move manipulation of electrode;

2.8 back root cleaning, welding

Fillet in normal shear carries out back root cleaning process after being soldered to 30mm; Back root cleaning adopts carbon arc air gouging, uses electric angle grinder thoroughly to remove oxide layer and carburized layer, until expose metallic luster completely.

Ground floor weld seam welding after back chipping, adopts diameter to be the welding of φ 3.2mm welding rod.

2.9 interrupt welding

Due to absorption tower device diameters large (internal diameter 3500mm), wall thickness 98mm, one-pass weld length reaches 11 meters long, and manual electric arc welding approximately needs welding 33 layers, can not once be soldered;

When interrupting welding, postheating must be taked, after heat disappears the measure that hydrogen process etc. prevents crackle from producing.

After heat disappears hydrogen treatment process: heating-up temperature 300 ~ 350 DEG C, is incubated 0.5 ~ 1 hour, Slow cooling.

When again welding, confirm flawless, again could weld after preheating 130 ~ 150 DEG C.

2.10 welding surroundings

Windproof:

A. equipment welding region uses deep bead and the Polypropylence Sheet closed wind-proof that keeps out the wind.

B. the upper and lower 1.5 meters of settings of the inherent welding region of equipment are kept out the wind layer, avoid stack effect.

C. wind speed is greater than 8m/s, forbids to weld.

Rainproof:

A. equipment welding region uses Polypropylence Sheet covering rainproof.

B. when rainy day and relative humidity are greater than 80%, reliable safeguard procedures should be taked, otherwise forbid welding.

3, postwelding

3.1 after-baking

3.1.1 postwelding takes slow cooling measure, and carries out after heat immediately and to disappear hydrogen process.

The after heat hydrogen process mode of heating that disappears adopts electric infrared heating mode.

After heat disappears hydrogen treatment process: heating-up temperature 300 ~ 400 DEG C, is incubated 0.5 ~ 1.0 hour, Slow cooling.

3.2 postwelding cleaning and finishings

After welding job completes, immediately the welding slag of face of weld must be cleaned out, and remove the splash on weld seam and neighbouring surface, make the foreign material of wire brushing joint surface.

Postwelding uses electric angle grinder butt welded seam surface to polish, and makes face of weld rounding off, prevents that welding stress is concentrated.

Tower body inner surface weld seam answers equating.

3.3 postwelding inspections

3.3.1 appearance test

Postwelding, welder should carry out visual examination by butt welding mouth immediately, and performs inspection record.

3.3.2 nondestructiving inspecting test

After weld seam is soldered, weld seam surfaces externally and internally carries out magnetic powder inspection; Weld seam carries out 100% radiographic inspection; Carry out 100% ultrasonic examination check.

3.4 post weld heat treatment

In this construction, need the situation of heat-treating:

After fillet in normal shear welding 30mm before back chipping process, carry out after heat immediately and to disappear hydrogen process;

During any interruption welding, after heat all should be carried out immediately and to disappear hydrogen process;

Carry out after heat after weld seam has all welded immediately to disappear hydrogen process;

The process that eliminates stress is carried out after weld seam nondestructive inspection completes;

Mode of heating and heating plate, heat-insulation layer layout

1) the every side of weld seam heat treatment width of heating weld seam must not be less than 3 times of mother metal thickness, and namely width of heating is that 600mm is wide.

2) adopt equipment inner wall one side to arrange mode of heating, need layout 36 to be with the crawler type far-infrared ceramic electric heating sheets of iron-clad, heating face is of a size of 630 × 330mm, and width of heating is 330mm.Employing equipment outer wall one side arranges mode of heating, and need layout 36 crawler type far-infrared ceramic electric heating sheets, heating face is of a size of 630 × 330mm, and width of heating is 330mm.Heating plate layout such as Fig. 4 a and 4b:(4a is the sectional view of 4b);

3) the two-sided layout mode of heating of the inside and outside wall of equipment, need layout 72 crawler type far-infrared ceramic electric heating sheets, heating face is of a size of 630 × 330mm, and width of heating is 330mm.Heating plate is arranged as Fig. 5 a and 5b (5a is the sectional view of 5b);

4) select heating plate arrangement, job site electricity consumption general arrangement should be taken into full account.

5) heating plate is fixing: heating plate fixing as Fig. 6 a at equipment inner wall, and what heating plate was arranged at equipment outer wall fixes as Fig. 6 b:

6) arrangement of heating plate in welding process

6.1) layout of preheating heating plate when equipment inner wall welds

During equipment inner wall welding, arrange crawler type far-infrared ceramic electric heating sheets at equipment outer wall, heating face is of a size of 520 × 430mm, and width of heating is 520mm, about needs 22.During inwall welding, outer wall heating plate electrified regulation always, within ensureing girth joint and both sides 100mm, temperature is under preheat temperature.

6.2) layout of preheating heating plate during back chipping

When equipment outer wall back chipping, arrange the crawler type far-infrared ceramic electric heating sheets of band iron-clad at equipment inner wall, heating face is of a size of 520 × 430mm, and width of heating is 520mm, about needs 22.Preheating 100 DEG C during back chipping.

6.3) layout of preheating heating plate when outer wall welds

During the welding of equipment outer wall, arrange the crawler type far-infrared ceramic electric heating sheets of band iron-clad at equipment inner wall, heating face is of a size of 520 × 430mm, and width of heating is 520mm, about needs 22.During outer wall welding, inwall heating plate electrified regulation always, within ensureing girth joint and both sides 100mm, temperature is under preheat temperature.

6.4) postwelding disappear hydrogen process time heating plate layout

Postwelding disappear hydrogen process time, arrange crawler type far-infrared ceramic electric heating sheets at equipment outer wall, heating face is of a size of 520 × 430mm, and width of heating is 520mm, about needs 22.Disappear hydrogen process time, heating plate is electrified regulation always, and Insulation taked by inside and outside wall, and carries out after heat by welding process requirement and to disappear hydrogen process, ensures after-baking temperature and time.

6.5) layout of heating plate during PWHT of stress relieving

During PWHT of stress relieving, crawler type far-infrared ceramic electric heating sheets is arranged at equipment outer wall, heating face is of a size of 630 × 330mm, width of heating is 330mm, about need 36 (when this is for employing outer wall heated on one side mode, need 36 heating plates according to inwall heated on one side mode, according to inside and outside Bilateral heating mode, then need 72 heating plates).During post weld heat treatment, heating plate is electrified regulation always, and inside and outside wall all takes Insulation, and carries out PWHT of stress relieving by welding process requirement, ensures PWHT of stress relieving heating-up temperature, firing rate, temperature retention time and cooling velocity.

7) heat-insulation layer all lays equipment is inside and outside, and applied thickness must not lower than 120mm.It is outside heating tape 1.5 times that heat-insulation layer lays width, i.e. every side 450mm, altogether 1500mm.

Heat treatment point for measuring temperature is arranged

Point for measuring temperature respectively divides equally layout 4 point at equipment inside and outside wall, and inside and outside point for measuring temperature arranges difference 45 °, as Fig. 7 a.Point for measuring temperature is fixedly taked: be welded on by the core wire of barrel soldering welding rod on weld seam surfaces externally and internally, thermocouple welding is carried out thermometric on core wire, as Fig. 7 b.

Technology for Heating Processing

1) after heat disappears hydrogen treatment process

Heating-up temperature: the after heat hydrogen process heating-up temperature that disappears is 325 ± 25 DEG C.

Firing rate: after heat disappear hydrogen process firing rate control can control.

Temperature retention time: as the insulation time started when being heated to 325 DEG C, temperature retention time is 0.5-1.0 hour, and between soak, holding temperature must not exceed tolerance.

Cooling velocity: during cooling, must not remove heat-insulation layer, Slow cooling under the protection of heat-insulation layer.

2) hidden lino removal technique

Heating-up temperature: hidden lino removal heating-up temperature is 575 ± 25 DEG C.

Firing rate: can not control when heating-up temperature is below 300 DEG C; When more than 300 DEG C, firing rate≤50 DEG C/hr.

Temperature retention time: as the insulation time started when being heated to 575 DEG C, temperature retention time >=4 hour, between soak, holding temperature must not exceed tolerance.

Cooling velocity: more than 300 DEG C when cooling, cooling velocity≤65 DEG C/hr, when being cooled to below 300 DEG C, must not remove heat-insulation layer, Slow cooling under the protection of heat-insulation layer.

Adopt this method, the effect obtained in this example is as follows:

1, the construction period

According to the scheme of the horizontal welding in scene, the man-hour of preresearch estimates is 30-35 working day; Adopt be 20 ~ 25 working days actual hours needed for our rule.

2, economic benefit

If adopt the scheme of on-the-spot horizontal welding, use crane: main loop wheel machine >=1600T, auxiliary loop wheel machine 500T, tower body site welding technology place needs cure process, Standing position of a crane needs cure process, and due to the increase of crane tonnage, the advance and retreat field of large-scale facility is taken and used machine-team to take increasing; And adopt this method and save part place sclerosis expense, particularly save the usage charges of crane.

3, construction quality

Due to field condition and the stress influence of the vertical aerial welding in scene, so adopt the method for horizontal welding to be difficult to meet the welding quality requirement of pressure vessel at all, and after this method, through construction and detection, quality requirement can be met completely.

Claims (3)

1. the welding method on absorption tower, step comprises: one) welds prepares; Two) weld; Three) post weld heat treatment; Four) postwelding cleaning, finishing and postwelding inspection; It is characterized in that:

Described step one) job requirements comprise:

1) groove type is set:

Large V-butt is positioned at absorption tower outer wall, and little V-butt is positioned at absorption tower inwall,

The groove of absorption tower inwall is set to little V-butt, and the groove of absorption tower outer wall is set to large V-butt;

For in the adjacent two sections on absorption tower:

Spacing b between top weldment and bottom weldment is 2mm ~ 3mm; Between at the bottom of the slope of little V-butt and at the bottom of large V-butt slope, spacing P is 1mm ~ 3mm; For little V-butt, the dark H in slope is 28mm ~ 32mm;

For little V-butt, the opening angle α between at the bottom of the Po Bi of top weldment and slope is 40 ° ~ 45 °, and the opening angle β between at the bottom of the Po Bi of bottom weldment and slope is 1 ° ~ 5 °; For large V-butt, the opening angle α between at the bottom of the Po Bi of top weldment and slope is 40 ° ~ 45 °, and the opening angle β between at the bottom of the Po Bi of bottom weldment and slope is 1 ° ~ 5 °;

First weld absorption tower outer wall, after the inwall back chipping of absorption tower, then weld absorption tower inwall;

2) organize right:

Set up scaffold, segmental hoisting, aloft welding are adopted to the tower body on absorption tower; Group to before should by cleaning groove face and groove near the inside and outside wall of weldment 45mm ~ 50mm scope, until send metallic luster; Should accomplish that the unfitness of butt joint of inwall is no more than 3mm during group pair;

3) tack welding:

The wlding that tack welding uses must be consistent with the wlding used when formally welding; Before tack welding, butt-welding fitting is preheated to 130 DEG C ~ 150 DEG C; The number of welds of tack welding is determined according to absorption tower diameter, and at weldment surface often distance 280mm ~ 320mm tack welding a bit, the fusion length of tack welding is no less than 50mm, throat depth 3 ~ 5mm;

Described step 2) job requirements comprise:

1) striking

Striking should be carried out in groove face, or adopts run-on tab striking;

2) arc and joint is received

2.1) slowly should mention welding gun when receiving arc, note filling up arc crater, find that crater crack and shrinkage cavity defect should be removed immediately;

2.2) change welding rod when welding should control to complete in 2 ~ 3 seconds;

3) preheating:

The scope of preheating comprises the width of each 270mm ~ 330mm in both sides, welding point center; Temperature measuring point should be selected to be positioned at 48mm ~ 52mm place, weld seam both sides, will remain the monitoring to preheat temperature in welding process; Preheat temperature is 130 DEG C ~ 150 DEG C;

4) welder arranges:

Manual arc welder mode in a center of symmetry is adopted to distribute welding, the speed of welding be consistent and operative orientation; Spacing between adjacent welder is 550mm ~ 650mm;

5) root layer welding:

5.1) root layer throat depth is not less than 3mm, and is not more than 5mm;

5.2) root layer weld seam adopts weave bead welding "the" shape manipulation of electrode;

5.3) root layer weld seam should carry out visual examination and penetrant inspection after being soldered immediately, finds that defect should be removed immediately;

6) packed layer welding:

6.1) packed layer throat depth should not be greater than 4mm;

6.2), when filling ground floor welding, attentional manipulation weld heat input, prevents the arc burn of root layer;

6.3) when filling weldering, adopt multi-pass welding, adopt straight line not swing manipulation of electrode;

6.4) multilayer fill weldering time, every layer be soldered after should check face of weld quality immediately, find defect should remove immediately, the welding of lower floor's weld seam can be carried out;

6.5), during multilayer welding, the strict interlayer temperature that controls is at 130 DEG C ~ 150 DEG C;

7) capping layer welding:

7.1) cover welding adopts multi-pass welding, adopts straight line not swing manipulation of electrode, should fill up weld seam;

7.2) cosmetic welding scoops out attentional manipulation weld heat input, prevents face of weld from producing undercut defect;

7.3) cover welding should be specifically noted that slow blow-out, fills up arc crater;

7.4), after weld seam is soldered, require polishing, weld seam rounding off, absorption tower inner wall surface weld seam answers equating, and crator, welding slag should be removed totally;

8) back root cleaning, welding:

8.1) fillet in normal shear carries out back root cleaning process after being soldered to 30mm;

8.2) back root cleaning will thoroughly remove oxide layer and carburized layer, until expose metallic luster completely;

8.3), after back chipping process, weldquality is checked;

8.4) face of weld after back chipping is detected a flaw, can weld after passed examination;

9) welding is interrupted:

Postheating when weldment that is large for workload, that can not once be soldered interrupts welding, after heat disappear hydrogen treatment measures; The disappear requirement of hydrogen process of after heat heats 300 DEG C ~ 350 DEG C to welding region, is incubated 0.5 hour ~ 1 hour, then Slow cooling; When again welding, confirm flawless, again could weld after preheating 130 DEG C ~ 150 DEG C;

10) welding surroundings

10.1) windproof:

A. welding region uses deep bead and the Polypropylence Sheet closed wind-proof that keeps out the wind;

B. upper and lower 1.3 ~ 1.8 meters of settings of the inherent welding region in absorption tower are kept out the wind layer;

C., time wind speed is greater than 8m/s, forbid to weld;

10.2) rainproof:

A. welding region uses Polypropylence Sheet covering rainproof;

B. when rainy day and relative humidity are greater than 80%, reliable safeguard procedures should be taked, otherwise forbid welding;

Described step 3) job requirements comprise:

Postwelding takes slow cooling measure, and carries out after heat immediately and to disappear hydrogen process; The after heat hydrogen process mode of heating that disappears adopts electric infrared heating mode; The after heat hydrogen treatment process requirement that disappears is, welding region heating 300 ~ 400 DEG C, is incubated 0.5 ~ 1.0 hour, Slow cooling.

2. the welding method on absorption tower according to claim 1, is characterized in that first to carry out stress analysis in this welding method:

Aloft during welding, the impact of absorption tower gravity should be taken into full account;

A, absorption tower gravity: during aerial group pair, absorption tower gravity vertically downward, acts on welding point and is mainly compression, during welding, the tensile stress produced when can offset part welding;

B, welding stress: during aerial welding, still can produce welding stress, welding residual stress is solved by the hidden lino removal of subsequent step;

C, Cross Wind Force: during aerial welding, the aerial wind-force surface wind that compares is large, when aerial group to after completing, absorption tower upper-lower section has been formed as a whole, Cross Wind Force is mainly to absorption tower mass action, and the shear stress of its Welded Joints is very little, then do not consider;

The solution of welding stress: in welding process, takes weld preheating, rational groove type, size, and strict control group, to quality, uses little heat input welding technology measure, comprehensive above-mentioned measure, reduces welding stress;

Welding residual stress: eliminated by PWHT of stress relieving.

3. the welding method on absorption tower according to claim 1, is characterized in that the requirement of post weld heat treatment is as follows:

One, mode of heating and heating plate, heat-insulation layer layout:

1) the every side of weld seam heat treatment width of heating weld seam is not less than 3 times of absorption tower wall thickness;

2) adopt absorption tower inwall one side to arrange mode of heating, need the crawler type far-infrared ceramic electric heating sheets arranging band iron-clad, heating face is of a size of 630 × 330mm, and width of heating is 330mm;

Adopt absorption tower outer wall one side to arrange mode of heating, need to arrange crawler type far-infrared ceramic electric heating sheets, heating face is of a size of 630 × 330mm, and width of heating is 330mm;

3) the two-sided layout mode of heating of the inside and outside wall in absorption tower, need to arrange crawler type far-infrared ceramic electric heating sheets, heating face is of a size of 630 × 330mm, and width of heating is 330mm;

4) arrangement of heating plate in welding process:

4.1) layout of preheating heating plate when absorption tower inwall welds: during the welding of absorption tower inwall, arrange crawler type far-infrared ceramic electric heating sheets at absorption tower outer wall, heating face is of a size of 520 × 430mm, and width of heating is 520mm; During inwall welding, outer wall heating plate electrified regulation always, within ensureing girth joint and both sides 100mm, temperature is under preheat temperature;

4.2) layout of preheating heating plate during back chipping: when absorption tower outer wall back chipping, arrange the crawler type far-infrared ceramic electric heating sheets of band iron-clad at absorption tower inwall, heating face is of a size of 520 × 430mm, and width of heating is 520mm; Preheating 100 DEG C during back chipping;

4.3) layout of preheating heating plate when outer wall welds: during the welding of absorption tower outer wall, arrange the crawler type far-infrared ceramic electric heating sheets of band iron-clad at absorption tower inwall, heating face is of a size of 520 × 430mm, and width of heating is 520mm; During outer wall welding, inwall heating plate electrified regulation always, within ensureing girth joint and both sides 100mm, temperature is under preheat temperature;

4.4) postwelding disappear hydrogen process time heating plate layout: postwelding disappear hydrogen process time, arrange crawler type far-infrared ceramic electric heating sheets at absorption tower outer wall, heating face is of a size of 520 × 430mm, and width of heating is 520mm; Disappear hydrogen process time, heating plate is electrified regulation always, and Insulation taked by inside and outside wall, and carries out after heat by welding process requirement and to disappear hydrogen process, ensures after-baking temperature and time;

4.5) layout of heating plate during PWHT of stress relieving: during PWHT of stress relieving, arrange crawler type far-infrared ceramic electric heating sheets at absorption tower outer wall, heating face is of a size of 630 × 330mm, and width of heating is 330mm; During post weld heat treatment, heating plate is electrified regulation always, and inside and outside wall all takes Insulation, and carries out PWHT of stress relieving by welding process requirement;

5) heat-insulation layer is inside and outside on absorption tower all lays, and applied thickness must not lower than 120mm; It is outside heating tape 1.5 times that heat-insulation layer lays width;

Two, heat treatment point for measuring temperature is arranged:

Point for measuring temperature on absorption tower inside and outside wall respectively divide equally layout 4 point, inside and outside point for measuring temperature arranges difference 45 °;

Point for measuring temperature is fixedly taked: be welded on the inside and outside surface of weld seam by the core wire of absorption tower welding welding rod, thermocouple welding is carried out thermometric on core wire;

Three, Technology for Heating Processing:

1) after heat disappears hydrogen treatment process:

Heating-up temperature: the after heat hydrogen process heating-up temperature that disappears is 325 ± 25 DEG C;

Temperature retention time: as the insulation time started when being heated to 325 DEG C, temperature retention time is 0.5 hour ~ 1.0 hours, between soak, holding temperature must not exceed ± and 25 DEG C;

Cooling velocity: during cooling, must not remove heat-insulation layer, Slow cooling under the protection of heat-insulation layer;

2) hidden lino removal technique:

Heating-up temperature: hidden lino removal heating-up temperature is 575 ± 25 DEG C;

Firing rate: when heating-up temperature is more than 300 DEG C, firing rate≤50 DEG C/hr;

Temperature retention time: as the insulation time started when being heated to 575 DEG C, temperature retention time >=4 hour, between soak, holding temperature must not exceed ± and 25 DEG C;

Cooling velocity: more than 300 DEG C when cooling, cooling velocity≤65 DEG C/hr, when being cooled to below 300 DEG C, must not remove heat-insulation layer, Slow cooling under the protection of heat-insulation layer.