CN201225491Y - Oil delivery pipeline on-line restoring reinforced structure - Google Patents

Abstract

The utility model relates to a petroleum pipeline on-line repair welding structure in long-time operated pipeline modification works, and relates to the technical field of welding and pipeline systems. The petroleum pipeline on-line repair welding structure is characterized in that the minimum distance kept between the surface corrosion of adjacent reinforced plates is 25 mm; and the minimum distance between a reinforced plate and a girth weld and between the reinforced plate and a spiral weld is 50 mm; and the minimum distance between repair welding adjacent point corrosion pits, between the point corrosion pits and the adjacent surface corrosion, between the point corrosion pits and the girth weld and between the point corrosion pits and the spiral weld is 25 mm. The on-line repair welding structure of the utility model has favorable bearing weld, long endurance life and reasonability, primely solves the problem existing in the prior petroleum pipeline on-line repair welding technology.

Description

On-line repairing-reinforcing structure for oil pipelines

Technical field

The utility model is the on-line repairing-reinforcing structure for oil pipelines that moves old for many years pipeline modification engineering.Relate to welding and pipe-line system technical field.

Background technique

The reparation of body defective is an important process content moving old for many years pipeline modification engineering.The repair method of oil and gas pipeline body defective is more, according to the type and the body degree of injury of defective, can select the recovery techniques such as composite material reinforcement of sleeve, anchor clamps, repair welding, benefit plate or replace tubes and rising in recent years.Carrying out recovery technique when selecting, the validity of recovery technique, Security, could directly use and Economy is the four big factors that consider successively when selecting.Though sleeve, anchor clamps and composite material reparation have technical advantage separately, sleeve and anchor clamps need customized, and some domestic can not production also needs external import (as epoxy sleeve, anchor clamps, ClockSpring sleeve etc.).More pipe body corrosion defective (only serious corrosion and corrosion area are more concentrated) appears for state's interior conduit, because sleeve, anchor clamps or the ClockSpring sleeve is customized, the haul-cycle time is long, and expense is higher, and in most cases these recovery techniques are uneconomical suitable.

China's northeast pipeline is built in the seventies in 20th century mostly, and in the running that reaches surplus in the of 30 year, in various degree aging appearred in pipeline at present, has been found that and repaired about 30,000 place's corrosion defaults, and the 70000 places corrosion of also having an appointment is repaired as yet.Increasing year by year of corrosion default and CRACKING ACCIDENT indicating that the service requirement of east pipeline is descending, and the military service function is being degenerated gradually.So we are faced with following urgency problem to be solved: at first, domestic do not have a body defect repair standard that site operation can foundation; To the reparation of (comprising weld defect) of body defective, how to act by rule of thumb, lack necessary theoretical foundation and guidance, the risk of reparation and difficult quality are held; Secondly, the application of the novel in recent years repair materials of international pipeline industry, recovery technique has improved quality and level that body is repaired greatly, and this and the domestic old restorative procedure of using till today in decades form sharp contrast.For the overall reparation level that improves state's interior tube body defective, press for the correlative study work of carrying out novel recovery technique.

Show through finding on-the-spot to pipeline and each dimension repairing personnel of oil/gas pipe reason place service technique commonly used, for many years for the like this numerous corrosion default of east pipeline, using also is at most that the most timely and effective for repairing technology is to carry out the repair welding and the reparation of benefit plate of etch pit or face corrosion.Trace it to its cause main still drawing materials and easy construction.For mending plate, can directly on the discarded pipeline section of pipeline, draw materials, and processing also mainly is cutting and chamfering.Welding consumables is on-the-spot standing, and welding procedure adopts the dimension repairing personnel experience practice for many years.Easy, the easy row of whole repair process is so these recovery technique frequencies of utilization are very high.

Although pipe body corrosion hole, face corrosion repair welding technology have been used for many years on the pipeline at home, but to technical requirementss such as the Applicable scope of repair welding technology, welding procedures, (corrosion depth is carried out Welding Repair between the etch pit of 2.0～2.5mm still to rest on the accumulation of spot repair experience.Corrosion depth greater than the face corrosion of 2mm, takes to mend the plate reparation more than or equal to the etch pit of 2.5mm and corrosion depth).Whether these posterior infromations are reasonable, whether still have bigger safety allowance, and take what kind of welding procedure and welding technique to guarantee the quality and the safety of welding, need carry out theoretic discussion and at the welding procedure test research of east pipeline 16Mn tubing.

Repair corrosion default for mending plate, carried out more theory and experimental study abroad.U.S. Edison institute of welding had once carried out the bulge test that Leak hole is mended plate, and whole seven samples all occur destroying on the axial angle weld seam that the benefit plate is connected with body.Analysis result shows, fillet weld exists bigger inherent strain to concentrate, and this makes fillet weld pressure-bearing deficiency, and shortens fatigue life.Theory analysis shows that welding procedure is concentrated with the unreasonable bigger stress of fillet weld appearance that all can cause of mending board size.Repairs but mend plate for the scene both at home and abroad at present, experimentally maximumly mend board size restriction (mend board diameter should less than 400mm) and be theoretically unsound, and welding method also is confined to traditional manual electric arc welding mode, do not have can foundation welding procedure specification.Concentrate the influence of diagonal angle weld strength in order to reduce stress, need be on stress analysis, weld properties and metallurgical analysis equal angles comprehensive study basis, the maximum and the minimum dimension restriction of developing the rational welding method and mending plate.

The model utility content

The purpose of this utility model is that the old for many years pipeline modification engineering of a kind of operation of design weld seam pressure-bearing is sufficient, fatigue life is long, rational on-line repairing-reinforcing structure for oil pipelines.

The utility model is in repair welding, mends on the basis of plate, to being applicable to the renovation reinforced structure of welding technique under various pipeline materials and the operating conditions.

Common renovation reinforced structure is:

For the corrosion default diameter between between 68～352mm and the mother metal residual wall thickness be more than the 4.8mm or unmeasured corrosion of least residue wall thickness, adopt to mend the renovation reinforced structure of plate, the material of mending plate and wall thickness are with identical by the welded tube road; Mend plate and cover corrosion default, divide root bead, three layers of weldering of filling and block to be connected with low-hydrogen electrode mending between panel edges and the pipeline; The back layer is welded on when the anterior layer temperature is lower than 150 ℃ and carries out, and does not have the welding slag between every layer of welding bead.

Is that to be not more than 20mm and mother metal least residue wall thickness be that pitting corrosion hole more than the 4.8mm directly divides one to three layer of repair welding to fill up with low-hydrogen electrode for face corrosion more than the 4.8mm or diameter for diameter less than 68mm and mother metal least residue wall thickness; Repeatedly fill up welding if desired, the weld metal temperature of each repair welding is below 150 ℃, and do not have welding slag between the weld seam of repair welding.

When corrosion default more for a long time, in order to guarantee the reinforcement quality, between the face of mending plate and adjacent repair welding corrodes, and circumferential weld and spiral weld between keep certain distance, minimum range between adjacent two stiffening plates should be got the higher value of 1/2 (d1+d2) and 100mm, and d1, d2 are respectively adjacent two corrosion default diameters.

Through a large amount of tests, only also be nowhere near, sometimes or even not all right at all by the said structure reinforcement.Therefore the present invention is sufficient to strengthening structure proposition weld seam pressure-bearing, fatigue life is long, rational technological scheme:

The minimum range that keeps between the face corrosion of adjacent repair welding is 25mm; The minimum range of mending plate and circumferential weld and spiral weld is 50mm;

Carry out between the consecutive points etch pit of Welding Repair, between pitting corrosion hole and adjacent surface corrosion and the minimum range between pitting corrosion hole and circumferential weld and spiral weld be 25mm;

Wherein: mend the plate side of being plate, fall angled side plate or plectane, it is 180～700mm that circle is mended the plate maximum diameter; The axial length L of square benefit plate is calculated as follows with the ratio of downward projection radial width B:

$\frac{d}{360\sin ({\cos }^{-1}\frac{2\×{360}^2-\frac{d^2}{4}}{2\×{360}^2}+{\sin }^{-1}\frac{\frac{d}{2}}{360})}$

Following table is the Elongation numerical value of the different size corrosion default that by formula calculates:

Corrosion default diameter (d)	250mm	275mm	300mm	325mm	350mm
						Elongation	1.07	1.09	1.11	1.13	1.16

After benefit plate covering corrosion default was meant that mending plate covers corrosion default, the minimum range of mending panel edges and corrosion default edge should be got the higher value of 1/2d and 50mm, and d is the corrosion default diameter.

Need to prove that the corrosion default that reaches on spiral weld, the circumferential weld on the pipeline pit must not adopt the reinforcement reparation.

The online repair welding of pipeline mainly exists burns and produces two risks of hydrogen induced cracking.When on pipeline with pressure, welding,, will burn if when deposite metal intensity can not born built-in thermal stress welding pool below.In case burn, oil and gas leakage very likely sets off an explosion, the normal operation of serious threat personal security and pipeline.Therefore, preventing to burn is the matter of utmost importance that the online repair welding of pipeline is considered.

Because during the online welding of pipeline, the mobile meeting of the interior fed sheet of a media of pipe causes postwelding cold soon, is easy to generate hydrogen induced cracking.The generation of hydrogen induced cracking must possess three conditions simultaneously: have a certain amount of hydrogen content in the weld seam, responsive microstructure and act on tensile stress on the weld seam.Eliminate one of above-mentioned three kinds of factors, just can avoid the generation of hydrogen induced cracking.The residual tension that acts on the weld seam is inevitably, can only reduce stress by improving welding procedure.And adopt low-hydrogen electrode and low hydrogen welding procedure in the welding, also can only reduce the hydrogen content in the weld seam to a certain extent.Therefore, for fear of producing hydrogen induced cracking, the domestic and international research emphasis is the generation that how to reduce the heat affected zone hardness number and prevent sensitive organization.

The relation of Argentina scholar J.L.Otegui etc. the has adopted The Numerical Simulation Methods minimum wall thickness (MINI W.) repaired of tracheae thread casing and pressure, flow velocity; Found that flow velocity is also corresponding to be reduced along with the reducing of the pressure of gas in the pipeline, the cooling action of welding zone is weakened greatly, avoid burning required minimum wall thickness (MINI W.) and increase on the contrary; Wherein I weldering thickness is 4.65mm when the pipeline operating pressure is 5.88MPa in when welding labour, and I weldering thickness was 4.80mm and 5.30mm when the pipeline operating pressure was dropped to 4.70MPa and 3.53MPa respectively.Therefore, medium is in flowing state in the pipe, can reduce the possibility of burning.

It should be noted:

For reducing welding stress, welding should be snapped from the edge of etch pit or face corrosion, forms circular or oval welding bead, and successively passes to the center, the center portion of last corrosion due to welding hole or face corrosion; Welding begins from both sides upwards welding from the point that descends most of circle etch pit; Welding begins from both sides upwards welding from next angle of square etch pit;

The starting point that should avoid per pass circle or oval welding bead is in same position;

For the repair welding of pitting corrosion hole, can not surpass 60 seconds lasting weld interval, and temperature raises too highly to avoid tube wall to be heated for a long time, surpasses 982 ℃ and burn; If also need to continue to fill up welding, to wait until that then weld metal is cooled to below 150 ℃, and can carry out after removing welding slag;

Multilayer welding can be filled up etch pit or face corrosion if desired, and the root bead welding current is as much as possible little, burns avoiding, and fills and the capping electric current can suitably increase.

Mend in the plate repair welding process, adopt normal welding procedure, the possibility of burning is less relatively, and emphasis is to consider to produce bigger welding stress in the time of may causing welding owing to mend rigidly fixing between plate and the pipeline, causes the generation of hydrogen induced cracking.When the benefit board size was big, axially weld seam preferably can have 2 welders to weld simultaneously and finish simultaneously.During multi-pass welding, the arcing point that should avoid the per pass welding is at same position.

Little weld heat input is adopted in the welding of pitting corrosion hole, and weld interval is short as far as possible, and more lath martensite tissue appears in HAZ, and hardness is also bigger.Little weld heat input is adopted in the face corrosion, and multi-pass welding connects, and HAZ organizes based on ferrite+pearlite, and hardness is lower, the better performances of joint.Main cause is, adopts multi-pass welding to connect, and the welding of back road has thermal processes act to the welding of preceding road, and the welding of preceding road is welded the road, back has pre-heat effect, makes its better performances.Therefore, adopt little weld heat input in the in-service pipeline dimension repairing process, it is useful that multi-pass welding connects the butt joint performance.

Therefore renovation reinforced construction joint pressure-bearing foot of the present utility model, fatigue life be long, rationally, solved the problem that exists in the online reparation welding technique of present oil transport pipeline preferably.

Description of drawings

Metallographic seam organization figure after Fig. 1 pitting corrosion hole repair welding

Metallographic HAZ organization chart after Fig. 2 pitting corrosion hole repair welding

The hardness of hardness test is got position view ready after Fig. 3 pitting corrosion hole repair welding

Metallographic seam organization figure after Fig. 4 face corrosion repair welding

Metallographic HAZ organization chart after Fig. 5 face corrosion repair welding

Embodiment

Embodiment. this example is an experimental technique.This test is to adopt Northeast China pipeline networks 16Mn steel pipe, diameter 720mm, and wall thickness 7.1mm, welding is that medium is a water in pipe, test pressure 4MPa carries out under the condition that ambient temperature is 10 ℃.

The concrete renovation reinforced structure of this example is:

Two corrosion default diameters are respectively 69mm, 352mm, are respectively the face corrosion of 6.8mm, 6.6mm at a distance of 500mm and repair welding mother metal residual wall thickness, and these two corrosion defaults are at a distance of 500mm, with the distance of spiral weld greater than 50mm; Adopt to mend the renovation reinforced structure of plate, the material of mending plate and wall thickness are with identical by the welded tube road, and the benefit plate selects for use diameter to be respectively the plectane of 120mm, 426mm; Mend plate and cover corrosion default when welding, the distance of mending panel edges and corrosion default edge is respectively 50mm and 180mm; Adopting diameter is the E5015-G low-hydrogen electrode of 3.2mm, and the root bead electric current is 70～95A, and arc voltage is 20～25V, and filling out/cover electric current is 90～125A, and arc voltage is 18～25V; Before the welding, tackle weld routinely and carry out preheating, remove surface moisture and moisture fully, heating means are flame heating, and width of heating is 150mm around the face corrosion; Every welding bead interpass temperature will be lower than 150 ℃, and will remove the welding slag of every layer of welding bead clean.

Its concrete welding parameter is as follows:

The welding parameter table

Welding bead	The wlding model	Wlding specification (mm)	Direct-current polarity	Welding current (A)	Arc voltage (V)	Welding speed (cm/min)	Heat input (KJ/cm)
								Root bead	E5015-G	3.2	DCEP	70-95	20-25	9-14	9-11
Filling/capping	E5015-G	3. 2	DCEP	90-125	18-25	8-12	11-16

After this benefit plate welding is finished, done conventional test:

Bulge test is the result show, the pipeline pressure-bearing satisfies the normal service condition of pipeline after the reparation of benefit plate.Mend the face-bend testing result of plate repair welding test specimen, the face-bend testing of weld seam there is no open defect, meets standard-required.Though the limit crackle of 2 long 1.0mm and 1 long 1.4mm occurs, do not exceed standard-required.Therefore, this renovation reinforced structure adopts corresponding welding procedure, and weld seam has certain plastic deformation, and is insensitive to hydrogen induced cracking, can meet the demands.

Following table is the stretch test result of face corrosion repair welding test specimen.

Face corrosion welding piece stretch test result

As can be seen, fracture position is all at mother metal, and tensile strength is all greater than mother metal tensile strength.Therefore, this renovation reinforced structure adopts corresponding welding procedure, and joint strength can meet the demands.

Following table is the face-bend testing result of face corrosion repair welding test specimen.

Face corrosion welding piece flexuraltest result

As seen, this renovation reinforced structure adopts corresponding welding procedure, and weld seam has certain plastic deformation, and is insensitive to hydrogen induced cracking, can satisfy standard-required.

Following table is the Impulse Test Result of face corrosion repair welding test specimen.

Face corrosion welding piece flexuraltest result

As seen, this renovation reinforced structure adopts corresponding welding procedure, and weld seam has toughness preferably, and is insensitive to hydrogen induced cracking, can satisfy standard-required.

Following table is a face corrosion hardness profile table, gets the position ready as shown in Figure 3.As can be seen, maximum hardness all appears at HAZ, and HAZ is the weak part in the labour repair welding, but does not all surpass the requirement that API 1104 standard appendix B HAZ hardness are no more than 350Hv.And all much smaller than the master gage definite value.

Face corrosion hardness profile table

Apart from face corrosion A _1-1The tubulation weld hardness distribution table of different distance

Metallurgical analysis result such as Fig. 4-shown in Figure 5.From tissue topography, weld seam has passed through multi-pass welding, and the welding of preceding road makes ferrite content increase to the heat effect of road, back welding, and the directivity of columnar crystal is broken, and pearlite is also relative even with the ferrite distribution, and this will be favourable to the performance of welded joint.HAZ has experienced repeatedly heat effect equally, make HAZ more ferrite and pearlitic structrure occur, and it is also more even to distribute, and performance increases.This is consistent with the better result that the mechanical property test of front obtains.

Benefit hardens and really analyzes

By bulge test, flexuraltest, metallurgical analysis and hardness test adopt the welding procedure among the rules WPS-GWXF-S002 to mend the plate welding as can be seen, can satisfy the requirement of the normal operating pressure of pipeline; Distance between circumferential weld or tubulation weld seam and benefit plate fillet joint is greater than 21mm, and angle joint just can not exert an influence to circumferential weld and tubulation weld seam; And require according to ASME 31.4: the minimum separable of stiffening plate and circumferential weld, tubulation weld seam should be 50mm.

And face corrosion repair welding test result shows:

1. be 80mm to extreme length, the least residue wall thickness is face corrosion the carrying out repair welding (the face corrosion is form of pot bottom) of 4.0mm, hydrogen induced cracking can not occur burning and producing;

2. when etch pit distance in two sides was greater than 21mm, the temperature field of back welding was very little to the influence of first face of weld corrosion weld seam and HAZ tissue.

Repair welding is carried out in the pitting corrosion hole that two diameters is respectively 12mm, 20mm, and this two etch pit is at a distance of 100mm, and apart from the distance of spiral weld greater than 25mm; Adopting diameter is the E5015-G low-hydrogen electrode of 3.2mm, is 70～90A at welding current, and arc voltage is 20～25V, and be no more than 60 seconds lasting weld interval; If once do not finish repair welding, also need to continue to fill up welding, to wait until that then weld metal is cooled to below 150 ℃, and can carry out after removing welding slag.

Equally, after these two pitting corrosion hole repair weldings, carry out conventional test.

Metallographic structure such as Fig. 1 after the pitting corrosion hole repair welding-shown in Figure 2, as can be seen from Figure: greater than 21mm, the etch pit temperature field of back welding is very little to the influence of preceding corrosion due to welding hole weld seam and HAZ tissue for the distance between adjacent two pitting corrosion of the in-service pipeline hole.Wherein weld seam is based on ferrite+pearlitic structrure, and HAZ is organized as the master with ferrite+lath martensite.The tissue of the flow velocity butt joint of medium has certain influence in the pipe, increase the rate of cooling of weld seam, columnar crystal can be thicker, content of pearlite in alloy can reduce, and sorbite or troostite can occur, and the sorbite tissue is thinner than pearlite, troostite is also thinner than sorbite, it is high that its strength ratio pearlite is wanted, and combination property is better, and is insensitive to hydrogen induced cracking.Increase the rate of cooling of HAZ, more lath martensite tissue can appear in HAZ, and plate martensite can not occur, because plate martensite generally forms in greater than 0.6% austenite in carbon content, therefore concerning 16Mn, can not form plate martensite, also just insensitive to hydrogen induced cracking.

Hardness test result after the pitting corrosion repair welding is as shown in the table.

The pitting corrosion scale of hardness

Pitting corrosion hole repair welding analysis result: comprehensive above weld seam and HAZ tissue and hardness analysis, more lath martensite has appearred in the tissue of pitting corrosion hole, though degree of tissue is bigger, requirement all is not above standard.And lath martensite has certain toughness, and is insensitive to hydrogen induced cracking.Test result shows: for the pitting corrosion of diameter 20mm, the least residue wall thickness that can carry out repair welding is 4.0mm.When distance was greater than 21mm between two pitting corrosion hole, the temperature field of back welding was very little to the influence of preceding etch pit weld seam and HAZ tissue.And standard SY/T 6554-2003 requires: the mother metal least residue wall thickness that great majority welding and hot-tapping are recommended is 4.8mm.The Security of execute-in-place is considered in combined test analysis and standard, document requirement, and the least residue wall thickness that regulation can be carried out the pitting corrosion of repair welding is 4.8mm, and the minimum range of carrying out between the consecutive points etch pit of repair welding is 25mm.

The welding result analysis of pitting corrosion hole: greater than 21mm, the etch pit temperature field of back welding is very little to the influence of preceding corrosion due to welding hole weld seam and HAZ tissue to the distance between adjacent two pitting corrosion of the in-service pipeline hole.Wherein weld seam is based on ferrite+pearlitic structrure, and HAZ is organized as the master with ferrite+lath martensite.The tissue of the flow velocity butt joint of medium has certain influence in the pipe, increase the rate of cooling of weld seam, columnar crystal can be thicker, content of pearlite in alloy can reduce, and sorbite or troostite can occur, and the sorbite tissue is thinner than pearlite, troostite is also thinner than sorbite, it is high that its strength ratio pearlite is wanted, and combination property is better, and is insensitive to hydrogen induced cracking.Increase the rate of cooling of HAZ, more lath martensite tissue can appear in HAZ, and plate martensite can not occur, because plate martensite generally forms in greater than 0.6% austenite in carbon content, therefore concerning 16Mn, can not form plate martensite, also just insensitive to hydrogen induced cracking.

In pitting corrosion welded joint analysis of experiments, the tissue and the hardness profile that are primarily aimed at welded joint are analyzed.Joint microstructure is different at face of weld and root, and main cause is that pitting corrosion hole weld heat input is little, and the root rate of cooling is the fastest, so root tissue is the sensitive part that produces hydrogen induced cracking.If root does not produce hydrogen induced cracking, joint just hydrogen induced cracking can not occur.

This routine weldment draws as drawing a conclusion according to test result and relevant criterion after tested:

Repair process is easy, the renovation reinforced structure decrease of benefit plate of easy row the stress influence of concentrating the diagonal angle weld strength, renovation reinforced rational in infrastructure, the maximum and the minimum dimension restriction of scientifically having determined to mend plate;

This renovation reinforced construction joint pressure-bearing foot, fatigue life be long, rationally, solved the problem that exists in the online reparation welding technique of present oil transport pipeline preferably.

Claims (3)

1. the on-line repairing-reinforcing structure for oil pipelines of an old pipeline modification engineering comprises the benefit plate structure of corrosion location; Material and the wall thickness of benefit plate of mending the plate strengthening structure mended plate and covered corrosion default with identical by repairing pipes, divides root bead, three layers of weldering of filling and block to be connected with low-hydrogen electrode between benefit panel edges and pipeline; It is characterized in that mending plate cover with other face corrosion default between keep 25mm and above distance or keep the corrosion default of 50mm and above distance with circumferential weld and spiral weld after, the minimum range at benefit panel edges and corrosion default edge is got the higher value of 1/2 and 50mm of corrosion default diameter d.

2. on-line repairing-reinforcing structure for oil pipelines according to claim 1 is characterized in that the described benefit plate side of being plate, falls angled side plate or plectane, and it is 180～700mm that circle is mended the plate maximum diameter; The axial length L of square benefit plate is calculated as follows with the ratio of downward projection radial width B:

$\frac{d}{360\sin ({\cos }^{-1}\frac{2\×{360}^2-\frac{d^2}{4}}{2\×{360}^2}+{\sin }^{-1}\frac{\frac{d}{2}}{360})}$

3. on-line repairing-reinforcing structure for oil pipelines according to claim 1 is characterized in that to minimum range between the little adjacent etch pit of corrosion location, between the corrosion of etch pit and adjacent surface and between etch pit and weld seam and spiral weld being that the pitting corrosion hole employing low-hydrogen electrode of 25mm divides one to three layer of repair welding to fill up.

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