2016年7月27日星期三

Definition of pipe fittings

We usually contact is fitting, but for the true definition of pipe fittings must be not all people know. The so-called fitting, is to pipe connection into line parts. According to the connection method can be divided into the socket type pipe fittings, flanges threaded pipe fittings, pipe fittings and welding pipe fittings four classes. Use the same as the pipe materials. Elbow (elbow), flange, tee, four-way tube (cross) and reducer (reducer), etc. Bend to turn his arm; Flange is used to make the pipe with pipe connecting parts, connection pipe, tee to the meeting-place of three tube; Cross pipe used in the meeting-place of four tube; Reducer is used for different pipe diameter of two pipes are connected.

Classification of pipe fitting

The kinds of pipe fittings is very complex, this needs us to classify a reasonable and orderly, to ensure that each kind of role play to the extreme. Induction has the following several main types:
1. The hole diameter pipe fittings, in accordance with the requirements will be fitting end or help expand to form various shapes of pipe fittings;
2. With edge and bottom sealing fitting, increase the pipe's overall strength to pipe the inner or outer edge or the pipe end seal pipe fittings;
3. Change the pipe cross section, according to the requirements, the circular section into a square, oval, polygons, and so on.
4. Bend pipe fittings, we contact more, is the straight pipe into different curvature radius of bend, such as elbow, elbow, etc.
5. With flange and flange pipe fittings, the former refers to the pipe end to the medial or lateral convex and the latter refers to swell in the circumferential direction of the tube or groove pipe fittings;
6. Variable wall thickness of pipe fittings, refers to along the length direction pipe wall thickness changes;
7. Variable diameter pipe fittings, refers to one part of the tube or pipe diameter decreases

2016年7月26日星期二

The effect of pipe material quality

Tube billet quality on the quality of the structure with seamless steel tube:
The merits of the billet quality is the action of the primary factors on the quality of the seamless tube. In order to guarantee reasonable perforation process and obtain high quality seamless tube, the necessary geometry size of tube billet, macrostructure and surface state put forward strict requirements.
Pipe diameter is too big or elliptic spend big, can make the perforation when nip condition is bad, will also precipitated by tube billet diameter and large amount of compression of the occurrence of folds.
Internal organization matter refers to the shrinkage cavity and central loose, the accumulation of non-metallic inclusions, gas content, etc. Stringency of such requests, with the purpose of the seamless tube and steel grade differences.
Is the most primary tube billet surface quality, because in the pipe to any disability city to products on seamless tube, and the location of the disabled will lead to stress concentration, by plastic deformation will lead to disability deepen, extended.
In word to come up with output of high quality seamless pipe products, the good tube billet quality is the first step.

The formation of weld burr and clear:


By high frequency current skin effect and proximity effect, current concentration in the weld heated to a molten state, the lateral extrusion roller pressure welding, the extrusion pressure, excess metal and oxide accumulation in the upper seam surface burr formation; Affected by extrusion and the joint action of gravity and some extra metal and oxide along the tube axis direction within the burr in the medial droop.
Burr width at around 0.5 ~ 3 ㎜, usually within the burr height is uneven, the general is 0.2 ~ 0.6 ㎜. Individual height can reach more than 1 ㎜. Outside burr planing method is commonly used in clearing and inside burr in steel pipe inside the space is little, clear technical difficulty is increased. Because of the existence of burr inside when cold drawn or cold rolled steel pipe again finishing, will be formed in the steel pipe inner surface crack, collapse or scratches. So for precision welded pipe, don't remove the burr cannot reach the inner surface quality requirement, also can't be hind leg's machining.
Outside burr removal system have a cutter and the cutter type, use a cutter for machine knives, and the cutter with two deburring, tool change don't need to stop.
Remove the burr technology is difficult, due to the burr of the special-purpose device inside the steel tube, working environment is very poor, can't see, touch less than, it is the strip forming process of precision and accuracy of the equipment, and the weld shape, often not guaranteed. Data reported abroad, inner hole above 14 ㎜ welded pipe can be remove the burr, actually inner hole under 25 ㎜ within the burr removal is difficult. Domestic technology generally, pore over 50 ㎜ large diameter welded steel pipe can be remove the burr.
Remove the burr, usually in continuous welded pipe production line, can also be used offline methods to remove.
Remove burrs in methods, mainly has the following several ways:
Cutting method: this method is to use fixed or rotating blade, the cutting head into the tube for cutting burr.
Rolling method: this method is used in tube rolling device, make the inside burr produces plastic deformation, the effect of thinning inside burr height.
Oxidation method: at the start of the steel pipe welding, oxygen to inside weld with airway nozzle jet flow, the use of weld seam welding heat, make inside burr accelerated oxidation, and under the air rushed out of the loss.
Drawing method: steel pipe through the mould, under the influence of floating plug circular blade, remove burrs in steel pipe.

Welded pipe forming process:

Welded pipe forming process:
Welded pipe forming process, the welding machine composition form and sizing roller design and adjustment method will directly affect the welding quality of the wheat from the chaff. The traditional forming process for roll forming technology, has a radius of single, double radius; W inflection pass system, the method of forming plus two high, three or four roller roller, roller pressing roller, two rollers or four rollers sizing to guarantee the forming quality. This traditional roll forming technology, mostly used for diameter less than 114 ㎜ welded pipe units. America's line of roll forming process, the steel union CTA forming technology, Japan once FF or popular titles include FFX flexible forming technology, etc., after forming of the joint shape and good surface has good quality, suitable for welded pipe unit specification is wider. Various forming process technology, have different advantages and disadvantages, suitable for different conditions, according to the product outline, the purpose is to be considered in the equipment selection, in order to choose different forming technology.
In order to reduce the elastic deformation, the deformation of precision welded pipe unit process in time are better than common welding pipe increased 2 ~ 3 times. On deformation arrangement, should reduce initial deformation Angle, ensure the stability of the nip, curved Angle between the appropriate increase, the rear part of the deformation decrease and increase the deformation path is not only reduce the deformation force, also can make the strip has the opportunity to release the surface stress, surface gradient of stress increase slowly, can avoid the crack. In the process of adjustment, first of all, should guarantee the vertical centerline of unity, for different center as basis, looking for accurate positioning and middle size, in a horizontal position, should be arranged according to the process, form the mountain line (down) flat straight line, not a curve. Before didn't wear a belt, you should adjust the groove shape of each frame, measure the size for different, guarantee the stability of the product into the frame. In adjustment to equilibrium force, can not be forced deformation on a rack, ensure uniform ascending Angle stability change.
Precision welded pipe production, control and adjust the good welded pipe units forming and sizing stand equipment accumulated error and roll bounce rate is older of welded pipe units can also be the key to the production of precision welded pipe.

2016年7月25日星期一

The Key Technical of Precision weled steel tube

A, about the quality of the raw material requirements:
Precision welded steel pipe of raw materials, in addition to the must meet the basic requirement of ordinary high-frequency welded steel pipe materials, still must meet the following requirements:
Chemical composition:
Smelting, the key is to improve the purity of steel, reduce the amount of non-metallic inclusions in steel, sulfur and phosphorus content is less than 0.03%, in order to adapt to cold hind leg deformation processing, sulfur content had better not more than 0.02%, so we will strictly control the steel chemical composition. At the same time in order to ensure the product has good mechanical properties, cold bending, welding, such as process performance, still need to appropriately increase some elements, such as Nb, Ni, V.
2 steel strip shape and size:
Steel strip rolling, the AGC should be adopted and flatness control system, improve the steel strip thickness accuracy and shape accuracy. Also, using the method of controlled cooling, improve the tenacity of steel belt. Slitting steel strip width dimension accuracy requirement for control, steel strip edges shall be without creasing and burr, in order to improve the welding quality.
3 rust on the surface of the structural steel pipe:
Steel strip for iron oxide yellow rust on the surface of the water of crystallization, in the process of welding, high temperature can make the hydrogen oxygen out, such as can't discharge, exists in the weld, easy to produce porosity micro cracks, change the organization structure, reduce the material plastic, reduce elongation, so avoid steel strip surface rust.

Thick wall welding tube

Thick wall  welding  tube production manufacturing process can be divided into cold drawing and cold rolling and hot rolling of three basic ways, the material of steel pipe for 10 #, 20 #, 35 #, 45 # called common steel, 16 mn between common steel and alloy steel pipe is called the low alloy steel pipe, steel pipe material for 27 simn, 12 cr1mov, 10 crmo910, 15 crmo, 35 crmo collectively known as the alloy steel pipe and stainless steel pipe. According to the purpose can be divided into structure with seamless steel tube; Delivery with seamless steel tube; Boiler seamless steel tube; Boiler with high-pressure seamless steel tube; Chemical fertilizer equipment with high-pressure seamless steel tube; Geologic brick, seamless steel tube; Brick of oil exploration in seamless steel tube; Seamless steel tube used in oil cracking; Shipping with seamless steel tube; Cold drawn cold rolled precision seamless steel tube; All kinds of alloy pipe.
API seamless steel pipe said method for outer diameter, wall thickness, thick wall seamless steel tube is mainly used in mechanical processing, coal mining, hydraulic steel, such as a variety of purposes. Classification of thick wall seamless steel pipe, hot-rolled thick wall seamless steel tube, cold rolling thick wall seamless steel tube, cold drawn thick-walled seamless steel tube, extrusion thick-walled seamless steel pipe, pipe jacking construction with stainless steel seamless steel tube (GB/T14975-1994) is widely used in chemical industry, petroleum, textile, medical, food, machinery and other industrial corrosion of pipeline and components and parts are made of stainless steel hot rolling (crowded, expanding) and cold drawing (rolling) seamless steel tube. Fluid conveying stainless steel seamless steel tube (GB/T14976-1994) is used for conveying fluid made of stainless steel hot rolling (crowded, expanding) and cold drawing (rolling) seamless steel tube.
Alien seamless steel tube is in addition to the outside of the pipe cross section shape of the floorboard of the API seamless steel tube. According to the size of steel pipe cross section shape is different and can be divided into such as wall thickness seamless steel tube (code-named D), ranging from wall thickness seamless steel tube (code-named BD), variable diameter seamless steel tube (code-named BJ). Alien seamless steel tube is widely used in all kinds of parts, tools and machinery parts. Compared with those of circular tube section tube usually have large moment of inertia and section modulus, have bigger bending torsional capacity, can greatly reduce the structure weight, save steel.

2016年7月23日星期六

Forming method of hollow section

Referred to as the bending pipe forming way, party is called bending torque tube forming. There are two basic methods: bending forming bending and empty.
1, solid bent
Real curved, just as its name implies is to compaction the bending, real turn inside and outside the interior and exterior wall two-way compaction roller and the tube billet.
1) the real bending rebound is small, the advantages of accurate molding, and as long as accurate roller type, inside molding R is more accurate.
2) real disadvantage is that the bending tensile/thinning effect. First, the real turn will make the roots stretching, bending tensile effect makes the meander-line longitudinal length shorten; Second, real break curved metal due to stretching and thinning.
2, empty
Empty bending is through the roller and the outer wall of tube billet one-way contact form make the pick-up bending moment, empty curved meander-line causes compression, compression effect makes the meander-line longitudinal elongation, bent metal accumulation in thickening, this is an empty bending compression/thickening effect.
1) empty bending can be in to the advantages of real curved side length of the bending, such as the top of the torque tube/side synchronous bending and finishing. Empty corner can also bend R < 0.2 t inside without breaking the wall.
2) empty torque tube bending fault is on the top/side synchronous empty turn, because on the roller and the lower roller pressure at the same time, the forming force beyond the tipping point, easily causing instability concave of edge, and also affects the stable operation of unit and forming quality. This is the moment when the empty tube and circular tube bending forming different features.
In practical application, these two basic methods, in the torque tube forming should be according to the product need to be configured to reasonable technical position. Should pay attention to the tensile/thinning effect of solid forming and empty bending forming of the effects of compression/thickening effect on product quality, otherwise will lead to the torque tube forming side concave, the finished tube longitudinal buckling, and difficult to straightening.
If you would like purchase square tube(hollow section) with good quality and competitive price,pls contact us free.

2016年7月22日星期五

Useful of Boiler Steel Tube

Boiler steel tube refers to both ends open and has a hollow section, the length and the surrounding of the larger steel, according to the production methods can be divided into seamless steel pipe and welded steel pipe, boiler steel pipe specifications with overall dimensions. Boiler steel pipe (such as the diameter or length) and wall thickness, according to the size range is very wide, from small diameter capillary until several meters in diameter, large diameter pipe. Steel pipe can be used in the pipeline, thermal technology equipment, industrial machinery, petroleum geological exploration, containers, chemical industry, and special purpose. The classification of steel pipe: steel pipe seamless steel pipe and welded steel pipe (tube) two kinds big. According to the cross section shape and can be divided into circular tube and special-shaped tube, steel tube is widely used, but there are some square, rectangle, semicircle, hexagonal, equilateral triangle, octagonal special-shaped steel tube. For fluid under pressure steel pipe are hydraulic experiment was carried out to test the compression ability and the quality, under the pressure of regulation does not leak, soaked or expansion of qualified, some steel pipe according to the standard or the buyer requires edge test, flaring test, flattening test, etc

2016年7月21日星期四

The identification method of fake thick-walled seamless pipe

1. And inferior thick-walled seamless steel tube is easy to fold. Folding is formed on the surface of the thick wall seamless steel tube line, this kind of defect often throughout the entire product longitudinal. Causes of fold is due to the pursuit of the false and inferior, high efficiency, large reduction, handle, when the next rolling produce folding, folding products will be cracking after bending, the strength of the large thick wall seamless steel tube.
(2) and inferior appearance often have thick wall seamless steel tube piping phenomenon. Pits was caused by groove wear thick wall seamless steel tube surface irregular uneven defects. Due to the false and inferior thick-walled seamless steel tube manufacturer to pursuit of profit, often appear the groove rolling.
(3) and inferior thick-walled seamless steel tube surface are prone to scarring. For two reasons: 1. The thick wall seamless steel tube material and inferior uneven, impurities. 2. And inferior material manufacturer guide equipment simple, easy to stick steel, these impurities after the roll bite are prone to scarring.
4. Easy generation and inferior material surface crack, the reason is that it's blank is adobe, adobe air, adobe in the process of cooling due to the effect of thermal stress, cracks, after rolling there is crack.
5. Thick wall seamless steel tube is easy to scratch and inferior reason is false and inferior material manufacturer equipment simple, easy to produce burr, scratch thick-walled seamless steel tube surface. Deep scratches to reduce the strength of the thick wall seamless steel tube.
6. And inferior thick-walled seamless steel pipe without metallic luster, reddish or similar to the color of the pig iron, two point two, its billet is adobe reasons. 2, and inferior material rolling temperature is not standard, their steel temperature is through visual inspection, so can't austenitic area of the rolling by the regulation, the performance of the thick wall seamless steel tube nature is not up to standard.
7. And inferior transverse reinforcement of thin and thick wall seamless steel tube is low, often appear phenomenon of discontent, because manufacturers to achieve big minus tolerance, finished product quantity of the previous way slants big, small iron type, groove filling.
8 and inferior thick-walled seamless steel tube cross-section oval, because the factory in order to save material, the quantity of the finished product roll before 2 slants big, the strength of rebar is greatly decreased, but also do not conform to the standard of rebar shape size.
9. High quality thick wall seamless steel tube components uniform, cold shearing machine high tonnage, cutting head end face smooth and neat, and shoddy material because the material is poor, cutting head end face often have meat, or uneven, and no metallic luster. And due to low and inferior material manufacturers cut head, end there will be a big handle.
10. And inferior thick-walled seamless steel pipe material with impurity, more steel small density, size and out-of-tolerance is serious, so in the absence of vernier caliper, can be checked to weigh it. For rebar 20, for example, maximum minus tolerance specified in the national standard of 5%, scale of 9 m in the theory of single weight is 120 kg, it should be the smallest weight: 120 X (l - 5%) = 114 kg and 114 kg weigh out the weight of the single than small, is false and inferior thick-walled seamless steel pipe, because it is minus tolerance more than 5%. In general the whole amount to match the effect will be better, mainly considering the cumulative error and probability theory to this problem.

2016年7月19日星期二

Purchasing hollow sections Q345B notes on common knowledge

Purchasing  Q345B hollow sections  notes on common knowledge
1) general terms (1) the delivery status Refers to the final delivery products plastic deformation or the state of the final heat treatment. Don't usually after heat treatment delivery of said hot rolled or cold drawing (rolling) or manufacturing state; After heat treatment delivery according to heat treatment state, or according to the categories called normalizing heat treatment (often), tempering, quenching, annealing condition. When ordering, delivery status should be indicated in the contract. (2) according to the actual weight delivery or delivery shall be ordered to theoretical weight Is the actual weight, delivery, product weight by weighing (weighing) weight of delivery; Theoretical weight, the delivery, the product weight is calculated on steel nominal size
1) general terms
1) delivery status
Refers to the final delivery products plastic deformation or the state of the final heat treatment. Don't usually after heat treatment delivery of said hot rolled or cold drawing (rolling) or manufacturing state; After heat treatment delivery according to heat treatment state, or according to the categories called normalizing heat treatment (often), tempering, quenching, annealing condition. When ordering, delivery status should be indicated in the contract.
(2) according to the actual weight delivery or delivery shall be ordered to theoretical weight
Is the actual weight, delivery, product weight by weighing (weighing) weight of delivery;
Theoretical weight, the delivery, the product weight is calculated according to the nominal dimension steel weight. Its computation formula is as follows (according to theoretical weight, the delivery must indicate in the contract) :
Torque tube Q345B theoretical weight per meter (steel density of 7.85 kg/dm3) formula:
W = 0.02466 (D - S) S
Type: W - torque tube Q345B theoretical weight per meter, kg/m.
D - moment of Q345B pipe nominal diameter, mm;
S - moment of Q345B pipe nominal wall thickness, mm.
(3) guarantee conditions
According to the provisions of the current standard test project and to ensure that comply with the provisions of the standard, as the guarantee conditions. Guarantee condition is divided into:
A, basic guarantee conditions (also known as will protect condition). No matter whether the customer in the contract. Must be stipulated in the standard for the inspection, and ensure the test results conform to the prescribed standards.
Such as chemical composition, mechanical properties, size deviation, surface quality and inspection, the water pressure experiment or crushed or flaring process performance experiment, will guarantee conditions.
B, protocols guarantee condition: in the standard in addition to the basic guarantee conditions, there are \"according to buyer's request, the supply and demand both sides talks things over, and in the contract note? Quot; or\" when the buyer request... , should be indicated in the contract \", and the customer, the standard of basic guarantee conditions and weiwei (such as composition, mechanical properties, size deviation, etc.) or increase inspection items, such as torque tube Q345B ovality, unequal wall thickness). The above terms and requirements, in order, by supply and demand both sides talks things over, supply the technical agreement signing and indicate in the contract. Therefore, these conditions is also known as protocols guarantee conditions. Have agreements guarantee conditions of products, is to increase.
(4) of
Standard of the \"group\" means a test unit, the inspection lot. If the batch delivery unit group, said the batch of delivery. When delivery batch big, a batch of delivery can include a few test batch; When the bulk delivery, a test batch can be divided into several batch of delivery.
The composition of the \"group\" usually has the following requirements (see the relevant standards) :
A, each batch should be from the same brand (steel grade). And the same furnace (cans), or the same furnace number, the same specifications and the same heat treatment system (furnace) of Q345B torque tubes.
B, for quality carbon steel structure tubes, fluid tubes, can be different furnace (cans) of the same brand, the same specifications and the same heat treatment system (furnace) of Q345B torque tubes.
C, torque tube welding Q345B each batch shall be made by the same brand (steel grade), the same specifications of Q345B torque tubes.
(5) high quality steel and advanced high quality steel
In GB/T699-1999 and GB/T3077-1999 standard, behind the brand with \"A\" word, for the high quality steel, and vice in general and high grade steel.
High quality steel in part or all of the following is better than that of high quality steel:
A, narrowing the scope of component content;
B, to reduce the harmful elements, such as sulfur, phosphorus, copper content;
C, the guarantee of high purity (non-metallic inclusion content less);
D, ensure higher mechanical properties and process performance.
6 vertically and horizontally
Standard according to the longitudinal, it refers to processing parallel to the direction (that is, the processing direction); Horizontal, it refers to processing direction (vertical machining namely Q345B party torque tube axial direction).
Do impact experiment, direction vertical longitudinal fracture with sample processing. Therefore calls transverse fracture; Transverse fracture of the sample with the parallel processing direction, therefore calls the longitudinal fracture.
(2) Q345B torque tube shape, size of terms
1) nominal size and actual size
A, nominal size: size is specified in the standard name, is the ideal size of users and manufacturers hope to get, is also stated in the contract to the order of size.
, the actual size: B is given in the production process of actual size, the size is often greater than or less than the nominal size. This is greater than or less than the nominal size of the phenomenon known as deviation.
(2) the deviation and tolerance
A, deviation: in the process of production, due to the difficult to meet the requirements of nominal size, actual size is often greater than or less than the nominal size, so the standard stipulated in the actual size and there is A difference between nominal size allowed. Difference between positive deviation, is called differential negative is called negative deviation.
B, tolerance: standard specified in the positive and negative deviation value is the sum of absolute value is called tolerance, also called "tolerance zone".
Deviation is a direction, namely to "positive" or "negative" said; Tolerance is no direction, therefore, called the deviation value is "tolerance" or "negative tolerance is wrong to call it".
(3) delivery length
The delivery length and length according to user requirements or the length of the contract. In the standard of delivery length with the following provisions:
Length (also called A, usually not specified length) : all the length within the length of the prescribed standards and no fixed length requirements, is usually the length. Such as structural pipe standards: hot rolling torque tube (extrusion and expansion) Q345B 3000 mm to 12000 mm; Torque tube cold drawing (rolling) Q345B 2000 MMM ~ 10500 mm.
B, the specified length: specified length should be in usually length range, the requirements of the contract is a fixed length. But in practice are cut into absolute specified length is unlikely, so the standard to the specified length in the deviation values are allowed.
To the criteria of tube structure:
The production scale length of the tube, the length of the tube yield declines larger than usual, manufacturing enterprises put forward price demand is reasonable. Mark-up on various enterprises differ, is generally based on the basic price extra 10% or so.
C, foot length: times ruler length should be within the scope of the usually length, the contract shall indicate the haploid feet in length and constitute a total length of multiples (such as 3000 mm x 3, which is 3000 mm 3 multiples, length is 9000 mm). Practice, should be on the basis of the total length and allow deviation is 20 mm, plus each haploid feet should leave a margin incision length. Tube structure, for example, rules remain incision cushion: outer diameter 159 mm or less for 5 ~ 10 mm; For 10 ~ 15 mm outside diameter > 159 mm.
Unless otherwise stipulated in the standard times ruler and the provisions of the length deviation and cutting allowance should be made by supply and demand both sides negotiate and indicate in the contract. Times the length scales as specified length, will bring enterprises yield significantly lower, so the production enterprise put forward the price is reasonable, the mark-up with specified length mark-up on basic same.
D, scope, length: the length range in length range, usually when the user requirements of a range of fixed length, need to indicate in the contract.
For example: usually length 3000 ~ 3000 mm, and the range of specified length is 6000 ~ 8000 mm or 8000 ~ 10000 mm.
Visible, foot length range than the length and the length times for loose, but more than the usual length and yan, will also bring yield of lower production enterprises. Production enterprises put forward the price is reasonable, therefore, the mark-up on basic pay extra 4% or so in general.
(4) uneven wall thickness
Q345B the wall thickness can't be everywhere the same moment, on the cross section and longitudinal tube body wall thickness range phenomenon exists objectively, the uneven wall thickness. In order to control the inhomogeneity, in some Q345B torque tube standard stipulated in the payment of the uneven thickness of the permission of the index, general provisions do not exceed 80% of the wall thickness tolerance (after the supply and demand both sides talks things over the execution).
(5) ovality
On the circular cross section of a torque tube Q345B exists the phenomenon of outside diameter range, namely there is not necessarily perpendicular, minimum and maximum overall diameter diameter is the largest diameter of which is the difference between the smallest diameter ovality (or not roundness). Torque tube to control the ovality, some Q345B standard stipulated in the ovality indicators, without the permission of the general rules for no more than the outside diameter tolerance of 80% (after the supply and demand both sides talks things over the execution).
6. Bending
Torque tube Q345B curve shaped on the length direction, use Numbers show the curve is called bending degrees. The degree of curvature of standard stipulated in the general can be divided into the following two kinds:
A, partial bending: use A meter long ruler by quantity at the maximum bending moment tube Q345B, measuring the chord high (mm), is the local bending numerical, its unit is mm/m, said method such as 2.5 mm/m. This method can also be applied to the pipe bending.
B, the total length of the total bending: use a thin line, from the pipe ends taut, measurement of Q345B party torque tube bend biggest string (mm), then computes the percentage of growth degree (in meters), namely for Q345B torque tube length of the length direction of bending.
For example: Q345B square torque tube length is 8 m, measured the maximum string 30 mm high, then the length tube bending should be followed:
0.03 present 8 m x 100% = 0.375%

2016年7月18日星期一

Pressurized fluid conveying with spiral seam submerged arc welding pipe

Pressurized fluid conveying with spiral seam submerged arc welded steel pipe is mainly used for conveying oil, natural gas pipeline; Pressurized fluid conveying with high frequency welding spiral seam steel pipe), using high-frequency welded lap welding method, used in pressurized fluid conveying spiral seam high frequency welding steel pipe. Steel tube confined ability, good plasticity, easy to welding and processing molding; General low-pressure fluid conveying spiral seam submerged arc welding steel pipe, use double-sided automatic submerged arc welding or welding by one side into the legal system for water, gas, air and steam general low-pressure fluid conveying with submerged arc welding steel pipe Now commonly used standard spiral welded steel pipe, API 5 l (American petroleum institute, also known as the pipeline steel pipe, which is divided into PSL1 and PSL2 two level)
Pressurized fluid conveying with spiral tube bending process performance 1) performance As stipulated in the table below the bend heart after bending diameter 180 degrees, reinforced by bending parts surface shall not crack. 2) reverse bending performance According to the buyer's request, reinforced can reverse bending performance test. Reverse bending test of curved heart than bending test diameter increase, a steel bar diameter. Positively curved 45 degree first, and then reverse bending 23 degrees, reverse bending after 23 degrees. After reverse bend test, reinforced by bending parts surface shall not crack. 4. The surface quality: steel surface permits can not have crack, scarring, and folding. Steel on the surface of the convex block is allowed, but must not exceed the height of the horizontal rib, reinforced depth and other defects on the surface height shall not be greater than their positions to allow the size deviation. 5. Size, shape, weight, and allowable deviation: 1) nominal diameter range and recommended diameter steel bar nominal diameter in the range of 6 ~ 25 mm, steel standards recommended by the nominal diameter is 6, 8, 10, 12, 16, 20, 25, 32, 40, 50 mm. 2) ribbed steel plate surface shape and size of allowable deviation Ribbed reinforced cross rib shall meet the following basic requirements: cross rib with steel plate axis of beta should not be less than 45 degree Angle, when the Angle is not greater than 70 degrees, reinforcement relative to the direction of the horizontal rib on both sides should instead; L cross rib and spacing shall not be greater than 0.7 times the diameter of the steel bar nominal; Horizontal rib on the side and Angle on the surface of the steel shall not be less than 45 degrees; Gap between reinforcement relative to the end of cross rib on both sides (including the longitudinal rib width) 20% of the combined steel should not be greater than nominal circumference; When the steel bar nominal diameter is not more than 12 mm, relative costal area should not be less than 0.055;  nominal diameter is 14 mm and 16 mm, relative costal area should not be less than 0.060; Nominal diameter greater than 16 mm, relative costal area should not be less than 0.065. 3) length and allowable deviation, length: a reinforced usually according to the specified length delivery, specific delivery length should be indicated in the contract;  structural steel pipe to delivery, each dish should be a steel bar, allow 5% per batch  plate number (less than two sets can have two sets) consists of two steel. Its diameter disc weight and plate shall be formulated by the supply and demand both sides talks things over. B, the length of the allowable deviation, reinforced by the length of delivery when the length of the allowable deviation shall not be greater than + 50 mm. C, bending and end: straight steel bar bending change should not affect the normal use, the total curvature is not more than 40% of the total length of reinforcement; Reinforced ends should be cut integrity, local deformation shall not influence the use.

Advantage of Sprial Steel Pipe

Determines the structure of the spiral steel pipe is superior features in areas such as power, chemical, oil and nuclear industry is becoming more and more widely used. Spiral pipe technology research has involved flow pattern and pressure drop characteristics research, strengthening heat transfer research various aspects, such as Hunan Great Steel Pipe Co.,Ltd-- large diameter spiral steel pipe manufacturer.
spiral steel pipe technology in many fields of chemical industry such as heat transfer and mixing get extensive application, good results are obtained. But the spiral pipe technology application in mass transfer separation until now still less. In recent years, many researchers in hebei province of large diameter spiral steel pipe factory in hebei province of large diameter spiral steel pipe manufacturer will spiral pipe technology used in micro filtration, nanofiltration, penetration and hollow fiber membrane in the membrane distillation and mass transfer separation process, has achieved good results because the spiral tube can form inside the pipe and tube axial vertical secondary flow, the secondary flow and axial mainstream compound into a spiral of forward motion for laminated circulating fluid, so it is not just rely on radial diffusion of fluid, and the effect of the radial secondary flow, the equivalent of the boundary layer on the damage, update the mass transfer surface. To enhance the mixing of fluid in the laminar flow movement, improve the effect of mass transfer. Spiral tube will also improve the outflow of tube type, namely the shell liquid flow pattern. Increase the radial mixing tube outside the liquid, reduce the number of shell side flow and the dead zone, at the same time because of the close to cross-flow, mass transfer of fiber surface constantly updated, the mass transfer coefficient of shell side will further increase of large diameter spiral steel pipe manufacturer in hebei. Herein lies the spiral steel pipe general superiority. But it is in many practical applications and other special function.

2016年7月12日星期二

Australia lowered this year and iron ore price forecast

The Australian government on Thursday (July 7) in quarter resources report in 2016 iron ore price forecast from $45 to $44.2 a tonne, and forecast to 2017 from the $55 per tonne to $44. The Australian government said at the same time, since this year, iron ore prices rose nearly 30%, but in the first half of the average price of $48 per ton from a year ago are still down 13%.
According to the report, "despite the sharp rise in iron ore prices this year, but the market fundamentals have not changed, still excess iron ore supply, and lower demand growth." Have other report predicts that China's economic transition as the world's largest steel exporter to no longer by the credit to promote growth, China's steel production this year and next year will drop to 783 million tons and 783 million tons respectively.
Australia is the world's largest exporter of iron ore, but because of the biggest importer, China's economic growth is slowing, lead to impact on Australian iron ore trade.
The Australian government is expected, with strong growth and a slowdown in demand, supply in the rest of 2016, iron ore prices will moderate.
Hunan great steel pipe co.,ltd will focus on the economic matter.

Metal hardness testing method

Refers to the metal surface hardness against other hard objects into more ability. Through hardness test can reflect the metal material in different chemical composition, organizational structure and heat treatment process under the condition of differences in performance, to determine the applicability of the material, or material for a specific purpose by hardening or softening treatment effect.
Metal hardness testing method on the Richter scale, shore hardness, brinell hardness, Webster's hardness, ultrasonic hardness, etc. The magnitude of the hardness and shore hardness, test in the test force is dynamic and impact, belongs to the dynamic test method. Brinell hardness, Webster's hardness, ultrasonic hardness belongs to static test method.
The principle of the test method, use scope is:
1, the magnitude of the hardness
Detection principle:
Using 1 mm punch from the sample surface rebound rate of hardness and impact velocity ratio calculation.
Scope of application:
Suitable for large metal parts and carbon steel pipe products, that is, quality of large objects.
2, shore hardness,
Detection principle:
Using the punch sets in the rebound height and fixed on the surface of the specimen height ratio calculated hardness.
Scope of application:
Application is more common in the industry of roll.
3, brinell hardness
Detection principle:
Mainly measurement principle of two kinds of indentation diameter and depth.
Scope of application:
In mild steel pipe standard, the most versatile brinell hardness.
4, Webster's hardness
Detection principle:
With pressure needle into the depth of the characterization of material hardness, define the pressure into the depth of 0.1 mm for a Webster's hardness.
Scope of application: widely used soft metal.
5, ultrasonic hardness
Detection principle:
The vickers is rectangular pyramid head vibration lever incentive to the free vibration frequency, analyte when the pressure head at a constant load and vertical at contact, resonate, and using the resonant frequency is calculated by measuring the hardness of content.
Applicable scope: is suitable for thin workpiece of nondestructive testing.
Hunan Great Steel Pipe Co.,ltd  could finish all the testing well.

2016年7月11日星期一

Structural steel pipe

Structural steel pipe: general structure with steel pipe, structure pipe for short.
Structure steel pipe, this standard is applicable to the general structure, mechanical structure with seamless steel tubes, seamless steel tube fluid standards applicable to general seamless steel pipe conveying fluid. Seamless steel pipe steel pipe company  supplies structure.
Structure with stainless steel seamless steel tube  is widely used in chemical industry, petroleum, textile, medical, food, machinery and other industrial corrosion of pipeline and components and parts are made of stainless steel hot rolling (crowded, expanding) and cold drawing (rolling) seamless steel tube. Structural steel pipe weight calculation formula: [] - wall thickness (diameter) * wall thickness * = 0.02466 kg/m (weight of per meter)
Standard: GB/T8162-2008
Material: 45 # 10 # 20 # 35 # Q235 Q295 20 cr 30 cr Q345 35 cr 40 cr 12 crmo 20 crmo 35 crmo 42 crmo 12 crmov 12 cr1mov 16 mn
Purpose: seamless structural steel pipe is used for general structure and the mechanical structure of seamless steel tube.

New challenge


In June,2016, Hunan Great Steel Pipe Co., LTD. received a challenge order with below request and conducted researches immediately:


1) Pipe Specification: Φ1219 * 28.6 * 12000 mm, Steel Grade: API 5 l PSL2 X70M


2) At temperature -41℃,for V-shaped notch specimen, CVN test from welding seam and HAZ, minimum impact value for single specimen shall ≥30J and average impact value shall ≥40J. And CVN test from base material, minimum impact value for single specimen shall ≥60J and average impact value shall ≥80J.


After multiple welding procedure tests, Yulong has successfully optimized the existing welding procedure which is adopted during the pilot production. And after various physical and chemical properties testing and quality inspection for the pilot produced pipe, all the quality indexes of the carbon steel pipe are satisfied with specification standard and customer requirements. Since getting the production approval from the customer, we have already produced 4866MT qualified pipes.


The successful production of DSAW steel pipe with large diameter, thick wall thickness and high steel grade under -41℃ low temperature impact test requirements marks Jiangsu Yulong Steel Pipe Co., LTD. has gained a big breakthrough in pipe manufacturing technology and will have a greater advantage in the future market competition.

2016年7月8日星期五

LSAW STEEL PIPE

LSAW steel pipe is steel plate production, and is used in the production of spiral welded pipe hot rolled coil. The rolling process of hot strip mill has a series of advantages, which has the ability of producing high quality pipeline steel. For example, a water cooling system is installed on the output stage to accelerate the cooling, which allows the use of low alloy components to achieve a special strength grade and low temperature toughness, thereby improving the ability of the steel to be welded. But this system in the steel plate production plant basically did not. The content of alloy coil (carbon equivalent) are often lower than similar grades of steel, it also improves the weldability of spiral welded steel pipe. More to the point, as a result of the spiral welded pipe plate rolling direction is vertical pipe axis direction (the clip solution depending on the steel pipe of the spiral angle), and straight seam steel pipe plate rolling direction vertical to the axis direction of the steel pipe. Therefore, the crack resistance of spiral welded pipe material is better than straight seam steel pipe.
In welding process, spiral welded pipe and straight seam steel pipe welding method is consistent, but straight seam welded pipe inevitably will have a lot of T-shaped seam, so the existence of welding defects but also greatly enhance the probability, and T-shaped seam welding residual stress force is larger, the weld metal often in triaxial state of stress, increase the possibility of cracks. Moreover, according to the process of submerged arc welding, each weld should have arc ignition and extinguishing tube when the pressure is under internal pressure, usually on the tube wall to produce two main stresses, namely, the radial stress Delta Y and the axial stress Delta X. The synthesis of Y (l/4sin2 alpha +cos2 alpha) 1/2, which is the helix angle of the welded joint of the spiral welded pipe. Spiral welded pipe seam angle is 50-75 degrees, so the stress synthesis of spiral weld seam welded pipe is principal stress 60-85%. In the same work under pressure, with a diameter ratio of spiral welded pipe  wall thickness can be reduced. According to the above characteristics:DSAW steel pipe Bao Po, due to the weld is to be force and resultant stress is relatively small, Bao Po mouth is generally not originated in the spiral seam and its safety better than straight seam welded steel pipe is high.

2016年7月5日星期二

The situation of steel enterprise in the last six month

Held on June 29, cisa organization in the second quarter of the steel industry economic symposium, on behalf of the said iron and steel enterprise, iron and steel enterprise management benefit gradually turn for the better in the first half of this year, significantly better than the fourth quarter, most corporate profitability or loss-mitigation compared to the same.
1 - in May, according to cisa, sinosteel association, member of the iron and steel enterprise profit of 8.736 billion yuan, an increase of 7.38 times; Percentage of loss-incurring enterprises 28.28%, fell 13.13% year on year; Return on sales of 0.83%. From the monthly, a turnround in March, profit of 2.745 billion yuan; April and may achieve profit is 8.383 billion yuan and 8.522 billion yuan respectively.
In the first half of the industry production control is more rational, this is one of the reasons for the efficiency improvement. According to statistics, in May, China steel association, member of pig iron and carbon steel pipe enterprise, crude steel, rolled steel production 53.2495 million tons, 54.486 million tons and 54.486 million tons respectively, fell 1.43% year-on-year, down 0.68%, an increase of 0.3%. 1 - may, member of pig iron and steel enterprise, crude steel, rolled steel production 250.872 million tons, 254.7175 million tons and 254.7175 million tons respectively, fell by 2.91%, 2.64% and 2.31% respectively, compared to the drop were greater than the national average.
In addition, iron and steel enterprises in steel prices to calm, take measures actively stabilize prices, malignant price decrease. Enterprises in the aspect of inventory control is more rational. Statistics show that the steel enterprise inventory levels are lower than the same period last year, and basic is from 10% to 20% year-on-year, the overall level is low. In early June, China steel association member mills steel inventories of 14.2 million tons, rose 1.7%, down 12.93% year-on-year.
In addition, from the first half of corporate profits, the income gap between enterprise have a tendency to expand, benefit differentiation is obvious. Iron and steel enterprises still face financing difficulties, heavy historical burden, surplus personnel shunt placement under pressure. The direction for the second half of the representatives think that to practice early steel assistant manager would put forward the "production capacity, production control, protect benefit" policy, to grasp the good production rhythm, and to strengthen market, achieve steady profit, work earnestly implement dissolve excess capacity.
Hunan Great Steel Pipe Co.ltd will insist stable price for our customer.

Big diameter LSAW steel pipe should accelerate industry supply and demand dynamics

Vice President of China federation of logistics and purchasing Cai Jin is introduced, the current national commodity e-commerce platform, there are more than 580 steel involved more than 100, steel electricity in all commodities walk at the forefront in the electricity business.
"Economic growth is slowing, electric power, steel, non-ferrous industries such as coal downstream demand. Combined with the national environmental protection regulation increasing, adverse effect on the formation of coal industry." Expert analysis, in the next period of time in our province coal prices will remain at the low end. Similarly, mild steel pipe prices are weakening, the current steel market overall weak demand, light volume, prices in the short term to have improved markedly.
Specific will increase working strength in seven aspects: one is to further deepen the reform, promoting the transformation government function at all levels of the government, we will deepen reform of the state-owned enterprises and support the economic development of non-public sectors of the thick wall straight seam welded steel pipe, the maximum release reform bonuses, fundamental problem or a reform, the second is to speed up the transformation and upgrading of industry, and further bring into play the function of science and technology innovation support, upgrade traditional industries, the development of strategic emerging industries, to develop the producer services, in particular, promote the development of industrialization and information fusion.
3 it is to improve the quality of urbanization, urban agglomeration and urban layout, improve the urban comprehensive functions, but also accelerate the reform of urban old industrial zone, its resource exhausted city transformation and independent industrial relocation. Four is to speed up the development of modern agriculture, increasing food production capacity, the construction of green ecological agricultural base. Development of deep processing of agricultural products, the first to build a new type of agricultural management system. Five is a major livelihood project, we will continue to turn shantytowns into new housing areas, such as, carrying out the employment and entrepreneurship support policy to six is to strengthen the protection of forests, grasslands, wetlands and other key ecological, promote the overall status improving environment, finally, to further expand the opening to the outside world, deepen the northeast region's open, push with Europe and the United States developed countries in promoting the old industrial bases in northeast and promote the development of high-end industry cooperation.
Big diameter LSAW steel pipe should accelerate industry supply and demand dynamics

2016年7月2日星期六

Safe use of alloy steel pipe

Now because most factories will be alloy steel pipe production line, just want to use the characteristic of alloy steel pipe resistance to high temperature and high pressure, to help realize factory production safety, after all, for a factory, the production safety is king, but the premise is to safe use of alloy steel pipe, so how to realize the safe use of alloy carbon steel pipe?
First of all, the alloy steel pipe products conform to the requirements of the enterprise production, generally at the time of purchase of alloy steel pipe, our staff will provide some of the coefficient of safety in production for enterprise to the seller, then seller according to the requirements to select the type of alloy steel pipe as well as enterprise safe production. Now on the market there are many types of alloy steel pipe, and because the contain of the alloy elements, on the temperature and pressure are also different, so in the choice to data provided by enterprise to choose from.
Second, the alloy steel pipe surface inspection, generally produce alloy steel pipe surface treatment is very good, but in order to avoid the unqualified alloy steel pipe, at the time of purchase and check on the surface of the alloy steel pipe. Again, alloy steel pipe conditions of use, in use process, do not use the temperature or pressure, than the alloy steel pipe can withstand maximum, slightly tap is will shorten the service life of alloy steel pipe, and serious situation is may be accident.
Finally, alloy steel pipe daily management, at the time of using alloy steel pipe to prevent alloy steel pipe rust, so in the daily management, to ensure that the use of alloy steel pipe in a dry condition, don't appear the phenomenon such as the oil on it, if found to be positive after processing, prevent the use of time, the oil heating, alloy steel pipe is heated unevenly, and caused the tragedy.
Hunan great steel pipe co.,ltd have much pipe inventory of alloy steel pipe.