CC BY
12
УДК 622.692
WELDING RENOVATION OF SUPPORTING UNITS IN GAP-CROSSING PIPELINE STRUCTURES
A.R. Dzyubyk1, V.M. Palash2, I.B. Nazar3, L. V. Dzyubyk4, R. V. Palash5
Existing elements of overpass's supporting units in pipeline transport had been analyzed. Also in this project operational loads that occur in areas of land pipelines were studied using a mathematical model that takes into account the possibility of vertical displacement supporting structure. Proposed to use welded /-beam section as a cross-bar for support. Calculation of selected beams and selection geometrical sizes of elements depending on the applied load were done. We have analyzed the influence of welding cycle on the formation of stress and deformation occurring at manufacturing of metal cross-bar /-section.
Keywords: support, pipeline, tension, welded joint, strength, bearing capacity.
Introduction and urgency of the problem. Pipeline overpasses occupy 2 % of the total length of pipelines, what is quite small amount. But they greatly affect the total performance of the system.
Gap-crossing structures or pipeline bridges serve to avoid major natural or man-made obstacles, such as steep cliffs, deep ravines, large boulders, swampy areas, roads or railways. Supporting units must be not just strong enough to support the pipeline (weight of the pipes and liquids or gases in it etc.), but also must be strong enough to face the influence of the external factors (the influence of the environment, axial position, subsidence of pillars etc.) Last can greatly change tensions that can lead to cracks [1, 2].
Usage of standard building components and their installation schemes do not always satisfy the operating conditions, especially in potentially dangerous areas like mountain massifs. There may be a slight overload cross-bars supporting units support pipeline. In particular, under the influence of temperature changes (daily and seasonal), changes in operation modes pipelines all that can lead to horizontal and vertical movement of pipes leading to cracking (Fig 1, a) and fracture of standard concrete structures (Fig. 1, b).
1 доц. А.Р. Дзюбик, канд. техн. наук - НУ "Львiвська полггехшка";
проф. В.М. Палаш, канд. техн. наук - НУ "Львiвська полггехшка";
3 доц. 1.Б. Назар, канд. техн. наук - НУ "Львiвська полггехшка";
4 Л.В. Дзюбик, канд. техн. наук - НУ "Львiвська полггехшка";
доц. Р.В. Палаш, канд. техн. наук - НУ "Львiвська полиехшка"
а)
Fig. 1 gap-crossing supporting unit [4]:
a) cracks in concrete cross-bar; b) cross-bar fracture
230
Збiрник науково-техшчних праць
One way to restore supporting unit are installing on them a metal casing caps that are connected to metal bolt [4, 5] After removal of the destroyed concrete beam, metal cylindrical structure was installed. However, the question of choice is not disclosed. It is known [6] that complex beam cross section are used more often. They take into consideration specifics conditions (presence of a significant cross-load), and the cost of materials and complexity of manufacturing is more economical compared to other types.
Main task and object of the work. In designing beam engineering structures static calculation scheme must be performed. We have to determine the estimated efforts of the load and make constructive design that would satisfy the requirements of strength, stiffness, durability and operating conditions. Taking into account the conditions of a cross-bar [1-4] and system of loadings metal welded I-beam should be used. It is important to evaluate the welding deformation of the structure.
Main part. Installing duty operation perform for lifting the pipeline to replace the cross-bars. Thus there is a change of reactions in towers and redistribution of bending moments at least in two adjacent runs.
In this project mathematical model is used that represents the pipeline in the form of a continuous beam many supporting beams, mounted on bearings with the possibility of vertical adjustment [7, 8]. To determine the moments and reactions of towers a system of linear algebraic equations were used derived from the conditions of equality beam deflection, elastic movement of supports and conditions of the balance of forces and moments:
Nr Np Nq
JRR,(L-ai) + JpPk(L-ck) + XqAj(L-b0)= 0 , (1)
i=1 k=1 j=1
Nr Np Nq
JRR, + JpPk + X qAj = 0 , (2)
i=1 k =1 j=1
Nr Np Nq
wo + 00ai + £ Rm&(ai - am) K (ai,am)+Kfti = zt - £ P0(ai - ck) K (a„ck)- X qHj (ai). (3)
m=1 k=1 j=1
where ai,Ki, zi, i = 1, NR — coordinates, compliance rates and the initial position supports; [dm,dm+1), m = 1,2,...,ND — some parts of the flyover pipeline where the bending rigidity Dm = (nd3 SmEm) /8 is constant, dr , Sm, Em diameter, thickness and Young's modulus of deflection; at points ck, k = 1,2,...,Np concentrated loads act on the pipeline Pk, and at [bj,bj+1), j = 1,Nq (within the areas of a constant rigidity) distributed load of constant intensity qj. Than A j = bJ+1 - bj Sustainable length of the load, and b0 = (bj+1 + bj)/2 — their centers; Ri, i = 1,Nr — supports reaction; S(x) — Dirac function, 0(x) — Heaviside function; K(x,a) — Cauchy function; wo,0o,M0 ,Q0 initial parameters of deflection, angle of rotation, bending moment and power of section; H j(x) — Cauchy integral of the function.
Using equation (1)—(3) we can get the necessary information to perform repair work. For this we use the results of pipeline inspection (the reaction of some sup-
ports, their relative spatial location and position of the axis of the pipeline). It is actual for the case of study sites of pipes adjacent to the ground where their elastic interaction leads to reduction in the burden on the edges of the pipe and the corresponding increase on neighboring pillars. This pipe is considered as a system of finite rod elements mounted on elastic bearings [7].
Analysis of the results showed that the value of reactions supports changes in the operating and repairing load may significantly grow. When designing pipelines or performing their repair the value of supports reactions ranging from 50 kN to 100 kN. The influence of external factors such as landslides, supports compliance etc. increase this amount to 200 kN.
Conditions of design. Consider the design of welded beam length l = 5500 mm, which is free on supports. Because of the significant burden and advice literature [3, 6] will use structural steel brand 15 ХСНД that has now foreign analogs. It is characterized by good technological weldability and not prone to cracking as a result of the thermal cycle of welding. Allowable stress factors based on the conditions 0.9 and set overload n = 1,2 at p = 225 MPa. Beam cross-bar evenly loaded with its own weight (q) and two point loads (P) of pipelines (Fig. 2). The distance between the axes of the pipes is 2.5 m, they are located symmetrically relative to the center of cross-bar. Due to the influence of natural factors pipes can do transverse movement. The largest beam deflection of cross-bar f) shall not exceed 1/500 of its length. Planning is done on the basis of existing pressures, the possibility of transverse displacement of pipes and provision of general and local strength. The size of the load (P) taken as 100 kN
Calculation of loads from concentrated forces carried out we take like one of the pipes is located above the top line of influence and that is M£ = 0,227 MNm. This line spur of the moment and transverse forces built to analyze possible cases of pipe displacement across cross-bars in the transverse direction.
Fig. 2 Calculation of loads in the beam, P, q - loadfrom pipe weight and cross-bar
Then resistance torque, taking into account the allowable stress, will be W = 0,000677 m3. The total value of the transverse force concentrated and evenly distributed loads equal Q = 156,33 kN.
Designing of cross-bar welded beam. The lowest elevation beam stiffness of f 1
conditions — is =- (Fig. 3, a). After consideration of allowable stresses and
l 500 V 5 7
geometrical characteristics of beam get the following relationship [7, 8]:
h = 0,8[a]p • l[1 -(4/3)(a/l)2]/(4Ef) = 0,096. Then, for the length of cross-bar
5.5 m, its height by stiffness will be 0.53 m. To determine the height of the smallest section, you must know the thickness of the vertical sheet. For this purpose, the follo-
wing approximate equation is used: SB = 5 = 5,828==6 mm. than -
h = (1,3-1,4)^M/SB [a]p =(0,437-0,471) m.
Since the resulting value is greater than the required minimum, we take the height of the vertical wall (hB ) equal to 0.5 m. It takes into account the installation of two shelves designed for /-section. Using the previous calculations, you can set the required cross-sectional area of a shelf: F = 850 mm2. Then, accordingly, its thickness (Sp) will be 10 mm, and the width (s p) 85 mm. The resulting geometric characteristics of beam cross-bar shown in Fig. 3 b.
Checking for most normal stress in the surface layer of the beam:
amax = Mymax = 229,1 MPa and tangential tension at gravity center of the beam in its
QS
reference section: t = ^— = 60,8 MPa. This means that the construction satisfies the ISb
conditions of strength.
Sustainability of the beam is achieved welding of stiffeners to the vertical wall. We accept the distance between the stiffeners: a = 1,5 • hB = 1,5 • 0,5 = 0,75 == 0,8 m. To test the stability of the wall you must consider the stiffeners, and then determine the critical stress and stability check of the construction [6, 8]. Here, the normal stress in the surface layer of the vertical sheet is a = 229,1 MPa.
Average tangential tension of transverse forces in the middle run is:
Q
hB§B
= 18,18 MPa. Local tension am under concentrated force (Fig. 3, c):
P
am =-= 152,8 MPa. The value of the notional length (z), which concentrated load
Sbz
from the effects of a pipeline is divided in the vertical wall of cross-bar:
z = 3,25 • 3— = 5,45 cm. \hn '
To verify the installation stiffeners (Fig. 3, d) use is recommended in the literature [6, 8] following equation:
a+am f+f t f < 1,
a aMo) V To)
where ao - normal stress on the upper edge of the vertical sheet To - the average tangential stress, aMo - factors that take into account the geometric characteristics of the projected beam cross-bar.
Applying appropriate expression [6, 8], found that ao = 600 MPa; to = 233,4 MPa; aMo = 533,8; am = 152,8 MPa and t = 18,8 MPa, means
V 2 / \ 2
229,1 152,8 ^ ( 18,8
600 533,8 1 (233,4
+--— I +1 —-— I = 0,672 <1 - vertical sheet resistance in the middle of a
span is provided. Similarly, the test performed in other sections of the supporting pipe-centers.
Design of welded joints. Legs upper and lower joints is taken equal to the thickness of the vertical wall, K = 6 mm (Fig. 3, d). In the lower joints are tangential
Q ■ S
stress: t = —Q-= 52,1 MPa. Here Q - the largest force in the transverse beam,
0,7 ■ 2 ■ I ■ K
S - static moment relative to the center of gravity, I - inertia moment the beam. Despite the fact that the working tension low, legs length is not changed. In the upper joints, to the calculated stresses added value (tp ) from the concentrated power P. Local tensions at the joint K = 6 mm and the coefficient (n), equals the following: n ■ P
tp =-= 87,3 MPa. Allowable stresses in lap joints determine the value of
2 ■ z ■ 0,7 ■ K
[T] = 0,65 ■ [a]p = 146 MPa. Conditions strength: tpe3 < [t] for designed welded joints
( tpe3 =s]t2 + tp 2 = 90,4 MPa). Legs of stiffeners joints accept the same.
b) Y,
a)
a
£
■ù
K=6 mm
dj
-L
K=6 mm
llliuillllllllllllllllllllllllllllllllllllin
a = 800 mm
Fig. 3. Calculation welded beams geometric parameters:
a) calculation the height of the beam depending on the stiffness conditions; b) chosen profile of beams; c) taking into account the local influence of concentrated force made by weight ofpipeline; d) the location of the beam stiffeners
Definition shrink force and deformation. When welding stresses and deformations can affect the geometric dimensions of welded construction [9, 10]. For T (I)-beams is the most significant bending. They are caused by shrinkage of longitudinal joints. If first perform welding T-beam and then I-beam the deformation of deflection have to be find each weld separately. The difference between the obtained values will cause the resulting deflection. Automatic submerged arc method recommended for this type of structures [6]. Based on recommendations of literary data [9], to determi-
ned weld legs (6 mm), accept that the welding current (Iwd) = 450 A; Voltage (Uarc) = 34 U; welding speed (V) 40 m/h; efficiency (Z = 0,9.
Determine where the heat spreads from the welding heat source: S0 = 2Sp + SB = 2 10 + 6 = 26 mm. Then brought linear welding energy is:
q0 = I-Un = 4766 J/cm2. The dimensions of the active area by the Troche's method
V So
[10, 11]: bn = b + b2, where b1,b2 - width heating to plastics and elastic-plastic deformation in element.
Here: b = 0'484q°, C/ - volumetric heat capacity, j/(cm3 °C), for steels cyT
5,2 j/(cm3 °C)), b2l = K2 (h, - b), i = 1,2; h, - width of areas where heat spreads; T * -temperature loss of stability of material (T* = 600for low-alloy steels). If hi > 30 cm, than b2i is: b2i = K2(30 - bi). Coefficient K2 depends on q0 and is calculated by the formula [11]: K2 = 7.143 10-2 + 0.2086 10-2 • q0 10-3 - 0.054 10-4 • q0 10-3.
So, K2 = 0.133. Then to the left and right sides of the shelf beams, for shelves of I-beams b2L Sh = b2R Sh = 0.133 • (14 -4.9) = 1.21 cm. For vertical h, > 30cm, than b2B = 0,133 • (30 - b) = 3.33 cm.
Then to the left and right sides of the shelf beams for shelves. Fn = (2b + 2b2n + Sb ) Sn + (b + b2B )SB + K 2, where K2 - sectional area of welds T-beam. So, FN = 401,5 mm2. Then reactive tensions by the Troche's method [10] equal: <tp = °T Fn , where aT - proportional limit
F - Fn
of material (<T = 350 MPa); F-sectional area (for T-beam (Fm) 3850 mm2 and for I-beam (FI) 4700 mm2). Then reactive tensions for T-beam <PT = 40,75 MPa; and <PI = 32,68 MPa for I-beam.
The obtained values allow to calculate the longitudinal shortening of beams:
p longitudinal j a /longitudinal _ psbrmkage
Short. = ^ r , E • F
where l - the length of the beam (5500 mm); PshSgkudinal = (<t + \<p\) • Fn - shrink force of longitudinal shortening; E - Young's modulus.
Then we get that T-Beam shrink force (PTog^hn^e) is 159,93 kN for the longitudinal reducing (Al^^T-beam) 1,067 mm, and for I-beam P-nga^bmAage = 154,16 kN and AlSSfOT/-beam = 0,856 mm.
The next step is to determine the center of gravity of welding elements and their active zones. This will help determine the bending moments during welding. (Fig. 4): Mx = PsSonnbugd!nale>', where e - eccentricity (distance from the center of mass
the active zone to the center of gravity of the cross section of welded construction): for 7-beam 189,9 mm, for I-beam 246,2 mm.
Thus, the bending moments as a result of shrinkage forces are: for 7-beam -Mx T = 29793 N-m an MxI = 37829 N-m for I-beam. From here you can find the deflection figures (Ix) from the cross-sectional moment of: fy = Mx 1 . for 7-beam
8 ' E ' Ix
(fy T) is 13,24 mm, and for I-beam (fyI) - 5,52 mm.
Fig. 4 Calculation of T-beam deflection Then we get the following definition of total deflection:
fy I = fy T - fyI = 7,72 mm.
Bending tensions that caused by this deflection, is of:
4' E' h ' f
G = 4 E h fmax = 111,5 MPa.
So, as a result of implementation of welding operations, there is quite a significant deflection. It does not exceed the regulatory requirements for this type of ele-
fmax 1 1
ment < "600 + 700 [6], but when performing repair work is necessary to take into
account. According to the sample above, other support structures were designed (Table. 1) Taken into account the need for typical elements because their thickness in all cases are the same.
Table. 1. Calculating beam's cross-sections for different loans._
p, kN Calculated loans Sizes of elements, mm Conditions of strength
MN-m Q, kN &B hb sp sp z, mm Jf T+f T * 1 (To (Jmo ) \ to ) text < [t]
50 0,077 79,06 6 320 10 74 52,1 0,598 50,0
100 0,152 156,33 6 500 10 85 54,5 0,672 90,4
150 0,227 233,61 6 530 10 140 64,4 0,639 117,2
200 0,302 310,87 6 620 10 155 66,6 0,897 149,1
As we see the increasing load on cross-bar makes necessary to use of large cross section. In this vertical sheet resistance is provided in all cases. However, for maximum load there is a slight excess of the limit stresses in welds. In this case it is necessary to increase the thickness of the zone beams.
Науковий вкник НЛТУ Украши. - 2016. - Вип. 26.1
For selected /-beam with it liner characteristics the calculation were made to find the level of internal forces, causing shrinkage of the material after welding cycle welding cycle is done. Since the legs and thick welds elements were the same in all cases, the mode options match the options above.
Table 2. Calculations of welding stresses and deformations
Р, kN Fn , mm2 plongi. kN T-beam.shrinkage' plongi. kN I-beam.shrinkage , fy Т , mm fyi, mm fy E, mm Cbd, MPa
50 389,9 159,93 154,16 23,85 9,31 14,54 137,3
100 401,5 156,87 153,63 13,24 5,52 7,72 111,5
150 459,1 178,57 174,04 8,42 3,34 5,07 77,5
200 474,8 182,62 178,61 6,68 2,69 3,98 70,8
Thus, increasing the beam cross-section leads to increasing shrinkage forces during welding on the same linear energies. This increases rigidity, which would reduce the total value of construction deformation and value of bending stress that it causes.
Conclusions. Analysis used in pipeline transportation elements overpasses show that the usage of welded beams in repair works allows to satisfy much more exploitation conditions. The calculation and choice of beams geometrical sizes of elements for the case of the overpasses with two pipelines. Learned influences of welding cycle on stress and deformation occurring in the cross-bar. The total welding deformation can be from 4 to 14 mm. Therefore, to satisfy specified position welding deformations should be taken into account.
Лггература
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Надклано до редакцп 24.02.2016 р.
Дзюбик А.Р., Палаш В.М., Назар 1.Б., Дзюбик Л.В., Палаш Р.В. Засто-сування зварних опорних вузлiв шд час ремонту надземних переходiв ма-пстральних трубопроводiв
Проанал1зовано наявш елементи опорних вузл1в надземних переход1в у трубопроводному транспорт^ Вивчено експлуатацшш навантаження, як виникають у надземних дшянках мапстральних трубопровод1в ¡з використанням математично! модели що вра-ховуе можливють вертикального змщення опорних вузл1в. Запропоновано використо-вувати зварну балку двотаврового перер1зу для ригеля опори. Проведено розрахунок прийнято! балки та виб1р геометричних розм1р1в ц елеменпв залежно вщ прикладеного навантаження. Дослщжено вплив зварювального циклу на напруження та деформацп, що виникають шд час виготовлення металевого ригеля двотаврового перер1зу.
Ключовi слова: опора, трубопровод, напруження, зварний шов, мщшсть, несна здатшсть.
Дзюбык А.Р., Палаш В.Н., Назар И.Б., ДзюбыкЛ.В., Палаш Р.В. Применение сварных опорных узлов при ремонте надземных переходов магистральных трубопроводов
Проанализированы существующие элементы опорных узлов надземных переходов в трубопроводном транспорте. Изучены эксплуатационные нагрузки, возникающие в надземных участках магистральных трубопроводов с использованием математической модели, учитывающей возможность вертикального смещения опорных узлов. Предложено использовать сварную балку двутаврового сечения для ригеля опоры. Проведен расчет балки и выбор геометрических размеров ее элементов в зависимости от приложенной нагрузки. Исследовано влияние сварочного цикла на напряжения и деформации, возникающие при изготовлении металлического ригеля двутаврового сечения.
Ключевые слова: опора, трубопровод, напряжение, сварной шов, прочность, несущая способность.
УДК 630.32.002.5
ВИКОРИСТАННЯ ПЛАСТИКОВИХ ЛОТКОВИХ СИСТЕМ ДЛЯ ПЕРВИННОГО ТРАНСПОРТУВАННЯ ДЕРЕВИНИ
В.В. Кий1,1.Ф. Коляджин2
Порушено проблему технолопчного освоения сухостшних ялинових насаджень на схилах Карпат. Проаналiзовано можливi засоби первинного транспортування дере-вини пiд час ix розроблення. Оценено пошкодження, якi виникають унаслщок викорис-тання рiзниx засобiв трелювання деревини та ефективностi ix використання. Обгрунто-вано доцiльнiсть використання пластикових лоткових систем на трелювальш в гiрськиx умовах пiд час загегавельних робiт у суxостiйниx насадженнях.
Ключовi слова: лотковi системи, транспортування, сухостшш насадження, техно-логiя, деревина.
1 доц. В.В. Кий, канд. техн. наук - НЛТУ Украши, м. Львгв;
2 директор 1.Ф. Коляджин, канд. с.-г. наук - державне шдприемство "Брошнгвске л1сове господарство"
238
Збiрник науково-техшчних праць
