Kā iegūt augstas kvalitātes cauruļu līkumu?

Kas ir caurules līkums?

Pipe bend is a type of pipe fitting product for any offset or change of direction in the piping systems. It signifies that there is a “bend” i.e,  a change in direction of the piping (usually for some specific reason) – but it lacks specific, engineering definition as to direction and degree. Bends are usually made by using a bending machine (hot bending and cold bending) on site and suited for a specific need. Use of pipe bends are economic as it reduces number of expensive fittings.

Type of Pipe bend

A pipe bend means a piece of pipe which are bent to some angle to join two pipings. they can be nearly any bending radius and angles . Pipe bends are commonly produced on site to meet a specific need by hot induction bending or cold bending. A elbow means a specific pipe bend as per the standard ANSI/ASME B16.9 (or EN 10253, or other pipe fittings standards). Commonly the elbows have a bending radius of 1.5D or 1D (Here the D means nominal diameter of this bend) ,which are called “Long Radius elbow (LR elbow)” or “Short Radius elbow(SR elbow)” . and the angle of an elbow is 45 degree or 90 degree usually, some times there are also custom-designed elbows which are 30 degree,60 degree ,180 degree or other angles.

The pipe bends should be as per the standard of ANSI/ASME B16.49 which did not specific the bending radius and angle , the regular pipe bend radius are 2.5D, 3D ,5D ,7D or 8D , but it can be any other bending radius according to the design need, and bending angle can be in any degree, 5 ,10 ,15, 90 degree or any other. People said “All bends are elbows but all elbows are not bend”, it is not true . Actually “All elbows are pipe bends but not all bends are elbows” is more reasonable.

3D pipe bend : A 3D pipe bend is a pipe bend that the bend radius is 3 times the pipe outside diameter. 5D caurules līkums : The RADIUS of a 5D pipe bend is actually what is 5 times the nominal diameter. So if you had a 10″ diameter pipe, the radius of the centerline of the bend would be 50 inches. 7D caurules līkums 12D caurules līkums 180 Degree pipe bend

Small size caurules līkums: Small size pipe bending is a pipe bend that the bend radius is 3 times the pipe outside diameter. Large size caurules līkums: The large size pipe bending is used to change the direction of run of pipe. Butt-welded caurules līkums Seamless caurules līkums High pressure caurules līkums: A High pressure pipe bending is a pipe bend that used in high pressure application.

Pipe bend, Bend pipe, Pipe bending, ANSI, ISO, JIS and DIN Standards, Measures 1/2 to 48 Inches.

Pattern	figure
Nominal size	1/2”-48” (DN15-DN1200)
Wall thickness	2-100mm
Angle	Degree15,20,45,60,90,135,180
Type	3, 4, 5, 6, 7, 8, 10, 45, 90 and 180D

Materiāls

They are manufactured utilizing higher grade raw material, advanced machines and technologies.

• Carbon steel:
  • SA234 WPB, SA234 WPC,SA42 WPL6, SA42 WPL3
  • WP1. MSS-SP75, WPHY,WPHY 46,WPHY 52
  • WPHY 56,WPHY 60,WPHY 65, WPHY 70
  • DIN 1629 St37, RST37.2 St52, STPG38
• Stainless:
  • ASTM/ASME SA403 304,304L ,316, 316L, WP304L, 3 WP316 WP347 (H) ,WP317 (L),WP321.
  • DIN 1.4301, 1.4306, 1.4401, 1.4571
  • JIS SUS304,SUS304, SUS304L, SUS316, SUS316
• Alloy:
• ASTM/ASME SA234 WP12, WP11,WP22, WP5, WP9, WP91, ASTM B361 GR.3003-6061, ASTM B366 UNS
• N04400,N08800, N08825 N1001-N10276-N10665, WPT2-WPT12
• ASTM 182 F1, F5, F6, F7, F9, F11, F12, F22, F51, 16MnR Cr5Mo
• 12Cr1MoV 10CrMo910 15CrMo 12Cr2Mo1, St45.8

Elbows Or Pipe Bends Manufacturing Process:

Mandrel method (Hot Forming)

• One of the most common Pipe Fittings Manufacturing Process for manufacturing Elbows Or Pipe Bends from the pipe is mandrel method which is kind of hot forming methods.
• In this method, the pipe is cut in pieces and push with the help of hydraulic ram. It is pushed over a die called “mandrel” which allows the pipe to expand and bend simultaneously.
• This method can be used to manufacture a wide range of the diameter of elkoņi or pipe bends
• 
  
• ELBOWS Or Pipe Bends Mandrel method

Extrusion Method

In cold Extrusion method, a pipe with the same diameter as finished product is pushed through a die and formed into its desired shape. Usually applied to stainless steel small to medium sizes elbows or pipe bends.

Extrusion Method

UO Method

UO method is used to manufacture medium size of the elbow, tee, and reducers. The plate is cut out into a specially designed shape, it is formed first into a U-shape using a die and then into an O-shape or tubular form using another die, that is why this method is known as UO method. Once the fittings formed in tumbler shaped it is welded from inside and outside of the closing seam. A cut plate is 1st from in U shape and then in O shape.

UO Method

Hot Forming Method

In a Hot Forming Die Bending method, a Pipe is heated to forming temperature & formed in the die with the specific shape, this process may be repeated as needed to obtain the required shape, size and wall thickness. Usually applied to thick-wall items that cannot be bent on a mandrel die.

Hot Forming method for elbow or pipe bend Ražošana

Kā aprēķināt cauruļu līkumu

Whether you are bending pipe for running electrical conduit or a metal project, calculating the bend for the start and end point can be an important factor. While there are different types of pipe benders on the market, they all share a common identification for the operation. Identified on all pipe benders is the size of pipe the unit will bend along with a number called the “take up.” The take up measurement is used for adding or deducting an allowance in the overall length of the bend. By following a basic process, you can calculate pipe bends regardless of the type of bender or the diameter of pipe.

Identify the take up measurement that is located on the pipe-bending shoe itself. This is the addition or deduction of measurement to the length of pipe from the front mark on the bending shoe. Also be aware that there is a second center-of-bend mark located approximately in the center of the bending shoe. Also located along the running length of the shoe are angle markings with lines. These numbers and lines correspond to actual angles that can be bent into the pipe by aligning the pipe with the angled line marked on the outside of the shoe.

Izlieciet 90 grādu leņķi ½ diametra caurulei ar ½ collas liekteni. Dažāda izmēra caurulēm un dažādu izmēru liekšanas ierīcēm process paliks tāds pats, atšķirsies tikai pacelšanas mērījums. Uz ½ collas caurules uz kurpes var būt norādīts uzraksts "stublājs paceļas 5 collas no bultas vai līnijas". Šie 5 collas ir summa, kas jāatskaita no 90 grādu līkuma kopējā garuma.

Izmantojiet mērlenti un zīmuli un atzīmējiet 12 collas no caurules gala. Tas būs attālums no līkuma līdz caurules galam. Izmantojot atvilkuma mērījumu uz kurpes, izmēriet 5 collas atpakaļ no 12 collu atzīmes un uzzīmējiet vienlaidu zīmuļa līniju.

Novietojiet cauruli uz līdzenas virsmas un ievietojiet cauruli liekšanas ierīcē. Cietā zīmuļa atzīme jānovieto 5 collas atpakaļ no 12 collu atzīmes, un tai jābūt vienā līknē ar priekšējo zīmi vai bultiņu uz liekšanas kurpes. Ar vienmērīgu kustību velciet atpakaļ rokturi, līdz caurule atrodas 90 grādu pozīcijā attiecībā pret līdzeno virsmu. Novietojiet mazo līmeņrādi pret caurules vertikālo daļu un pārbaudiet, vai tā ir līdzenumā. Tādējādi iegūsiet perfektu 90 grādu saliekumu. Pārbaudiet kopējā līkuma augstumu, novietojot mērlentes galu uz līmeņrāža pamatnes un izmēriet caurules galu. Tam jābūt precīzi 12 collas.

Practice with other angled bends by using the deduction measurement and the center of the bend mark on the shoe. All pipe benders may have their own quirks and slight measurement adjustments that will have to be done. The actual end result also depends on how well and secure you hold the pipe in the bender, prior to the first bend you place on the pipe.

What is an elbow?

Elbow angle can be easily calculated using simple geometrical technique of mathematics. Lets give an example for you. Refer to Fig.2. Pipe direction is changing at point A with the help of an elbow and again the direction is changing at the point G using another elbow.

Fig.3: Code equation for minimum thickness requirement calculation

Here,

End Connections:

For connecting elbow/bend to pipe the following type of end connections are available

• Butt welded: Used alongwith large bore (>=2 inch) piping
• Socket welded: Used alongwith pipe size
• Screwed:
• Flanged:

What is the difference between a Pipe Bend and an elbow?

The difference between them is as follows:

1. Bend is a generic term for any offset or change of direction in the piping. It is a vague term that also includes elbows.
2. Elkonis ir inženiertehnisks termins, un tos klasificē kā 90 grādu vai 45 grādu, īsa vai gara rādiusa.
3. Elbows have industrial standards and have limitations to size, bend radius and angle. The angles are usually 45 deg or 90 degrees. All others offsets are classified as pipe bends.
4. Loki parasti tiek izgatavoti vai izgatavoti atbilstoši cauruļvadu vajadzībām; tomēr līkumi ir iepriekš izgatavoti un standarta, un tie ir pieejami no plaukta.
5. Līkumi nekad nav asi stūri, bet elkoņi ir. Cauruļu lieces paņēmieniem ir ierobežojumi attiecībā uz to, cik lielu materiāla retināšanu var pieļaut, lai droši noturētu ietvertā šķidruma spiedienu. Tā kā līkumi ir iepriekš izgatavoti, lieti vai metināti, tie var būt asi, piemēram, taisnie leņķi un atgriezeniskie līkumi, kas ir 180 grādu leņķī.
6. Elkonis ir standarta veidgabals, bet līkumi tiek izgatavoti pēc pasūtījuma.
7. Līkumos, kad caurule ir saliekta un nav metināšanas, ir mazāka caurules berze un plūsma ir vienmērīgāka. Elkoņos metināšana var radīt zināmu berzi.
8. Visi līkumi ir līkumi, bet visi līkumi nav līkumi.
9. Līkumam ir lielāks rādiuss nekā elkoņiem.
10. Parasti būtiskākā atšķirība ir izliekuma rādiuss. Kolenēm parasti ir izliekuma rādiuss no viena līdz divreiz lielākam par caurules diametru. Loku izliekuma rādiuss ir vairāk nekā divas reizes lielāks par diametru.

Short Radius and Long Radius

Elbows are again classified as long radius or short radius elbows. The difference between them is the length and curvature. A short radius elbow will be giving the piping a sharper turn than a long radius elbow.

1. In a long radius elbow the radius of curvature is 1.5 times the nominal diameter. In a standard elbow the radius of curvature is 1.0 times the nominal diameter of the pipe.
2. Long radius elbows give less frictional resistance to the fluid than the short elbows.
3. Long radius elbows create lesser pressure drop than short radius elbows.
4. Short radius is less costly than long radius elbows.
5. The short radius elbows are used where there is scarcity of space.

In addition to this classification the elbows are 45 degrees, 90 degrees and 180 degrees also called as a return elbow.

The 45 degrees elbow turns the fluid /piping at 45 degrees and so on.

Miter bends

Another type of bend is a Miter bend. A Miter bend is a bend which is made by cutting pipe ends at an angle and joining the pipe ends. A true miter bend is a 90 degree bend made by cutting two pipes at 45 degrees and joining them by welding.  Similarly three pipes cut at 22.5 degrees will give a 90 degree miter bend.

In the next article we will discuss about various pipe fittings.

“All bends are elbows but all elbows are not bends.”

Infact, the pipe is bent to form an elbow.

Elbows are pre-fabricated and are firm in design.

There are issues with bends since the tickness at the bend radius reduces as we bend the pipe.

Sharp bends are normally called Elbows. Bends typically have a minimum bending radius of 1.5 times pipe radius (R). If this bending radius is less than 1.5R, it is called Elbow. Reference to any international / industry standard need to be traced. 1.5, 3 & 4.5 R are the most common bending radii in industry.

An “elbow” and a “bend” are two different animals – as the terms are generally employed in the process industry.

A BEND is the generic term for what is called in piping as an “offset” – a change in direction of the piping. A bend is usually meant to mean nothing more than that there is a “bend” – a change in direction of the piping (usually for some specific reason) – but it lacks specific, engineering definition as to direction and degree. Bends are usually custom-made (using a bending machine) on site and suited for a specific need.

An ELBOW, on the other hand, is a specific, standard, engineered bend pre-fabricated as a spool piece and designed to either be screwed, flanged, or welded to the piping it is associated with. An elbow can be 45Deg or 90Deg. Var būt arī pēc pasūtījuma veidoti līkumi, lai gan vairums no tiem ir kategorizēti kā "īsā rādiusa" vai garā rādiusa".

A bend can be an elbow; an elbow does not mean a bend. If you use the term elbow, it should also carry the qualifiers of type (45 or 90Deg) un rādiuss (īss vai garš) - papildus nominālajam izmēram.

Additionally, if you are using tube and not pipe, there is a marked difference. As you can bend tube for pressure applications you will get less interuption and turbulence in your flow; this translates to less pressure drop than with fitted 90 or 45Deg elbows.

Long radius elbow is used to change the direction of flow gradually, 90 degrees.

• Short radius elbow is used to change the direction of flow rapidly, 90 degrees.
• 45° elbow is used to change the flow only 45°.
• Return bends are used to change the direction of flow 180°.

Apstrāde:

Fiziskā atšķirība starp garā rādiusa un īsā rādiusa elkoņiem ir grafiski attēlota pievienotajā darbgrāmatā, ko esmu izveidojis šim pavedienam.

Tālāk ir aprakstīti kritēriji, kurus izmantoju, pieņemot lēmumu par to, kuru izmantot:

Garā rādiusa līkumus izmanto, ja:

• ir jāsamazina berzes šķidruma spiediena zudumi līdz minimumam;
• ir pietiekami daudz vietas un tilpuma, lai varētu veikt plašāku pagriezienu un radītu mazāku spiediena kritumu;
• transportējamais šķidrums ir abrazīvs vai satur cietas daļiņas.

Īsā rādiusa līkumus izmanto, ja:

• ir nepieciešams samazināt elkoņu izmaksas;
• trūkst vietas un tilpuma, lai varētu izmantot garā rādiusa tipu.

Avots: Ķīna Caurules Bend Manufacturer - Yaang Pipe Industry Co., Limited (www.ugsteelmill.com)

(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)

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Atsauces:

• https://www.marineinsight.com/tech/pipeing/pipes-and-bends-an-essential-guide-for-second-engineers-part-2/
• http://www.whatispiping.com/piping-elbows-and-bends
• https://www.yaang.com
• https://hardhatengineer.com/pipe-fittings/pipe-fittings-manufacturing-process/