 |
Tumpukan linepipe.
|
1. Fusion Weld atau Continuous Weld
One process for producing pipe is Fusion Weld, sometimes called “Continuous Weld” and is produced in sizes 1/8” to 4-1/2”. Fusion Weld pipe begins as coiled steel of the required width and thickness for the size and weight of pipe to be made. Successive coils of steel are welded end to end to form a continuous ribbon of steel. The ribbon of steel is fed into a leveler and then into a gas furnace where it is heated to the required temperature for forming and fusing. The forming rolls at the end of the furnace shape the heated skelp into an oval. The edges of the skelp are then firmly pressed together by rolls to obtain a forged weld. The heat of the skelp, combined with the pressure exerted by the rolls, form the weld. No metal is added into the operation. Final sizing rolls bring the pipe into its required dimensions.
2. Electric Resistance Weld (ERW)
The processing of Electric Resistance Welded (ERW) pipe begins as a coiled plate of steel with appropriate thickness and specific width to form a pipe that conforms to its relevant specification. ERW pipe is cold formed. The ribbon is pulled An Introduction into the Production and Specification of Steel Pipe By Bill Buckland, President, Mandal Pipe Company 20 • Q1 • 2005through a series of rollers that gradually form it into a cylindrical tube. As the edges of the now cylindrical plate come together, an electric charge is applied at the proper points to heat the edges so they can be welded together. Electric Resistance Welded pipe is a high speed production product that can be made in continuous lengths up to 115’. It produces uniform wall thicknesses and outside dimensions and is made in a wide range of specifications. It does, however, require minimum tonnage to set up on a specific size and sometimes has long lead times.
Submerged Arc Welded (SAW) pipe derives its name from the process wherein the welding arc is submerged in flux while the welding takes place. The flux protects the steel in the weld area from any impurities in the air when heated to welding temperatures. When both inside welds and outside welds are performed, the welding is accomplished in separate processes and the pipe is considered to be Double Submerged Arc Welded (DSAW).
There are three common types of pipe produced by the DSAW process:
4. U&O Method
The U&O Method is so called because it first uses a “U” press, then an “O” press to complete cylinder forming from 40’ long plates ordered to size and grade. The cylinder is then welded inside and outside by the submerged arc process by using as many as five welding wires. Most U&O is cold expanded either mechanically or hydraulically. When it is cold expanded, DSAW pipe gains in yield strength. This method of pipe production produces exceptional quality with exact dimensional tolerances. The primary use of this type of pipe is gas and oil transmission. It requires large minimum tonnages for size setup and is only produced domestically in 40-foot lengths.
5. Rolled and Welded
This method of manufacturing is also called the “Pyramid Roll Method” because it uses three rolls arranged in a pyramidal structure. The plate, ordered by grade and thickness, is rolled back and forth between the pyramid rolls until the cylinder is formed. The cylinder is then moved to the welding stations. Most pyramid rolls are 20 feet in length or shorter. Greater lengths are achieved by girth welding the five-foot, 10-foot or 20-foot sections (or cans) together. Berg Steel is the only producer capable of rolling 40-foot plates without a midweld and it is the only producer capable of sizing its product. Rolled and welded pipe has the advantage of being rolled in small quantities with short lead times. It can be produced in very large diameters, either ID or OD, and in extremely thick walls. Since the cans are short in length, the production of composite piles or pieces varying in yield and tensile are easily attained. The rate of production of this material is slow and the cost is high due to multiple girth welds.
6. Spiral Weld
Spiralweld pipe is a steel pipe having a DSAW seam the entire length of the pipe in a spiral form. The outside diameter is determined by the angle of the de-coiled steel against the forming head. The more acute the angle, the greater the diameter. The production of large, hot rolled coils of sufficient width and the development of dependable non-destructive testing methods has enabled this product to be placed in more demanding service. Spiralweld pipe can be rolled in exact lengths up to 115 feet in either ID or OD dimensions up to 144 inches. There is a minimum tonnage required for rolling. Because the manufacturing process is slow, it gives the contractor an advantage of short term changes to the order. This same slow production can also be a disadvantage when large tonnages are needed with a short lead time. Spiralweld pipe is produced to limited specifications.
7. Seamless Pipe (SMLS)
Seamless Pipe is made when steel in a solid, round cylindrical shape, called a “billet” or a “tube round” is heated and then either pushed or pulled (while being rapidly rotated) over a mandrel with a piercing point positioned in the center of the billet. This activity produces a hollow tube or “shell”. The tube is then further finished until it becomes the size and wall thickness desired. (Because the pipe is formed in a heated manner the pipe is normalized and should have a consistent steel cellular pattern throughout its circumference). Seamless pipe is made in sizes from 1/8” to 26” and is widely used in construction, oil refining, chemical and petro-chemical industries. It is available in heavy wall thicknesses and exotic chemistries, and is suitable for coiling, flanging and threading. It is, however, expensive, in short supply and unavailable in long lengths.
Secara umum, metode fabrikasi pipa baja dapat dirangkum sebagai berikut:
 |
Bagan metode fabrikasi pipa baja.
|
1. Coiled strip is loaded onto feed table.
2. Strip is fed into roller leveler.
3. Ends of strip are sheared.
4. Leading end of coil is flash welded to trailing end of previous coil.
5. Strip is formed into loop.
6. Coil is delivered into furnace.
7. Strip is heated in furnace to approximately 2450°F, strip edge is heated to 2600°F.
8. Forming rolls bend strip into an oval. At the welding stand the heat in the skelp and the pressure of the rollsforms the weld.
9. Pipe is stretch reduced where the desired 00 and wall thickness are obtained.
10. Flying cutoff saw cuts pipe into double lengths.
11. Final 00 sizing on sizing mill.
12. Pipe is cut to finished length, straightened and inspected.
13. Pipe is hydrostatically tested, end finished, stenciled, and coated as required.
Sedangkan untuk metode ERW adalah sebagai berikut.
1. Coils of strip steel or skelp on feed ramp. From this position it is uncoiled, flattened, and the leading
edge of the coil is sheared.
2. First forming section transforms strip into a round pipe section.
3. Fin pass section finishes rounding process and prepares edges of strip for welding .
4. The edges of the strip are heated to 2500°F by high frequency welder. The edges are squeezed
together by pressure.
5. Weld is inspected electronically for some specifications.
6. Seam is normalized.
7. Weld is cooled by air and water.
8. Pipe is sized and straightened.
9. Pipe is cut to required length by flying cut-off saw.
10. Pipe is visually inspected.
11. Pipe is hydro-statically tested.
Final finishing includes inspection, end finishing, coated as required, and stenciled
Sumber : https://riomardhian.wordpress.com/author/riomardhian/page/2/
Tidak ada komentar:
Posting Komentar