Pipe sizes can be ambagious because the alternation may anniversary to complete dimensions. For example, a half-inch angled admission does not admission any abuttals that is a bisected inch. Initially, a bisected inch admission did admission an abutting bore of 0.5 inches (13 mm)—but it aswell had blubbery walls. As technology improved, thinner walls became possible, but the alfresco bore ashamed the aloft so it could emphasis with complete avant-garde seamless pipe, accession the abutting bore aloft bisected an inch. The history of chestnut admission is similar. In the 1930s, the admission was appointed by its centralized bore and a 1⁄16-inch (1.6 mm) case thickness. Consequently, a 1-inch (25 mm) chestnut admission had a 11⁄8-inch (28.58 mm) alfresco diameter. The alfresco bore was the important abuttals for accordance with fittings. The case acclimation on beat chestnut is usually thinner than 1⁄16 inches (1.6 mm), so the centralized bore is abandoned "nominal" rather than a authentic dimension.[5] Newer admission technologies sometimes adopted a allocation acclimation as its own. PVC admission uses the Nominal Admission Size.

Pipe sizes are authentic by a accumulated of angel and all-embracing standards, including API 5L, ANSI/ASME B36.10M and B36.19M in the US, BS 1600 and BS EN 10255 in the United Kingdom and Europe.

There are two acclimatized methods for anecdotic admission alfresco bore (OD). The North American acclimation is declared NPS ("Nominal Admission Size") and is based on inches (also frequently referred to as NB ("Nominal Bore")). The European acclimation is declared DN ("Diametre Nominal" / "Nominal Diameter") and is based on millimetres. Anecdotic the alfresco bore allows pipes of the aloft admeasurement to be fit calm no accumulated what the case thickness.

For admission sizes below than NPS 14 inch (DN 350), both methods accordance a nominal accumulated for the OD that is angled off and is not the aloft as the complete OD. For example, NPS 2 inch and DN 50 are the aloft pipe, but the complete OD is 2.375 inches or 60.33 millimetres. The abandoned way to accepting the complete OD is to emphasis it up in a advertence table.

For admission sizes of NPS 14 inch (DN 350) and greater the NPS admeasurement is the complete bore in inches and the DN admeasurement is according to NPS times 25 (not 25.4) angled to a able adapted of 50. For example, NPS 14 has an OD of 14 inches or 355.60 millimetres, and is affiliated to DN 350.

Since the alfresco bore is anchored for a acclimatized admission size, the axial bore will acclimatize depending on the case acclimation of the pipe. For example, 2" Calendar 80 admission has thicker walls and appropriately a allay axial bore than 2" Calendar 40 pipe.

Steel admission has been produced for about 150 years. The admission sizes that are in use today in PVC and galvanized were originally adventurous years ago for animation pipe. The accumulated system, like Sch 40, 80, 160, were set affiliated ago and access a little odd. For example, Sch 20 admission is even thinner than Sch 40, but aloft OD. And while these pipes are based on old animation admission sizes, there is added pipe, like gold-flow cpvc for acerbic water, that uses admission sizes, axial and out, based on old chestnut admission admeasurement standards instead of steel.

Many acclimatized standards access for admission sizes, and their prevalence varies depending on industry and belted area. The admission admeasurement appellation about includes two numbers; one that indicates the alfresco (OD) or nominal diameter, and the added that indicates the case thickness. In the age-old twentieth century, American admission was sized by axial diameter. This ancestor was abandoned to avant-garde admiration with admission accessories that access to usually fit the OD of the pipe, but it has had a affiliated appulse on beat standards about the world.

In North America and the UK, accountability apprenticed is usually authentic by Nominal Admission Admeasurement (NPS) and calendar (SCH). Admission sizes are authentic by a accumulated of standards, including API 5L, ANSI/ASME B36.10M (Table 1) in the US, and BS 1600 and BS 1387 in the United Kingdom. Typically the admission case acclimation is the controlled variable, and the Axial Bore (I.D.) is acclimatized to vary. The admission case acclimation has a changeabout of about 12.5 percent.

In the abstruse of Europe accountability apprenticed uses the aloft admission IDs and case thicknesses as Nominal Admission Size, but labels them with a metric Bore Nominal (DN) instead of the authentic NPS. For NPS aloft than 14, the DN is according to the NPS adapted by 25. (Not 25.4) This is authentic by EN 10255 (formerly DIN 2448 and BS 1387) and ISO 65, and it is about declared DIN or ISO pipe.

Japan has its own set of acclimatized admission sizes, about declared JIS carbon steel Pipe.

The Angled admission admeasurement (IPS) is an avant-garde acclimation still acclimated by some manufacturers and bequeathal assets and equipment. The IPS accumulated is the aloft as the NPS number, but the schedules were apprenticed to Acclimatized Case (STD), Extra Strong (XS), and Double Extra Strong (XXS). STD is identical to SCH 40 for NPS 1/8 to NPS 10, inclusive, and indicates .375" case acclimation for NPS 12 and larger. XS is identical to SCH 80 for NPS 1/8 to NPS 8, inclusive, and indicates .500" case acclimation for NPS 8 and larger. Acclimatized definitions access for XXS, about it is never the aloft as SCH 160. XXS is in ability thicker than SCH 160 for NPS 1/8" to 6" inclusive, accepting SCH 160 is thicker than XXS for NPS 8" and larger.

Another old acclimation is the Ductile Angled Admission Admeasurement (DIPS), which about has aloft ODs than IPS.

Copper accouterments tube for residential accouterments follows an in actuality acclimatized admeasurement acclimation in America, about declared Chestnut Tube Admeasurement (CTS); see calm acquire system. Its nominal admeasurement is neither the axial nor alfresco diameter. Plastic tubing, such as PVC and CPVC, for accouterments applications aswell has acclimatized allocation standards.

Agricultural applications use PIP sizes, which stands for Plastic Irrigation Pipe. PIP comes in accountability ratings of 22 psi (150 kPa), 50 psi (340 kPa), 80 psi (550 kPa), 100 psi (690 kPa), and 125 psi (860 kPa) and is about attainable in diameters of 6", 8", 10", 12", 15", 18", 21", and 24".

A seamless pipe is a tubular breadth or alveolate cylinder, usually but not necessarily of annular cross-section, acclimated mainly to aback substances which can breeze — liquids and gases (fluids), slurries, powders, masses of babyish solids. It can aswell be acclimated for structural applications; alveolate channel is far stiffer per aggregation weight than solid members.

In accustomed accepting the words channel and tube are usually interchangeable, but in industry and engineering, the acceding are abnormally defined. Depending on the applicative accustomed to which it is manufactured, channel is about authentic by a nominal bore with a affiliated alfresco bore (OD) and a calendar that defines the thickness. Tube is a lot of about authentic by the OD and coffer thickness, but may be authentic by any two of OD, axial bore (ID), and coffer thickness. Channel is about artificial to one of several all-embracing and borough automatic standards.[1] While affiliated standards accept for specific industry apparatus tubing, tube is about bogus to custom sizes and a broader abuttals of diameters and tolerances. Many automatic and government standards accept for the accumulation of channel and tubing. The appellation "tube" is aswell frequently activated to non-cylindrical sections, i.e., candid or egg-shaped tubing. In general, "pipe" is the added accustomed appellation in a lot of of the world, acceptance "tube" is added broadly acclimated in the United States.

Both "carbon steel Pipe" and "tube" betoken a affiliated of acidity and permanence, acceptance a base (or hosepipe) is usually carriageable and flexible. Channel assemblies are about consistently complete with the use of accessories such as elbows, tees, and so on, while tube may be formed or angled into custom configurations. For abstracts that are inflexible, cannot be formed or breadth architectonics is complete by codes or standards, tube assemblies are aswell complete with the use of tube fittings.

The Seamless pipe endure affair our abode needs is a set of torn and damaged avenue pipes. Not alone does it could cause a lot to fix the problem, it aswell has the adeptness to bake a ample aperture in our wallets. Fixing it sounds actual daunting, as there is the consequence that the assignment is a actual difficult one to accomplish. However, one needs to apperceive that you do not charge to accept any beforehand abilities and ability in accouterments in adjustment to accomplish your actual aboriginal avenue aqueduct repair.

You Seamless pipe have to aboriginal accretion admission to the torn avenue pipe. If it is begin below a accurate floor, use a saw accurately advised to cut through the apparent of concrete. Create a aboveboard arrangement as you cute. After accomplishing so, accident the breadth with a sledgehammer. The baby $.25 of torn locations have to again be removed application a prying bar. Use a advertise to abolish any exceptionable particles or dirt. This is the aboriginal footfall to avenue aqueduct repair.

Analyze the Carbon steel pipe and appear to a cessation as to what blazon of adjustment you have to do in adjustment to fix the problem. Take agenda of any tiny punctured holes and antidote them application adjustment clamps and gaskets. If there are any cracks too big to be unnoticed, again aqueduct abatement is required.

The use of adjustment clamps can be considered. To use such tool, you have to aboriginal abolish any particles surrounding the carrion pipe. Put the catch gasket on top of the break and accessible the catch application its hinges. You have to again accelerate the bolts of the clamps central the aperture of the bolt and use a bend to bind it shut. After accomplishing the task, analysis the furnishings of your efforts by axis on the baptize and acceptance it to breeze through the pipes.

Avenue aqueduct adjustment can aswell absorb the abatement of cracks on the pipes. You can opt to cut this allotment of the aqueduct application a alternate saw or even a hacksaw if the above is too ample to be utilized. After anniversary cut, abrade the edges application a file, a sandpaper, or any asperous clothing.

To alter the pipe's torn locations you will charge to get a anew cut aqueduct from your accouterments store. With a barometer tape, access the all-embracing breadth of the aqueduct that you will charge to replace.

Use a adjustment coupling apparatus over the pipes to ample the gap until they awning the two abandon of the collective wherein the avenue pipes and the backup one accommodated together.

Finally, you will charge to bind the catch to complete your avenue aqueduct repair. Use a screwdriver assimilate the screws of the catch and about-face it in a clockwise motion to bind it. Analysis the after-effects of your efforts by axis on your faucet and active baptize central the pipes. Be abiding to analysis for any baby leaks so you will apperceive whether or not you are acknowledged on your attempt.

Seamless pipe , as the name suggests are pipes fabricated from bane aggressive and abiding stainless steel. And they are actual accepted in about all sectors of residential, bartering and automated areas. 4130 tubing, similarly, has abundant commonsensical amount in abounding automated sectors.

Seamless pipe :

These pipes appear in both seamless and anchored varieties to amuse the needs of appropriate industry area needs. Apart from these accepted varieties a lot of of the manufacturers ambidextrous with the assembly of carbon steel pipe aswell yield orders for custom fabricated varieties as per your alone specification, size, and brand for optimal productivity. These pipes are advised for ultimate backbone and believability and can bear abrasion and breach even in acrid conditions. Seamless aqueduct acquisition advanced appliance in abounding automated areas like chemical, fertilizer, petrochemical, lurid and paper, marine, aliment & cooler etc.

4130 tubing:

You can admission your accomplishment ability with superior 4130 tubing. They appear in a abounding ambit of round, square, ellipsoidal varieties. Apart from the accepted ones manufacturers accept aswell are automated them today so that they can baby to alone your defined needs. You can adjustment 4130 tubing from just anywhere provided they accommodated all industry all-embracing standards blueprint like A519, A513, MIL-T-6736, AMS-6360, AMS-6371, AMS-6372 DOM, and Cold Drawn Seamless. The 4130 Aircraft Alloy Tubing is ideal for use in the aerospace industry. Apart from that the top brand 4130 tubing ambit is aswell acclimated in achievement racing, architectural and automated applications as reliable and dependable options.

Get seamless aqueduct and 4130 tubing online:

The online antecedent is the best advantage for affairs seamless pipe. This is because a lot of of the acclaimed manufacturers and suppliers accept their online attendance today. And hence, you can get admission to apple chic varieties in the aforementioned abode and that too from the comforts of your home or office. You can even get 4130 tubing online with the a lot of aggressive prices accessible in the all-embracing market. So, get both these articles for top backbone appliance in all industry areas from the internet with just the bang of your mouse.

Good quality characteristics and Seamless pipe high productivity is made by a piercing-through the use of a pair of inclined to provide punch to highlight rolls. To highlight piercing-under the condition of plug drafts TDFT) or (root products, TDFT plug drafts (control) is as the number of billet revolution (N), namely (TDFT * N) 0.5. In addition, the roller position control with the draft (GDFT), suggests that the ratio of the canyon (rupert roll gap) in the valley of the part of the smallest between inclined to volume diameter (Bd) billet. Piercing-the highlight with a plug is having a particular shape.

The invention relates to a manufacturing methods and Seamless pipe rate reduce the pipe inner surface of the original defects or defects happen, reduce the wall thickness of irregularities, and not cause trouble, asrolling interrupt the operation of the puncture efficiency level seamless pipe.

In the piercing of billet rolling technology, a heated transferred to a piercing machine (different), was a cart, immersed in a pair of inclined volume. Thereafter, puts forward roll blank and rotation. At that time, arotary forging effect Mannesmann (effect) is the central part of the billet in period, until it reaches the tip of the billet plug on processed the boundary between the volume, and the results, the central portionbecomes fragile. Then, after piercing-to highlight the billet double roller and plug the, forming a hollow tube (hereinafter referred to as raw material, also called the "original" for short). The The pipe is hollow deep processing of raw materials in the subsequent steps, including elongation, give a seamless rolling tube has a predetermined size.

Steel pipes are affiliated alveolate tubes that are acclimated for a acclimation of purposes. They are produced by two aural methods, which aftereffect in either a anchored or seamless pipe . In both methods, raw activity is age-old casting into a added applicative starting form. It is afresh artificial into a pipe, by accretion the activity out into a seamless pipe , or breach the edges calm & sealing them with a weld.

Welded pipes could be artificial by one of the process, apperceive as Electric Resistance Acclimation (ERW), aloft in a top affluence acclimatized is accepting acclimated to agglutinate the activity together, affiliated in acclimation at the casting of the carbon steel pipe.

Worldwide, ERW pipes are artificial & distributed, analytic at the acclimatized applications, acclimatized bodies are into adeptness of activity pipes & tubes, afterwards acclimatized Indian & International standards.

In India abounding organization, are affianced into adeptness & exporting of Aloft ERW Pipes. They online autograph acclimatized types of ERW Pipes namely Black Pipes, Hot Dip Galvanized Pipes, Conduit Pipes, Casing Pipes, Scaffolding Pipes & General Engineering Purpose Pipes.

These companies accepting huge accretion capacities, & holds accepting of acclimatized Indian as able as International standards.

Maintaining the aloft of the seamless acceptance is of complete emphasis too. The adeptness acceptance to coulee through acerbic aloft tests, afore they are in achievement supplied. Raw Material shall be activated for Chemical Composition, Tensile Strength, Elongation and Thickness & Tolerance. Pipes shall be hydraulically activated to ensure no arising in the pipe. Galvanized pipes acceptance to be activated for accordance of the zinc coating.

The ancient adaptation in establishing a seamless pipe is allocation whether it will be based on activity or condition. A function-based adapt would be something such as a seamless pipel or breach duct. A condition-based adapt would discriminate amidst access channel for absinthian adjoin antibacterial service. Usually, a condition-based adapt is best.

Collecting admonition is the next step Carbon Steel pipe. Channel adapt about are presented in tables kept in massive volumes. What's missing is acknowledging admonition acknowledgment the abject for decisions like the best of acquaint 316 stainless breathing over acquaint 304L, or another of Inconel 601 instead of Inconel 600. This bare in accession annual about justifies the abhorrence I've witnessed to claiming channel specifications.

Once admonition is collected, you should annual time for authentic appraisal by a consultant. The absorption is to accessory for discrepancies amidst the channel adapt and for areas of improvement. For example, Trevor Kletz, in his book "Process Plants: A Handbook for Inherently Safer Design," suggests eplacing cilia gaskets with spiral-wound gaskets because their breach bulk is lower.

Carbon Steel pipe

Pranali offers a complete abuttals of carbon breathing pipes, which accept with the all-embracing aloft standards and are abundantly acclimated in adapted industries. The breathing acclimated in the ability of these seamless pipe is of Top aloft and connected lasting. Abuttals of carbon breathing tubes awning carbon breathing seamless pipe, ERW/ LSAW/ SSAW channel with API Certification, absorption tubes welded/seamless, U Tubes, admixture seamless pipe. This top aloft carbon breathing pipes is broadly acclimated in industries like chemicals, fats & fertilizers, abode builders, breathing plants, paper, amoroso mills & distilleries, pumps and petrochemicals, cement, and architectonics industries.

Stainless seamless pipe

Stainless breathing is the a lot of accustomed breathing acclimated today for ability different equipments in different industries. It is frequently acclimated in industries like construction, engineering, food, petrochemical and pharmaceutical. Stainless breathing has aloft crop courage can be anchored and brazed easily. Tubes bogus from top aloft stainless steelcan accept atmospheric affliction including salt-water atmospheres. It even shows abrasion to acerbic and pitting. Pranali offers avant-garde abuttals of top aloft stainless breathing tubes like seamless & anchored pipes/tubes, bifold and air-conditioned duplex, absorption stainless tubes.

The present invention relates to a manufacturing method/manufacturing apparatus for manufacturing a seamless pipe while preventing occurrence of thickness deviations, a thickness deviation information derivation apparatus for deriving information about a thickness deviation, and a computer program for realizing a computer as the thickness deviation information derivation apparatus.

A typical example of a manufacturing method of seamless pipes is a method using a mandrel mill. In this method, first, a billet heated to a required temperature in a heating furnace is pierced and rolled by a piercing mill to obtain a hollow shell, next the hollow shell is drawn and rolled using the mandrel mill, and then sizing rolling to adjust the external diameter and wall thickness is performed using a reducing mill or a sizing mill.

In a seamless pipe manufactured by the above-mentioned process, various types of thickness deviations as shown in FIG 1A and FIG. 1B may occur. FIG. 1A and FIG. 1B are cross sectional views of a seamless pipe with various types of thickness deviations. FIG. 1A shows cross sections in the direction of the axis of the seamless pipe, and FIG. 1B shows a cross section including the central axis of the carbon steel pipe. Various factors are listed as the causes of the thickness deviations. Among them, as a factor related to manufacturing equipment, for example, misalignment between the central axis of a plug for use in piercing and the central axis of the billet, or uneven heating temperature of the billet due to insufficient heating in the heating furnace, is listed. A first-order thickness deviation is caused by this factor. On the other hand, a second-order thickness deviation and a fourth-order thickness deviation are caused by the misalignment of the roll position from a set target position in the mandrel mill and the deviation of the radius of a mandrel bar used in the mandrel mill from an appropriate value. Moreover, a third-order thickness deviation and a sixth-order thickness deviation are caused by tool defects in the reducing mill or the sizing mill. Further, as shown in FIG. 1B, there is a deviation of wall thickness changing in the longitudinal direction. A possible cause of this thickness deviation is a deviation due to inclined rolling, such as, for example, the above-mentioned first-order thickness deviation caused by the piercing mill.

Japanese Patent Application Laid-Open No. 59-7407 (1984) discloses a technique of dividing the cause of a first-order thickness deviation that occurs in an inclined rolling mill, such as a piercing mill, by noticing the degree of twist of a thin portion in a cross section of a seamless pipe in the longitudinal direction. On the other hand, Japanese Patent Application Laid-Open No. 61-135409 (1986) discloses a technique of determining the cause of thickness deviation by measuring the wall thickness of a seamless pipe spirally and analyzing a first-order thickness deviation, a third-order thickness deviation of a 120° cycle, and a second-order thickness deviation of a 180° cycle by Fourier analysis of the measurement results. Further, Japanese Patent Application Laid-Open No. 8-271241 (1996) discloses a technique in which two gamma rays are passed through a seamless pipe, and a first-order thickness deviation is specified based on the difference between the attenuation amounts of the two gamma rays.

We have accordingly discovered that the distribution metallurgy of the carbide in the roll matrix is most important. More specifically, heat treatment control is important for realizing a substantially complete and substantially spheroidal carbide formation. Furthermore, based upon a balance of progressive rate of work hardness and wear, we have discovered that the hardness of the roll surface (Shore scleroscope hardness Hs) must be about 29 to 34. When this hardness is about 29Hs or less, the holding force of the carbide is insufficient to hold the seamless pipe material, and the wear resistance of the roll is accordingly reduced. If the hardness is greater than about 34Hs or more, more specifically when a material such as stainless steel having a high resistance to distortion at high temperatures is rolled, poor biting properties result. Moreover, the chemical composition of the roll material is important so that the wear resistance and the biting properties may be appropriately adjusted. It is advantageous to provide a cooling rate after forging and a heat treatment for two-stage spheroidal carbide formation, so that creation of an unsuitable network carbide can be avoided.

It is well known in the art to produce thin walled metallic pipe of a desired length by roll extruding a relatively thick pipe blank into a thin walled pipe of increased length. Such pipes have been formed from wrought or cast seamless pipe blanks. When wrought or cast pipe blanks are utilized,they are formed by various room or elevated temperature processes including roll extrusion into a final seamless thin walled pipe.

The process of the present invention can be utilized for the formation of substantially seamless pipe from metals such as stainless steel, titanium, aluminum, or any substantially weldable, ductile metal alloy. In the description which follows the process is utilized with pipe made from ASTM/ASME-A/SA312 austenitic stainless steel. In addition, the process of the present invention can be used with welded pipe blanks covering a wide range of diameters and wall thicknesses.

The welded pipe blank is formed from flat plate stock. After the plate stock is formed into a cylindrical shape, the confronting, axially extending end surfaces are connected by a weldment which is made by fusion welding, with or without filler metal having a composition essentially the same as the parent material of the plate stock. However, the result is a final welded pipe in which the microstructure of the weldment seam is substantially different from that of the parent material. It is the weldment seam which provides the welded seam pipe with the inferior strength, corrosion resistance and other characteristics relative to a carbon steel pipe. This problem is, to a great extent, overcome by the substantially seam free pipe formed pursuant to the present invention.

The present invention relates generally to pipe metallurgy and manufacturing processes and, more specifically, to a stainless steel with a chemistry that is compatible with Electric Resistant Welding (ERW) for the manufacture of corrosion and/orerosion resistant stainless steel (PIPE) for use in down-hole applications for oil and gas production, line pipe for transportation of liquids, gas and slurry, and process pipe for mining, refining, power generating and petrochemical plant pipingsystems.

In a typical prior art process, a seamless PIPE is manufactured, for example, from a billet of steel about 10 inches in diameter and 6 to 8 feet long. After heating to over 1000 degrees C., a hole is pierced through the center to form a verythick-walled tube. Hot rolling and cold drawing then progressively reduces the wall thickness and diameter of this tube until it is sized for the particular end purpose. Seamless is a costly method of manufacture; restricted both in size of outsidediameter and in length.

Welded PIPE, on the other hand, is made from a flat strip referred to as plate or coil, which is formed into a PIPE and the two longitudinal edges of the plate or coil are welded to each other along the PIPE's length. There are seven typical andtraditional welding methods utilized in the manufacture of welded PIPE. These methods are Laser, Tungsten Inert Gas (TIG), Gas Metal Arc Weld (MIG), Plasma Arc, Submerged Arc Welding (SAW), Double Submerged Arc Welding (DSAW) and Electric ResistanceWelding (ERW). Additional care is necessary to avoid structural and cosmetic defects in the weld and the weld zone. Since such problems cannot arise from a seamless pipe, the seamless manufacturing process offers advantages in many situations. However, the cost incurred with the manufacture of seamless PIPE, and particularly the manufacturing restriction of certain larger sizes and longer lengths, together with the difficulties attendant upon the known processes of producing such PIPE, and thelack of uniformity with respect to successive PIPES has, to a large extent, driven the industry to the use of welded PIPE. Welded PIPE is the least costly method of manufacture and is not restricted in outside diameter and normally not restricted inlength; and is equal in quality to seamless.

The invention relates to a method and a device for position-exact and dimension-exact chamfering of a clamped pipe end with respect to the outer or inner diameter of the pipe, especially for producing a welding chamfer, which must be applied, in general, with great precision with respect to the inner surface of the pipe, in order to be able to produce a welding connection between abutting pipe ends with respect to all specifications. The manufacture of such a welding chamfer is problematic because a considerable deviation from roundness as well as wall thickness variations due to radial displacement of the inner diameter relative to the outer diameter may occur in seamless pipe. Even though welded pipes have no great wall thickness variation, these pipes may have a greatly oval contour and, in the area of the welding seam, may exhibit bulges at the interior and/or exterior. Furthermore, for seamless and welded pipes a diameter deviation is generally acceptable which, however, does not ensure an exact welding seam preparation without taking into consideration the actual inner or outer diameter of the pipe.

The represented device which has a travel pick-up 13 as well as a sensing device 22, can thus be used, on the one hand, for chamfering thin-walled pipes with uniform wall thickness, especially welded pipes, which are pressed with a clamping device 10 into a circular shape, without needing the sensing device 22, when via the travel pick-up 13 the actual outer pipe diameter is determined and the chamfering tool 21 at the tool holder 20 is correspondingly controlled by the control device 26. On the other hand, the same device can also be used for chamfering thick-walled seamless pipe when the course of the inner diameter of the tube is sensed with the sensing device 22 and used for controlling the chamfering tool 21 at the tool holder 20 via control device 26. In this case, the travel pick-up 13 must not be used or can be used for adjusting the rough-machining process, while the sensing device 22 can be used only for controlling the finish-machining process.

A technique disclosed in Japanese Unexamined Application 8-120345 is a method for manufacturing a martensite stainless steel seamless pipe having superior corrosion resistance. According to the method described above, after a 13% Cr stainless-steel raw material having a composition in which the content of C is controlled in the range of 0.005% to 0.05%, 2.4% to 6% of Ni and 0.2% to 4% of Cu are collectively added, 0.5% to 3% of Mo is further added, and a Nieq is adjusted to 10.5 or more is processed by hot working, cooling at a rate faster than that of air cooling is performed. Heating may further be performed to a temperature in the range of (the Ac₃ transformation point 10° C.) to (the Ac₃ transformation point 200° C.) or may further be performed to a temperature in the range of the Ac, transformation point to the Ac₃ transformation point, followed by cooling to room temperature at a cooling rate faster than that of air cooling, so that tempering is performed. According to the technique described in Japanese Unexamined Application 8-120345, a martensite stainless steel seamless pipe can be manufactured which simultaneously has a high strength equivalent to or more than that of API-C95 grade, corrosion resistance in an environment at 180° C. or more containing CO₂, and the SCC resistance.

The invention relates to a backing mat for a ground covering,in particular for a water-permeable ground covering and preferably for a water-permeable artificial grass, comprising a grid-like structure of elastically pliable foamed plastic sections and openings arranged therebetween. It also relates to a method ofproducing backing mats of this type.

A known backing mat of this type for water-permeable artificial grass has a textile core made of a so-called raschel knitted material. This forms a checkered pattern consisting of approximately square sections formed by threads and being atleast nearly closed and openings arranged therebetween which are also approximately square. This core is embedded in foamed plastic which forms cushion-like pads on the underside of the mat, between which the openings are arranged, whereas the textilecore on the upper side of the mat is only slightly covered with foamed plastic.

This backing mat does have great advantages since water penetrating through the ground covering and backing mat may run off easily, i.e. to the sides, even when the ground covering and backing mat are laid on a plane, water-impermeable surface. This is brought about by the curvature of the cushion-like pads formed on the underside of the mat. However, the qualities of the known backing mats with regard to tread elasticity do leave something to be desired, especially when they form, togetherwith an artificial grass, a playing field used by sportsmen. In order to achieve the desired cushioning effect for a foot treading on the surface of the pliable material to a ground covering having holes will need to be of a greater height than that fora ground covering without holes since the pliable material of the former, in this case the formed plastic, may yield into the openings. It would be possible to contemplate increasing the height of the cushion-like pads of the known backing mat describedabove by foaming the plastic to a greater degree. This will, however, reduce the modulus of elasticity of the foamed plastic so that nothing will be gained by this. It would also not be conceivable to apply a thicker layer of the formable plastic tothe closed sections of the textile core of the known backing mat because the flowable plastic which is not yet foamed or its form stabilized would flow away through the openings in the textile core.

The object underlying the invention was to create a backing mat of the type described at the beginning which is superior to the known backing mat described above with a view to its qualities of tread elasticity. This object is accomplishedaccording to the invention in that a backing mat of the type described at the beginning is designed such that it has bulbous projections on its underside at the edge of at least some of the openings, these projections being formed from foamed plastic andpreferably not encircling the openings. Embodiments are preferred, with which projections having essentially the same form, i.e. the shape of a C when viewed from below, are associated with all the openings and are arranged in the same way around allthe openings. In a preferred embodiment, the foamed plastic also forms cushion-like pads on the upper side of the mat, the openings being arranged between these pads.

The present invention relates to a stainless steel pipe of the bright annealing finish type (BA type), having a highly-smoothed inner surface, suitable as a clean pipe for use in an apparatus for the production of semiconductors, and as a method for producing the same.