TPi April 2008

OCTG water, gas &

The benefits of spiral welding

include: optimum weld geometry within narrow tolerances; hardness in weld and HAZ max 248 HV5; OD tolerance of pipe body equal to OD tolerance of pipe end; no repeated weld repair; no pipe with skelp-end weld; 100% U/T, 100% x-ray and 100% visual inspection; process control by metallographic examination; and retention of quality records for a five year period. The company offers a wide range of anti-corrosive coatings, including cement mortar, epoxy and polyurethane, polypropylene and polyethylene, and bitumen and coal-tar enamel. For three-layer polyethylene coating, the pipe surface is first cleaned by shot blasting, then preheated to the required temperature using an induction heating system. Following preheating, epoxy primer is applied to the pipe surface, and the extruded adhesive and polyethylene are coated to the pipe by the wrapping method. Finally, the pipe is cooled with water. Polyethylene coated steel line pipe incorporates the good properties of steel andpolyethylene. BorusanMannesmann Boru’s three-layer PE coating has the following advantages: wide service temperature range; superior adhesion strength; high resistance against mechanical damage during shipment, storage and laying; high, long-lasting electrical coating resistance; resistance against thermal and light ageing; and perfect bendability on-site by using adequate tools and in accordance with the relevant standards.

calibration process (cold expanding or roll sizing) is necessary. The diameter tolerance of the pipe end and body of a joint is small, particularly with regard to ovality. The mechanical properties are present in the base material. Since any cold expansion reduces the material’s ductility, the spiral-weld pipe has a higher safety margin. When carrying out field cold-bending, it is not necessary to take the weld seam position into account. There is a favourable orientation of the weld seam and of the strip’s direction of rolling relative to the direction of principal stress. The submerged arc welding (SAW) process is widely used for welding thick sections, but can also be applied to plate as thin as 4mm. The principle of spiral pipe production is to bend steel strip spirally into a cylindrical pipe shape, and weld the edges together. The high currents obtained by multiple electrodes generate considerable heat, which leads to deep penetration of the base metal. Borusan Mannesmann Boru exercises control of the contour of the deposit and the extent of the penetration into the base metal. These two factors have an important effect on the chemical composition andmetallurgical properties of the weld metal.

Borusan Mannesmann Boru operates five mills – four in Turkey and one in Italy – with a total production capacity of 925,000 tons, and is one of the five largest steel welded pipe producers in Europe. At its Izmit plant, which has a current total capacity of 200,000 tons, the company produces SAW (submerged arc welding) spiral line pipes between 14" and 100" in diameter, for oil, gas and water pipelines, and piling applications. The company has wide experience and a long track record in oil and gas pipeline applications, both in Turkey and international markets, with high grade API standards. Borusan Mannesmann Boru operates under the ‘Six Sigma’ methodology, segmenting its activities according to customer needs. The Projects segment specialises in pipeline solutions/ contracts, providing SSAW large diameter and ERW pipe solutions, and offers customers specific project contract solutions. Spirally welded pipes have been used all over the world for high-pressure pipeline projects, due to their high quality and suitability as high strength steel pipes. In addition to being an alternative to longitudinally welded pipe, spirally welded pipe has other advantages. No

The company’s standards for high pressure gas/petroleum line pipes

PE 100 and cast iron pipe fittings Dokerler Dokum Plastic Polyethylene Industry And Trade Inc, Turkey, is a major manufacturer of PE 100 and cast iron pipe fittings for city water and gas systems. The company is researching several solutions in city water and gas applications by transferring its wide experience and high quality in asbestos cement, PVC and GRP, and cast iron fittings to PE 100 fittings. PE 100 fittings bearing the Dokerler brand name are manufactured according to the requirements of the high technology, and meet the standards such as TSE (TS 418-3 EN 12201-3 and TS EN 1555-3) and ISO 9001:2000. The fittings are produced as Electrofusion (EF) and Spigot for both PN 10 and PN 16 operating pressures. All Dokerler EF fittings come with an adhesive label with a standard barcode for use with electrofusion welding machines. All the necessary information for the welding process is entered into the welding machine automatically with the help of this barcode, in order to minimise operator errors.

A Dokerler coupler, ▲ ▲ showing the barcode for use with electro- fusion welding machines

Dokerler Dokum Plastic Polyethylene Industry And Trade Inc – Turkey dokerler@yahoo.com • www.dokerler.com

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Tube Products International April 2008

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