TPT May 2008

T echnology U pdate

Seamless tube and pipe for boiler applications

Steel pipes and wheels producer Interpipe, Ukraine, manufactures a wide variety of seamless pipe products for special applications. The company’s principal products are boiler pipes, roller pipes, pipes for submerged pump stations, precision pipes and cold drawn pipes. These products are primarily used in the power, oil and gas, machinery, automotive and shipbuilding industries. Boiler tubes and pipes are the specific products used in boiler plants (steam generators), operating under high pressure and high temperature, and are used in industries where indirect heating and steam are used. The major consumers are heat power plants, petroleum processing and chemical plants, as well as the food industry. In boiler plants the pipes are built up as coils in units and welded by high frequency welding. Inside the boiler, water circulates in tubes externally by hot gas, which can be generated inside the boiler itself (conventional steam generator), or outside the boiler (heat recovery steam generator). The growth surge in the power industry and the growth in demand for electrical energy has directly challenged producers of power generation equipment. As a result of these circumstances, Interpipe launched a new line for the production of boiler pipes up to 24m in length and from 31.8mm to 114.3mm in diameter, according to ASTM, DIN, EN standards. The new production line is situated at one of the company’s mills – Interpipe Niko Tube. The first step was the test rolling of boiler pipes from low-alloy steel grades 13CrMo4-4, 16Mo3, 13CrMo4-5, 10CrMo9-10 in the range from 32mm to 76mm. As a result of test rolling, many of the issues associated with boiler pipe production were identified and defined, such as the high requirements of metal

cleanness, internal cleanness (descaling) and external surface and precision of geometric measurements. The advantages of rolling at pipe-rolling mill 30-120 are: high quality of internal surface (due to free moving long mandrel); availability of large squeezes at 24 stand stretch-reducing mill that helps to avoid internal cutting; and high total deformation providing high quality metal structure. The company made the decision to reduce the diameter of boiler pipes from 57mm to 32mm. The heat treatment of boiler pipes depends on the grade of steel, class and category based on standard and includes annealing and tempering. Pipe quality is monitored by testing such as stretching, flattening, dispensing, chemical analysis, hydro and eddy-current and ultrasonic (for avail- ability of longitudinal, transversal defect, exfoliations). The process flow currently includes hot rolling through the piercing mill, continuous rolling mill and sizer. To exclude the influence of limescale at surface (as a result of heating), the line is equipped with a capacity of descaling water (p=160atm). In order to provide the highest quality of heat treatment (normalising and tempering), the tempering furnace of 111m has been considerably upgraded. The company has also installed a new finishing line which includes equipment for pipe straightening in oblique roll straightening machines, pipe facing, and finishing line control room. It also has a geometry measuring and a non-destructive testing machine (MAC), which provides ultrasonic, electromagnetic testing and grade verification. The line project facility has a capacity of 30,000 tubes per year. Production facilities include a continuous mandrel mill for the production of seamless pipes (32mm to 114.3mm); general finishing floors (including testing equipment); and a quench and tempering heat treatment line for seamless OCTG and transport line pipes, other equipment comprises upsetting lines for seamless OCTG, non-destructive testing (ultrasonic, electromagnetic, magnetic and vortex-current), lines for pipe and coup- ling threading, hydrotesting, coating and bundling, and a finishing line and annealing heat treatment line for boiler pipes. Interpipe – Ukraine Email : officechudnovskydp@interpipe.biz Website : www.interpipe.biz

 Hot mill in operation

70

M ay 2008

www.read-tpt.com

›