N. P. Starostin, O. A. Ammosova

ESTIMATED DETERMINATION OF HEAT-AFFECTED ZONES FOR WELDING OF POLYETHYLENE PIPES AT LOW TEMPERATURES

The boundaries of heat-affected zones (HAZ) are determined by mathematical modeling of the thermal process of butt welding of polyethylene pipes for gas pipelines. When choosing the process conditions for welding of polyethylene pipes, as well as when investigating the quality of the welded joint, determination of the boundary of the heat-affected zone is of great importance, since structural changes of the welded materials occur in this zone. The mathematical model used takes into account the heat of the phase transition in the temperature range, as well as the thermal effect of burr formed during upsetting. The adequacy of the proposed mathematical model is shown by comparing the experimental and calculated temperature data. The temperature was recorded using a multichannel temperature programmer with a Thermodat-17E3 graphical display. The problem was solved numerically by the finite difference method. The developed algorithms are implemented as a set of programs in the Delphi environment. Numerical simulation was carried out for a 63×5.8 PE 100 GAZ SDR11 pipe. The admissible area of heat-affected zones is defined. It is formed at admissible air temperatures. The computational experiments have shown the possibility of controlling the temperature regime for welding under conditions of low ambient temperatures and providing the same temperature field variation in the HAZ as at permissible air temperatures. The time of its formation is fixed. By preheating the ends of a welded pipe and using a thermal enclosure weld during cooling at low temperatures, the desired location of the HAZ boundary is achieved.

References:

1.Kuliczkowska E., Gierczak M. Buckling failure numerical analysis of HDPE pipes used for the trenchless rehabilitation of a reinforced concrete sewer. Engineering Failure Analysis, 2013, no. 32, pp. 106–112. DOI: 10.1016/j.engfailanal.2013.03.007.

2.Luo X., Lu S., Shi J., Li X., Zheng J. Numerical simulation of strength failure of buried polyethylene pipe under foundation settlement. Engineering Failure Analysis, 2015, no. 48, pp. 144–152. DOI: 10.1016/j.engfailanal.2014.11.014.

3.Gould S.J.F., Davis P., Beale D.J., Marlow D.R. Failure analysis of a PVC sewer pipeline by fractography and materials characterization. Engineering Failure Analysis, 2013, no. 34, pp. 41–50. DOI: 10.1016/j.engfailanal.2013.07.009.

4.Borovsky B.I., Kunsky M.O. Optimization of gas supply systems in residential city districts. Stroitelstvo i Tekhnogennaya Bezopasnost, 2014, no. 50, pp. 29–33. (In Russian).

5.Petrishin A. K voprosu ispolzovaniya polietilena v truboprovodakh. In: Materialy mezhdunarodnoy nauchno-prakticheskoy konferentsii “Nauka segodnya: zadachi i puti ikh resheniya”, Russia, Vologda, 31 May, 2017 [Science Today: Problems and Ways of Solving Them: Proceedings of the International Scientific and Practical Conference]. Tyumen, Marker LLC Publ., 2017, pp. 31–32. ISBN: 978–5–906850–51–5. (In Russian).

6.Lee B.Y., Kim Y.K., Hwnag W.G., Kim J.S., Lee S.Y. Improvement of butt-welding characteristics of double wall polyethylene pipes. Metals and Materials International, 2012, vol. 18, no. 5, pp. 851–856. DOI: 10.1007/s12540-012-5016-5.

7.Panaskar N., Terkar R. Study of joining different types of polymers by friction stir welding. In: Mandal D.K., Syan C.S., eds. CAD/CAM, Robotics and Factories of the Future, Ser. Lecture Notes in Mechanical Engineering, Springer, New Delhi, 2016, pp. 731–739. DOI: 10.1007/978-81-322-2740-3_70.

8.SP 40–102–2000. Svod pravil po proektirovaniyu i stroitelstvu. Proektirovanie i montazh truboprovodov system vodosnabzheniya i kanalizatsii iz polimernykh materialov. Obshchie trebovaniya [Design and Assembly of Polymer Pipelines for Water-Supply and Sewage Systems. General Requirements: Handbook of Instructions]. (In Russian).

9.Starostin N.P., Ammosova O.A. Simulation of the Thermal Process of Butt Welding of Polyethylene Pipes at Low Temperatures. Journal of Engineering Physics and Thermophysics, 2016, vol. 89, iss. 3, pp. 714–720. DOI: 10.1007/s10891-016-1430-8.

10.Rodionov A.K., Babenko F.I., Kovalenko N.A. Crack resistance of welded butt joints in polyethylene pipes. Materialy. Tekhnologii. Instrumenty, 2003, vol. 8, no. 3, pp. 19–20. (In Russian).

11.Lai H.S., Tun N.N., Kil S.H., Yoon K.B. Effect of defects on the burst failure of butt fusion welded polyethylene pipes. Journal of Mechanical Science and Technology, 2016, vol. 30, no. 5, pp. 1973–1981. DOI: 10.1007/s12206-016-0403-3.

12.Tariq F., Naz N., Khan M.A., Baloch R.A. Failure analysis of high density polyethylene butt weld joint. Journal of Failure Analysis and Prevention, 2012, vol. 12, no. 2, pp. 168–180. DOI: 10.1007/s11668-011-9536-y.

13.Zakar F., Budinski M. Fracture of a saddle fusion (weld) joint in high density polyethylene (HDPE) pipe. Engineering Failure Analysis, 2017, vol. 82 pp. 481–492. DOI: 10.1016/j.engfailanal.2017.03.009.

14.Avdonin N.A. Matematicheskoe opisanie protsessov kristallizatsii [Mathematical Description of Crystallization Processes]. Riga, Zinatne Publ., 1980, 180 p. (In Russian).

15.Vabishchevich P.N. Chislennye metody resheniya zadach so svobodnoy granitsey [Numerical Methods for Solving Problems with a Free Boundary]. Moscow, MGU Publ., 1987, 164 p. (In Russian).

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