The quality problem of the heat exchange tube welding common have?

The quality problem of the heat exchange tube welding common have?

Accounts for a significant proportion of chemical production equipment, heat exchanger, accounted for about 20% ~ 40% of the equipment investment;Heat transfer of the chemical industry the most basic unit operation, the heat exchanger in shape or not huge influence on chemical production.Tube and shell heat exchanger with their large structure consolidating, adaptability, sophisticated production technology and other advantages to become the primary chemical heat exchange equipment.Because heat exchanger under abrasive, corrosive medium, flow, particularly is fixed tubesheet heat exchanger, and temperature difference stress and tube sheet and the heat exchange tube connection easy to leak, the heat exchanger of reason, because simple ignore some details when producing, tube plate and welding heat exchange tube, see more quality problems, followed by water and organic compounds have strong corrosion is also promoting


The length, the welding is not in conformity with the rules
The production tube plate processing groove is often small, such as normal heat exchange tube Φ 19 x2, I3 Φ x2 25 gb rules shall not be less than 2 mm, Φ 32 x2 5 above is not less than 2 mm, when the wall thickness must add appropriate increases.And the practice is short of.Other common heat exchange tube Φ 19 x2, 25 x2 Φ extended length l1 is not less than 1. 5 mm, when the working condition of high pressure reach l2 lengthened to 2 5 mm;Φ 32 x2 5 out heat exchange tube length is not less than 2 mm, when the working condition of high pressure out of l2 strengthen for up to 3 0 mm length.But practice for assembling, blanking control owe good elements such as, or even some of the welder welding habit factors, often also can not reach the requested dimensions.Welding length must be less than the rules so requests, the load to drop, GB151 accounting choose pulled off stress q = sigma t. a/л dl is qualified in planning, but perhaps overruns in practice.
Second, the treatment method of owe good before welding
Before welding processing way to owe good cause welding quality is poor see more in the process of making carbon steel tube heat exchange tube head after finishing not net or pipe head finishing a long time not assembled and rust;Tube plate processing after long time place rust or besmear antirust oil, after assembling are hard to arrange, then cause the impurities in welding of meat.
Three, the welding method
Welding way wrong cause poor quality when choosing craft arc welding, arc and arc directly on the cohesion of the fillet weld, the tube plate vertical position welding, weld forming, are more easily causes slag inclusion and porosity.
Particularly in the fixed tube plate heat exchanger tube heat exchanger tube plate and the heat exchange tube welding joint under load, simple welding defects induced is extended, and some chemical medium easy corrosion;Tube and shell heat exchanger itself in the production process, the more high request, some aspects are often neglected, simple faults occur, fewer in overpressure inspection is difficult to find, in making accurate selection method, ensure the welding quality.Especially about the use environment difference, the request high heat exchanger, especially carbon steel heat exchanger, and the use of special technology, such as double welding, center view, etc., can greatly improve the quality of heat exchanger, satisfied with strict request.

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