VGB Guideline Tubes for condensers and other heat exchangers

Transcription

1 VGB Guideline Tubes for condensers and other heat exchangers (Part C: Titanium) Part 1: Materials, Manufacture and Testing Part 2: Recommendations for Operation Part 3: Causes of Tube Damage VGB-R 114 Le Published by First Edition 1981 Second Edition 1990 (Printed in 1998)

2 VGB Guideline Tubes for condensers and other heat exchangers (Part C: Titanium) Part 1: Materials, Manufacture and Testing Part 2: Recommendations for Operation Part 3: Causes of Tube Damage VGB-R 114 Le Published by First Edition 1981 Second Edition 1990 (Printed in 1998) Reproduction in whole or in part only with prior permission of the publishers. Obtainable from: VGB-KRAFTWERKSTECHNIK GmbH Verlag technisch-wissenschaftlicher Schriften Klinkestraße 27 31, D Essen

3 Preface The present Part C of the guideline Tubes for condensers and other heat exchangers refers to tubes made of titanium and used in condensers and other heat exchangers. The grades concerned include seamless and longitudinally welded tubes. In general, seamless tubes are manufactured from hot-drawn tube blanks which are subsequently cold drawn. Seamless tubes are delivered in the heattreated condition. Welded tubes are manufactured from annealed, cut sheet using a continuous weld process in a protective gas atmosphere (e.g. TIG). They are generally delivered without heat treatment and with metallically blank surfaces. The guideline provides the operators of thermal power stations with recommendations concerning appropriate ordering procedures for tubing for condensers and other heat exchangers and is intended to enable them to avoid operational problems and damage. This edition contains detailed descriptions of damage, and information in the form of typical photographs of failures, in order both to increase awareness and permit correct evaluation. It makes use of extensive experience and numerous recommendations, but makes no claim to completeness. The experience gained in the use of this guideline, together with suggestions for improvement, will be evaluated and it is requested that they be notified to the VGB offices. Preparation of this guideline was carried out by the working group Condensation within the VGB technical committee Steam turbines and operation thereof.

4 The following gentlemen were involved: Schroeder (Chairman), Fichte, Früh, Gehring, Gerz, Heeren, Hinkelbein, Höxtermann, Müller, Ockert, Plotz, Schleithoff, Schöttle, Seipp and Vornbäumen. The opportunity is taken here to thank them for their efforts. The second revision of the VGB guideline was undertaken by Messrs. Allmer (Chairman), Dege, Eimer, Fichte, Höxtermann, König, Multer, Schleithoff, Seipp and Zinke. Essen, August 1990 The present English translation was prepared by Dr. John Hickling (CMC), Nürnberg.

5 Contents Part 1: Materials, Manufacture and Testing Page 1.1 Materials Material properties Chemical composition Manufacture of the tubes Type Dimensions Heat treatment Surface condition Internal surface condition Permissible flaws Testing Aim Testing location Tester Extent of testing Testing by the manufacturer Testing for composition Dimensional check Testing for surface condition Testing for leak-tightness Non-destructive examination Documentation of test results Testing by the authorised material expert Testing Tensile test Ring flattening test Flaring test Testing of the tube inner surface Repetition of testing Certification of material testing Conditions for release Identification Test certificates Identification, packing, transport and storage... 14

6 Part 2: Recommendations for Operation Measures for the avoidance of damage 2.1 General Condensers Testing for leak-tightness before commissioning Commissioning Normal operation Shutdown periods Oil, hydrogen and other auxiliary coolers Part 3: Causes of tube damage 3.1 Tube damage due to operational factors Hydrogen-induced damage Vibration Droplet impingement erosion Manufacturing defects Lack-of-fusion defects Porosity Notches at the seam edge Manufacturing defects in seamless tubes References Appendix (Tables)... 26