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The following is a full English translation of the original work, published in French under the title:

LA RESISTANCE A LA CORROSION DE
L' INTERIEUR DES PROFILS CREUX EN ACIER

An introductory summary has been added by the Corus Tubes, Corby, U.K. in 2002
InternalCorrosion.doc

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SUMMARY


RESISTANCE TO INTERNAL CORROSION
IN STEEL HOLLOW SECTIONS

This report covers detailed investigations into internal corrosion in steel structural hollow sections
which have seen service in widely differing geographical and environmenta1 locations.
The samples investigated were removed from the following structures.

America
Pittsburg
Trolley bus poles. Urban atmosphere. 40-50 Years service.


Dayton, Ohio.
Lighting columns. Urban atmosphere. 59 years service.

Britain
Nore Forts
Tubular gangway. Marine atmosphere.
10 years service.


S.S. Aquitania
Lifeboat davits. Marine atmosphere. 37 years service.


Chelsea F.C.
Floodlighting tower. Urban atmosphere. 21 years service.

Germany
Wiesental
Transmission towers. Rural atmosphere. 18 years service.


Hiltrup
Roof trusses. Highly corrosive atmosphere over pickling
bath. 10 years service. (Dismantled due to heavy external
corrosion).

Japan

Lighting columns. Urban atmosphere. 5-11 years service.
(Investigation into location of drain holes at base of
columns).

Italy

Lattice braced tower cranes. Urban atmosphere. 10-20 years
service. Tubular steel framed buildings. Industrial
atmosphere. 25-30 years service.

France
Valenciennes
Outside loading gantry. Industrial atmosphere. 14 years
service.



Sulphate store. Highly corrosive next to pickling plant. 10
years service. (Roof bracings and stair handrails)



Stores building. Industrial atmosphere. 15 years service.



Factory building. Industrial atmosphere. 16 years service.

These investigations all show that steel hollow sections which have been sealed by welding or have
their ends flattened do not corrode internally. The majority of such samples investigated still had the
original mill scale adhering to their inner surfaces. Samples which had holes through the wall of the
section (unplugged drilled holes, damaged seam welds, and holes due to external corrosion) all
showed some corrosion adjacent to the hole but elsewhere remained unimpaired, revealing only slight
internal corrosion. Sections which have been sealed at one end only show internal corrosion adjacent InternalCorrosion.doc

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to the open end but elsewhere are not seriously impaired.
The report also deals with hot dip galvanising of structural hollow sections, including drilling,
draining and venting. It touches briefly upon the subject of 'breathing', and the advisability of
providing "pressure balancing" holes to obviate ingress of water during inhalation due to temperature
changes.
It also refers briefly to concrete filling and moisture venting.



The following companies and organisations referred to in this booklet are now part of the
organizations shown:
British Steel Tubes Division and Stewarts & Lloyds are now part of Corus Tubes, Corby, UK
GIE-Cometube and Cometube are now part of Arcelor Tubes, Aubervilliers, France
Mannesmannrohren-Werke are now part of V & M Tubes, Dusseldorf, Germany
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ACKNOWLEDGEMENTS
The author wishes to thank all the organisations which took part in this research work. In particular,
he would like to extend his appreciation to the members of the Technical Commission of CIDECT as
well as to the experts on corrosion not belonging to CIDECT, who have made it possible to gather the
data on which this work is based. InternalCorrosion.doc

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TABLE OF CONTENTS.

1. FOREWORD.
6

2. BACKGROUND TO THE INVESTIGATION.
6
2.1. Theoretical
6
2.2. Practical

3. SURVEY OF EXISTING LITERATURE.
7
3.1. Article by G. B. Godfrey - Extract from the Civil Engineer
7
3.2. Report by O. W. Blodgett - The Lincoln Electric Company
7
3.3. Bulletin of the American iron & Steel Institute
7

4. INVESTIGATIONS CARRIED OUT THROUGHOUT THE WORLD
9

4.1. American experience
9

4.2. British experience
10

4.3. German experience
17

4.4. Japanese experience
20

4.5. Italian experience
22

5. INVESTIGATI0NS CARRIED OUT RECENTLY IN FRANCE
24
5.1. Taking of samples in Valenciennes
24

5.2. Taking of samples in Dunkirk
28

5.3. General report of the Laboratoire National d'Essais, Paris
35

6. SOME SPECIAL CASES
41

6.1. Steel structures in heated spaces
41

6.2. Galvanised structures
42

6.3. Concrete filled columns
44

7. CONCLUSIONS
46

8. BIBLIOGRAPHY
47 InternalCorrosion.doc

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1. FOREWARD.
It is perhaps strange that so much energy and not inconsiderable sums of money have been devoted to
an investigation to prove that in the case of hollow sections sealed at both ends internal corrosion does
not exist.
It should be obvious!
If the research over the years has been haphazard it is simply because no international organisation has
taken the initiative to coordinate and analise the available information. It is to fill this gap that
CIDECT some years ago asked GIE Cometube to collate the existing information and from it form an
authorative understanding of the conclusions to be drawn from existing structures.
This investigation into the simple protection of the interior of hollow sections was carried out by
Cometube, who are indebted to the following for financial assistance.
The Federation of Steel Tube Makers (CSFTA).
The International Committee for the Development and Study of Tubular
Construction (CIDECT).
This investigation has made possible the reports of the National Test Laboratory (LNE) in Paris.
The purpose of this paper is to present the information which is available world-wide, together with
that which has been gained from more recent investigations in France.
2. BACKGROUND.
2.1. Theoretical
Corrosion can only take place if certain elements are present; iron, oxygen and water, in the form of
moisture in the air. If a section is hermetically sealed the moisture in the entrapped air will allow only
a limited amount of corrosion to take place. As the oxygen is used up oxidation will cease, since the
entrapped air cannot be replenished.
2.2. Practical.
On the basis of this theory it seems obvious that the protection of hollow sections is simply a question
of air tightness. Thus the general outlines of the investigation are clearly defined; the inspection of
structures which have been standing for many years must prove that the normal methods of fabrication
are sufficient to prevent internal corrosion. InternalCorrosion.doc

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3. SURVEY OF EXISTING LITERATURE.
It is impossible to list here, even briefly, all the publications which have been issued on this subject
and which may have come to our notice. We shall therefore limit ourselves to mentioning some
particularly interesting accounts which are based either on very detailed theoretical investigations or
refer to significant experiments.
3.1. Article by G. B. Godfrey from "The Civil Engineer" Journal of May1961 [1].
This article describes the investigation carried out at that time (1961) and mentions particular cases
where observations could be made on existing structures, more often than not as a result of fortuitous
accidents, such as that which occurred to the footbridge at Le Nore.
Further details on this particular structure is given in the chapter dealing with British experiencies.
3.2 Report by Omer W. Blodgett in the Lincoln Electric Co. Journal of August 1967 [2]
This report investigates the problems presented by the welding of hollow sections used in structures
and in particular the protection given to the interior of sections when closed by welding.
On the basis of his own observations and on foreign experience, he reaches the conclusions which we
reproduce in full below.
1) Sealed hollow sections require no internal protective coating and may be regarded as
essentially immune from corrosive attack.
2) Condensation in a sealed section is impossible, and when found upon inspection is evidence of
an opening having developed -possibly a small opening that is drawing surface water in
through capilliary action.
3) Adding a "pressure equilibrium hole" at any point in a hollow structure where water cannot
enter by gravity will prevent aspiration in an imperfectly sealed system. (If the engineer has
qualms about condensation, he might as well put the hole at a low point where it would serve
for drainage also - merely to satisfy his peace of mind.')
4) An "open" system should generally be kept as tight as feasible with rubber gaskets used at
manholes and such closures positioned so as to avoid water accumulation and the possibility
of its entrance by capillarity action or aspiration. A strategically placed pressure equilibrium
hole might be advisable. Such Systems should be protected with an interior coating.
5) A ventilated hollow structure should be internally protected and have adequate ventilation
holes at each end and in the sides.
6) Bolt and rivet holes should be avoided where-ever possible; they create conditions conducive
to water entrance by capillarity action.