Hydrogen embrittlement of a crude oil pipeline

(Tube rupture under the federal motorway A9, August 1993)

1. History

In November of 1918, the British Foreign Secretary George Curzon commented the outcome of World War I with: "The Allied cause had been floated to victory on a wave of oil [1]".

As in 1930's the German Reich was preparing for another war, it was to realize that crude oil would play an even greater role. Since there was a lack of natural oil sources, only the hydrogenation of coal came into question.

Two chemical processes were available, the Fischer-Tropsch-synthesis and the Bergius-Pier-synthesis. The former method is based primarily on the use of high temperatures, the latter on the application of high pressures.

These both processes are operating with brown coal, which was abundant in central Germany. Accordingly, three refineries were built namely in Leuna at the river Saale, in Zeitz at the river Weiße Elster and in Boehlen at the river Pleiße. Mainly aviation fuel was produced.

The Leuna works were built during the First World War, when lack of gunpowder threatened. Here saltpetre was produced by means of the synthesis of ammonia by the Haber-Bosch-Process. Until the outbreak of World War I, saltpetre was imported from Chile. The two other plants were start-ups. From the government the slogan of "self-sufficiency" was coined which was widely believed by the people (see [2]).

On 12 May 1944 Allied aircraft appeared over these works. With their bombs, they finished all the dreams of victory.

After the war it was possible to set the plants in function again. The Russian occupation power soon regarded East Germany as the main front against Western imperialism (the western side saw it the other way around) and laid a pipeline for crude oil. This pipeline called "Friendship" led first to Schwedt at river Oder and finally to the Leuna site. In the immediate neighbourhood, in the village Spergau (altitude about sea level 107 m), a tank farm was built.

From Spergau, a pipeline was led to the Boehlen plant (1970), via the Elster flood plane. The course of the line swung out slightly to the south, which is due to that the open mining of Zwenkau must be bypassed (4 km wide).

For processing the crude oil, in 1974 the plant of Zeitz was completed by a refinery for the production of Diesel fuel. In order to deliver the necessary amount of crude oil to the Zeitz plant, a diversion was welded into the Boehlen pipeline. This was performed in the Elster flood plane, near Zwenkau-Löbschütz. Finally, they separated the Boehlen plant from the pipeline so that the oil came exclusively to the Zeitz plant.

When diesel refining is performed, as byproduct, raw gasoline is produced. For further treatment, the gasoline was pumped to the Boehlen plant by means of an additional pipe ("product line").

Since the pipeline was aimed originally at the Boehlen plant, with a length of 50 km, she was considerably longer than the air-distance of about 30 km.

The pipeline crossed the river Saale (altitude 94 m) by forming a "culvert" (in german, in a special meaning, called dueker). Then the line went on to a (high) level plane. After 2 km the pipeline met the federal motorway A9 at kilometre 141.5 and an altitude of 127 m. The nearest municipality was the village of Rippach at the small Rippach river (altitude 112 m), the nearest town was Weissenfels at the Saale river.

There the highway is about ground level. Into the underground, they drilled a tunnel and placed a protective tube there with a length of 45 m. In the protective pipe, the oil pipe was inserted. The distance from the top edge of road was about 3.6 m, thus the pipeline significantly deviated from the normal burial depth (about 1 m).

The landscape east of the highway is flat as a table. It falls from the southeast to northwest from and merges with the Leipzig lowlands. As namesake of this "plate" serves the city Luetzen (see [3]). In 1632, here the Protestants fought under King Gustav II Adolf of Sweden against the Catholics under Wallenstein. The Protestants won the battle to the extent that the opponent conceded the field, but lost their commander.

In 1813, Napoleon arrived in Luetzen. The night of 1 for the 2 May he spent at the monument of the Swedish king. Then he went about 6 km uphill to the village Großgoerschen arranged southeast of Luetzen. There he met a Prussian-Russian army. This Bataille de Luetzen ended with a slight advantage for Napoleon.

Behind the highway the oil line meets a gas line (coming from the Soviet Union), to which she went parallel, until both lines reached the flood plane of the Weiße Elster. The watershed was passed nearby Kleingoerschen (height of 145 m).

This region is also used by a raft ditch for crossing the watershed. That raft ditch had been dug in the Middle Ages with the aim to carry wood from the mountains to the salt mines located near the river.

In the official maps of the GDR (school atlas), the course of the pipeline is displayed only roughly, in Figure 1 it is given more accurately.

Map of pipelines in the center of the GDR (section from [4]); course of the oil pipeline Spergau-Zeitz registered as a black line; the culvert under the highway is marked with <b>L</b> (as leakage), the watershed with <b>W</b>
Figure 1: Map of pipelines in the center of the GDR (section from [4]); course of the oil pipeline Spergau-Zeitz registered as a black line; the culvert under the highway is marked with L (as leakage), the watershed with W

From the river Saale to the watershed, the oil was pumped about 51 meters uphill.

The hydrogenation plant Zeitz was arranged in the flood plain of the Weiße Elster at an altitude of 143 m. As "heating oil", the whole fuel production of the refinery Zeitz was delivered to West Berlin. As the monthly transfer volume was irregular, the system worked discontinuously, which was also valid for the operation of the pump in the tank farm Spergau.

When the leaders in Moscow were told of this business, they reduced the delivery quantity and increased the price of oil with the result that Earl Curzon was right for the third time (compare [5]).

The interruption mode of the Zeitz plant was initially maintained after reunification of Germany.

Specifications:

Tubing welded with a longitudinal seam in lengths of 6 m, two of these sections are joined at the factory by a circumferential weld
Welding process in the plant submerged arc welding
Welding process in the field manual arc welding (circumferential weld)
Tube dimensions 530 x 8 mm
Steel Ch G S 14 according to GOST 5058-65 corresponding to StE360.7 of DIN 17172
Design pressure 64 bar
Operating pressure 33 bar
Operation mode discontinuously (several hours cycles)
Check for leaks monthly as a differential pressure measurement

The tightness and leakage, respectively, was tested in a way that the pipeline has been brought to service pressure against the closed valve of the customer (Zeitz). Then the pipeline was closed also on the pump side. After a holding time of one day, the decrease in the pressure was determined. Between 3 and 6 June of 1993, the pump operation had rested. This interruption was followed by a leakage test.

On 26 August 1993, at 20.30 clocks, the oil pump switched off. The cause of the shutdown was detected in a drop in pressure. The maintenance personal tried to restart the pump several times, without reaching the operating pressure. Three hours later they finished their effort.

In the next morning, on both sides of the highway, the police discovered ponds in size of up to 50 m, from which a strong odour emanated. It was recognized that the ponds were not filled with water but with oil. About 1 million litres of oil have spilled into the environment. Following drainage channels, the oil began to flow out gradually towards the river Saale.

The pipeline was excavated, Figure 2.

Accident site as viewed from the east (side of Zeitz).
The ruptured pipe has already been taken, only the protective tube can be seen (arrow).Laying depth of the pipe is about twice that of the taller people standing at the high way
(approx. 2 x 1.8 m = 3.60 m).
Photograph taken from [6]
Figure 2: Accident site as viewed from the east (side of Zeitz ). The ruptured pipe has already been taken, only the protective tube can be seen (arrow).

Laying depth of the pipe is about twice that of the taller people standing at the high way (approx. 2 x 1.8 m = 3.60 m). Photograph taken from [6]

After they had pulled the tube from its protective sheathe, a crack in the length of 1.9 meters became evident. The fracture had occurred nearby the longitudinal welding seam (Figure 3).
Pipe with gaping crack at the longitudinal weld. Photograph taken from [6]
Figure 3: Pipe with gaping crack at the longitudinal weld. Photograph taken from [6]
The crack was found in the 6.30 clock position, which is about in the bottom of the tube. A channel-like loss of material was found, obviously due to corrosion. As a result of this process, a thick black coating was formed (Figure 4).
Pipe wall with black layer, final fracture light (marked by arrow).
Photograph taken from [6]
Figure 4: Pipe wall with black layer, final fracture light (marked by arrow). Photograph taken from [6]
Already from the coloring it could be seen that layer did not consist of rust, but of iron sulphide. Thus it could be concluded that an attack had occurred by hydrogen sulfide, which is always contained in the crude oil. Organic sulfur compounds (mercaptans) as derivatives of hydrogen sulfide have the same effect and will not be treated separately.

Metallographic sections were taken, among others, from the center of the leak area. The height of the tube edge and the two weld layers are slightly offset from each other. The edges of the inner layer were groove-like attacked. From such a groove the crack had started (Figure 5).

Metallographic section through the center of the leak;
slight offset in the height of the pipe at both edges and welding positions,
corrosion grooves at the edges of the inner layer.
Photograph taken from [6]
Figure 5: Metallographic section through the center of the leak; slight offset in the height of the pipe at both edges and welding positions, corrosion grooves at the edges of the inner layer. Photograph taken from [6]

Pipes with longitudinal seam tend to be so-called degree of camber, which is weakly visible in the micrograph. Here, the degree of camber was 2.3 mm [6]. Since reunification of Germany, the traffic on the highway had risen strongly. Thus it was assumed that the tube was excited to vibrate, i.e., it suffered cyclic bending. Such a crack would have been situated transversely, whereas cracks arising from the internal pressure are oriented axially (except creep cracks at circular weld seams in steam power plant).

It now penetrated to the public that the damage was caused by corrosion. This led to the assumption that, in East Germany the entire piping system was rotten, see [7] and [8].

Two samples were delivered (I and II). The first sample was taken from the center of the leak, the second from its outer edge.

2. Investigation

2.1. Analysis of the dark layer on pipe

The X-ray analysis revealed the presence of chlorine in addition to iron and sulfur, see Figure 6.

Energy-dispersive X-ray analysis) of the coating on the tube inner wall:
Iron, sulfur and chlorine
Figure 6: Energy-dispersive X-ray analysis) of the coating on the tube inner wall: Iron, sulfur and chlorine
When cleaning the samples with inhibited hydrochloric acid, a foul odour was developed, as it is typical for hydrogen sulphide.

FeS + 2HCl = FeCl2 + H2S

Thus the cover layer consisted of iron sulphide.

2.1 Macro photos (light optical)

Sample I

First, the sample is so positioned that the inner wall can be seen. The corrosion was strong, so that the seam itself hardly emerges. Of the fracture surface, the inlet area is visible insofar as it deviates greatly from the vertical orientation (Fig. 7).

Sample I, view of the inner wall, which is strongly corroded; transition from the inner wall to the fracture surface marked.
Figure 7: Sample I, view of the inner wall, which is strongly corroded;
transition from the inner wall to the fracture surface marked.
After erecting the sample, a threefold division of the fracture surface can be seen (A, B, R). The area A is arranged beneath the inner wall, and occupies about 40% of the cross section. The fracture surface appears smoothed by corrosion. The attack was so intensive that the crack was greatly broadened.

In area B, the crack structures are well preserved. The crack was starting at zone A. The crack surface is divided into many fronts. There are signs of a transversely oriented lamellar structure.

The final fracture R stands out brightly, i.e. it is a shear lip. Its width is not more than 1 mm (Figure 8).

Sample I, erected, fracture surface divided into three zones (A, B, R)<br>
A - smoothed area (old crack),<br>
B - lamellar area (fresh crack),<br>
R - shear lip (final fracture)<br>
Figure 8: Sample I, erected, fracture surface divided into three zones (A, B, R)
A – smoothed area (old crack),
B – lamellar area (fresh crack), R – shear lip (final fracture)

Sample II (shown only in the lying state)

A strong shadow cast marks the transition from the zone of weak corrosion to that of strong corrosion (from right to left). The edge of the fresh fracture site appears frayed (Fig. 9).

Probe II, inner wall; vertical shadow cast in the middle marks corrosion;
frayed edge of fresh fracture (left)
Figure 9: Probe II, inner wall; vertical shadow cast in the middle marks corrosion;
frayed edge of fresh fracture (left)

2.3. Electron microscopy images of the fracture surface (SEM)

Sample I

The overview image is limited to the freshly broken areas. Striking again is the lamination of the fracture surface, both in the fresh service crack region (area B) and in the fast fracture region R (Fig. 10).

Fresh service fracture area, general lamellar structures
Figure 10: Fresh service fracture area B showing general lamellar structures
(area A as old crack and area R as final fracture; detail from Figure 8)

In Figure 11 the most recent fracture region (crack-tip) is considered. There are facets pattern in the service crack area B. The fast fracture R appears fibrous.

Transition from the crack initiation zone B to final fracture zone R;
facets in region B
Figure 11: Transition from the crack initiation zone B to final fracture zone R; facets in region B
(detail from Figure 10, left part of the area, sample 90° turned to the left)

The facets of the crack path take their origin at crevices (cavities) whose cause is given by the presence of sulphide inclusions (Fig. 12)

Crack region B, facets start at inclusion crevices
Figure 12: Crack region B, facets start inclusion crevices (detail from Figure 5)

In area B, the local crack regions are separated from each other by shear ridges (Figure 13).

Start of the fracture facets at inclusion crevices;
facets separated by shear ridges
Figure 13: Start of the fracture facets at inclusion crevices; facets separated by shear ridges
(detail from Figure 12, middle)

A deep lying field of crack facets ("rosette") started on a narrow inclusion cavity, which was broadened during fracture (Figure 14).

A unilateral rosette starts from an inclusion cavity;
the rosette is surrounded by shear ridges.
Figure 14: A unilateral rosette starts from an inclusion cavity; the rosette is surrounded by shear ridges
(detail from Figure 13, bottom right).

At higher magnification a further rosette is shown, in Figure 15. The structures are well preserved.

Deepened rosette
Figure 15: Deepened rosette (detail from Figure 13, top left)

A symmetrical rosette was created ahead of the main crack front. The facets radiate symmetrically, i.e. also back to main crack front (Figure 16 and Figure 117).

Region of facets ahead of the crack front (detail of Figure 5, bulge)
Figure 16: Region of facets ahead of the crack front (detail of Figure 11, bulge)

Symmetrical emanation of facets from the inclusion cavity
Figure 17: Symmetrical emanation of facets from the inclusion cavity (detail from Figure 16)

Sample II

As expected, isolated rosettes were found (Figure 18 and Figure 19).

Facet areas
Figure 18: Facet areas

Figure 13:
Symmetrical emanation of facets from the inclusion crevice (detail from Figure 12, left)
Figure 19: Symmetrical emanation of facets from the inclusion crevice (detail from Figure 18, left)

3. Discussion

3.1. Results

  • The crack was arranged next to the longitudinal weld, which entailed the formation of a ridge.
  • The ruptured portion of the tube was arranged such that the weld was below.
  • The bottom of the pipe was heavily corroded and covered with iron sulphide.
  • The inlet area of the crack had been broadened by corrosion.
  • On the fresh service crack surface, fine faceted structures (rosettes) were found, which originated at inclusion cavities.

    3.2. Discussion of singular points

    Through its bilateral elevation a weld represents a natural notch. Furthermore, when bending the plates for welding, the difficulty is that fully rounding off edges, so a ridge is formed increasing the circumferential stress.

    The fact that the pipe floor was severely attacked points out that the aggressive constituents of the oil were collected here. The formation of such a sump in turn requires that course of the tube was locally deepened. Thus a bag has been formed under the highway.

    When the pipeline was laid, they should have to dig the trench pretty deep to keep the slope evenly. Instead, under the motorway, they went abruptly deeper, cf. Figure 2.

    To some degree, crude oil is contaminated with water and sulphur compounds, especially hydrogen sulphide. At standstills, the oil decomposes. Water sinks to the bottom and flows from the mountain side to the lowest point. The water runs all contaminants with it, including the hydrogen sulphide. It reacts with the iron according to the formula:

    Fe2+ + H2S = FeS + 2H+

    The hydrogen sulphide attacks the steel not only strong, but also hinders the hydrogen atoms on the recombination, so that the hydrogen can extensively penetrate the steel. Such contaminated raw products (beside crude oil also natural gas) are called "sour".

    From the accident site to the watershed was a dam height of nearly 20 m with a storage length of about 9 km (no cross valleys). Thus, the catchment area of the pipe swamp formed under the motorway was significant.

    3.3. Fracture mechanism

    Subjects with fine structures, some of which are isolated from the main crack and radiate back to it (rosettes), there is a fracture pattern, as it is produced in softer steels (strength less than 1000 MPa) with hydrogen. How large the single rosette will grow depends on the distance to neighbouring inclusions. The amount of hydrogen that is stored in the respective cavity is essential also.

    When welding steel, pores or fusion defects collect such an amount of hydrogen that the breaking areas are visible to the naked eye. Figure shows such a case at a weld bend test. The fracture is clearly distinct from the surrounding brittle fracture; therefore one speaks of "fisheyes". The fineness of the fracture pattern arises from the fact that the crack propagates not along cleavage planes ({100}-planes), but along sliding planes ({110}-planes), see [9].

    Two macroscopic fisheyes on the fracture surface of a weld bend test
(as example)
    Figure 20: Two macroscopic fisheyes on the fracture surface of a weld bend test (as example)
    In steel, hydrogen diffuses through the lattice in the atomic state. Because of its smallness the hydrogen atom can reach considerable diffusion rates, about l micron per second.

    In their path through the steel the hydrogen atoms meet cavities. There they are collected and recombine to gas.

    The resulting pressure is not high enough to initiate the fracture process, with one exception: This is the "blistering", which is only possible with very heavy charging. In the technical field such kind of charging is present during the attack of acids or hydrogen sulphide. The cracks are arranged in the rolling plane (thickness direction), since the inclusion cavities for this plane have their maximum cross-section, and also act as notches.

    By tearing of the remaining material, blisters grow and the pipe wall collapses eventually. This kind of cracking occurs only, if hydrogen sulphide or acids are applied continuously [10]. In the present case such a continuous attack did not work. In general, by superposition of the internal load with an external load, eventually the material is brought to flow. On the cavity walls, the hydrogen is returned to the atomic state and sucked into the matrix (Tribosorption). In deformation induced submicroscopic cavities, hydrogen recombines again. In the form of tiny bubbles, hydrogen inhibits in the gliding process and tears the slip planes.

    3.4. Cause and sequence of the damage

    In the present case, the hydrogen sulphide (and water) could accumulate locally. This was due to that a short deepening was inserted in a long slope of the pipe. With the start of pumping, the oil begins to flow gradually and flushes away the sump, that is, at the moment, in which the operating pressure is reached, the hydrogen uptake is stopped. The hydrogen, however, needs some time to diffuse into the high-strained areas and to build critical inner loads at the inclusions there (incubation period). It therefore seems to have been necessary for the initiation of cracking that the charging with hydrogen and the mechanical load were superimposed in time. If the pump is operating against the closed valve of the customer side, the swamp remains preserved. This case could have been present in June of same year, as the operation mode was changed from a multi-day interruption into the leak test. A crack nucleus originated. To propagate the crack further, only small inputs hydrogen were necessary as they have arisen in the two following leak tests, and finally during normal operation.

    In the current case, the seam was welded with a machine (submerged arc welding). Because of the strong heat input, in contrast to the manual welding, the hardening of the heat affected zone is low, the residual stresses are, however, are high. Therefore, the lower sensitivity of the material to hydrogen embrittlement is compensated by a higher stress level.

    The found older crack probably originated during a previous leak test. Although blunted by corrosion, he worked as a starting notch.

    As hydrogen sulphide delivers the driving force that kind of damage is termed sulphide stress cracking.

    The present diagnosis ruled out the suspicion of the general decay of the pipeline. The repair could be confined to eliminate the reason for the swamp formation, thus making the pipe slope evenly.

    The line was re-laid on a length of 180 m. For three further years, the pipeline served as a lifeline to the refinery Zeitz, until it was closed. The cleaning of the contaminated soil was transferred to bacteria, see [11], [12]. But four years were needed. Costs of about 67 million German marks had incurred. Thus, in the remediation of environmental damage, a new dimension had been reached.

    Against the staff of the pumping station a court case was opened. The reproach was spoken that, with 3 hours, the period during which an attempt was made to move to the pump again, was relatively large, . It raised the question of how one can recognize that the fault does not lie in the pump, but in the line. On the receiving end, a device should be installed, which measures the incoming amount of oil. But that was not common at that time.

    In Germany, until then, such a damage of a pipeline for oil – in contrast to those for gas – had not occurred. The staff was overwhelmed by the situation, and the court case was laid down. After all, the term "hydrogen-induced cracking" was used [14].

    Over time, the entire distance pipeline system in East Germany was subjected to a so-called stress test. Over time in East Germany the entire pipeline system was subjected to a so-called stress test. Here a pipe section is filled with water, and the steel is loaded to about its elastic limit. In addition to the pressure you measure the amount of water added and receive a kind of force-displacement curve. After a holding time of 60-90 minutes, the pressure is released. Then the application of pressure is repeated [15], [16].

    Already in the first test section, with a pressure of 86 bar instead of respectively 125 and 129 bar in the neighborhood, a premature rupture occurred, There sulphide deposits and again mini fisheyes were found on the fracture surface. This tube section leads north from the river Oder to the Schwedt refinery. Between the villages Crussow and Schoeneberg the line crosses a hill at a height of 67 m. On its further way to Berkholz the line drops with low points of 40 m, and then rises again. One of those low points was the site of premature rupture (Spring-lake?). Apparently, the flow of oil from Russia now and then was interrupted.

    The experts of the GDR would have preferred to use seamless rolled tubes of West Germanx (e.g. by the Mannesmann company) instead of bent and welded steel sheets. But the United States stopped the trade. This "pipe embargo" lasted from 1963-66. That they had acted shortsighted proves the present case. In the 1980s the commercial contract "large tubes in exchange for natural gas" was completed. The U.S. attempt to impose an embargo also, was refused by the government of West Germany.

    3.5. Measures of precautions

    The introduction of hydrogen is obtained as the result of corrosion and this in turn of a separation of oil constituents. As long as the oil flows, the pipeline is protected from corrosion. Other disasters, economic and political crises can cause the oil flow to be interrupted. The critical moment is starting again. As with all media-induced fractures, a certain threshold from the concentration of the hydrogen and the amount of the mechanical load had to be exceeded. Hydrogen cracks grow relatively fast.

    As far as the stress, it depends on the degree of triaxiality expressed by the so-called stress intensity factor. Insofar welded pipes are more susceptible than seamless rolled.

    The hydrogen supply depends of the ratio of the lengths of the catchment area and storage area (sink) at a minimum slope. Therefore, the height position of the line can be changed only gradually. It is in the nature of a culvert (dueker) that the height changes abruptly. Therefore the culvert represents a weak point and should be used sparingly, not in street, but only at river crossings.

    When testing the pipeline by using a pig, sulphide deposits are of special interest, because cracks can hide among.

    When a prolonged standstill is expected, the pipeline should be emptied, rinsed and blown dry.

    The interruption kind of diesel fuel refining in Zeitz had already caused a hydrogen-related damage (in 1978). After the system had been resting for a long time, a vessel (B204) was subjected to a pressure test. Then the plant went into operation. A few days later the vessel threw away its cover, see [17]. The plant had been shut in the wet state, resulting in a continuous loading revealed by hydrogen. The authorities took this loss as a reason to prohibit pressure tests on H2S-loaded plants.

    4. Summary

    While pumping of the crude oil rested some days, water and hydrogen sulphide were separated from the oil and enriched in a tube deepening beneath the motorway, such forming a swamp. As result, the pipe base was heavily attacked by corrosion and charged with hydrogen. During a subsequent leak test this swamp remained preserved so that the operational stress and the supply of hydrogen were superimposed. A crack was originated, which grew over the next three months.

    The hydrogen was collected at the inclusion cavities. Starting at these sites, the steel was broken with the formation of microscopic fisheyes. A prerequisite for the damage was that the tube was arranged with the welding seam in the bottom. In previous shutdowns, already cracking had expired. This crack was arrested and then broadened by corrosion, but still acted as a starting notch.

    Literature

    1. Address to Inter-Allied Petroleum Council, London, Nov. 21, 1918 (cited from: The NewYork Times, November 23 [1918])
    2. Walser, Martin: A gushing fountain. Suhrkamp Verlag Frankfurt am Main 1998, p. 289 (Excerpt in Appendix)
    3. Tour atlas districts Halle.Leipzig VEB Touristverlag Berlin/Leipzig 1978. p. 158
    4. School atlas of the GDR. VEB Hermann Haak Gotha 1988, p. 10
    5. Tellkamp, Uwe: Tower – History from a sunken land. suhrkamp taschenbuch 4160. Suhrkamp Verlag Frankfurt am Main 2010, p. 930 (Excerpt in Appendix))
    6. Report of Technical Inspection Hannover/Sachsen-Anhalt of 17.09.1993 (own paper of 15.09.1993 as assistance)
    7. Bild am Sonntag vom 12.09.1993, pp. 14/15, by Markus Walter: Oil pipeline – the ticking time bomb. Decades old rusty pipes. Civil protection is poorly equipped.
    8. STERN, 26.9.1993: Environmental risk. Around 1000 kilometres of oil pipelines in the new federal states do not meet Western safety standards and pollute the environment. Although the pipelines were led only in the 70s, they already show holes and cracks.
    9. Kikuta, Y.; Araki, T.; Kuroda, T.: Analysis of fracture morphology of hydrogen assisted cracking in steel and its welds. ASTM STP 645, Philadelphia 1978, pp. 107-127
    10. Moeser, M.: On the hydrogen fracture of low-strength steels – fisheyes and blister cracks. Neue Huette, Leipzig 29 (1984) 6, pp. 229-234
    11. Mitteldeutsche Zeitung 07.08.1994, by Bärbel Schmuck: Environment. Where bacteria can eat away the oil. One year ago today on the A9 at Weissenfels: Largest oil spill in Saxony-Anhalt.
    12. Daei, B.; Schmitz, J.; Stölting, K.; Patzig, D.: Ecologically sound method to restore the functionality of contaminated areas with a view to subsequent use; illustrated by examples from practice. Environmental Agency of Brandenburg, studies and conference proceedings, Volume 4: Waste Management and Mining, pp. 55-59
    13. LOBBE TatSachen Nr. 13/1998, p. 16
    14. Hallesches Tageblatt of 18.05.1995: Trial set for pipeline rupture at Weissenfels. No human error found in oil spill off the A9 / Extensive analysis revealed corrosion causes. (Excerpt in Appendix)
    15. Dechant, K.-E.: Stress test – testing target and past experiences. 3R International 15 (1976) pp. 26-30
    16. Leipnitz, R.; da la Camp, H.-J.; Kuhn, G.; Dube, R.: Inspection and rehabilitation of pipelines. Rehabilitation by means of the stress test – a practical way to increase the reliability, durability and safety of existing pipelines. Workshop on the prevention of water pollution due to pipeline accidents, Berlin 2005 (Publications of the German Federal Environmental Agency)
    17. Möser, M.: Damage in an elbow of an ethylene plant, VDI Report No. 902, 1991; pp. 281-304

    Concerning the mechanism of hydrogen fracture see also: Fractography and mechanism of hydrogen cracking – the fisheye concept

    Furthermore, from refinery Zeitz, the following case is of interest:
    Cracking of an elbow due to hydrogen sulphide – hydrogen embrittlement

    A similar case is the rupture of a city gas line with a resting gas column caused by water accumulation in a trough:
    Rupture of a gas pipeline due to hydrogen embrittlement

    Martin Möser, 03 Dezember 2012, English version 11.04.2013

    Appendix

    Essential parts of sources [1], [2], [5] und [14] in direct quotation:

    Quote [1]"FLOATED TO VICTORY ON A WAVE OF OIL"
    Earl Curzon Tells How Allied Ingenuity Overcame Petroleum Crisis of 1916
    LONDON, Nov. – Earl Curzon, member of the British War Cabinet, presided tonight at a dinner given by the British Government to the Interallied Petroleum Conference. In toasting the French, American and Italian delegates, Earl Curzon declared that the Allied cause had been "floated to victory on a wave of oil" because if it had not been for the great fleets of motor trucks the war could not have been won. In the late eighteen months the Council has dealt with 13,000,000 tons of oil.
    In December 1916, Earl Curzon said, the oil situation was critical. Stocks were so depleted that the British fleet was obliged to restrict operations. At the time when tank ships were being sunk in increasing numbers the idea was conceived of carrying oil in the double bottoms of ordinary cargo vessels, and 1.000,000 tons were transported in this manner. ...

    Quote [2] (Walser, A gushing fountain) to self-sufficiency (Autarkie):
    John, the central character of the autobiographical novel, is on the way home from the island Daenholm at Stralsund to Wasserburg on the lake of Konstanz. On the Daenholm he took part in the Empire championship of the Navy HJ where he won the signal waving. His friends have left the train in Berlin, to look at the local ruins. The train has reached Central Germany. Now, for half an hour, the train passes a wilderness of tubes and rods.
    "Leuna, said the soldiers, there gasoline is made. From coal. Once we are self-sufficient, the war is won. One roared: Tonight or Never. Another remembered: self-sufficiency, self-sufficiency."

    Quote [5] (Tellkamp, Tower) to the oil economy of the GDR in their last years:
    The hero of the novel, Christian, has two uncles, Meno (mother's brother) and Ulrich (father's brother). The former uncle is lecturer in a publishing house, the latter works as a technical director in a State-owned enterprise. In the family, Ulrich is the only member of the communist party. Meno wrote in his diary:
    "Ulrich worried. Aged. Difficulties in operations. ...The world market prices of crude oil and, consequently, of industrial petroleum-based products had fallen sharply since `86. Otherwise, the price we have to pay to the SU for oil on the base of CMEA agreement is well above the world market level. This makes our products more costly. We are no longer able to obtain the necessary gains when selling the products into the West. "

    Citation [14] for trial
    By order of 13 April 1995, the case is laid down. This was proclaimed by the Attorney General Ingo Sierth of the prosecutors of district Halle, branch Naumburg. The investigation was done in two ways. On the one hand it was examined whether the failure has been induced culpably. On the other hand it was investigated on suspicion that environmental damage has been increased culpably by a delayed shutdown of the pumping operation.
    Expert: The fracture was caused by hydrogen-induced cracking, which emanated from corrosion grooves and cracks at the weld root. These cracks could have come from a previous stress corrosion cracking or strain-induced corrosion cracking. A crack in the pipeline system Spergau-Zeitz occurred a few minutes after the start of the main pump 26 August 1993, at 20.30 clock. The pumping was stopped at 23.50 clock on suspicion of a leak. After a time-consuming analysis of the situation, and a consideration of the factors influencing, the expert witness believes that already at 23.10 clock suspicions of a leak of pipeline existed which had justified the termination of operations. In this case, it needs to be kept in mind that, in practice, the operators would have only a short span of time for recognition the problem and to find the right decision, which is in contrast to the long duration of time which was available to the expert witness.
    Outdated and not very reliable control and monitoring devices are one reason that it was not been possible for the operators to recognize the damage to the pipeline quickly.

    above article als PDF
    back to Failure Events
    back to Home