Seal design ends explosive decompression

Some believe that Economos' biggest triumph in the battle to beat pollution has gone almost entirely unnoticed outside the oil industry.

Since the beginning of the North Sea oil industry more than 30 years ago, few companies have made a greater contribution to reducing offshore production leakages than Economos, Europe's leading designer and manufacturer of seal technology.

Some believe that Economos' biggest triumph in the battle to beat pollution has gone almost entirely unnoticed outside the oil industry.

Explosive decompression in seals, one of the most serious problems, which used to regularly disrupt oil production, has now been almost entirely eliminated.

This major technological advance came about through the Economos' commitment to advanced materials technological research and development.

With the development of a new generation of seal polymers designed to contain the insidious phenomenon of explosive decompression in seals, the number of spillages caused by this pressurisation effect has now been dramatically reduced.

This triumph of technological innovation by Economos has resulted in safer offshore oil production and a cleaner environment.

It is an unfortunate but inescapable fact of life that accidents happen in offshore production, sometimes causing spills and blowouts of oil, gas and other substances.

The causes of such incidents are usually due to human error, material defects, component failure or equipment malfunction, often aggravated through working in extreme conditions.

When such an incident occurs the cost of cleaning up pollution, lost production and increased insurance premiums can be severe.

Explosive decompression in seals used to be one of the industry's major problems, causing many seals to suddenly fail and result in spillages.

In 1994 in the Usinsk area of Russia, a seal on a land pipeline ruptured, leading to the spill of more than 100,000t of oil and causing heavy pollution around the Pechora River.

The cost to the environment, and to the production consortium, was catastrophic.

Explosive decompression can happen when any gas filled fluid is passing through an elastomer seal.

When the pressure inside the seal fluctuates inappropriately between high and low, massive heat can build up, inducing the oil or gases flowing past the seal to molecularly migrate into the seal's polymer material, eventually causing it to rupture.

But simply, pressure compresses the gas contained in the liquid retained by the seal and forces it into the microscopic molecular spaces in the surrounding seal material.

When the seal system undergoes rapid depressurisation the gas that has seeped into the polymer expands and moves outwards towards the surface.

This process usually results in cracks and fragmentation developing in the seal, and it then eventually bursts apart, often causing spillage.

Explosive decompression usually occurred because of factors like the seal being badly fitted, wear and tear, or because its polymer material was of poor quality.

At a time when explosive decompression used to be a more frequent problem, often causing an entire production system to be shut down, high-density seals that were not over-rigid in low temperatures were usually used, designed with a safety margin of 100/1.

When Economos established its UK division in Aberdeen it set out to overcome the problem of explosive decompression in seals and aimed to improve even further on existing seal safety standards.

After tanker transportation and drilling operations, pipelines are the main environmental risk areas in offshore oil operations.

Statistics show that the average probability of accidents occurring on underwater pipelines around North Europe are 6.4x10e-4, with the probable cause of such an event likely to be a material defect.

Explosive decompression still remains a possible cause of seal failure today if the seal material is made of an unsuitable or poor quality material.

Thanks, however, to Economos' unrivalled track record in designing and manufacturing high quality seals able to meet just about any extreme operational circumstances, the incidence of spillages caused today by explosive decompression in any of its seals has been virtually eliminated.

Along the many thousands of kilometres of complex systems of underwater pipelines carrying oil and gas under the North Sea and which are fitted with Economos' seals, the incidence of explosive decompression is now rare.

Economos' research and development laboratories have enabled it to keep right at the very forefront of seal technology.

As a result, virtually every year the company has launched new high performance sealing materials derived from its versatile Ecopur polyurethanes and its range of high quality elastomer materials, such as HNBR and FKM materials.

That same high level of expertise and R and D was brought to bear on the problem of explosive decompression, and a new variant of H-Ecopur was developed to successfully overcome the molecular migration phenomenon that caused it.

Economos' expertise has now become firmly established in every sector of the offshore oil and gas industry.

Its ability to super-fast manufacture seals, supported by an outstanding technical support and back-up service, has earned the company an unrivalled reputation for being able to provide a solution to any difficult sealing application, whether in low or high temperatures or pressures or for unusual profile applications, and for being able to do without the usual expensive tooling costs or delays.

First established in the UK in 1989, Economos has 12 manufacturing centres across England, Scotland and Wales.

Experienced engineers who can design and manufacture almost any seal or component, without the delays or costs associated with traditional moulding methods, staff each of these.

Economos' secret is its in-house developed CNC seal production centres with unique software and world-class materials.

As part of the Austrian based Economos group, which operates over 24 subsidiaries, the UK company draws on worldwide expertise.

The central laboratories and R and D functions are constantly improving their equipment, materials and production software.

Economos' Aberdeen facility, which specialises in the North Sea oil and gas industry, has invested hugely in setting up revolutionary NG40 state-of-the-art CNC seal manufacturing machine to complement its IP series equipment.

These machines can turn seals up to 16in diameter with a high standard of precision and quality.

The Economos portfolio of expertise covers almost all sectors of the offshore oil and gas market, and through working with some of the major players over many years the company has won considerable standing.

Its ability to manufacture seals with very short lead times is the industry's benchmark for service.

This ability is supported by a first-rate technical support and backup service, from media compatibility and FEA analysis of designs, right through to development of special materials, and all without tooling costs or time delays.

In the North Sea oil and gas industry, Economos has become the hallmark of quality and reliability.

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