Heraeus Helps Barrier Develop Insulation System

A custom-built infrared system from Heraeus Noblelight has helped the Wallsend-based Barrier Group to develop a thermal insulation system for submarine pipelines. The high-power infrared system is used to cure adhesive to ensure that a polypropylene material, which imparts impact resistance, corrosion protection and additional thermal insulation, can be efficiently applied to an insulation shell around a conventional steel pipe.

This is claimed to result in reduced lay tension, together with improvements in pipe-laying productivity. The Barrier Group provides corrosion-protection coatings for steelwork and pipelines in the oil-and-gas sector. It has now diversified into areas such as passive fire protection, metal spraying, powder coatings and subsea insulation. One result of this has been the development of the patented Bubbletherm system, where a conventional steel pipe is enclosed with epoxy syntactic insulation and the whole assembly is further insulated and protected with a wrapping of a proprietary polypropylene material.

Subsea pipelines are used to carry oil and oil-and-gas mixes from subsea wellheads to onshore refineries or offshore processing platforms. Oil discharges from wellheads at temperatures typically between +80C and +160C. To prevent wax and hydrate formation, which could restrict oil flow, it is important that the oil does not cool significantly in the ambient subsea temperatures. As a result, pipe insulation is vital; conventionally, this achieved by pipe-in-pipe manufacture, where the annular space between the inner and outer pipes is filled with lightweight insulation material.

This kind of pipe is expensive to produce and, because it uses two individual steel pipes, it is also heavy. As a result, a reel pipe-laying vessel can only carry a restricted tonnage, which, in turn, restricts the length of pipe it can lay before returning to the port for re-loading. With the new Bubbletherm pipe, which is said to be cheaper to produce than competitive pipes, it is now possible to lay pipe with reduced reload cycles and with lower levels of tension. When the pipe is laid from an 'S' lay vessel, it is possible to lay 20km of pipe in 11 days compared with the 45 days of its pipe-in-pipe counterpart.

An important step in the manufacture of the new pipeline system is the application of the polypropylene protective wrap. This is carried out as a continuous process, where the wrap is overlapped to provide a three-ply coating. The infrared system comprises five modules, with a total of 24 QRC short-wave emitters delivering a total power of 50.4kW. The first module is used to provide the rapid activation of the adhesive on the wrap, while the second module heats the top of the wrap to maintain flexibility.

The third module provides additional heat before the wrap is brought into contact with the insulation and the final two modules apply heat to the insulation as it is rotated to ensure that hot adhesive is not applied to a cold surface. Precise temperature control is provided by optical pyrometers for modules one, three and five. The QRC emitters used in this application provide high-energy short-wave radiation rapidly and responsively. They feature a quartz reflective coating with a special nano and micro structure, which provides the reflector with very high diffusion characteristics to ensure the stability of process parameters, such as temperature and coating homogeneity.

Dave Robinson, adhesives consultant at Barrier, said: 'The high power and the response of the infrared emitters are vital to the curing process. 'The Heraeus units are capable of bringing the adhesive very rapidly to its working temperature and, just as importantly, they can switch off very quickly so that there is no damage to the wrap material,' he added. Heraeus specialises in the production and application of energy sources covering the electromagnetic spectrum, from ultraviolet to infrared.


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