Specialist thermal insulation manufacturer Armacell is launching what claims to be an industry first with a low density thermal elastomeric foam insulation product which retains flexibility even at extreme cryogenic temperatures of 200°C. Cryogenic processes which utilise such low temperatures and require technical thermal insulation materials include the freeze drying of foods, metal alloy production utilising liquid nitrogen, and the manufacture of some pharmaceutical and chemical products.

An area of growing significance is the freezing of large volumes of natural gas down to condensation temperatures (-162°C), with the resultant liquid gas then having a reduced volume of less than 0.17% of the gaseous product. The costs of both storage and transportation of natural gas in a liquid form (LNG) are therefore considerably reduced. Armacell high performance insulation systems maintain the cryotechnical validity of this process throughout, from initial production to final regasification where the gas is fed into pipework for eventual distribution to consumer markets.

Armacell have an established reputation for the supply of consistent, high-quality engineered foam materials. This includes-NBR (nitrile butadiene rubber) insulation products, suitable for refrigeration applications operating at temperatures down to -50°C. With the introduction of their cryogenic elastomeric insulation product range, known as Armaflex LTD, temperatures as low as -200°C can now be accommodated. This same product also has an upper temperature thermal limit of +125°C, which ensures that internal surfaces of pipework, tanks and vessels can be safely subject to steam or high temperature chemical cleaning without detriment to the insulation materials.

The Armaflex LTD cryogenic insulation materials utilise a completely new diene terpolymer where a much lower glass transition point has been achieved. This is the point (-50°C), where the mechanical behaviour of conventional NBR materials changes, with the rubber increasingly losing flexibility through hardening. However, the Armaflex LTD products maintain full strength and flexibility over the temperature range of -200°C to +125°C. This ensures that vibration and impacts can be absorbed, with the risk of cracking from extreme temperature cycling or mechanical strain considerably reduced. The closed cell material has a very low thermal conductivity and also a high resistance to water vapour transmission providing a ‘built-in’ vapour barrier. These characteristics reduce the risk of corrosion under insulation (CUI), providing significant savings on installation, while the cryogenic foams, unlike rigid foams, also eliminate the need for expansion joints or additional vapour barriers to achieve even further installation savings.

Where there is a requirement for sound attenuation, then Armacell’s ArmaSound insulation can also be incorporated as part of a multi-layer thermal - acoustic system to achieve a cost effective result. The innermost layer of the Armacell LTD insulation is fabricated with an outer reinforced-foil anti-abrasive layer. This provides added surface strength as well as enhanced protection from severe vibration and pipework movements.

Armaflex LTD products are supplied in pre-formed tubes of 2 metres in length. These provide a standard 25mm thick insulation cover available in ten standard pipework sizes from 18 to 114mm outside diameter. For tanks, vessels, pipework bends or junctions and intermediate valves etc, Armaflex LTD is also available in continuous sheets or covering rolls to provide tailored sizes to suit the specific installation requirements. Continuous rolls are 1 metre wide x 4 metres long, while covering rolls are available as a 25m2 sheet. For maximum effectiveness and protection against mechanical damage, it is recommended that all insulated pipework and equipment is fitted with a final outer layer of contoured stainless steel sheeting or Armacell’s Arma-Chek R cladding material.

The first major application of Armaflex LTD cryogenic insulation materials was for China’s prestigious LNG dock and terminal located in Nianyu Bay at the coast of Dalian City, Liaoning Province. Tankers up to a capacity of 200,000 m3 can be accommodated, and in the first phase completed at the end of 2011, 3 million tonnes of LNG are being converted into 4.2 billion m3 of natural gas annually. The Armacell high performance cryotechnical process has been successfully utilised on vaporisation pipes, pumps, valves and other fittings, to ensure that energy losses during the liquidation, storage and regasification processes are maintained at as low a level as possible.