A branch of Al Mojel Trading and Contracting Company, Riyadh-based Saudi Perlite Industries produces a vital material used in the cryogenic gas manufacturing sector.

With a factory in Riyadh Industrial Area, where the company operates two production lines, and another in Jeddah Industrial Zone, Saudi Perlite can produce 120,000 cu m of high quality expanded perlite under the trade name Cryolite Perlite insulation. This material has found wide acceptance in the insulation of cryogenic and low temperature storage tanks, cold boxes and in shipping containers.

Cryolite has been applied in several petrochemical plants in both Saudi Arabia and neighbouring states. In the Kingdom, Cryolite has been supplied to major companies including Saudi Aramco, Yanpet, Petrokemya, Kemya, National Industrial Gases Company (Gas).

Cryolite is a trusted product used by international contractors including Chiyoda Petrostar and Mitsubishi Heavy Industries of Japan and Germany's Linde.

Perlite is a generic term for naturally-occurring siliceous volcanic rock. The distinguishing feature which sets perlite apart from other volcanic glasses is that when heated to a suitable point in its softening range, it expands by four to twenty times its original volume.

This expansion is due to the presence of two to six per cent combined water in the crude perlite rock. When quickly heated to more than 1600F (870C), the crude rock pops in a manner similar to popcorn as the combined water vapourises and creates countless tiny bubbles in the heat softened glassy particles. It is these tiny glass-sealed bubbles which account for the excellent insulating properties and light weight of expanded perlite cryolite.

Expanded perlite can be manufactured to weigh from 32 kg/cu m to 240 kg/cu m, making it especially suitable for use in insulating applications. Cryolite perlite is used in the manufacture of cryogenic, low temperature and high temperature insulation.

Perlite insulation suitable for nonevacuated cryogenic or low temperature use exhibits low thermal conductivity throughout a range of densities. However, the normal recommended density range is 48 to 72 kg/cu m. Along with its excellent thermal properties, it is easy to handle and install, noncombustible and meets fire regulations, lowers insurance rates, does not shrink, swell warp or slump. Because it is inorganic, it is rot and vermin proof, and as a result of its closed cell structure, the material does not retain moisture.

There are many different design concepts for low temperature and cryogenic storage vessels. However, most are of double wall construction with the annulus filled with expanded perlite cryolite.

Packaged or bulk perlite may be used to insulate smaller vessels by pouring or blowing the insulation in place. Portable perlite expansion plants are usually used to insulate storage tanks, cold boxes, ships and other double wall vessels and pipes. In these applications, perlite ore is expanded on-site and the expanded perlite insulation is conveyed pneumatically into the annulus.