Electrical Pre-heating — Resitherm

Electrical pre-heating provides a simple and rapid method of dry-process pipe pre-stressing.

Construction Cost Savings:

• minimises the need for conventional expansion compensation elements
• fewer welds, fittings, couplings and pipe supports
• fewer excavations and backfills (when replacing U-shaped expansion loops)
• reduced thermal expansion stress on branch connections
• lower pumping costs during operation

Electrical Pre-heating Procedure:

• arrival on site, site handover, health and safety briefing
• assembly of the pre-heating unit (Resitherm device, power generator, sensors)
• welding of connection studs to all pipe ends
• connection of heating cables to the pipeline
• marking the “zero” position of the pipeline prior to commencement of pre-heating
• commencement of pre-heating
• monitoring of thermal expansion and temperature throughout the heating process
• attainment of target temperature and thermal expansion; handover of the pipeline route for backfilling and compaction
• disconnection of the equipment upon completion of backfilling and compaction
• demobilisation, site clean-up, departure from site

The Electrical Pre-heating Technology Enables:

• thermal pre-heating in locations where no heating medium (hot water) is available
• pre-stressing of individual pipeline sections to different target temperatures, regardless of any available heating medium temperature
• pre-stressing of a single pipeline branch, e.g. a process pipeline, independently of the rest of the network
• flexible sequential pre-stressing of individual pipeline network sections in an order determined by construction progress
• a more cost-effective solution that is superior both structurally and operationally compared to installation methods using single-acting expansion compensators
• optimisation of heat distribution networks installed cold — an alternative to the use of U-shaped expansion loops
• sectional thermal pre-heating (progressive pre-stressing) during the construction of long-distance transmission pipelines
• installation of selected heat network sections requiring local thermal pre-heating, without the need to complete adjacent or connecting sections first
• restoration of pre-stress during any repair of heat network pipeline sections, regardless of the original installation method