InduSeal® for repair of district heating pipes

The problem

Older district heating pipes develop leaks in the weld seam, or the wall corrodes locally. A conventional repair replaces a pipe section and requires a long excavation. In cities and on transmission lines, digging and shutdown are often the expensive part of the job.

Service life

InduSeal can extend the service life of the district heating pipe by more than 30 years. A plate of suitable wall thickness is laid over the leaking weld seam or the damage. Even with concentrated corrosion between pipe and plate, InduSeal maintains a thickness equal to or greater than the wall of the original pipe when corrosion proceeds at a normal rate. The overall service life of the line can thus be maintained at the level assessed at the time of repair.

The solution

The plate is in pressure vessel steel P355GH / 1.0473 to EN 10028-2 and has a higher yield strength than a normal district heating pipe, so it does not change the structural behaviour of the line. The wall thickness is greater than the original pipe, and the fillet weld can transfer 100 % of the pipe's axial forces. InduSeal is designed in accordance with EN 13941 and EN 13480.

Excavation and economics

Instead of digging up the whole line, holes of 2×2 to 5×5 metres per 16 metres can be enough. That limits both the excavation work and the disruption around the route and suits cities and sensitive areas. An economic comparison with replacement of long pipe sections shows that the repair cost can be reduced by over 50 %, because less labour, fewer materials and less time are used. The plate can be included in the joint renovation programme you are running anyway, also preventively on the stretches where most leaks have been recorded.

• 2×2 to 5×5 metres per 16 metres instead of the whole route
• Over 50 % lower repair cost than replacing long sections
• Can be combined with joint renovation, also preventively

Installation in operation

InduSeal can be installed while the district heating pipe is in operation. That requires the correct welding procedure specification (WPS) for welding on water-filled and pressurised pipe. The utility then avoids the downtime. The line can remain in operation during installation when that WPS is used.

• Installation on water-filled and pressurised pipe when the WPS allows it
• State diameter, wall thickness, operating pressure and temperature
• Certificate for the plate is agreed when the steel is ordered

Where it is used

InduSeal is used as a standard repair method at one of Denmark's largest district heating transmission companies. The company extends the service life of older lines without extensive excavation. The result is better integrity on the lines and fewer costly shutdowns. The method extends the life of the pipes already in the ground and reduces the need for new materials and earthworks.

Enquiry

State company, contact, pipe dimensions, type of damage, quantity and where the line is located. Upload a drawing or photo if you have one. The enquiry is given the category InduSeal at INDUSTRISTÅL A/S, so it can be followed from first contact to quotation.