Pipe in pipe applications – which type of spacer or spider do you need?

FT Pipeline Systems has, over the years, become synonymous with supplying quality products to the pipeline industry. In recent years they have increased their knowledge in all the different types of pipe spacers that facilitate contractors when it comes to pipe in pipe applications.

FTPS offers a choice of spacers that accommodates large diameter, heavy-weight metallic pipework through to smaller plastic carrier pipes, and include in their range the ability to provide bundled solutions, or cluster spacers, as they are known. All options can be utilised on the majority of requirements, but a combination of commercial and technical considerations need to be taken into account so as to come up with the best solution for the job.

Heavy weight solutions

Starting with the heavy stuff – large diameter steel or DI mains require heavy duty solutions. Included in this part of the range are stainless steel or FBE coated carbon steel half-moon spacers. These are two-piece products that come with either a skid or a roller and can accommodate the carrier pipe in either the invert position or as centre-restrained to combat flotation.

HDXT spacers going on a large diameter plastic waste water main

The roller option is certainly the top of the range, with Apogee wheels which prevent rotation of the pipe during the installation phase and remove considerable amounts of energy from the process. The reinforced glass fibre wheels make for a surprisingly easy installation. We have demonstrated a tonne of steel pipe being pushed inside another pipe, by hand, using FT Pipeline Systems roller spacers.

Another option for larger diameters is the KwikZip HDXT solution, which has the added option of using reinforcement in the risers.

Medium and light weight

This is the most competitive area of the product range with three options being viable. These include the roller and skid half-moon products and the HDXT, but also the HDX and HD ranges, as well as another supply chain option – the KMS and KAS solutions. The ranges are basically a choice of skid solutions and FTPS will happily provide you with suitable options. The products all provide a range of riser height which allows relative clearance from the bottom of the tunnel pipe and an even spread of the load. The minimum height is 20mm, through to 125mm and all pipe materials can be accommodated and up to 2000kg static load.

A KMS spacer with 36mm riser height installed on a steel main

The pipe material, weight per metre, diameter and length of the tunnel all come into play. We liken the options to types of cheese – there are many varieties, expensive specialist Cheddar Gorge, middle of the road Cathedral City and the supermarket’s own brand. There’s something for everyone!

Smaller is still possible

The “bow” range allows applications on the smallest of requirements

The range of spacers doesn’t end there, and the smaller annulus can be accommodated with the HD range which covers pipework up to 355mm with between 10mm and 40mm non-corroding, non-metallic heavy duty bow spring casing spacers. The 155 and 380 series, able to be installed on pipework from 2” diameter, provide between 20mm and 50mm bow height. The range is rounded off with the GT series – known as the “bow” series – which is suitable for rock bolts, soil nails, anchors, drop pipes and cameras.

So, which type of spacer do I need?

With such a range of products available, it’s easy to be daunted by the choice. The easiest route to the solution is to provide them with the basic information and let a company such as FT Pipeline Systems guide you through the process:

  • Tunnel ID and material
  • Carrier OD and material
  • Weight per metre
  • Length of the tunnel
  • Grouted or not

For more information please email enquiries@ftpipelinesystems.co.uk.



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