The purpose of Phenolic blocks is to isolate the pipe clamp from the pipework.  This will limit heat transfer and thermal bridging, so in simple terms, it creates a barrier between the pipe and the clip.  They are load-bearing insulation rings for steel, copper, and PVC pipes.

Features of Phenolic Blocks

• • ◼️ Come wrapped in a foil covering which provides an effective vapour barrier.
  • ◼️ All blocks bigger than 50NB have a metal spreader plate – which distributes the load throughout the block
  • ◼️ Made from a high-density Phenolic foam
  • ◼️ They can withstand temperatures from -50°C – +110°C
  • ◼️ All blocks have a bore coating to ensure the copper pipes don’t corrode.
  • ◼️ All the blocks are BS 5970
  • ◼️ They are CE-marked which means the manufacturer has checked that these products meet EU safety, health and environmental requirements.

Phenolic blocks come in various sizes ranging from ½“ NB – 6” NB which in metric terms is 15mm – 159mm OD.  The thicknesses available are 15mm, 20mm, 25mm, 30mm, 40mm, and 50mm.  To explain, NB (Nominal Bore) is the inside pipe diameter and OD is the outside pipe diameter.

Lastly, unlined pipe clamps or split band clips can secure the blocks around the pipes.  To work out the required pipe clamp, find the NB or OD of the pipe (make sure to specify which size you are using when you order the phenolics).  Next, add 2 times the thickness of the block, so if the block is a 25mm thick block you add 50mm to the size of the pipe to get your pipe clip size.  So if the pipe is 28mm and the block is a 25mm thick block you add 50mm block thickness to the 28mm pipe thickness meaning you need a 78mm pipe clip.

For any more information see our detailed blog here.

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