The pipe wall, manufactured on the TOPFIBRA EFW Machine consists of several layers. Starting from the inner side they are:
Liner
a) Internal Liner
It is the layer which is directly in contact with the internal fluid. It is rich in resin (approx. 90% by weight) and reinforced with a “surfacing veil” made of the “C” glass (chemical resistant very light fiberglass mat) or a polyester veil.
The thickness is approximately 0.2 mm for 1 surfacing veil, but it can be doubled.
NOTE: For the characteristics and specifications of the resin and of all the fiberglass reinforcements, please see the relevant chapters in the Raw Materials Handbook.
b) Anti-diffusion barrier
It is part of the internal liner, is resin rich (approx. 70% by weight) and is reinforced with chopped roving of the “E” glass. Its function is to stop the propagation of the micro-cracks from the mechanical layer (inner skin) to the internal liner.
The thickness of the diffusion barrier can be from 0.8 mm to 2 mm or more, depending on the Project Specification. The standard thickness is 0.8 mm.
Inner Skin
It forms the mechanical resistant layer together with the core and the outer skin.
It is reinforced with a high strength hoop wound fiberglass roving (50÷60% by weight), and chopped roving (10÷20% by weight). The resin content is 25÷30% by weight.
Mortar Core
Mortar core serves to increase the thickness and the stiffness of the pipe without using a lot of valuable raw materials. The main constituent of the Mortar Core is silica sand, with a few hoop and chop roving, which is as low in resin as possible.
The TOPFIBRA pipes can also be manufactured without the mortar core, when a very high pressure is required or for special Client Specification requirements. In this case, the Inner and Outer Skins are a unique layer. The Pipe Design program allows the selection of this option, or selects it automatically when designing a high pressure pipe with low stiffness requirement, or if the mortar core is too thin.
Outer Skin
Same as the Inner Skin. Generally, it has the same thickness as the Inner Skin, but it can be different.
Outer Liner
The outer liner can be simply made of pure resin, but can be also reinforced with a surfacing veil in order to increase the finishing and the chemical resistance to the environment.