PIPES AND DUCTWORK
Another common problem with pipe support brackets is that the insulation is compressed. This places the copper and steel in closer contact, resulting in a likelihood of galvanic corrosion, along with loss of energy efficiency. That’s why pipes in refrigeration and air-
conditioning applications must always be isolated from their mounting element with an adequate closed-cell insulation thickness that considers the line temperature, pipe size, ambient temperature, relative humidity conditions as well as halogen and nitride content of the material (appropriate choice of insulation). It is also important to use pipe support
hanger brackets that do not compress the insulation and maintain the same thickness along the length of pipe. Within hot water systems there can be
significant heat loss as a result of un-insulated pipe support brackets or, again, where the material has been compressed, with the consequence being increased energy costs. The extent of this loss of energy can be
significant with thermal heat flow calculations for a 60°C hot water pipe in continual use showing a heat loss of 0.06w/k per bracket (on a 26.9mm diameter copper pipe with a 27mm insulation thickness). This can have a major impact on total energy costs of running a building especially where many supports are used. Conversely, installing closed-cell pre- insulated pipe support brackets that prevent
the crushing of insulation can avoid both galvanic corrosion and excessive energy loss. For example, when our ArmaFix Ecolight supports are used with the equivalent insulation tube thickness, the required insulation is maintained to provide an energy efficient system.
This improves the energy efficiency of both hot and cold pipework, with an annual energy saving of approximately £2.50 to £5 per bracket. This quickly adds up when you
consider that a pipework system in a large installation may incorporate hundreds of pipe supports. A reliable connection between the clamps
and an ArmaFlex insulation can only be achieved by sourcing a compatible pipe support from the same insulation manufacturer, because it ensures matching nominal wall thicknesses and system performance.
The answer We can see that pipe support brackets represent a potential weak spot in HVAC systems. If the pipe is not thermally isolated from the pipe bracket with an appropriate insulation material, thermal bridging causes condensation or heat loss and bimetallic corrosion, as does crushing of the insulation by the bracket hanger. Most heating professionals understand that the presence of different metals can result in galvanic corrosion. All metals react with their environment, although some are more reactive than others. Knowing this and factoring it in at design stage can avoid issues with the HVAC system. That’s why insulating both pipework and pipe support brackets with closed cell insulation plays an important role in maintaining system efficiency and integrity. An integrated approach, where the insulation materials are from a single source offers greater compatibility in terms of condensation control, fire behaviour, energy saving and ease of installation.
www.acr-news.com April 2020 37
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