Modern Building Services

24 MODERN BUILDING SERVICES SEPTEMBER 2022 FEATURE INSTALLER’S VIEW D uring site visits, Alan has encountered a number of problems with M&E installations, and these are the most common installation issues he has come across. 1. Expanding pipework incorrectly supported Thermal expansion and contraction of pipework are one of the largest dynamic forces acting upon piped services. If it is overlooked, or pipes are incorrectly anchored into place, the consequences can be extremely destructive. The forces created by thermal expansion can be large enough to cause pipe bowing, buckling, damage pumps and valves, and even fracture the pipe or damage the structure of the building. What causes thermal expansion? Temperature changes cause an object or substance to change shape, area, or volume. Pipes will generally expand when heated, and contract when cooled. This is caused by the molecular structure expanding due to the increased kinetic energy at a higher temperature – causing the molecules to move around more. The rate of thermal expansion usually depends on three key factors: • The pipe material • The length of the pipe • The minimum and maximum temperature Plastic pipe types usually expand significantly more than metal pipes. For example, a 50m PE pipe with a +50° temperature differential will expand by 500mm whereas a steel pipe will only expand by around 30mm. Designing pipe systems for expanding pipework It is important that pipe supports to deal with expanding pipework are addressed at the design stage of a project to avoid significant problems occurring. There are usually two ways to deal with expansion: • Using natural pipe bends or expansion loops • Using expansion joints, for example, bellows Designing systems with expansion joints can be complex, and this is where we have often seen issues on site with the supports used alongside the expansion joint. “One of the most common issues we see is that expansion bellows are installed without appropriate anchor points throughout the system. A combination of fixed anchor points, pipe guides, and/or expansion devices are required alongside the bellows, in specific locations throughout the pipe system, to ensure it works effectively. Otherwise, the bellows can buckle as in this example.” “Alan Sharman , has been Technical Adviser at Walraven for five years. During this time he has visited construction sites to provide technical advice and solution recommendations to contractors”. 4 common installation problems we see on site