Commercial Gas Pipework Design

Why commercial gas pipework design matters

Poorly designed pipework can leave appliances starved of pressure at peak demand, even when the meter and overall supply are perfectly adequate. Good commercial gas pipework design accounts for the demand of every appliance on the system, the length and layout of pipe runs, and the pressure drop that occurs along the way, so that every appliance receives gas at the pressure it needs to operate safely and efficiently.

Gas pipe sizing fundamentals

Gas pipe sizing balances pipe diameter against length and total demand: a longer run or higher demand generally needs a larger diameter to keep pressure loss acceptable, while short runs serving modest demand can often use smaller pipe without issue. Sizing calculations follow the methodology set out in IGEM/UP/2 for larger and more complex installations, with BS 6891 providing guidance for lower pressure installations more typical of smaller commercial premises.

Getting this balance wrong in either direction has consequences — undersized pipe causes pressure problems at appliances, while oversized pipe adds unnecessary cost and can, in some cases, affect gas velocity and the behaviour of the system.

Understanding pressure loss along a run

Pressure loss occurs as gas flows along pipework due to friction against the pipe wall, and increases with flow rate, pipe length, and the number of bends, tees and fittings along the route. Good design minimises unnecessary fittings and routes pipework as directly as practical, while still accounting for the pressure loss that unavoidable fittings and longer runs will introduce.

On larger commercial installations with multiple branches serving different areas, pressure loss needs to be calculated for each branch individually, since the appliance furthest from the meter or with the most restrictive route is often the one most at risk of insufficient pressure.

Material selection and installation method

Pipe material — commonly steel, copper, or in some applications corrugated stainless steel tubing — affects both pressure loss characteristics and suitability for different environments. Material choice also interacts with how the pipework is installed, supported, and protected, particularly where it passes through walls, floors, or areas with higher risk of mechanical damage.

Planning for future demand

Good commercial gas pipework design often considers reasonably foreseeable future demand, not just the appliances installed on day one. Designing with some allowance for additional equipment can avoid costly pipework upgrades later, though this needs to be balanced sensibly against the cost of oversizing for demand that may never materialise.

Getting your pipework designed properly

Whether you're planning a new installation, adding appliances to an existing system, or investigating a pressure problem at an appliance, our engineers can calculate demand, size pipework correctly, and design a layout that performs reliably. Call 0208 935 5572 to discuss your project.

Diversity and simultaneous demand

Not every appliance on a commercial system fires at exactly the same moment, and pipework design sometimes applies a diversity factor to reflect realistic simultaneous demand rather than assuming every appliance runs flat out together. This needs to be done carefully and conservatively, since underestimating simultaneous demand to save on pipe diameter can leave a system undersized in practice, particularly in catering environments where several appliances commonly do fire together at service times.

Working with other trades on site

On larger projects, gas pipework design needs to be coordinated with other building services such as ventilation, electrical containment, and structural elements, since pipe routes often compete for the same ceiling voids or risers. Early coordination avoids clashes being discovered on site, which can cause delays and costly re-routing partway through installation.