Engineering services Engineering expertise to meet the highest nuclear codes and standards

Safe, efficient removal of detrimental liquids and gases

Drain traps designed, manufactured and supplied by Rolls-Royce perform two vital safety and plant integrity functions: to enable liquid to be drained from a gas process system through a technique such as liquid purge; and to remove trapped gases from a liquid process system, for example by gas release.

Liquid purge drain traps are used to remove condensate from air receivers and to extract moisture from process systems to reduce corrosion and maintain a fixed level of liquid in process tanks. Rolls-Royce designs feature metal-to-metal seats for maximum durability.

Gas release drain traps operate in liquid systems in which pressurised gas is detrimental to the operation of process components or where it could prove a danger, such as posing the risk of explosion. They are also used to bleed evolved gas from process vessels and release trapped air from a process system at start-up. Most of those used in gas service feature soft elastomer seats to minimise gas loss.

Both designs use a needle valve actuated by a float mechanism. In gas drain traps the buoyancy of the float closes the needle valve, while in liquid purge drain traps the float opens the valve.

Safety-critical systems to combat ignition risks

Proven Rolls-Royce technology provides nuclear customers with dependable high-pressure rated flame arrestors that prevent the propagation of flame fronts in process piping. When a flame occurs, the flame arrestor rapidly removes enough heat from the travelling flame front to ensure safe and complete quenching of the ignition mix.

Rolls-Royce flame arrestors feature monolithic construction utilising a large thermal mass and a high coefficient of heat transfer. Flame arrestors are typically installed upstream and downstream of possible ignition sources in piping systems containing flammable gases.

Typical applications include:

  • Upstream and downstream of catalytic re-combiner systems
  • Exhaust systems that eject combustible gases to the atmosphere
  • Tritium recovery and removal systems
  • Hydrogen generators for fuel cells
  • Cover gas systems in reactors where radiolytic breakdown of water occurs, resulting in the production of hydrogen and oxygen.

Precision elements for pressure reduction and metering

Precision-engineered flow restriction elements designed and manufactured by Rolls-Royce provide nuclear facilities with reliable and efficient pressure-reduction and metering applications.

Rolls-Royce provides four designs of flow restriction elements: single-stage orifice plate, multi-stage orifice plate, venturi and nozzle, depending on the application and accuracy requirements.

Components used for pressure-reduction typically feature in bypass lines (to prevent pump dead-heading, for example) and in flow control and sampling systems. To ensure elements meet the needs of all these applications, they are manufactured in two configurations:

  • single-stage for lower pressure-drop requirements
  • multi-stage for higher pressure drops, to prevent cavitation.

Flow-rate measurement elements provide a robust and simple way to measure the flow in a range of process streams in a nuclear power plant.

Supporting capabilities:

  • Components supported by extensive pressure drop and recovery calculations
  • ASME code acceptability
  • Resistance to cavitation
  • Plate, venturi or nozzle styles
  • Calibration testing for higher-accuracy applications

Safe, accurate fluid sampling at atmospheric pressure

Pressure reducing coils, or PRCs, enable process fluids from high pressure process systems to be sampled. These units are designed to tap off a small amount of the process fluid and pass it through a long coil of narrow-bore tubing. In operation, high frictional losses caused by the coil’s narrow bore size reduce both the pressure and flow rate of the process fluid. To the point at which samples can be taken safely at atmospheric pressure and low flow rates.

In service PRCs deliver many advantages compared with other pressure reducing systems, which require the added complexity of O-rings, actuators, power connections and controls. Further benefits derive from the easy adaptability of PRCs to match the needs of different process fluids and operating conditions. Rolls-Royce can also supply PRCs as seismically qualified units and, if necessary, to meet any specific site requirements.

Prime benefits of PRCs include:

  • No moving parts
  • Robust
  • Safe and simple
  • No cavitation concerns
  • Fluid is cooled as it passes through the coil

Safe, Instant visual inspection capability

Sight glasses provide direct visual confirmation of the flow in pressurised piping and rapid examination of fluids for particulate content within nuclear process systems.

Typically sight glasses are used to monitor flow and quality in liquid or slurry systems. For example, a sight glass downstream of a solid media vessel enables monitoring for filter screen failure. While a sight glass in a sluicing line will verify resin transfer into exchange columns. This replaces expensive flow-measurement instrumentation when precise flow measurement is not needed.

Rolls-Royce sight glass configurations include:

  • Designs including paddle wheels to allow visual monitoring of clear fluid flow
  • Back-lit double-glass designs to allow detection of fine particulate matter
  • Leakage collection indicators, which are long-bodied sight glasses with large viewing windows and multiple tube inputs to enable leaks from any of the input line systems to be seen. This configuration is ideal for monitoring the interspace of double seals from a remote location to confirm instantly if a pump seal is leaking, without depending on expensive instrumentation

All Rolls-Royce sight glasses and leakage indicators are built to the defined pressure-boundary integrity of the process equipment.

Efficient removal of process contaminates

Y-strainers provide valuable protection from component damage or contamination in relatively clean process streams, by effectively filtering out light particulate. They contain a cylindrical mesh screen through which the fluid flow passes and any particulate larger than the screen mesh is trapped. Y-strainers can prove particularly beneficial immediately after start-up. This is when assembly of the system may have created weld burrs, fragments, dust particles etc that could damage pumps, filters or valves. This could require costly replacements and downtime.

Y-strainers from Rolls-Royce are compact and fit easily in-line. Their filter cartridges can be tailored to alter system pressure drop or to change acceptable screen size. Filter cartridges are designed to be changed easily without costly delays.

Benefits of Rolls-Royce Y-strainers include:

  • Tailored to meet strict leak-tightness requirements
  • The cartridge is positively sealed to the body by O-rings, ensuring better particle retention and a positive seal
  • Available in a broad variety of screen mesh sizes and pipe diameters
  • Available to suit any style of end connection (butt-weld, socket weld, flange etc)
  • Particulate trap baskets minimise further contamination and are easily removed for cleaning and reinsertion.