Marine Hydraulic Oil

Castrol Transaqua DW

Castrol Transaqua DW Water-Based Subsea Production Control Fluid


Castrol Transaqua DW is a water-based hydraulic control fluid specifically formulated for use as the control medium in subsea production control systems. The fluid incorporates all the features required for operation throughout the control system including Sub Surface Safety Valves (SSSV) and intelligent well completions.

Castrol Transaqua DW has been developed and qualified under a Quality Management System with ISO 9001:1994 certification and an Environmental Management System with ISO 14001:1996 certification for Research and Development. Qualification testing was carried out in accordance with ISO 13628-6 Annex C (2006 E) and Petrobras specifications.

  • Designed for use in all conventional and high-pressure, high-temperature applications (according to API 17 TR8) and specially formulated to allow operation in deepwater or extremely long step-outs.
  • Can operate over a temperature range of -5ºC (23ºF) to 150ºC (356ºF).
  • Suitable for use within Electro-Hydraulic Multiplex (EH-Mux) or direct hydraulic control systems.
  • Designed for use throughout the entire production and workover control systems, covering Topsides and Subsea applications: both open water and wellbore; and Downhole from the control of a single SSSV through to complex intelligent well completions.

Castrol Transaqua HT2-N Water-Based Subsea Production Control Fluid Product Advantages:

  • Tested according to OSPAR requirements. Rigorous environmental testing has also been completed in many geographies worldwide, including Gulf of Mexico and Brazil.
  • Has a similar formulation to the field-proven Castrol Transaqua™ HT.
  • Has a density balanced to that of seawater to reduce the effects of hydrostatic head, when operating subsea.
  • Contains a fluorescent leak tracer to allow rapid detection of subsea leaks either visually or using a dedicated ROV mountable leak detection sensor.
  • Maintains corrosion performance with seawater contamination.
  • Tolerant of the high well temperatures encountered by those parts of the control system located at the well bore.
  • Fully compatible and miscible in all proportions with other products in the Castrol Transaqua range and most other water-based subsea control fluids.
  • Compatible with a wide range of materials commonly used in subsea control systems (see Tables 3 & 4). More detailed compatibility information is available on request.


Density @40C: 1.0229 g/ml

Density @60C: 0.9962 g/ml

Viscosity @40C: 1.24 mm2/s

Viscosity @ 100C: 0.47 mm2/s

Metals to be avoided
The following metals are best avoided with all glycol water-based fluids: Aluminium, Cadmium, Magnesium and Zinc. For coasting compatibility date please contact Castrol Offshore.

Seal Materials to be Avoided
Rubber Impregnated Fabric Composites are not compatible with Castrol Transaqua DW. These materials must be changed out from equipment to be used with Castrol Transaqua HT2-N.

Painted and other Surface Coatings
It is recommended that in accordance with good working practice the internal surface of the hydraulic system should not be coated. However, external surfaces may require coating and as with all control fluids conventional paint systems will tend to soften or strip. It is therefore recommended that these be replaced by cured epoxy, nylon, or phenolic types as commonly used subsea. Surface preparation prior to paint application is critical.

Where it is necessary to use internal surface coatings such as PTFE these should be assessed for suitability of use. Manufacturers’ guidelines should be observed concerning cure times and temperatures and as with paint systems surface preparation specifications should be adhered to.



Care and Handling:

This product has been manufactured to a tightly controlled cleanliness specification. Any container that has been opened for use must be re-sealed to avoid contamination ingress from the environment (eg particulates or water). Any contaminants entering the product can affect its performance. The integrity of the product once the container is opened is the responsibility of the end user. It is good practice to use tarpaulins or drum lids to cover all containers to prevent ingress of contamination.

As with all glycol-based control fluids, CastroI Transaqua DW must never be mixed with control fluids of different base types such as synthetic fluids (e.g. Castrol Brayco Micronic SV/3) or mineral oils (such as the Castrol Hyspin range). Contamination of Castrol Transaqua DW by either of these types of products can seriously affect the product performance.

If you need advice on any of the above, please contact your local Castrol Technical Service Engineer for more specific details.


All containers should be stored under cover and protected from exposure to direct sunlight. Do not store containers in temperatures below minus 5ºC or above 45°C. 208L plastic drums can be stored a maximum of 2 high, providing a pallet is used to distribute the upper load evenly. In addition, the fill level of the upper drums should be less than or equal to the fill level of the lower drums. It is not recommended to store 208L plastic drums horizontally.

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Product Data Sheet

Material Safety Data Sheet


Castrol Transaqua HT2-N Lubricant Oil

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